The family structures that were very common a century ago are not nearly as common today. In the US around the year 1900 most families had 3 generations living in one home (e.g., children, parents, and uncle/aunt/grandparent) and most did manual labor. Today, very few families live with multiple generations. Most modern families fall into one of two types: nuclear, or blended. The Nuclear Family is a family group consisting of mother & father and their children. This is the family type that is mostly preferred. One variation of this type is the single-parent family, which can be created by unwed motherhood, divorce, or death of a spouse. The second most common form is the Blended Family, which is the family created by remarriage including step-siblings and parents. Finally, all of the family relations you have past your nuclear or blended family we call Extended Family, which are one's relatives beyond nuclear and blended family levels (i.e. cousins, aunts & uncles, grand and great grandparents).
The US Census Bureau conducts annual surveys of the US population and publishes them as the Current Population Surveys. Table \(\PageIndex{1}\) represents the US family Types as of October 1, 2008. You will notice that marrieds comprise the largest proportion of family types in 2008.  Next is divorced, widowed, then separated (see Table UC1. Opposite Sex Unmarried Couples by Labor Force Status of Both Partners: 2008 retrieved 30 March 2009 from www.census.gov/population/www...m/cps2008.html).
Table \(\PageIndex{1}\): US Family Types, 2008
Types
Numbers
Percentages
Married
123,671,000
52%
Widowed
14,314,000
6%
Divorced
23,346,000
10%
Separated
5,183,000
2%
Never Married - Single
71,479,000
30%
Total Families 15 and over
237,993,000
100%
Look at Figure \(\PageIndex{1}\) below to see the US trend of actual numbers in millions of family types. It shows that the single largest type of family in the US has always been marrieds then never marrieds. The divorced overtook widowed category in the 1970s and has been higher ever since. Why are the trends upward? Simply put, these are numbers and not rates nor percentages. The population has grown and therefore the population size has been steadily increasing.
What are the functions of families? In studying the family, Functional Theorists (See Chapter 3) have identified some common and nearly universal family functions. That means almost all families in all countries around the world have at least some of these functions in common. Table 2 shows many of the global functions of the family.
Table \(\PageIndex{2}\): Global Functions of the Family
Functions
1. Economic support - food, clothing, shelter, etc.
2. Emotional support - intimacy, companionship, belonging, etc.
3. Socialization of child - raising children, parenting
4. Control of sexuality - defines and controls when and with whom (e.g, marriage)
5. Control of reproduction - the types of relationships where children should/could be born
6. Ascribed status - contexts of race, SES, religion, kinship, etc.
Economic Support
By far, economic support is the most common function of today's families. When your parents let you raid their pantry, wash clothes in their laundry, or replenish your checking account, that's economic support. For another young adult, say in New Guinea, if she captures a wild animal and cooks it on an open fire, that's also economic support in a different cultural context. I've always been amazed at how far family economic cooperation extends. Some families cooperate in business-like relationships. In Quebec, Montreal there is an established pattern of Italian immigrants who help family and friends emigrate from Italy to Canada. They subsidize each other's travel costs, help each other find employment once in Canada, and even privately fund some mortgages for one another. Each participant is expected to support others in the same manner. To partake in this form of economic cooperation is to assume a very business-like relationship.
Emotional Support
Emotional relationships are also very common, but you must understand there is a tremendous amount of cultural diversity in how intimacy is experienced in various families around the world. Intimacy is the social, emotional, spiritual, intellectual, and physical trust that is mutually shared between family members. Family members share confidences, advice, trust, secrets, and ongoing mutual concern. Many family scientists believe that intimacy in family relationships functions as a strong buffer to the ongoing stresses experienced by family members outside of the home.
Socialization
Socialization of children is covered in more detail in a Chapter Four. For now, keep in mind that children are born with the potential to be raised as humans. They will realize this potential if older family members or friends take the time to protect and nurture them into their cultural and societal roles. Today the family is the core of primary socialization. But many other societal institutions contribute to the process including schools, religion, workplace, and media.
Sexuality and Reproduction Control
The family has traditionally asserted control of sexuality and reproduction. A few centuries ago the father and mother even selected the spouses for many of their children (they still do in many countries). Today, U.S. parents want their adult children to select their own spouses. Older family members tend to encourage pregnancy and childbirth only in marriage or a long-term relationship. Unwed mothers are mothers who are not legally married at the time of the child's birth. Being unwed brings up concerns of economic, emotional, social, and other forms of support for the mother that may or may not be present from the father. Many fathers reject their fatherly obligations in the case of unwed mothers.
When an unwed mother delivers the baby, it is often the older female family members who end up providing the functions of support for that child rather than the birth father. Table \(\PageIndex{3}\) shows the unwed mother births for the US in 2000 and 2006. Most of the 4,266,000 live US births in 2006 were to married mothers. But about 1/10 of teen mothers and 38 percent of all mothers were unwed (retrieved 30 March 2009 from www.census.gov/compendia/stat...es/09s0077.pdf). This trend of increasing unwed birth rates suggests that more and more families have less control by sanctioning childbirth within marriage. On the other side of the coin, many of these unwed mothers marry the child's fathers and many of those marriages eventually end in divorce.
Table \(\PageIndex{3}\): Percentage of All Births that were to Unwed Teens and Mothers of All Ages Years 2000 and 2006
Year
Births to Unwed Teens
Births to All Unwed Mothers
2000
11.8%
33.2%
2006
10.4%
35.8%
Taken from Statistical Abstracts of the US on 30 March 2009 from Table 87. Births to Teenage Mothers and Unmarried Women and Births With Low Birth Weight-States and Island Areas: 2000 to 2006 www.census.gov/compendia/stat...es/09s0087.pdf
Ascribed Status
Finally, ascribed status is there at birth. With your friends, have you noticed that one or two tend to be informally in charge of the details? You might be the one who calls everyone and makes reservations or buys the tickets for the others. If so, you would have the informal role of “organizer.” Status is a socially defined position, or what you do in a role. There are three types of status considerations: Ascribed Status is present at birth (race, sex, or class), Achieved Status is attained through one's choices and efforts (college student, movie star, teacher, or athlete), and Master Status is a status which stands out above our other statuses and which distracts others from seeing who we really are.
You were born into your racial, cultural-ethnic, religious and economic statuses. That shaped to some degree the way you grew up and were socialized. By far in our modern societies, achieved status (which comes as a result of your own efforts) is more important than ascribed (which you're born with) for most members of society. Although the degree of achievement you attain often depends heavily on the level of support families give to you.
Another consideration about groups and our roles in them is the fact that one single role can place a rather heavy burden on you (e.g., student). Role strain is the burden one feels within any given role. And when one role comes into direct conflict with another or other roles you might experience role conflict. Role conflict is the conflict and burdens one feels when the expectations of one role compete with the expectations of another role.
Groups
The first and most important unit of measure in sociology is the group, which is a set of two or more people who share common identity, interact regularly, and have shared expectations (roles), and function in their mutually agreed upon roles. Most people use the word “group” differently from the sociological use. They say group even if the cluster of people they are referring to don't even know each other (like 6 people standing at the same bus stop). Sociologists use “aggregate,” which is a number of people in the same place at the same time. So, people in the same movie theater, people at the same bus stop, and even people at a university football game are considered aggregates rather than groups. Sociologists also discuss categories. A category is a number of people who share common characteristics. Brown-eyed people, people who wear hats, and people who vote independent are categories-they don't necessarily share the same space, nor do they have shared expectations. In this text we mostly discuss trends and patterns in family groups and in large categories of family types.
Family groups are crucial to society and are what most of you will form in your own adult lives. Groups come in varying sizes: dyads, which are groups of two people and triads, which are groups of three people. The number of people in a group plays an important structural role in the nature of the group's functioning. Dyads are the simplest groups because 2 people have only 1 relationship between them. Triads have three relationships. A group of 4 has 6 relationships, 5 has 10, 6 has 15, 7 has 21, and one of my students from Brazil has 10 brothers and sisters and she counts 91 relationships just in her immediate family (not counting the brothers and sisters in law). When triads form it looks much like a triangle and these typically take much more energy than dyads. A newly married couple experience great freedoms and opportunities to nurture their marital relationship. A triad forms when their first child is born.  As Bill Cosby said in his book Fatherhood, “Children by their very nature are designed to ruin your marriage” (1987, Doubleday Publisher, NY).
As sociologists further study the nature of the group's relationships they realize that there are two broad types of groups: primary groups, which tend to be smaller, less formal, and more intimate (families and friends), and secondary groups, which tend to be larger, more formal, and much less personal (you and your doctor, mechanic, or accountant). Look at the diagram below in Figure \(\PageIndex{2}\). Typically with your primary groups, say with your family, you can be much more spontaneous and informal. On Friday night you can hang out wherever you want, change your plans as you want, and experience fun as much as you want. Contrast that to the relationship with your doctor. You have to call to get an appointment, wait if the doctor is behind, address him or her as “Doctor,” then once the diagnoses and co-pay are made you leave and have to make another formal appointment if you need another visit. Your Introduction to Sociology class is most likely large and secondary. Your family and friends tend to be few in numbers and primary in nature.
