What research method is used in order to establish what causes a behavior? an experiment What is the first step of the scientific method? pose a question In the science of human development, &quot;nurture&quot; refers to: environmental influences.
Vertical lines on one's nails, like those the writer seems to have, are a common phenomenon that often get more pronounced with age. There are many reasons for ridged nails but the most common is aging, says Dr. Phoebe Rich, M.D., FAAD, clinical adjunct professor of dermatology at Oregon Health Science University.
Common causes of ridges on nails. Nails are comprised of Keratin (protein) a tough substance that protects the end of each finger and toe. The following is a list of possible causes as to why vertical ridges may appear on the nails: 1  It is traditionally believed that ridge formation on the nails relates to a possible weakness in the digestive tract that results in compromised assimilation of nutrients (leaky gut, allergies, food sensitivities, maldigestion)