fei75766_ch15_463-494.indd 483  02/24/20 10:48 AM
Chapter 15    Buss: Evolutionary Theory of Personality483
scores onprosociality andindustriousness. VonRueden andcolleagues found, when 
controlling forage,sex,andvillage, thatphysical strength andeducational attainment 
werepositively related toprosocial behavior butnottoindustriousness. They also
found thatextraversion, agreeableness, conscientiousness, andopenness wereassoci -
atedwitheducational attainment. 
Finally, researchers haveexplored theorigins ofextraversion asitrelates to
reproductive success (Lukaszewski &Roney, 2011). Lukaszweski andRoney argue 
thatdifferences inextraversion mayhavecome about because theyarerelevant 
toreproductive payoffs. Inparticular, people whoareextraverted aremore liketo
approach potential mates, compete forsocial attention, andpursue attaining status 
andpower. Yetthese behaviors cangetoneintrouble andcreate conflict withoth-
erswhoarealsopursuing mates andtrying toattain power. Inthisway,extraversion 
mayco-develop withphysical strength, atleastinmen. Moreover, being physically 
attractive garners theattention ofothers andmayalsointeract withextraversion in
thatbeing attractive andextraverted ismore likely toleadtoreproductive success 
thanpossessing onlyoneofthose traits. Intheirresearch withuniversity undergradu -
ates,Lukaszweski andRoney found thatphysical attractiveness andphysical strength 
bothrelated toextraversion inmen. Inwomen, onlyphysical attractiveness related to
extraversion. 
Taken asawhole, these studies support Buss’ theory thatpersonality traits are
related to,andmaybetheresult of,reproductive andsurvival success andhence 
fitness. Inshort, personality traits haveadaptive functions inthecourse ofhuman 
evolution. 
Genetics and Personality
Partly duetohowgenetics wastaught inhigh-school biology, acommon assumption 
many people haveisthatthere isasimple andnearly one-to-one correspondence 
between genes andtraits. Recall howyoulearned tocalculate theprobability that
offspring would inherit atraitifitsparents wereeither dominant orrecessive carriers 
ofthattrait.There aresimple categorical traits (e.g., eyecolor) thatgettransmitted 
byonegene. Butallcomplex psychological traits thatareexpressed onacontinuum 
from lowtohighgettransmitted bymany, many genes. More technically, simple 
categorical traits are“monogenically” (single gene) transmitted, whereas traits that
range from alittletoalot(e.g., aggression, height, weight, anxiety) are“polygenically 
transmitted” (Ebstein, 2006; Evans etal.,2007). Simply put,monogenic  transmission 
happens when single genes produce single traits (phenotypes), and polygenic 
 transmission occurs when many genes interact tocreate asingle characteristic 
(Rutter, 2006). Thisdistinction isveryimportant inunderstanding afundamental 
ideainmodern genetics, namely ourgenome isthestarting point, nottheendpoint, 
forhowourgenes areexpressed (ourphenotype). There isno“smart” gene, “shy” 
gene, or“aggressive” gene. Many, many (dozens andmaybe more) genes arerespon -
sibleforpersonality traits.
When studying behavioral genetics, researchers usetwomajor methods toexam -
inetherelationship among genetics, behavior, andpersonality. With thefirstmethod, 
thequantitative trait loci (QTL) approach, theylookforthelocation ofspecific bits
ofDNA ongenes thatmight beassociated withparticular behaviors. Inthissense, itFinal PDF to printer