Family Systems Theory
One core definition that will help you in studying the family is that of Family Systems. Family Systems Theory claims that the family is understood best by conceptualizing it as a complex, dynamic, and changing collection of parts, subsystems and family members. Much like a mechanic would interface with the computer system of a broken down car to diagnose which systems are broken (transmission, electric, fuel, etc.) and repair it, a therapist or researcher would interact with family members to diagnose how and where the systems of the family are in need of repair or intervention. Family Systems Theory comes under the Functional Theory umbrella and shares the functional approach of considering the dysfunctions and functions of complex groups and organizations.
Sociological Imagination
The average person lives too narrow a life to get a clear and concise understanding of today's complex social world. Our daily lives are spent among friends and family, at work and at play, and watching TV and surfing the Internet. There is no way one person can grasp the big picture from their relatively isolated lives. There's just not enough time or capacity to be exposed to the complexities of a society of 310 million people. There are thousands of communities, millions of interpersonal interaction, billions of Internet information sources, and countless trends that transpire without many of us even knowing they exist. What can we do to make sense of it all?
Psychology gave us the understanding of self-esteem, economics gave us the understanding of supply and demand, and physics gave us the Einstein theory of E=MC2. When I learned of the sociological imagination by Mills, I realized that it gives us a framework for understanding our social world that far surpasses any common sense notion we might derive from our limited social experiences. C. Wright Mills (1916-1962), a contemporary sociologist, suggested that when we study the family we can gain valuable insight by approaching it at two core societal levels. He stated, “neither the life of an individual nor the history of a society can be understood without understanding both" (Mills, C. W. 1959. The Sociological Imagination page ii; Oxford U. Press). Mills identified “Troubles” (challenges on the personal level) and “Issues” (challenges on the larger social level) as key principles for wrapping our minds around many of the hidden social processes that transpire in an almost invisible manner in today's societies. Look at Figure 3 below to see a diagram of the Sociological Imagination and its two levels (personal and larger social).
Personal Troubles are private problems experienced within the character of the individual and the range of their immediate relation to others. Mills identified the fact that we function in our personal lives as actors and actresses who make choices about our friends, family, groups, work, school, and other issues within our control. We have a degree of influence in the outcome of matters within the personal level. A college student who parties 4 nights out of 7, who rarely attends class, and who never does his homework has a personal trouble that interferes with his odds of success in college. But, when 50 percent of all college students in the country never graduate we call it a larger social issue.
Larger Social Issues lie beyond one's personal control and the range of one's inner life. These pertain to society's organization and processes. To better understand larger social issues, let us define social facts. Social facts are social processes rooted in society rather than in the individual. Émile Durkheim (1858-1917, France) studied the “science of social facts” in an effort to identify social correlations and ultimately social laws designed to make sense of how modern societies worked given that they became increasingly diverse and complex (see Émile Durkheim, The Rules of the Sociological Method, (Edited by Steven Lukes; translated by W.D. Halls). New York: Free Press, 1982, pp. 50-59).
The national cost of a gallon of gas, the War in the Middle east, the repressed economy, the trend of having too few females in the 18-24 year old singles market, and the ever-increasing demand for plastic surgery are just a few of the social facts at play today. Social facts are typically outside of the control of average people. They occur in the complexities of modern society and impact us, but we rarely find a way to significantly impact them back. This is because, as Mills taught, we live much of our lives on the personal level and much of society happens at the larger social level. Without a knowledge of the larger social and personal levels of social experience, we live in what Mills called a false social conscious, which is an ignorance of social facts and the larger social picture.
A larger social issue is illustrated in the fact that nationwide, students come to college as freshmen ill-prepared to understand the rigors of college life. They haven't often been challenged enough in high school to make the necessary adjustments required to succeed as college students. Nationwide, the average teenager text messages, surfs the Net, plays video or online games, hangs out at the mall, watches TV and movies, spends hours each day with friends, and works at least part-time. Where and when would he or she get experience focusing attention on college studies and the rigors of self-discipline required to transition into college credits, a quarter or a semester, study, papers, projects, field trips, group work, or test taking.
In a survey conducted each year by the US Census Bureau, findings suggest that in 2006 the US has about 84 percent who've graduated high school ( http:// www.factfinder.uscensus.gov; see table R1501 at factfinder.census.gov/servlet...&-format=US-30). They also found that only 27 percent had a bachelors degree ( http:// www.factfinder.uscensus.gov; see table R1502 at factfinder.census.gov/servlet...G00_R1501_US30). Given the numbers of freshman students enrolling in college, the percentage with a bachelors degree should be closer to 50 percent.
The majority of college first year students drop out, because nationwide we have a deficit in the preparation and readiness of Freshmen attending college and a real disconnect in their ability to connect to college in such a way that they feel they belong to it. In fact college dropouts are an example of both a larger social issue and a personal trouble. Thousands of studies and millions of dollars have been spent on how to increase a freshman student's odds of success in college (graduating with a 4-year degree). There are millions and millions of dollars in grant monies awarded each year to help retain college students. Interestingly, almost all of the grants are targeted in such a way that a specific college can create a specific program to help each individual student stay in college and graduate.
The real power of the sociological imagination is found in how you and I learn to distinguish between the personal and social levels in our own lives. Once we do that we can make personal choices that serve us the best, given the larger social forces that we face. In 1991, I graduated with my Ph.D. and found myself in very competitive job market for University professor/researcher positions. With hundreds of my own job applications out there, I kept finishing second or third and was losing out to 10 year veteran professors who applied for entry level jobs. I looked carefully at the job market, my deep interest in teaching, the struggling economy, and my sense of urgency in obtaining a salary and benefits. I came to the decision to switch my job search focus from university research to college teaching positions. Again the competition was intense. On my 301st job application (that's not an exaggeration) I was interviewed and beat out 47 other candidates for my current position. In this case, knowing and seeing the larger social troubles that impacted my success or failure in finding a position was helpful. Because of the Sociological Imagination, I understood the larger social job market and was able to best situate myself within it to solve my personal trouble.
There are larger social trends that will be identified in the 16 chapters that follow this one. Some of them can teach you lessons to use in your own choices. Others simply provide a broad understanding of the context of the family in our complicated society.  They are not therapy, and they are not diagnostic. They are simply insightful and designed to help you understand better your personal family circumstances.
In this textbook you will find larger social evidences of many current United States family trends. Figure 4 shows these trends and where they will be discussed in this textbook. These changes were initiated in the Industrial Revolution where husbands were called upon to leave the cottage and venture into the factory as breadwinners. Women became homemakers and many eventually ended up in the labor force as well. The trend of having fewer children and having fewer of them die in or immediately after birth is directly related to medical technology and the value of having smaller families in our current service-based economy. The trend of lowering our standards of what exactly a “clean house” means is an adjustment that arguably needed to be made, because the post-World War II marketing campaigns convinced women that a spotless house was a good woman. Today, good women have varying levels of a clean house.
Table \(\PageIndex{4}\): Diagram of the United States' Larger Social Family Trends and Patterns in Recent Decades
Lower
Higher
Number of children per woman (Ch. 10)
Percent ever divorced (Ch. 12)
Infant mortality (Ch.15)
Complexity of remarried families (Ch. 3&13)
Standard of a "clean house"
Percent of elderly families (Ch. 14)
Average life expectancies (Ch. 14)
Quality of adoption process for children and families (Ch. 15)
Benefits from being married compared to other statuses (Ch. 9)
Number of cohabiters (Ch. 9)
Percent of women in labor force (Ch.4)
Bankruptcies (Ch. 11)
High Yet Declining
Intimate violence by spouse or partner (Ch. 16)
Divorce Rates (Ch. 12)
Cost of living and percent of income going to taxes (Ch. 11)
Abuse and neglect rates (Ch. 16)
Political efforts for and numbers of gay, lesbian, bisexual, and transgendered persons (Ch. 15)
STDs (except Chlamydia) (Ch 16)
Percent of births to unwed mothers (Ch. 10)
Percent of families in poverty(Ch. 11)
Median age at marriage (Ch. 9)
K-12 education completion rates (Ch. 11)
Numbers of professional mediators and therapists to aid in individual and family issues (Ch. 12)
Number of abortions (Ch.9)
Premarital sexual activity (Ch. 7)
Widowhood (Ch. 14)
Satisfaction and hope for family (Ch. 17)
Percent of US families that are Hispanic (Ch. 15)
Estimated cost to raise a child in US (Ch. 10)
Importance of family to modern society and its members (Ch. 1-17)
Of concern to many are the continuing high rates of divorce. I fully intend to present you with knowledge about what is happening and what you can do to prevent divorce and enhance the quality and satisfaction of your marriage. These other relatively high, yet declining rates will be discussed in further detail, also providing you with information about what you can do and what works. The higher categories include many trends. Some may comfort you while others may threaten or concern you. I urge you to study them, to listen to your professor, and to ask questions about the things in the study of the family that become important to you.
