fei75766_ch15_463-494.indd 471  02/24/20 10:48 AM
Chapter 15    Buss: Evolutionary Theory of Personality471
There aretwospecific main classes ofmechanism, namely physical andpsy-
chological. Physical mechanisms arephysiological organs andsystems thatevolved 
tosolve problems ofsurvival, whereas psychological mechanisms areinternal andspe-
cificcognitive, motivational, andpersonality systems thatsolve specific survival and
reproduction problems.
Anatomical andphysiological mechanisms areoften shared bymany species, 
whereas psychological mechanisms areoften more specific tospecies. Evolutionary 
biology focuses ontheorigin ofphysical mechanisms, whereas evolutionary psychol -
ogyfocuses ontheorigin ofpsychological mechanisms. Indeed, amajor contribution 
ofevolutionary psychology toevolutionary theory istheintroduction anddevelop -
ment ofpsychological mechanisms.
Examples ofsurvival andreproduction problems andtheir various physical 
andpsychological solutions arepresented inTable 15.1(Buss, 1991). Forexample, 
animals ofdifferent species haveevolved similar sensory systems. Inmost verte -
brates, andmammals inparticular, these taketheform ofeyes, ears, nose, skin, and
tongue. Senses areadaptive inthattheyfunction totakeindifferent kinds ofinfor -
mation from theoutside world andallow theorganism torespond appropriately. 
Sensory mechanisms differ between species ofanimals. Dogs, forinstance, hear
sounds withpitches between 10and35,000 cycles persecond (Hertz), whereas 
humans onlyhearsounds inthe20–20,000 cycles persecond (Hertz) range. 
TABLE 15.1
Examples of Evolutionary Problems and Their Solutions (Mechanisms)
Problem  Solution/Mechanism
Survival
Taking ininformation from theexternal world  Eyes, ears,nose, skin,&tongue
Temperature regulation  Ectothermic system, sweat glands
Disease andparasites  Immune system
Wounds andinjury  Blood clotting
Predators anddanger  Limbs andlocomotion
Fending offattacks ofenemy  Strength, aggression, speed
Trust/Cooperation  Conscientiousness, agreeableness
Alliance andgroup cohesion  Dominance, agreeableness
Food gathering  Creativity, intelligence
Shelter  Creativity, intelligence
Reproduction
Mate attraction  Dominance, surgency, creativity
Mate selection  Social intelligence, theory ofmind
Trust  Conscientiousness, dependability
Intrasex competition  Aggression, drive, achievement, 
resource acquisition, beauty
Intimacy  Love, attachment, agreeableness
Adapted from Buss, 1991 & MacDonald, 1995.Final PDF to printer