Tree of Origin

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Tree of Origin

• What Primate Behavior Can Tell Us About Human
  Social Evolution

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On Becoming Human

• What are the implications for our humanity of our
  evolutionary origins?
• Our mental heritage
• Evolutionary origins of ethics, morality,
  religion
• 40 million years of primate social evolution

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Comparative Studies

• Basic primate phylogeny and taxonomy
• Homologies, convergent evolution, parallel
  evolution
• Cultural evolution vs. biological evolution
• Tree of Origin studies of field and captive
  populations of primates, by primatologists

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Primate phylogeny
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Hominoid taxonomy
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Chapter 1

• Anne Pusey - Of Genes and Apes Chimpanzee Social
  Organization and Reproduction
• For many decades, chimpanzees have been observed
  at Gombe National Park and other African field
  sites. Now DNA analyses have begun to further
  enrich our understanding of their social life.
  Chimpanzee behavior and ecology are reviewed
  here, along with the genetic implications for
  kinship, paternity, and inbreeding.

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Chapter 2

• Frans de Waal - Apes from Venus Bonobos and
  Human Social Evolution
• Even though bonobos are as close to us as
  chimpanzees, the species is less well known both
  to science and to the general public. These
  make love, not war primates have evolved
  peaceful societies with female bonding and female
  dominance. As such, bonobos challenge
  traditional assumptions about human social
  evolution.

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Chapter 3

• Karen Strier - Beyond the Apes Reasons to
  Consider the Entire Primate Order
• What is special, or not so special, about the
  hominoids? Comparisons between humans and the
  anthropoid apes are highly informative, but we
  cannot make sense of this small taxonomic groups
  characteristics without taking a broader
  comparative perspective that encompasses the two
  hundred other extant primate species.

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Chapter 4

• Craig Stanford - The Apes Gift Meat-eating,
  Meat-sharing, and Human Evolution
• Meat is highly prized by both humans and
  chimpanzees. Data on cooperative hunting by male
  chimpanzees allow us to revisit the old
  Man-the-Hunter debate, initiated when only humans
  were thought to be carnivorous. As a part of
  political and mating strategies, hunting may have
  driven the evolution of social intelligence.

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Chapter 5

• Richard Wrangham - Out of the Pan, Into the fire
  How our Ancestors Evolution Depended on What
  They Ate
• What allowed the descendents of chimpanzee-like
  ancestors, 5 million to 6 million years ago, to
  colonize savanna woodlands? They appear to have
  depended on eating roots. About 4 million years
  later, our ancestors became human. A new
  hypothesis suggests that this happened as a
  result of the adoption of cooking.

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Chapter 6

• Richard Byrne - Social and Technical Forms of
  Primate Intelligence
• Can we reconstruct the ancient mind by
  speculating about the capacities upon which our
  ancestors cognitive evolution was founded? Was
  it in the social domain that things began - with
  deception and perspective-taking in the
  technical domain - with tool use or in the
  context of foraging and complex food manipulation?

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Chapter 7

• Robin Dunbar - Brains on Two Legs Groups Size
  and the Evolution of Intelligence
• Group size is a likely measure of social
  complexity, which in turn may have driven the
  evolution of intelligence. There is indeed
  evidence that primates who live in large groups
  have larger brains. The subsequent evolution of
  language further promoted effective information
  exchange and social integration.

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Chapter 8

• Charles Snowdon - From Primate Communication to
  Human Language
• Does animal vocal communication - from the
  babbling of marmosets to the song-learning of
  birds - provide clues about language origins?
  Since many features of human language are present
  in the communication of other species, meaningful
  parellels can be drawn. No nonhuman animal shows
  all of the human features, however.

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Chapter 9

• William McGrew - The Nature of Culture Prospects
  and Pitfalls of Cultural Primatology
• If other primates transfer skills and habits from
  one generation to the next, are we not fustified
  in speaking of culture as well? Wild chimpanzee
  communities, for example, vary greatly in tool
  use and special forms of communication. This
  intergroup diversity suggests that we are not the
  only cultural beings.

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Chimpanzee social groups

• Small temporary parties - communities
• Fusion-fission structure of populations
• Female sexual status and groups
• Males group more frequently, wider ranges
• Foraging ecology and groups

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Female ranges
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Group territoriality

• Groups (communities) in defined ranges
• Intergroup aggression at boundaries, against
  stranger females as well as males
• Aggressive displacement/elimination of groups by
  others

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Mating patterns

• Females advertise receptiveness
• Extreme polygyny - infanticide avoidance
• Male options opportunistic mating, aggressive
  guarding, consortships
• Sexual dimorphism
• Male philopatry - female-biased dispersal
• Inbreeding avoidance
• Male coalitions and dominance structures

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Female advertisement
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Chimp hunting meat sharing

• Prey on a variety of mammals (colobus)
• Hunting is seasonal, related to group size
• Hunting vs. scavenging
• Nutritional vs. social aspects of meat
• Other foods more profitable
• Use of meat in coalitions, courtship
• Man-the-Hunter model

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Chimpanzee model

• Male and female social strategies
• Intergroup aggression in chimps and human
  societies - killer ape myth
• Chimp politics and social relations -
  tit-for-tat, reconciliation, etc.
• Chimp polygyny vs human pair-bonding
• Resource sharing, protection against sexual
  coercion, male cooperation

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Bonobo biology

• pygmy chimpanzee
• Structural similarities to astralopithecines
• Locomotion - bipedalism, knuckle-walking
• Restricted range
• Foraging ecology
• Group size

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Bonobo vs. chimp
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Bonobo stature
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Sociosexual behavior

• Extensive non-reproductive sex
• Reconciliation from aggression
• Food sharing
• Extended receptivity and advertisement by females

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Genito-genital rubbing
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Mating patterns sociality

• Female-biased dispersal and male philopatry
• Socio-sexual behavior and female dispersal
• Secondary sisterhood
• Female coalitions and dominance
• Male maternal bonding
• Low confidence of paternity

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Bonobo model

• Food resources and group size
• Female receptivity -gt less male competition
• Reduced male coalitions
• Female collective power takeover
• Sociosexual bonding among females
• Confused paternity -gt no infanticide
• Low intergroup aggression

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Phylogeny, ecology, sociality