Simply studying something does not imply that you agree with it or support it for yourself or others any more than studying diseases in your basic health class means you have to go out and get one or support others in getting one. One of the many benefits of being a college student is that it expands and broadens your opinions. I found in my 8 years of college and university that my opinions became more entrenched and I was able to better understand my values and defend my own views. By keeping my mind open and my willingness to learn new things, I graduated a better person than when I started. I challenge you to keep your mind open. Trust that learning doesn't mean changing for the worse.
As mentioned above, the Industrial revolution changed societies and their families in an unprecedented way, such that Sociology as a discipline emerged as an answer to many of the new-found societal challenges. Societies had change in unprecedented ways and had formed a new collective of social complexities that the world had never witnessed before. Western Europe was transformed by the industrial revolution. culture . The Industrial Revolution transformed society at every level. Look at Table \(\PageIndex{5}\) below to see pre and post-Industrial Revolution social patterns and how different they were.
Table \(\PageIndex{5}\): Pre-Industrial and Post-Industrial Revolution Social Patterns
Pre-Industrial Revolution
Post-Industrial Revolution
Farm/Cottage
Factories
Family Work
Breadwinners/Homemakers
Small Towns
Large Cities
Large Families
Small Families
Homogamous Towns
Heterogamous Cities
Lower Standards of Living
Higher Standards of Living
People Died Younger
People Die Older
Prior to the Industrial Revolution, families lived on smaller farms and every able member of the family did work to support and sustain the family economy. Towns were small and very similar (homogamy) and families were large (more children=more workers). There was a lower standard of living and because of poor sanitation people died earlier. After the Industrial Revolution, farm work was replaced by factory work. Men left their homes and became breadwinners earning money to buy many of the goods that used to be made by hand at home (or bartered for by trading one's own homemade goods with another's). Women became the supervisors of home work. Much was still done by families to develop their own home goods while many women and children also went to the factories to work. Cities became larger and more diverse (heterogamy). Families became smaller (less farm work required fewer children). Eventually, standards of living increased and death rates declined.
It is important to note the value of women's work before and after the Industrial Revolution. Hard work was the norm and still is today for most women. Homemaking included much unpaid work. For example, my 93 year old Granny is an example of this. She worked hard her entire life both in a cotton factory and at home raising her children, grand-children, and at times great grand-children. When I was a boy, she taught me how to make lye soap by saving the fat from animals they ate. She'd take a metal bucket and poked holes in the bottom of it. Then she burned twigs and small branches until a pile of ashes built up in the bottom of the bucket. After that she filtered water from the well through the ashes and collected the lye water runoff in a can. She heated the animal fat and mixed it in the lye water from the can. When it cooled, it was cut up and used as lye soap. They'd also take that lye water runoff and soak dried white corn in it. The corn kernel shells would become loose and slip off after being soaked. They'd rinse this and use it for hominy. Or grind it up and make grits from it. We'll talk more about women and work in Chapter 4.
These pre and post-industrial changes impacted all of Western civilization because the Industrial Revolution hit all of these countries about the same way, Western Europe, United States, Canada, and later Japan and Australia. The Industrial Revolution brought some rather severe social conditions which included deplorable city living conditions, crowding, crime, extensive poverty, inadequate water and sewage, early death, frequent accidents, extreme pressures on families, and high illness rates. Today, sociology continues to rise to the call of finding solutions and answers to complex social problems, especially in the family.
Family Research
The American Sociological Association is the largest professional sociology organization in the world. There is a section of ASA members that focuses its studies specifically on the family. Here is an expert of their mission statement:
“Many of society's most pressing problems -- teenage childbearing, juvenile delinquency, substance abuse, domestic violence, child and elder abuse, divorce -- are related to or rooted in the family. The Section on Family was founded to provide a home for sociologists who are interested in exploring these issues in greater depth (retrieved 18 May, 2010 from www.asanet.org/sections/family.cfm).”
Many family sociologists also belong to the National Council on Family Relations (www.ncfr.org). Their mission statement reads as follows:
“The National Council on Family Relations (NCFR) provides an educational forum for family researchers, educators, and practitioners to share in the development and dissemination of knowledge about families and family relationships, establishes professional standards, and works to promote family well-being (retrieved 18 May, 2010 from ncfr.org/about/mission.asp).”
There are other family-related research organizations in the world, but these two rank among the largest and most prestigious organizations in the field of family studies. As with all of sociology and other social sciences, science and scientific rigor is paramount. It is not enough to simply study the family from our narrow personal points of view. We have to reach into the larger social picture and see the hidden social processes that teach us how to inform marriage and family therapy, provide useful and accurate data to governmental and policy-making figures, and provide reliable advice that will help the most people in the most efficient way.
This becomes a scientific endeavor then to study and examine the family with rules of scientific engagement and analysis. For those earning a Ph.D. in a family-related field, science is learned and executed with rigor. If the results of a study are made public and presented for critical review by other family scientists then scientific rigor is even stronger and more credibility can be afforded to those findings. For example, studies have shown that the leading factor of divorce is not any of the following: sex problems, failures to communicate, money mismanagement, nor even in-law troubles. What is the leading cause of divorce? Would you believe it is marrying too young? Specifically, if you marry at 17, 18, or 19 you are far more likely to divorce than if you wait to marry in your 20s. This was discovered and confirmed over decades of studying who divorced and which factors contributed more to divorce than others (See Chapter 12). The cool thing about knowing the risks of marrying as a teen is that you can choose to wait until you are older, more established in your sense of self, and more experienced in knowing your own likes and dislikes.
Family Culture
Another key point in studying the family is to understand that all families share some cultural traits in common, but all also have their own family culture uniqueness. Culture is the shared values, norms, symbols, language, objects, and way of life that is passed on from one generation to the next. Culture is what we learn from our parents, family, friends, peers, and schools. It is shared, not biologically determined. In other words, you are only born with drives, not culture. Most families in a society have similar family cultural traits. But, when you do marry you will learn that the success of your marriage is often based on how well you and your spouse merge your unique family cultures into a new version of a culture that is your own.
Yet, even though family cultures tend to be universal and desirable, we often judge other cultures as being “good, bad, or evil,” with our own culture typically being judged good. We have to consider our perspective when studying families from different cultures. Are we ethnocentric or cultural relativist?
Ethnocentrism is the tendency to judge others based on our own experiences. In this perspective, our culture is right, while cultures which differ from our own are wrong. I once visited a beautiful Catholic cathedral, Cathédrale St. Jean in Lyon, France. I fell in love with this beautiful and historic monument to the religious devotion of generations of builders. I learned that it took about 300 years to build, that England's King Henry the VIII married his Italian bride there, and that the a few families had 9 generations of builders working on it. I left with a deep sense of appreciation it all. On the bus back to our hotel, we met some American tourists who were angry about their vacation in France. The gentleman said, “these people will eat anything that crawls under the front porch, they never bathe, they dress funny, and they can't speak one *#&@ word of English!”
Another more valuable and helpful perspective about differing cultures is the perspective called Cultural Relativism, the tendency to look for the cultural context in which differences in cultures occur. If you've eaten a meal with your friend's family you have probably noticed a difference in subtle things like the food that is served and how it is prepared. You may have noticed that that family communicates in different ways from your own. You might also notice that their values of fun and relaxation also vary from your own. To dismiss your friend's family as being wrong because they aren't exactly like yours is being closed-minded. Cultural relativists like all the ice-cream flavors, if you will. They respect and appreciate cultural differences even if only from the spectators' point of view. They tend to be teachable, child-like, and open-minded. They tend to enjoy or learn to enjoy the many varieties of the human experience.
An ethnocentric thinks on the level of carrot soup, peel carrots, add water, and boil. The cultural relativist tends to think on the level of a complex stew, peel and prepare carrots, potatoes, onions, mushrooms, broth, tofu, and 10 secret herbs and spices and simmer for 2 hours. The diversity of the human experience is what makes it rich and flavorful.
Socialization
From the first moments of life, children begin a process of socialization wherein parents, family, and friends transmit the culture of the mainstream society and the family to the newborn. They assist in the child's development of his or her own social construction of reality, which is what people define as real because of their background assumptions and life experiences with others. An average US child's social construction of reality includes knowledge that he or she belongs, can depend on others to meet their needs, and has privileges and obligations that accompany membership in their family and community.  Most will leave home as young adults, find a spouse or life partner in their mid-to late 20s and work in a job for pay. To expect that of the average US Child is normal.
