Hominids

Hominoids #

Taxonomy #

• Hominoids: lesser + great apes
• Hominids: Asian, African apes
• Hominines: African apes
• Hominins: Humans + chimps

Hominoids

• → Hylobatids
• → Hominids
  • → Pongines
  • → Hominines
    • → Gorilla
    • → Pongo pygmaeus (Orangutan)
    • → Hominins
      • → Pan
        • → Pan troglodytes (Common Chimp)
        • → Pan paniscus (Bonobos)

Hominoids #

• 2.1.2.3 denture
• ectotympanic tube (like Old World monkeys)
• narrow nose w/ downward nostrils

Unique Traits #

• broad palate
• no tail
• Y-5 molars
• larger brain

Bodies #

• orthograde (upright) posture
• long, curved arms/fingers
• short legs
• mobile shoulders

Hylobatids (Hylobates or Gibbons) Lesser Apes #

• Smaller than Great Apes
• frugivorous
• monogamous
  • joint defense, small dimorphism
• SE Asia
• Short, low skull w/ projecting canine
• brachiation, orthograde (inherits from superclass hominoids)

Siamangs - throat pouches “gular sac” for loud defense

Hominids #

Pongo pygmaeus (Orangutan) #

• frugivorous
• Borneo, Sumatra
• Concave face, sagittal crest
• Big central canine

Locomotion: fist walking on ground, quadrumanous in trees (use all 4 limbs)

Social Organization: Solitary

• males defend female territories
• high sexual dimorphism — males change dramatically as they age

Gorillas (African Apes) #

Folivorous #

• large digestive systems
• shearing crests on molars
• large mandibles
• sagittal crest

Large Size #

• limited movement
• childhood: some bipedalism
• adults: knuckle-walking
  • males → terrestrial
  • children/females → arboreal

Social organization: Single male polygyny #

• single dominant “silverback” male
• defends/abducts females from other groups
• high sexual dimorphism
  • males: 2-3x larger
  • larger sagittal crests + canines
  • fat pads for chest pounding
  • silverbacks = status symbols

Sagittal vs Nuchal crest — top vs back of skull

(sexually dimorphic)

Chimpanzees (Pan troglodytes) #

• central/west Africa
• confined to equatorial forests (alongside all other African apes)
• separated from bonobos by Congo river
• no sagittal crest (round skull)

Fission-fusion social structure #

• males, females separate during day to forage/care/defend
• multi-male, multi-female
• males stick together, but females leave group after puberty (male continuity)
• moderate sexual dimorphism — males defend, females + children forage
  • size, behavior
• lots of behaviors/social expressions to communicate
• mating: swelling during estrus. Very mild competition due to good communications

Hunting #

• cooperative between male coalition
  • hunt colobus monkeys
• social, reproductive tool
  • alliances, gain trust

Violence #

• Infanticide: make females more receptive if baby not suspected to be theirs
• Warfare: attacks other groups if resources are scarce
• ★ Unique to chimps and humans

Culture #

• Troop specific learned behaviors (different groups have different skill)
• Learned through observation, imitation
  • could be done over years
  • ★ deliberate use and learning are unique
• Examples:

Deliberate use and learning are unique #

Examples:

• nut cracking w/ stone

• spear making to hunt galagos

• termite sticks

• communicative rituals

Bonobos #

• omnivorous, terrestrial + arboreal

Bonobos vs Chimps #

• long, lean body
• darker face
• more arboreal
• more bipedal
• very weakly territorial
• female dominant societies
• lots of sexual relations (unreproductive) ← no infanticide due to obscuring parents
• ← chimps have more competition, fewer resources due to sharing land w/ gorilla
• doesn’t kill, very peaceful towards strangers, very empathetic

bonobos have no competition ⇒ more affiliative

Contrasting chimpanzees and bonobos