1. Chapter 11 Primates and Human Evolution

2. Primate Characters
Grasping hands and feet with thumb and big toe often opposable
Sensitive pads on fingertips and nails instead of claws
A mobile shoulder joint, especially in humans
Large braincase and a postorbital bar
Flattened face with eyes rotated forward for stereoscopic vision
Usually have one offspring at a time
Females have only two mammary glands

3. Anthropoid Origins
Anthropoid (“human-like”) primates were thought to have originated in Africa.
Recent finds from the early Eocene of China and Thailand (above) have challenged this view because they are older.
Anthropoids are distinct in having rounded nostrils (not slit-like as in prosimians), usually large canines, molar-like premolars, and broad square molars.

4. Miocene Apes
Proconsul is the best- known early ape, early Miocene of Kenya.
Proconsul is designed for diverse locomotion styles (quadrupedal running, standing upright, swinging from branches) and could probably swing a stick for defense.
Proconsul

5. Hominoid Relationships
Hominidae – great apes
Hylobatidae – lesser apes
Pongidae (ape family) has been eliminated as a paraphyletic group, and Hominidae (human family) has been expanded to include most apes. Note in the right diagram that no common ancestors are known!

6. Classification of Apes and Humans
Superfamily Hominoidea
Family Hylobatidae – gibbons
Smaller tree-climbing apes
Family Hominidae
Subfamily Ponginae – Orang-utans
Slow climbers and brachiators
Subfamily Homininae
Terrestrial quadrupeds – chimps and gorillas
Infrafamily Hominini – Terrestrial bipeds – humans
Monophyletic group of humans and their closest relatives

7. Apes
Apes arose in the Miocene of Africa as grasslands developed there, have short 5‑cusp molars
Early-middle Miocene: Dryomorphs
Large canines, Africa to Eurasia
Middle-late Miocene: Ramapithecines
Small canines, very diverse, Africa to Asia
Pliocene: poor fossil record leaves many questions about hominid relationships, including the origins of living groups of apes
Baboon
Chimp

8. Apes
It was long believed that Ramapithecus was the first human and that the human/ape split occurred 15 M.Y. ago. DNA and protein similarities, however, suggested a mere 5 M.Y. ago split, with man, chimp, and gorilla being equally similar. Discovery of more skeletal material suggested that Ramapithecus is an orang-utan.
Gorillas and chimps have no definite fossil record, so tracing their ancestry is difficult.

9. Late Miocene Apes Sivapithecus (=Ramapithecus) of China region
Modern human
Chimp
Lower jaw of Gigantopithe-cus (late Miocene of India and Pleistocene of China)
Jaw and molars of Sivapithecus showing “Y” and cusp pattern
Hand of Dryopithecus

10. Humans and Upright Posture
Grasping hand
Gorilla
Loss of opposable toe in foot
Foot flat with straight toes for plantigrade walking
Walking on knuckles

11. Modifications for Bipedalism
Skull with ventral foramen magnum
Backbone develops an S-curve
Pelvis short with bowl-shaped ilium to support abdominal organs
Hip joint faces downward and sideways
Long, slender leg bones
Knee forms a straight hinge for standing
Foot a flat platform with non-opposable toes

12. Reasons for Bipedalism
Ability to stand tall for a better view
Freeing up the hands to use tools
Faster or more efficient locomotion
One theory is that forest-dwelling apes became restricted to west Africa where they gave rise to chimps and gorillas, while humans arose as an adaption to the open grasslands in east Africa.

13. Brain First Theory
The early popular theory was that the big brain was required for tool use, so it came before bipedalism.
This was confirmed by a skull at Piltdown, England, with a large braincase but primitive jaws (a).
Piltdown man turned out to be a hoax (a human cranium planted with an orang-utan jaw).
Australopithicus found in Africa (b) disproved the brain first theory with its small brain and bipedalism.

14. Piltdown Man Discovered 1912 near Piltdown, East Sussex, England
Exposed as a fraud in 1953
Parts of human skull and orang- utan jaw etched with acid and buried at an excavation site.
Why was the hoax so readily accepted by England’s experts?

15. Piltdown Man Most human fossils had been found in Africa.
There were racist views about Africa.
It was a relief to find evidence of human evolution in Europe.
Though the skull was from a modern human, Piltdown was considered intermediate in brain size between Homo erectus and Neanderthal Man!

16. Adult Chimp
Adult Human
Juvenile Chimp
Juvenile Chimp
Juvenile Human
Neoteny is the evolutionary process where juvenile traits are retained into adulthood.
Human evolution may be a case of neoteny. Enlargement of the human brain could have been accomplished by retaining the juvenile proportions of an ape. This could also explain the loss of hair in humans. But it fails to explain our large legs.

17. Early Human Fossils
Orrorin – teeth, jaw fragments, broken limb bones that suggest bipedalism, 6 M.Y. old
Sahelanthropus – distorted cranium (at right) with foramen magnum that suggests bipedalism, 6 M.Y. old
Ardipithecus – teeth, skull fragments, and limb bones from several individuals with somewhat large canines, thin tooth enamel, and clear evidence of bipedalism, 5.8 to 4.4 M.Y. old
Praeanthropus – Lucy (most of skeleton found in 1974) and other bones and teeth, 4.1 to 2.9 M.Y. old

18. Praeanthropus walked fully upright
Early hominids had the distinct human pelvis for upright walking. Fossil trackways also demonstrate full bipedality.