Also when discussing the average US child, it's safe to say that the most important socialization takes place early in life and in identifiable levels. Primary socialization typically begins at birth and moves forward until the beginning of the school years. Primary socialization includes all the ways the newborn is molded into a social being capable of interacting in and meeting the expectations of society. Most primary socialization is facilitated by the family, friends, day care, and to a certain degree various forms of media. Children watch about 3 hours per day of TV (by the time the average child attends kindergarten he has watched about 5,000 hours of TV). They also play video games, surf the Internet, play with friends, and read.
Around age 4-5 pre-school and kindergarten are presented as expectations for the children. Once they begin their schooling, they begin a different level of socialization. Secondary Socialization occurs in later childhood and adolescence when children go to school and come under the influence of non-family members. This level runs concurrently with primary socialization. Children realize at school that they are judged for their performance now and are no longer accepted unconditionally. In fact, to obtain approval from teachers and school employees, a tremendous amount of conformity is required-this is in contrast to having been accepted at home for being “mommy's little man or woman.”
As students children have to learn to belong and cooperate in large groups. They learn a new culture that extends beyond their narrow family culture and that has complexities and challenges that require effort on their part. This creates stressors for the children. By the time of graduation from high school the average US child has attended 15,000 hours of school away from home. They've also probably watched 15,000 hours of TV, and spent 5-10,000 playing (video games, friends, Internet, text messaging, etc.).
Friends, classmates, and peers become increasingly important in the lives of children in their secondary educational stage of socialization. Most 0-5 year-olds yearn for affection and approval from their parents and family members. By the time of pre-teen years, the desire for family diminishes and the yearning now becomes for friends and peers. Parents often lament the loss of influence over their children once the teen years arrive. Studies show that parents preserve at least some of their influence over their children by influencing their children's peers. Parents who host parties, excursions, and get-togethers find that their relationship with their children's friends keeps them better connected to their children. They learn that they can persuade their children at times through the peers.
The K-12 schooling years are brutal in terms of peer pressures. Often, people live much of their adult lives under the labels they were given in high school. Then it happens. You've probably already done this-graduation! Many new high school graduates face the strikingly harsh realities of adulthood shortly after graduation. Anomie often follows and it takes months and years at times for young adults to discover new regulating norms which ground them back into expectable routines of life.
The third level of socialization includes college, work, marriage/significant relationships, and a variety of adult roles and adventures. Adult socialization occurs as we assume adult roles such as wife/husband/employee/etc. We adapt to new roles which meet our needs and wants throughout the adult life course. Freshmen in college, new recruits in the military, volunteers for Peace Corps and Vista, employees, missionaries, travelers, and others find themselves following the same game plan that lead to their success during their primary and secondary socialization years-find out what's expected and strive to reach those expectations.
Opportunity
In the US and throughout the world there are rich and poor families. Where you belong has a great deal to do with who you were born to or adopted by. Where you end up in your economic standing has a great deal to do with how you act, given your own set of life chances. As identified by Max Weber, life chances are access to basic opportunities and resources in the marketplace. There are differences among family systems in which people live and have opportunities. This brings up a very important concept from Max Weber. Not all of us have the same life chances as others. For example, one of my best friends in high school came from a wealthy family. Her father was a neurosurgeon and they had many resources that myself and others like me didn't have (she and I were friends because we dated for a short while). When I went to college, I was the first ever on either my mother or father's side to go to college. I had no financial aid, no family support, and such bad high school grades that I had no scholarship funding. My friend on the other hand had a new car, new Apple computer, all expenses paid apartment and living costs. She and I had very different life chances from one another. Nevertheless I was able to earn my PhD. I worked numerous part-time jobs and eventually got my GPA high enough to earn a scholarship, and later graduate assistantship. I also had to take out thousands in student loans. But, even I had far greater life chances than most people in the world today. So did you. We have K-12 education, access to college, and the possibility of a career of our choosing. In many less developed countries low to no formal education is common fare.
Life chances can also be applied to the quality of your own marriage and family. If you came from a highly shaming family culture, then you are more likely to develop an addiction. If you came from a family where the parents divorced, then you are more likely to divorce. If you were born to a single mother you are more likely to become a single mother or father. These are known correlates but not causes. In other words you may be slightly disadvantaged because of the difficult family circumstances you were born in, but you are by no means doomed.
Understanding life chances simply raises your awareness by demonstrating trends from the larger social picture that might well apply to you in your personal level. For example, I have about 21 known correlates to divorce (see Workbook assignment to discover your own). My wife and I have been married now for 25 years. We knew we would have an uphill battle in some regards. But we faced our life chance issues together (still do) and try specifically to avoid some of the same mistakes our parents made.
Demography
Finally, the US family in our day has an important underpinning that influences the family in the larger social and personal levels. Demography is the scientific study of population growth and change. Everything in society influences demography and demography conversely influences everything in society. After World War II, the United States began to recover from the long-term negative effects of the war. Families had been separated, relatives had died or were injured, and women who had gone to the factories then returned home at war's end. The year 1946 reflected the impact of that upheaval in its very atypical demographic statistics. Starting in 1946 people married younger, had more children per woman, divorced then remarried again, and kept having one child after another. From 1946 to 1956 the birth rate rose and peaked, then began to decline again. By 1964 the national high birth rate was finally back to the level it was at before 1946. All those millions of children born from 1946-1964 were called the Baby Boom Generation (there are about 78 million of them alive today). Why was there such a change in family-related rates? The millions of deaths caused by the war, the long-term separation of family members from one another, and the deep shifts toward conservative values all contributed. The Baby Boom had landed. And after the Baby Boom Generation was in place, it conversely affected personal and larger social levels of society in every conceivable way.
The Baby Boomers are most likely your parents (Born 1946-1964). For a few of you they may be your grandparents. Their societal influence on the family changed the US forever. The earliest cohort of Baby Boomers (1946-51) has the world record for highest divorce rates. Collectively baby Boomers are still divorcing more than their parents ever divorced. They had their own children and many of you belong to Generations X or Y (X born 1965-1984 and Y born 1985-present). There are many of you because there were many Baby Boomers. The demographic processes of this country include these baby Boomers, their legacy, and their offspring. To understand the US family, you must understand the Baby Boomers and the underlying demographic forces in our day.
The core of demographic studies has three component concerns: births, deaths, and migration. All of demography can be reduced to this very simple formula:
This part of the formula, (Births-Deaths) is called Natural increase, which is all births minus all the deaths in a given population over a given time period. The other part of the formula, ((In-Migration)-(Out Migration)) is called Net Migration, which is all the in-migration minus all the out-migration in a given population over a given time period. In all the chapters that follow this one, the issues pertaining to the family are heavily influenced by demography's social force in the United States. This formula is not just a measure of larger social trends, it is also an indirect factor that impacts those social trends.
The Industrial revolution set into motion a surge of births and a lowering of deaths. After a century of this type of growth, billions of people lived on the earth. Eventually as the Industrial Revolution became the era of the computer chip, birth rates declined and death rates continued to increase. In Western civilizations this explains why migration is so important. Because fewer births mean less workers for the economy and more need for immigrants.


4.5: Examples of Rotational and 2-Dimensional Motion
Circular Motion
Using what we just derived regarding the parallel and perpendicular components of acceleration, we turn now to the special case of an object traveling in a circle. The parallel part of the acceleration obviously always points tangent to the circle, which narrows it down to two directions at any given point on the circle. If the object is speeding up, then of course the tangent points in the direction of motion, and if it is slowing down, the tangent vector points in the direction opposite to the motion. The perpendicular part must be at a right angle to this tangent, which means it must be toward or away from the center of the circle. Unlike the tangent case, however, both directions are not possible. We can see this by considering the average perpendicular acceleration vector over two nearby moments in time:
Figure 1.7.1 – Direction of Centripetal Acceleration
What is the magnitude of this centripetal acceleration ? Well, it depends upon how fast the object is going (the faster it is moving, the more acceleration is required to turn in the same circle), and the radius of the circle (the acceleration is greater when the radius is smaller). Deriving the magnitude is left as an exercise, but the answer comes out to be:
\[ |\overrightarrow a_c | = \dfrac{v^2}{r} \]
Sometimes circular motion is the result of something rotating. For example, a bug on the outer rim of a rotating turntable travels in a circle, and therefore experiences centripetal acceleration. Well, when we deal with rotating objects we often know only the rate of its rotation (say in rpms), and we have to translate into linear motion to know the speed. There is a simple and standard way to do this.
