Lesson 7 - Non-Human Primates & Human Evolution

Why study primates?

• Understand human biology, social behavior, culture

• Formulate hypothesis of how our ancestors behaved

• Living primates are still evolving (Primates have all evolved, so other primates are not replica of our shared common ancestors from thousands/millions of years ago)

How are there variations in primates?

There is great variation in primates

• Heterogeneous order (~500 species)

• Body size (from 40g mouse lemur to 200 kg gorilla)

• Brain size (2g in mouse lemur to 1.2 kg humans)

Show primate taxonomy.

Important names:

• Strepsirrhine

  • Some members of this group are lemurs

  • Primates that rely a lot on their sense of smell

• Haplorhine

  • Includes tarsier

  • Other group includes catarrhines and platyrrhines.

    • Catarrhines are from Old World (Africa + Asia). Two main groups:

      • Monkeys (cercopithecoidea) – external tail

      • Apes (hominoidea into subgroup hominidae) – lost ext. tail

    • Platyrrhine are from New World (Americas)

What is a primate?

• Grasping hands and feet (and tail)

• Opposable thumb (and toe)

▪ Flattened nails instead of claws (except marmosets, tamarins)

▪ Fingertip pads

• Diurnal (most primates, but some nocturnal)

• Arboreal (live in trees, humans are exceptions)

• Forward-facing eyes (depth perception, important for animals that jump from trees to trees)

• Increased reliance vision and less on olfaction (Other than strepsirrhine)

• Give birth to one offspring at a time (exception: marsupials usually give birth to twins)

• This is bc there is longer gestation + offspring dependency once born

• Diet: leaves, fruit, insects, some meat

• Generalized dentition (leaves, fruits, plant products, insects, small mammals)

• Large brains (relative to body size)

• Longer offspring dependency on mother

• Live in social groups (hierarchies, complex relationships)

(Not all primates have all these features, but have at least a few)

How do we study primates?

• Primatology, biological anthropology, comparative psychology

• Wild settings

• Zoos, research facilities

Primatology + Bio Anthro = mostly study in wild settings

Comp Psych = mostly study in captivity

What is researched with primates?

• Communication

• Social behavior, social structure

• Aggressive behavior

• Affiliative behavior

• Subsistence, diet, ecology

• Tool use

• Life history

• Conservation

Humans & Primates history.

• Origin of all primates ca 70-80mya

• Origin of old world monkeys and apes ca 30mya

• Important point: Shared common ancestor of humans and chimpanzees lived ca 7mya

  • Ie. we are most similar to chimpanzees, and they are more similar to us than either of us are to gorillas or orangutans

What are some key points about primates?

• Independent lines of research confirm that we are primates

• Primates originated around 70-79 mya

• Humans closest living relatives are great apes of Africa

• Humans closest living relative among the great apes of Africa are chimpanzees (Pan troglodytes) and bonobos (Pan paniscus)

• Have been looking at genetic + molecular data to confirm lineages → confirms anatomical data and that we are indeed primates

What are hominins?

• Modern humans and extinct ancestors.

• It is a subtribe, the group of individuals that include us and all other hominin species that are very closely related to us after split with chimpanzees

• The reason there are lots of skulls is because we know these close species due to fossil records

• It’s a very populated lineage, a lot happened, a lot of species lived during the 7 million years, and we are the only ones that survived

Who were two important contributors who started the fossil record?

William King (geologist) 1809-1886 → Homo Neanderthalensis (1864)

Raymond Dart 1893-1988), anatomist, anthropologist → Australopithecus Africanus (Taung child, 2.8 mya)

• Often the names of species come from the place they found the fossils

What is an example of a Possible Hominin?

Sahelanthropus tchadensis

• Discovered: 2001

• Where: West-central Africa (Chad) • When: 7-6 mya

• Small brain

• Prominent brow ridges

• Elongated skull

• Smaller canines

• Forward foramen magnum

• Walking upright

More sloping than our face, large canines (but smaller than other apes)

Mixed traits between what humans and apes would look like

It’s debated whether they walked upright

A specific hole in the skull (where the spine connects to the brain) can help show whether a species walk upright or not (humans it’s more centered, walk upright vs. chimpanzee it’s more in the back, means walks on all fours) – this species it’s debated whether the hole is in the center or far enough back to move more like an ape or a human

What is an example of an Archaic Hominin?

Australopithecus Afarensis (Lucy), Australopithecus Africanus

• 3.85 and 2.95 mya

• Southern, Eastern Africa

• Strong arms for climbing trees

• Ape-like face

• Smaller canines

• Small brain (400 cm3)

• Diet: grasses, seeds, roots (strong jaws)

• Adaptations for both life on ground and trees

Usually have a combination of ape-like features (long arms to live in trees, ape-like face) and human-like features (smaller canines like us)

Remember the two names on the slide (afarensis lived in east Africa, africanus lived in south Africa)

What is an example of a Megadont Archaic Hominin?

Paranthropus boisei

• Discovered: 1959

• 2.3-1.2 mya

• Lived in East Africa

• Large molars for grinding

• Large ridge at top of skull to anchor large jaw muscles

Large teeth: Prominent ridge at top of skull that controls muscles of jaw, implies they have massive muscles to control the jaw to use their teeth a lot to grind touch materials