What does it mean to be biologically human? Why are we such strange apes? January 24, 2005

Taxonomy “Carl” Linnaeus Classification system Hierarchical Binomial –Genus –species

Human Taxonomy KingdomAnimaliaAnimal PhylumChordataChordates SubphylumVertebrata Vertebrates ClassMammaliaMammals InfraclassEutheriaEutherians OrderPrimatesPrimates SuborderAnthropoideaAnthropoids InfraorderCatarrhiniCatarrhines SuperfamilyHominoideaHominoids FamilyHominidaeHominids GenusHomoHumans SpeciesHomo sapiens SubspeciesHomo sapiens sapiens

Why look at primates? Homologies: –Genetics –Brain Structure –Biochemistry –General physiology

Why look at primates? Analogies: similar traits that arise if species experience similar selective forces and adapt to them in similar ways. –Feeding ecologies of terrestrial primates

Major Primate Characteristics Grasping Tactile Hands Vision (stereoscopic) Brain Complexity Parental Investment Sociality

What do non-human primates look like? Prosimians –Lemurs –Tarsiers –Bushbabies –Loris –Aye Aye

What do non-human primates look like? New World Monkeys –Spider Monkey –Squirrel Monkey –Capuchin Monkey –Marmoset –Howler Monkey

What do non-human primates look like? New World Monkeys have prehensile tails.

What do non-human primates look like? Old World Monkeys –Baboons –Macaque –Langurs –Proboscis –Drills, Mandrills

What do non-human primates look like? “Lesser” Apes –Gibbons

What do non-human primates look like? “Great” Apes –OrangutanOrangutan –GorillaGorilla –ChimpanzeeChimpanzee –BonoboBonobo –Humans

Primates in Macroevolutionary Context Misconceptions: –Evolution is not teleological! –Diversity does not represent stages –All animals are equally “modern” –Evolution does not necessarily lead to smarter, stronger, or morally superior animals.

Phylogeny Evolutionary relationships among species (“family tree”)

Ancestral Traits Homologies between species.

Derived Traits Compared to non-human primates, humans have: –Less fur –More technology –Bipedal Locomotion

What do non-human primates teach us? Insights into fossil primates –Activity Patters (nocturnal, diurnal) –Locomotion Quadrapeds, Knucklewalkers, Brachiators, Bipeds –Diet/Feeding Ecology Insectivores, frugivores, folivores, carnivores, omnivores

What do non-human primates teach us? Feeding Ecology Sexual Dimorphism Mating Strategies All Related

What Females “Want” Offspring to survive Reliable food supply Help raising offspring

What Males “Want” Sex (pass on genes=maximize fitness) Avoid helping raise offspring when it interferes with further mating

Feeding Ecology and Mating Females map onto food resources Males map onto females

Gibbons Food Clumps Easy for females to defend food Easy for males to defend females Result: Monogamy

Orangutan Food dispersed and highly seasonal Females can’t defend resources (nomadic) Males can’t defend females Solitary, nomadic mating

Gorillas Large, dense food patches Multiple females form a territorial group One male can protect the group One male polygyny

Chimpanzees Food is densely distributed and plentiful No need for territoriality for females or males Multi-male polygyny

Sexual Dimorphism Differences in body size between males and females Highest when there is high competition between males for mates In humans, suggests that sometime in pre-history humans were polygynous

Sexual Dimorphism Monogamy: No Dimorphism Multi-male polygyny: mild Solitary mating: medium Single male polygyny: extreme