If we are talking about rotational motion, we need to discuss how we measure such motion. We clearly don’t measure the speed of a spinning top or turntable in terms of meters per second, but rather how much it turns in a period of time. How does one measure the angle through which something turns? One way is to divide the full circle up into 360 equally-sized pie slices. The magnitude of one of these angles we call a 'degree.' But really this division is arbitrary. So why was 360º selected? Well, given that we often have to deal with slices of pie, we can avoid having to use fractional degrees if we select a number with lots of factors, and 360 certainly fits the bill – it is divisible by 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 18, 20, 24, 30, 36, 40, 45, 60, 120, and 180.
But there is no reason at all that divisibility needs to be our only criterion. In fact, we don’t even need to divide the circle into an integral number of pieces. For example, we could divide it into 7.5 pieces and call the size of each piece “1 flibber.” We can even translate between different systems of units: \(1^f\) = 48º.
But there is another criterion that leads to a definition of a measurement of angles that is different from degrees. Suppose we want a simple translation from angle to arclength (the distance traveled along the circular curve subtended by that angle). We know that traveling around an entire circle requires a journey of a distance equal to \(2 \pi\) times the radius of the circle. So going around some fraction of a circle requires a journey equal to that fraction times \(2 \pi r\). So if we divide the circle into an uneven number of pieces such that \(2 \pi\) of these pieces fit into the circle, then in these units you can calculate the arclength by just multiplying the angle measured in those units (called radians ) by the radius of the circle:
If we want to translate between the speed that something is going around the circle to the angular speed at which the slice of the pie is being swept-out by this motion, we need only take a derivative:
This gives us an alternative way of expressing the centripetal acceleration:
\[ | \vec a _ c | = \frac{v^2}{r} = \frac{\left( r \omega \right) ^2}{r} = r \omega^2 \]
A bead is threaded onto a circular hoop of wire which lies in a vertical plane. The bead starts at the bottom of the hoop from rest, and is pushed around the hoop such that it speeds up at a steady rate. Find the angle that the bead's acceleration vector makes with the horizontal when it gets back to the bottom of the hoop.
- Solution
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The tangential motion of the bead is in one dimension, so we can use the usual kinematics equations to describe its motion along the circle. Let's call the radius of the circle \( R\) and the final velocity \(v\). The tangential acceleration is constant, the bead starts from rest, and the bead travels one circumference, so using Equation 1.4.3 , we get:
\[2a \Delta x = {v_f}^2 - {v_o}^2 \;\;\; \Rightarrow \;\;\; a_\parallel=\dfrac{\left(v^2-0^2\right)}{2\left(2\pi R \right)}=\dfrac{v^2}{4\pi R} \nonumber\]
The centripetal acceleration is toward the center of the circle, so it points upward and its magnitude is simply:
\[a_\bot=\dfrac{v^2}{R} \nonumber\]
The tangent of the angle that the full acceleration vector makes with the horizontal is the vertical component divided by the horizontal component, so:
\[\theta = \tan^{-1} \left(\dfrac{\dfrac{v^2}{R}}{ \dfrac{v^2}{4\pi R}}\right)=\tan^{-1} \left(4\pi \right) = 85^o \nonumber\]
Projectile Motion
For circular motion, we have the components of velocity changing in tandem in a specific manner to keep the path circular. Another – actually simpler – form of motion involves only a single fixed coordinate component of velocity changing, while the other components involve no change in velocity. What I am alluding to here is projectile motion , which comes about because the vertical component of motion is subject to constant acceleration (as we discussed when we talked about free-fall), while the horizontal component is unaffected by gravity’s influence. This kind of motion is only one small step from the free-fall we are already familiar with, in that it includes a totally independent horizontal component of motion that incorporates (to the extent that air resistance can be ignored) no acceleration. As simple as this sounds, a couple of examples muddy the waters a bit, and sorting them out is very instructive:
A hunter climbs a tree and fires a bullet directly at a monkey that is hanging from a branch of another tree at precisely the same height as the barrel of the hunter’s gun. The instant the bullet leaves the gun, the monkey lets go of the branch. Ignoring air resistance (and the size of the monkey - assume it is very small), what is the fate of the monkey?
- The monkey will be hit by the bullet.
- The bullet will pass beneath the monkey.
- The bullet will fly over the monkey’s head.
- Whether the bullet flies over the monkey’s head or passes beneath it depends upon how fast the bullet is moving when it leaves the barrel of the gun.

- Solution
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A (and E). The vertical motion of the monkey is independent of the horizontal motion, so in equal time spans, the bullet falls the same distance as the monkey. Since they started at the same level, they remain at the same level at all times, including when the horizontal position of the bullet equals the horizontal position of the monkey.
After falling out of the tree the last time he tried to shoot a monkey (his gun misfired), the hunter now decides to shoot a monkey from the ground. He is aiming upward at an angle, and is assuming the monkey will again let go of the branch just as the bullet is on its way. How should the hunter aim this time, if he is to bag his simian prize?
- He should aim right at the monkey.
- He should aim above the monkey.
- He should aim below the monkey.
- Unlike the level-shot case, where he should aim this time does depend upon how fast the bullet is coming out of the gun.
- The jerk should just aim at himself.
- Solution
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A (and E). If there was no gravity, the bullet would follow a straight line to the monkey. With gravity acting straight down, the amount that the bullet drops below that straight line is the same that an object starting from rest on that straight line falls in an equal time. So the bullet and the monkey remain the same distance from the straight line at all times. When the bullet’s horizontal position equals the monkey’s horizontal position, they will coincide.
The only difference between this example and the previous one is that in the previous case, the line joining the barrel of the gun and the target was horizontal. Still, not everyone may be as convinced in this case as in the previous one, so let's do the math...
Suppose there is no gravity. The path that the bullet takes (\(y\) as a function of \(x\)) can be written down pretty easily. If the point where the bullet exits the barrel is chosen to be the origin, then the straight line to the monkey has a slope equal to the ratio of the vertical and horizontal components of velocity:
\[y=mx+b=\left(\dfrac{v_{oy}}{v_{ox}} \right)x \nonumber \]
Now suppose there is gravity. We have separate horizontal and vertical equations of motion. Again, with the bullet starting at the origin, we have:
\[x=v_{ox}t \\ y=v_{oy}t-\frac{1}{2}gt^2 \nonumber \]
Now solve for \(t\) in the first equation and plug it into the first term of the second equation to get:
\[y=\dfrac{v_{oy}}{v_{ox}}x-\frac{1}{2}gt^2 \nonumber \]
Comparing this with the first equation above, we see that the \(y\) value would follow the same straight line if not for the second term, and the amount that the height of the bullet \(y\) is decreased from that line after a time \(t\) is exactly the same distance that the monkey falls from that line in the same time.
With the number of variables and constants involved in projectile motion problems, there are countless ways to construct problems. There is no substitute for independent thinking and creativity, but the steps given below provide a good starting point for solving these kinds of problems.
- Draw a picture, labeling it as completely as you can, using information you have been given. Then spend some time thinking about what is happening – put yourself into the situation.
While this is given as a step for projectile problems, this is actually how you should start every physics problem!
- Pick an \(x\), \(y\) origin as well as \(+x\) and \(+y\) directions. Often for projectile problems up is chosen as the positive direction (making the acceleration due to gravity a negative value), but this is by no means required. What is important is that you use the positive direction consistently throughout the constants and variables in the equations.
- Break any initial velocities into components along the \(x\) and \(y\) directions.
- Write down the equations of motion, circling quantities that you know, and underlining the number you are looking for. If you have too many un-circled quantities for the number of equations available, you cannot yet do the algebra, so you’ll need to review the statement of the problem for any values concealed in the language of the problem (if you just scan a problem for numbers without carefully reading it, you will miss these).
- Solve the algebra and reconstitute components back into vectors, if necessary.
- Briefly check to see if the answer makes sense.
This is actually how you should end every physics problem!
One thing in projectile motion that is a useful tool is known as the range equation. This was of particular use to military firing cannonballs or (farther back in history than that), catapults. This equation relates the distance that a projectile will fly assuming it lands at the same vertical position that it started, given the starting speed of the projectile and the starting angle. Let’s treat finding this equation as if it was a projectile motion problem given to us, and follow the procedure outlined above
Problem: A cannonball is fired at an angle θ up from the horizontal at a speed of vo. Ignoring air resistance, how far does the cannonball travel before landing back on ground level with where it was fired?
A cannonball is fired at an angle \(\theta\) up from the horizontal at a speed of \(v_o\). Ignoring air resistance, how far does the cannonball travel before landing back on ground level with where it was fired?
- Solution
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The diagram below labels the origin and the + directions. We are looking for \(R\) (referred to as the "range") in terms of the initial speed \(v_o\) of the projectile and the launch angle \(\theta\), which we treat as known values. The rest of the procedure is given below.