19. Evolution of Human Characters
Chimp
Ardipithecus
Praeanthropus
Palate of Lucy
Ape
Legs
Modern human
Fingers
Skeleton of Lucy (Praeanthropus), the most complete early hominid skeleton
Ape Praeanthropus Modern human

20. Australopiths All previously included in genus Australopithecus
Praeanthropus – small primitive forms such as Lucy (P. afarensis) with strong sexual dimorphism
Australopithecus – advanced gracile australo- piths that probably gave rise to Homo
Paranthropus – robust australopiths with broad faces and massive jaws (at right)
The last two have small canines and no diastema

21. Human Timeline

22. Later Australopiths
Australopithecus africanus (gracile, M.Y. ago)
Paranthropus robustus (robust, M.Y. ago)
Paranthropus boisei (robust, M.Y. old)

23. Human Relationships

24. Hominid Species Hominid species Age Brain size Height
Praeanthropus afarensis 4.0‑3.0 M.Y. 380‑450 cc 1.2 m
Australopithecus africanus 3.0‑2.3 M.Y. 380‑450 cc 1.4 m
Paranthropus robustus 1.9‑1.6 M.Y. 380‑450 cc 1.5 m
Paranthropus boisei 2.2‑1.2 M.Y. 380‑450 cc 1.5 m
Homo habilis 2.0‑1.6 M.Y. 630‑700 cc 1.3 m
Homo erectus 1.6‑0.3 M.Y. 800‑1300 cc 1.7 m
Homo sapiens 0.1‑0.0 M.Y. 1000‑2000 cc 1.8 m
- Neanderthal Man (replaced Homo erectus, large brow ridges, elaborate burials)
- Cro‑Magnon Man (replaced Neanderthal 40,000 yr, made cave art in France/Spain)
- Modern Man (developed from earlier forms, domesticated plants and animals)

25. Early Species of Homo
Homo habilis (“handy man”) was discovered in Olduvai Gorge, Kenya, in the 1960s by Louis Leakey and has a much larger brain than the australopiths.
Homo rudolfensis is a possible second species from Kenya with a larger brain but other more primitive features (skull above).
Without the enlarged brain both would better be classified as australopiths. Both are M.Y old.

26. Earliest Homo (Africa)
Homo habilis and Homo rudolfensis represent one or two species of early Homo from Kenya.
Homo probably evolved from the Australopithecus africanus.
The primary feature is a large increase in cranial size over Australopithecus.
Homo coexisted with robust Australopithecus for about a million years.
Homo habilis

27. Homo erectus – Exiting Africa
Prior to 2 mil-lion years ago humans were restricted to eastern Africa.
The earliest Homo erectus (or H. ergaster) (a) dates to 1.9 M.Y. ago and has a brain size of 830 cm3 but retains heavy jaws and brow and lacks a chin.
More specialized Homo erectus material is found throughout Eurasia dating M.Y. ago along with Acheulean hand axes (b-d).

28. Evolution of Homo Peking Man (Homo erectus) Neanderthal Man
Common in Africa and Asia
Neanderthal Man
(Homo sapiens neanderthalensis)
Common in Africa and Europe

29. Stone Tools
Neanderthal
(Homo sapiens)
Homo erectus
Homo habilis

30. Neanderthal Man
Neanderthal Man (a, c) is an archaic form of Homo sapiens that branched off half a million years ago and lived till 30,000 years ago.
Compared to modern man (b) they had a similar brain size but differences in head shape. Invading Cro Magnon man may have killed them.

31. Modern Man
Found in Africa and Israel dating back 100, ,000 years ago (skull above)
Spread into Europe 40,000 years ago (Cro-Magnon Man), but no evidence they mixed with Neanderthals, and to Australia at the same time
DNA evidence shows that the latest common ancestor of all living humans lived about 200,000 years ago in Africa (“Mitochondrial Eve”).

32. Dispersal of Modern Humans
The Americas were the last continents to be colonized, with the oldest well-documented site in Chile! The Ice-Age Bering Land Bridge is the obvious route, but there’s debate whether they tra-veled inland (big game hunters) or along the coast (fishermen).

33. Humans arrived in the Americas about 14,000 years ago.
The old theory is that humans traveled between the ice sheets of Canada in what is called the “ice-free corridor.”
An newer theory is that they came down the Pacific Coast by boat (supported by Dr. Heaton’s Alaska research).

34. LGM Ice Cover

35. Cast of human mandible in On Your Knees Cave (9,800 yr B.P.)
By Erik Hill,
Anchorage Daily News

36. Archaeological Excavation at On Your Knees Cave
Many bifaces, microblades, bone tools, and cultural charcoal beds were found inside and outside the cave.

37. Common mammals from On Your Knees Cave
Middle Wisconsin 50,000-24,000 yr B.P.
Brown bear
Black bear
Arctic fox
River otter
Harbor seal
Steller’s sea lion
Caribou
Saiga (or goat)
Long-tailed vole
Hoary marmot >
Heather vole >
Brown lemming >
Last Glacial Maximum 24,000-13,000 yr. B.P.
Red fox
Ringed seal
Maybe
Otter/Mink
Postglacial ,000 yr B.P.-present
Black-tailed deer
Human
Bold indicates index species

38. The Northwest Coast
The coast had more exposed land area during the Last Glacial Maximum than previously thought.
The period of maximum ice cover was very brief.
The coast provided an easy means of transportation
The coast had a more moderated climate then the interior.
The coast had a rich supply of seafood.
Making a living along the coast required similar culture at all latitudes, whereas traversing the interior requires diverse adaptations.
This could explain the rapid colonization of North and South America.