fei75766_ch15_463-494.indd 479  02/24/20 10:48 AM
Chapter 15    Buss: Evolutionary Theory of Personality479
theadaptations. Bussusescalluses asanexample: Calluses areevolved adaptations but
donotgetexpressed without input from theenvironment suchaswalking barefoot for
longperiods oftimeorplaying theguitar. Calluses getexpressed through genetically 
induced protein formation andthisgeneexpression onlyoccurs withinput from the
environment (Ulrich-Vinther, Schwarz, Pedersen, Soballe, &Andreassen, 2005).
More generally, thediscovery ofepigenetics isanevenmore powerful example 
ofhowgenetic influence isnotsetinstone atthemoment ofconception andinteracts 
withinput from theenvironment. Epigenetics ischange ingenefunction thatdoesnot
involve changes inDNA (Meaney, 2010; Rutter, 2006). Inother words, experiences 
thatanimals havecreate tagsthatattach totheoutside structure ofDNA andcon-
trolgeneexpression. Epigenetics hasfundamentally altered ourviewofgenetic influ-
ence. Itmakes clear thattheexperiences wehave(such aseating, drinking, orbeing 
exposed tochemicals) canaffect changes ingenes (Watters, 2006). Infact,cancers 
areoneofthemost widespread examples ofepigenetic change ingeneexpression and
demonstrate tragically howwhat weeat,drink, andsmoke canaltergenetic activity 
(Jones &Baylin, 2002). Infact,inaveryrealsense, changes inorgans, physiological 
systems, andbodies thatoccur overlongperiods oftime(i.e.,evolution) aretheresult 
notonlyofmutations ingenes butalsoepigenetic processes. Inshort, thatDNA is
notdestiny, itisperfectly consistent withevolutionary theory.
Executing Adaptations Requires Conscious Mechanisms
Tosaythatmechanisms (cognitive andpersonality) evolved tosolve important prob -
lemsofsurvival andreproduction doesnotmean theyrequire complex (conscious) 
mathematical abilities tooperate. Forexample, theideaof“inclusive fitness” 
revolves around theideathatwearemore likely tohelpoutabrother thanacousin 
andacousin more thanastranger because thebrother ismore closely related to
usandacousin ismore closely related thanastranger. Thisisnotamathematical 
calculation anymore thanaspider needs tounderstand geometry tospinaweb.
Moreover, when evolutionary psychologists talkabout “strategies,” these arenotto
bethought ofasconscious orwillful acts.Infact,people havenoawareness ofthese 
influences andwhen discussed often evenregret them. “Ugh, Iamnotattracted to
himbecause ofhisresources andfitness!” “Sexual strategy” isjustashort-hand term
foracumbersome ideathatevolution hasshaped ourpreferences formates based on
thefactthatweareattracted tothose whoproduce healthy andfitoffspring andide-
allycontinue toprovide forthem. Thisincreases thelikelihood thattheywillsurvive 
toreproductive ageandpassontheirhealthy genes.
Mechanisms are Optimally Designed
People sometimes draw theconclusion thatevolution produces solutions thatare
optimal. Infact,some adaptations arerather awkward. Evolutionary change occurs 
overhundreds ofgenerations andthere isalways alagbetween adaptation andenvi-
ronment. Human preference forfattyandsaltyfoods isagood example. Inancestral 
environments tensofthousands ofyears ago,fattyandsugary foods wereverydif-
ficult toobtain. Yettheyprovide important nutritional benefits. Over thelast100
years, fatandsugar havebecome cheap andplentiful. Ourwaistlines havebulged toFinal PDF to printer