We can do other things with this result. For example, suppose we wanted to fire the cannonball as far as possible. Obviously we want it to start at the fastest possible speed, but given that, what angle should we aim at? Let’s solve it! We want to maximize the range R in terms of our choice of angle. This is a straightforward calculus problem. Take the derivative and set it equal to zero to find the maximum:
\[ 0 = \frac{dR}{d\theta} = \frac{v_0^2}{g}\frac{d}{d\theta}\big( \cos2 \theta \big) \big( 2 \big) \ \Rightarrow \ \boxed{\theta = 45^\circ}\]
This really shouldn't be too surprising, based on a simple symmetry argument: If we shoot the projectile with a really steep angle, it goes nearly straight up and doesn't travel very far. We can send the projectile the same distance by choosing a sufficiently shallow angle. That means that every landing point in range of the launcher has two possible distinct values for launch angle, except for the one corresponding to the longest range . It makes sense that complimentary launch angles reach the same landing point: \(89^o\) and \(1^o\), \(52^o\) and \(38^o\), and so on, which means that the self-complimentary angle of \(45^o\) hits the maximum range.
The following example is a challenging application of this principle, and gives an idea of the rich diversity of problems that can be conceived for projectile motion:
Two warlords aim identical catapults (i.e. they both release rocks at the same speed) at each other, with both of them being at the same altitude. The warlords have made the necessary computations to crush the other, and fire their catapults simultaneously. Amazingly, the two stones do not collide with each other in mid-air, but instead the stone Alexander fired passes well below the stone that Genghis shot. Genghis is annihilated 8.0s after the catapults are fired, and Alexander only got to celebrate his victory for 4.0s before he too was destroyed.
- Find the maximum height reached by each of the rocks.
- Find the amount of time that elapses from the launch to moment that the rocks pass each other in the air.
- Find the angles at which each warlord fires his rock.
- Solution
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a. The time it takes a rock to travel to its peak height and back down again is equal to twice the time it takes to travel down from its peak height. Traveling down from its peak height, it starts with zero initial velocity, so we can calculate the height immediately for each rock:
\[ h_{A} = \frac{1}{2}g\left(\frac{t_A}{2}\right)^2 = \frac{1}{2} \left( 9.8 \dfrac{m}{s^2} \right) \left( \frac{8.0s}{2} \right)^2 = \boxed{78.4m} \\ h_{G} = \frac{1}{2}g\left(\frac{t_G}{2}\right)^2 = \frac{1}{2} \left( 9.8 \dfrac{m}{s^2} \right) \left( \frac{8.0s+4.0s}{2} \right)^2 = \boxed{176.4m} \nonumber \]
b. The x–components of the velocities of the rocks never change, and since it takes 12s for Genghis’s rock to travel the same horizontal distance as Alexander’s rock traveled in 8s, Alexander’s rock is traveling in the x-direction at a rate 1.5 times as great as Genghis’s rock is traveling in the x–direction. When they are at the same x–position (passing each other), the distance each has traveled is each one’s velocity times the time we are looking for, and we can express both of these distances in terms of the x–component of Genghis’s rock using the ratio described above:
\[ \begin{array}{l} x_A=v_{Ax}t, \;\;\;\;\; v_{Ax}=1.5v_{Gx} \;\;\; \Rightarrow \;\;\; x_A=1.5v_{Gx}t \\ x_G=v_{Gx}t \nonumber \end{array} \]
Since the rocks travel from both ends and are now at the same horizontal position, the sum of the distances they travel equals the total separation of the two warlords. This allows us to calculate the time:
\[ x_A + x_G = x_{tot} = v_G t_{tot} \;\;\; \Rightarrow \;\;\; \left( 1.5v_G \right) t + v_G t = v_G \left( 12.0s \right) \;\;\; \Rightarrow \;\;\; t=\dfrac{12.0s}{2.5} = \boxed{4.8s} \nonumber \]
c. Clearly there are two different angles that will result in the rock traveling the same distance. One can see this from the range equation, but from a physical standpoint, this happens because one rock spends less time in the air but has a greater x–velocity, while the other spends more time in the air with a smaller x–velocity. To spend 1.5 times as long in the air, Genghis’s rock needs to start with 1.5 times as much vertical component of velocity as Alexander’s rock. This means that the ratios of the x and y components of the two rock velocities are inverses of one another, which means that the two angles are complimentary (i.e. \(\theta_A = 90^o – \theta_G\)). But the total speeds of the rocks are the same, so:
\[\left. \begin{array}{l} v_{Ax} = v_o \cos \theta _A = v_o \cos \left( 90^o - \theta _G \right) = v_o\sin \theta _G \\ v_{Gx} = v_o\cos \theta _G \end{array} \right\}\;\;\; \Rightarrow \;\;\;\dfrac{v_{Ax}}{v_{Gx}} = 1.5 = \dfrac{\sin \theta _G}{\cos \theta _G}\;\;\; \Rightarrow \;\;\;\left\{ \begin{array}{l} \theta _G = \tan ^{ - 1}1.5 = \boxed{56.3^o}\\ \theta _A = 90^o - \theta _G = \boxed{33.7^o} \end{array} \right. \nonumber\]


10.6: Summary
The topics covered in this chapter can be summarized as follows:
| Section | Summary |
|---|---|
| 10.1 Alfred Wegener: The Father of Plate Tectonics | The evidence for continental drift in the early 20th century included the matching of continental shapes on either side of the Atlantic and the geological and fossil matchups between continents that are now thousands of kilometers apart. |
| 10.2 Global Geological Models of the Early 20th Century | The established theories of global geology were permanentism and contractionism, but neither of these theories was able to explain some of the evidence that supported the idea of continental drift. |
| 10.3 Geological Renaissance of the Mid-20th Century | Giant strides were made in understanding Earth during the middle decades of the 20th century, including discovering magnetic evidence of continental drift, mapping the topography of the ocean floor, describing the depth relationships of earthquakes along ocean trenches, measuring heat flow differences in various parts of the ocean floor, and mapping magnetic reversals on the sea floor. By the mid-1960s, the fundamentals of the theory of plate tectonics were in place. |
| 10.4 Plate, Plate Motions, and Plate Boundary Processes | Earth’s lithosphere is made up of over 20 plates that are moving in different directions at rates of between 1 cm/y and 10 cm/y. The three types of plate boundaries are divergent (plates moving apart and new crust forming), convergent (plates moving together and one being subducted), and transform (plates moving side by side). Divergent boundaries form where existing plates are rifted apart, and it is hypothesized that this is caused by a series of mantle plumes. Subduction zones are assumed to form where accumulation of sediment at a passive margin leads to separation of oceanic and continental lithosphere. Supercontinents form and break up through these processes. |
| 10.5 Mechanisms for Plate Motion | It is widely believed that ridge-push and slab-pull are the main mechanisms for plate motion, as opposed to traction by mantle convection. Mantle convection is a key factor for producing the conditions necessary for ridge-push and slab-pull. |
- List some of the evidence used by Wegener to support his idea of moving continents.
- What was the primary technical weakness with Wegener’s continental drift theory?
- How were mountains thought to be formed (a) by contractionists and (b) by permanentists?
- How were the trans-Atlantic paleontological matchups explained in the late 19th century?
- In the context of isostasy, what would prevent an area of continental crust from becoming part of an ocean?
- How did we learn about the topography of the sea floor in the early part of the 20th century?
- How does the temperature profile of the crust and the mantle indicate that part of the mantle must be convecting?
- What evidence from paleomagnetic studies provided support for continental drift?
- Which parts of the oceans are the deepest?
- Why is there less sediment in the ocean ridge areas than in other parts of the sea floor?
- How were the oceanic heat-flow data related to mantle convection?
- Describe the spatial and depth distribution of earthquakes at ocean ridges and ocean trenches.
- In the model for ocean basins developed by Harold Hess, what took place at oceanic ridges and what took place at oceanic trenches?
- What aspect of plate tectonics was not included in the Hess theory?
- Figure 10.36 shows the pattern of sea-floor magnetic anomalies in the area of a spreading ridge. Draw in the likely location of the ridge.
- What is a mantle plume and what is its expected lifespan?
- Describe the nature of movement at an ocean ridge transform fault (a) between the ridge segments, and (b) outside the ridge segments.
- How is it possible for a plate to include both oceanic and continental crust?
- What is the likely relationship between mantle plumes and the development of a continental rift?
- Why does subduction not take place at a continent-continent convergent zone?
- Divergent, convergent, and transform boundaries are shown in different colors on Fiugre 10.37. Which colors are the divergent boundaries, which are the convergent boundaries, and which are the transform boundaries?
- Name the plates on this map and show their approximate motion directions.
- Show the sense of motion on either side of the plate boundary to the west of Haida Gwaii (Queen Charlotte Islands).
