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4: Apes

  • Page ID
    299431
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    • According to primatology texts:

      • Monogamy

        • Very little sexual dimorphism; M and F may look indistinguishable

          • Sexual dimorphism: difference in appearance due to secondary sex characteristics (characteristics in M and F other than reproductive characteristics)

        • Pair bonds; F-dominated parental care

        • There may be mutual courtship between M and F

        • Does not necessarily mean that they mate for life

        • Sometimes “serial monogamy” (one partner to raise offspring together until the next partner)

        • Low reproductive variance (easier to find a mate)

        • In primates, it is more common in Strepsirrhines

      • Polyandry

        • One F mates with multiple M

        • Sexual dimorphism (F sometimes bigger than M)

        • M invest a lot of parental care, may sexually select traits in F

        • Sperm competition (M aren’t competing physically but compete by having larger testicles and higher quantities of sperm)

        • Often occurs in organisms with a genetic predisposition to have twins

        • In primates, it is more common in New World monkeys

      • Polygyny

        • Note: The strict “alpha” dominance hierarchy concept in wolves (that was also applied to other organisms) was later debunked due to flaws in research

        • One M mates with multiple F

        • High degrees of sexual dimorphism (M are often twice the size of F, weaponry)

        • Weapons used for fighting and protection (sharp canines, tusks, large size, etc.)

        • High reproductive variance (some M never reproduce at all while a few M father all of the offspring

        • Smallest testicle size (M don’t need to compete through sperm competition because only the dominant M is mating)

        • In primates, it is more common in Old World monkeys and apes

      • Polygynandry

        • M and F have multiple partners; relatively equal M-F dominance

        • Some sexual dimorphism

        • Competition between all M (not just one dominant M); competition between F, as well

        • Experience both physical competition and sperm competition

        • Some reproductive variance

        • In primates, it is more common in Old World monkeys and apes


    • No tail

    • Y-5 molars (5 cusps on 3rd molar)

    • Larger body size

    • Larger brain

    • Greater social complexity

    • Shoulder joint adaptations


    • Lesser Apes

      • Gibbons

      • Siamangs

    • Great Apes

      • Orangutans

      • Gorillas

      • Chimpanzees

      • Bonobos

      • Humans


    • Smaller body size

    • Long and thin arms

    • Less prominent facial features

    • More arboreal

    • More vegetarian

    • Monogamous

    • Native to Indonesia, Malaysia, Thailand

    • Siamangs have large gular sac (throat pouch) that can be inflated to the size of its head, allowing it to make loud, resonating calls or songs → Video


    • Social but often solitary

      • Spend much of their time alone foraging for fruit

      • Strong social relationships when they do interact

    • Arboreal

    • Intelligent

    • Polygynous

    • Sexual dimorphism

      • Cheek flaps in males

      • Adult males weigh more than twice as much as females

    • Native to Borneo and Sumatra (once ranged through Southeast Asia and China)


    • Sagittal crest (prominent ridge of bone on top of head)

    • More muscular arms than legs

    • Large bulging stomach for digesting vegetation

    • Diet: 

      • 67% fruit

      • 17% leaves, seeds, stems

      • 3% termites and caterpillars

    • "Silverback" - term used for "dominant" male

    • Polygynous

    • Sexual dimorphism

      • Full-grown male gorillas weigh 400 lbs and stand 6 ft tall

      • Females weigh half as much

    • Native to tropical forests of equatorial Africa


    • Polygynandrous

    • Highly intelligent and social

    • Tool-making and cultural adaptations

    • Larger distribution

      • Sympatric with gorillas

      • More competition with other primates 

    • Diet

      • Frugivores (mostly fruit)

      • Vegetation, bark, honey, insects, other chimps and monkeys

      • More omnivorous

      • Troop hunting culture

    • Relationships

      • May be aggressive and competitive

      • Male social relationships important

      • Violence between males and females

    • Native to tropical forests of equatorial Africa


    • Polygynandrous

    • Highly intelligent and social

    • Tool-making and cultural adaptations

    • Smaller distribution

      • Less competition with other primates

    • Diet

      • More emphasis on fruits and vegetation

    • Relationships

      • More “peaceful,” less competition

      • Variety of relationships

      • Females have higher status

      • Female social relationships also important

    • Native to Congo Basin in Central Africa


    Photos:

    • See Google slides below:


    4: Apes is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts.

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