- Where are Earth’s most recent sites of continental rifting and creation of new ocean floor?
- What is likely to happen to western California over the next 50 million years?
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Answers to Review Questions
can be found in Appendix 2.
Image Descriptions
Figure B image description: A black line with triangles pointing towards the coast stretches from the Oregon and Washington state up just past Vancouver Island to the southern tip of Haida Gwaii. This line also appears along the Alaskan coast and stretches part way down the Alaskan Pan-Handle. A thin red line stretches from the Alaskan Pan-Handle down just past the southern tip of Haida Gwaii. From that point, it alternates from being a thin red to a thick blue line to form uneven angles zig zagging south past Oregon state. [Return to Figure B]
Media Attributions
- Figures A, B: © Steven Earle. CC BY.


20.4: A New Alternative in the DSM-V
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The purpose for adding a second approach to the diagnosis of personality disorders is twofold: first, the APA Board of Trustees wanted to provide continuity in the diagnoses being offered by clinicians, but second, they recognised that few individuals with a personality disorder clearly fit into the criteria for just one personality disorder. Thus, an alternative method has been proposed that considers assessing both "impairments in personality functioning and pathological personality traits " (pg. 761; APA, 2013).
After listing general criteria for personality disorder that are quite similar to the traditional general criteria, the alternative approach addresses personality functioning in terms of two dimensions: self and interpersonal. The healthy vs. unhealthy aspects of the self involve one's sense of identity and one's self-direction, whereas the interpersonal component addresses empathy and intimacy. The individual is then assessed (as appropriate to the presumed, primary personality disorder) on 25 specific trait facets as they apply within five broad trait domains . The trait domains and associated facets are as follows:
Negative Affectivity: emotional lability, anxiousness, separation insecurity, submissiveness,
hostility, perseveration, depressivity, suspiciousness, restricted affectivity (lack of)
Detachment: withdrawal, intimacy avoidance, anhedonia, depressivity, restricted affectivity,
suspiciousness
Antagonism: manipulativeness, deceitfulness, grandiosity, attention seeking, callousness, hostility
Disinhibition: irresponsibility, impulsivity, distractibility, risk taking, rigid perfectionism (lack of)
Psychoticism: unusual beliefs and experiences, eccentricity, cognitive and perceptual
dysregulation
The DSM-V then offers examples of diagnostic criteria according to this methodology for antisocial PD, avoidant PD, borderline PD, narcissistic PD, obsessive-compulsive PD, and schizotypal PD, as well as a new diagnosis of Personality Disorder - Trait Specified . Personality Disorder - Trait Specified is diagnosed based on two criteria. First there must be moderate or greater impairment in the functioning of personality, as manifested in two or more of the areas identified above as identity, self-direction, empathy, and intimacy. Second, there must be one or more pathological traits as defined by the 5 domains/25 facets.
So, with three different, utilitarian approach to the diagnosis of personality disorders, it is clear that disordered personality development is every bit as complex and fascinating as normal personality development. This should not be surprising, since individuals are unique and complex, and we all experience different lives. It will be quite interesting to see how the DSM-VI handles this issue.


4.3E: Group Translocation
- Recall the following types of transport systems: PEP group translocation and the TAT pathway
With some exceptions, bacteria lack membrane-bound organelles as found in eukaryotes, but they may assemble proteins onto various types of inclusions such as gas vesicles and storage granules. Bacteria may have a single plasma membrane (Gram-positive bacteria) or an inner membrane plus an outer membrane separated by the periplasm ( Gram-negative bacteria). Proteins may be incorporated into the plasma membrane. They can also be trapped in either the periplasm or secreted into the environment, according to whether or not there is an outer membrane. The basic mechanism at the plasma membrane is similar to the eukaryotic one. In addition, bacteria may target proteins into or across the outer membrane. Systems for secreting proteins across the bacterial outer membrane may be quite complex. The systems play key roles in pathogenesis. These systems may be described as type I secretion, type II secretion, etc. In most Gram-positive bacteria, certain proteins are targeted for export across the plasma membrane and subsequent covalent attachment to the bacterial cell wall.
A specialized enzyme, sortase, cleaves the target protein at a characteristic recognition site near the protein C-terminus, such as an LPXTG motif (where X can be any amino acid), then transfers the protein onto the cell wall. Several analogous systems are found that also feature a signature motif on the extracytoplasmic face, a C-terminal transmembrane domain, and cluster of basic residues on the cytosolic face at the protein’s extreme C-terminus. The PEP-CTERM/exosortase system, found in many Gram-negative bacteria, seems to be related to extracellular polymeric substance production. The PGF-CTERM/archaeosortase A system in archaea is related to S-layer production. The GlyGly-CTERM/rhombosortase system, found in the Shewanella, Vibrio, and a few other genera, seems involved in the release of proteases, nucleases, and other enzymes.
PEP group translocation, also known as the phosphotransferase system or PTS, is a distinct method used by bacteria for sugar uptake where the source of energy is from phosphoenolpyruvate (PEP). It is known as a multi-component system that always involves enzymes of the plasma membrane and those in the cytoplasm. An example of this transport is found in E. coli cells. The system was discovered by Saul Roseman in 1964.
The twin-arginine translocation pathway (Tat pathway) is a protein export or secretion pathway found in plants, bacteria, and archaea. In contrast to the Sec pathway which transports proteins in an unfolded manner, the Tat pathway serves to actively translocate folded proteins across a lipid membrane bilayer. In bacteria, the Tat translocase is found in the cytoplasmic membrane and serves to export proteins to the cell envelope or to the extracellular space. In Gram-negative bacteria the Tat translocase is composed of three essential membrane proteins: TatA, TatB, and TatC. In the most widely studied Tat pathway, that of the Gram-negative bacterium Escherichia coli, these three proteins are expressed from an operon with a fourth Tat protein, TatD, which is not required for Tat function. A fifth Tat protein TatE that is homologous to the TatA protein is present at a much lower level in the cell than TatA. It is not believed to play any significant role in Tat function.
The Tat pathways of Gram-positive bacteria differ in that they do not have a TatB component. In these bacteria the Tat system is made up from a single TatA and TatC component, with the TatA protein being bifunctional and fulfilling the roles of both E. coli TatA and TatB. Not all bacteria carry the tatABC genes in their genome. However, of those that do, there seems to be no discrimination between pathogens and nonpathogens. Despite that fact, some pathogenic bacteria such as Pseudomonas aeruginosa, Legionella pneumophila, Yersinia pseudotuberculosis, and E. coli O157:H7 rely on a functioning Tat pathway for full virulence in infection models. In addition, a number of exported virulence factors have been shown to rely on the Tat pathway. One such category of virulence factors are the phospholipase C enzymes, which have been shown to be Tat-exported in Pseudomonas aeruginosa and thought to be Tat-exported in Mycobacterium tuberculosis.
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Key Points
- PEP is known as a multi-component system that always involves enzymes of the plasma membrane and those in the cytoplasm. An example of this transport is found in E. coli cells.
- The Tat pathway is a protein export, or secretion pathway, that serves to actively translocate folded proteins across a lipid membrane bilayer.
- Systems for secreting proteins across the bacterial outer membrane may be quite complex and play key roles in pathogenesis.
Key Terms
- phosphotransferase system : A distinct method used by bacteria for sugar uptake where the source of energy is from phosphoenolpyruvate (PEP).
- Tat pathway : A protein export or secretion pathway found in plants, bacteria, and archaea.


20.1C: The Levels of Classification
- Describe how taxonomic classification of organisms is accomplished and detail the levels of taxonomic classification from domain to species
Taxonomy (which literally means “arrangement law”) is the science of classifying organisms to construct internationally-shared classification systems with each organism placed into more and more inclusive groupings. Think about how a grocery store is organized. One large space is divided into departments, such as produce, dairy, and meats. Then each department further divides into aisles, then each aisle into categories and brands, and then, finally, a single product. This organization from larger to smaller, more-specific categories is called a hierarchical system.
The taxonomic classification system (also called the Linnaean system after its inventor, Carl Linnaeus, a Swedish botanist, zoologist, and physician) uses a hierarchical model. Moving from the point of origin, the groups become more specific, until one branch ends as a single species. For example, after the common beginning of all life, scientists divide organisms into three large categories called domains: Bacteria, Archaea, and Eukarya. Within each domain is a second category called a kingdom. After kingdoms, the subsequent categories of increasing specificity are: phylum, class, order, family, genus, and species.
The kingdom Animalia stems from the Eukarya domain. The full name of an organism technically has eight terms. For dogs, it is: Eukarya, Animalia, Chordata, Mammalia, Carnivora, Canidae, Canis , and lupus . Notice that each name is capitalized except for species and that genus and species names are italicized. Scientists generally refer to an organism only by its genus and species, which is its two-word scientific name, in what is called binomial nomenclature. Therefore, the scientific name of the dog is Canis lupus . The name at each level is also called a taxon. In other words, dogs are in order Carnivora. Carnivora is the name of the taxon at the order level; Canidae is the taxon at the family level, and so forth. Organisms also have a common name that people typically use; in this case, dog. Note that the dog is additionally a subspecies: the “familiaris” in Canis lupus familiaris . Subspecies are members of the same species that are capable of mating and reproducing viable offspring, but they are considered separate subspecies due to geographic or behavioral isolation or other factors.
Dogs actually share a domain (Eukarya) with the widest diversity of organisms, including plants and butterflies. At each sublevel, the organisms become more similar because they are more closely related. Historically, scientists classified organisms using physical characteristics, but as DNA technology developed, more precise phylogenies have been determined.
Recent genetic analysis and other advancements have found that some earlier phylogenetic classifications do not align with the evolutionary past; therefore, changes and updates must be made as new discoveries occur. Recall that phylogenetic trees are hypotheses and are modified as data becomes available. In addition, classification historically has focused on grouping organisms mainly by shared characteristics and does not necessarily illustrate how the various groups relate to each other from an evolutionary perspective. For example, despite the fact that a hippopotamus resembles a pig more than a whale, the hippopotamus may be the closest living relative to the whale.
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Key Points
- Categories within taxonomic classification are arranged in increasing specificity.
- The most general category in taxonomic classification is domain, which is the point of origin for all species; all species belong to one of these domains: Bacteria, Archaea, and Eukarya.
- Within each of the three domains, we find kingdoms, the second category within taxonomic classification, followed by subsequent categories that include phylum, class, order, family, genus, and species.
- At each classification category, organisms become more similar because they are more closely related.
- As scientific technology advances, changes to the taxonomic classification of many species must be altered as inaccuracies in classifications are discovered and corrected.
Key Terms
- binomial nomenclature : the scientific system of naming each species of organism with a Latinized name in two parts
- taxon : any of the taxonomic categories such as phylum or subspecies
- Linnaeus : Swedish botanist, physician and zoologist who laid the foundations for the modern scheme of nomenclature; known as the “father of modern taxonomy”


1.8: An Application to Resistor Networks
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The tools of linear algebra can be used to study the application of resistor networks. An example of an electrical circuit is below.
The jagged lines ( ) denote resistors and the numbers next to them give their resistance in ohms, written as \(\Omega\). The voltage source ( ) causes the current to flow in the direction from the shorter of the two lines toward the longer (as indicated by the arrow). The current for a circuit is labeled \(I_k\).
In the above figure, the current \(I_1\) has been labeled with an arrow in the counter clockwise direction. This is an entirely arbitrary decision and we could have chosen to label the current in the clockwise direction. With our choice of direction here, we define a positive current to flow in the counter clockwise direction and a negative current to flow in the clockwise direction.
The goal of this section is to use the values of resistors and voltage sources in a circuit to determine the current. An essential theorem for this application is Kirchhoff’s law.
Kirchhoff’s law allows us to set up a system of linear equations and solve for any unknown variables. When setting up this system, it is important to trace the circuit in the counter clockwise direction. If a resistor or voltage source is crossed against this direction, the related term must be given a negative sign.
We will explore this in the next example where we determine the value of the current in the initial diagram.
Example \(\PageIndex{1}\): Solving for Current
Applying Kirchhoff’s Law to the diagram below, determine the value for \(I_1\).
Solution
Begin in the bottom left corner, and trace the circuit in the counter clockwise direction. At the first resistor, multiplying resistance and current gives \(2I_1\). Continuing in this way through all three resistors gives \(2I_1 + 4I_1 + 2 I_1\). This must equal the voltage source in the same direction. Notice that the direction of the voltage source matches the counter clockwise direction specified, so the voltage is positive.
Therefore the equation and solution are given by \[\begin{aligned} 2I_1 + 4I_1 + 2 I_1 &= 18 \\ 8I_1 &= 18 \\ I_1 &= \frac{9}{4} A\end{aligned}\]
Since the answer is positive, this confirms that the current flows counter clockwise.
Example \(\PageIndex{2}\) Solving for Current
Applying Kirchhoff’s Law to the diagram below, determine the value for \(I_1\).
Solution
Begin in the top left corner this time, and trace the circuit in the counter clockwise direction. At the first resistor, multiplying resistance and current gives \(4I_1\). Continuing in this way through the four resistors gives \(4I_1 + 6I_1 + 1 I_1 + 3I_1\). This must equal the voltage source in the same direction. Notice that the direction of the voltage source is opposite to the counter clockwise direction, so the voltage is negative.
Therefore the equation and solution are given by \[\begin{aligned} 4I_1 + 6I_1 + 1 I_1 + 3I_1&= -27 \\ 14I_1 &= -27 \\ I_1 &= -\frac{27}{14} A\end{aligned}\]
Since the answer is negative, this tells us that the current flows clockwise.
A more complicated example follows. Two of the circuits below may be familiar; they were examined in the examples above. However as they are now part of a larger system of circuits, the answers will differ.
Example \(\PageIndex{3}\): Unknown Currents
The diagram below consists of four circuits. The current (\(I_k\)) in the four circuits is denoted by \(I_{1},I_{2},I_{3},I_{4}\). Using Kirchhoff’s Law, write an equation for each circuit and solve for each current.
Solution
The circuits are given in the following diagram.
Starting with the top left circuit, multiply the resistance by the amps and sum the resulting products. Specifically, consider the resistor labeled \(2 \Omega\) that is part of the circuits of \(I_1\) and \(I_2\). Notice that current \(I_2\) runs through this in a positive (counter clockwise) direction, and \(I_1\) runs through in the opposite (negative) direction. The product of resistance and amps is then \(2 (I_2 - I_1) = 2I_2 - 2I_1\). Continue in this way for each resistor, and set the sum of the products equal to the voltage source to write the equation: \[2I_{2}-2I_{1}+4I_{2}-4I_{3}+2I_{2}=18\nonumber \] The above process is used on each of the other three circuits, and the resulting equations are:
Upper right circuit: \[4I_{3} - 4I_{2} + 6I_{3} - 6I_{4} + I_{3} + 3I_{3} = -27\nonumber \] Lower right circuit: \[3I_{4} + 2I_{4} + 6I_{4} - 6I_{3} + I_{4} - I_{1} = 0\nonumber \] Lower left circuit: \[5I_{1}+I_{1}-I_{4}+2I_{1}-2I_{2}=-23\nonumber \]
Notice that the voltage for the upper right and lower left circuits are negative due to the clockwise direction they indicate.
The resulting system of four equations in four unknowns is \[\begin{aligned} 2I_{2}-2I_{1}+4I_{2}-4I_{3}+2I_{2}&=18 \\ 4I_{3} - 4I_{2} + 6I_{3} - 6I_{4} + I_{3} + I_{3} &= -27 \\ 2I_{4} + 3I_{4} + 6I_{4} - 6I_{3} + I_{4} - I_{1} &= 0 \\ 5I_{1}+I_{1}-I_{4}+2I_{1}-2I_{2}&= -23\end{aligned}\] Simplifying and rearranging with variables in order, we have: \[\begin{aligned} -2I_{1}+8I_{2}-4I_{3}&=18 \\ - 4I_{2} + 14I_{3} - 6I_{4} &= -27 \\ -I_{1} - 6I_{3} + 12I_{4} &= 0 \\ 8I_{1}-2I_{2} - I_{4} &= -23\end{aligned}\] The augmented matrix is \[\left[ \begin{array}{rrrr|r} -2 & 8 & -4 & 0 & 18 \\ 0 & -4 & 14 & -6 & -27 \\ -1 & 0 & -6 & 12 & 0 \\ 8 & -2 & 0 & -1 & -23 \end{array} \right]\nonumber \]
The solution to this matrix is \[\begin{aligned} I_{1} &= -3 A\\ I_{2} &= \frac{1}{4} A\\ I_{3} &= -\frac{5}{2} A\\ I_{4} &= -\frac{3}{2} A\end{aligned}\]
This tells us that currents \(I_1, I_3,\) and \(I_4\) travel clockwise while \(I_2\) travels counter clockwise.


11.6: Summary
Industrial production changed the relationship of people to their environments. Folk (pre-industrial) cultures used local resources and knowledge to hand-produce goods. Now the productions of goods and the provisioning of services can be split into innumerable spatially discrete pieces. Competition drives the costs of goods and services downward providing relentless pressure to cut costs. This process has pushed industrialization into most corners of the world as companies have looked further and further afield to find cheaper labor and materials and to find more customers. Industrialization has fueled a change in lifestyle, as goods have become cheaper, they have become more accessible to more people. Our lives have changed. We now live according to a schedule dictated by international production.