1. Copyright Pearson Prentice Hall
Biology
Copyright Pearson Prentice Hall

2. 32-3 Primates and Human Origins
Copyright Pearson Prentice Hall

3. Copyright Pearson Prentice Hall
What Is a Primate?
What characteristics do all primates share?
Copyright Pearson Prentice Hall

4. Copyright Pearson Prentice Hall
What Is a Primate?
What Is a Primate?
In general, primates have binocular vision, a well-developed cerebrum, relatively long fingers and toes, and arms that can rotate around their shoulder joints.
Copyright Pearson Prentice Hall

5. Copyright Pearson Prentice Hall
What Is a Primate?
Fingers, Toes, and Shoulders
Flexible digits enable primates to run along tree limbs and swing from branch to branch with ease.
Copyright Pearson Prentice Hall

6. Copyright Pearson Prentice Hall
What Is a Primate?
Primates’ arms are well adapted to climbing because they can rotate in broad circles around a strong shoulder joint.
In most primates, the thumb and big toe can move against the other digits. This characteristic allows primates to hold objects in their hands or feet.
Copyright Pearson Prentice Hall

7. Copyright Pearson Prentice Hall
What Is a Primate?
Well-Developed Cerebrum
The large cerebrum of primates enables them to display more complex behaviors than many other mammals.
Many species have social behaviors that include adoption of orphans and even warfare between rival primate troops.
Copyright Pearson Prentice Hall

8. Copyright Pearson Prentice Hall
What Is a Primate?
Binocular Vision 
Many primates have a flat face, so both eyes face forward with overlapping fields of view. This facial structure allows for binocular vision.
Binocular vision is the ability to merge visual images from both eyes, providing depth perception and a three-dimensional view of the world.
Copyright Pearson Prentice Hall

9. Copyright Pearson Prentice Hall
Evolution of Primates
What are the major evolutionary groups of primates?
Copyright Pearson Prentice Hall

10. Copyright Pearson Prentice Hall
Evolution of Primates
Evolution of Primates
The two main groups of primates are prosimians and anthropoids.
Copyright Pearson Prentice Hall

11. Lorises and bush babies
Evolution of Primates
Hominoids
New World monkeys
Lorises and bush babies
Old World monkeys
Lemurs
Tarsiers
Gibbons
Orangutans
Gorillas
Chimpanzees
Humans
The diagram illustrates the phylogeny of modern primates. The two main groups of primates are prosimians and anthropoids.
Prosimians
Anthropoids
Primate ancestor
Copyright Pearson Prentice Hall

12. Copyright Pearson Prentice Hall
Evolution of Primates
Prosimians 
Most prosimians alive today are small, nocturnal primates with large eyes that are adapted to seeing in the dark.
Living prosimians include bush babies, lemurs, lorises, and tarsiers.
Copyright Pearson Prentice Hall

13. Lorises and bush babies
Evolution of Primates
Lorises and bush babies
Lemurs
Tarsiers
Prosimians
Primate ancestor
Copyright Pearson Prentice Hall

14. Copyright Pearson Prentice Hall
Evolution of Primates
Anthropoids  
Humans, apes, and most monkeys belong to a group called anthropoids, which means humanlike primates.
This group split early in its evolutionary history into two major branches.
These branches separated as drifting continents moved apart.
Copyright Pearson Prentice Hall

15. Copyright Pearson Prentice Hall
Evolution of Primates
New World monkeys
Old World monkeys
Gibbons
Orangutans
Gorillas
Chimpanzees
Humans
Anthropoids
Copyright Pearson Prentice Hall

16. Copyright Pearson Prentice Hall
Evolution of Primates
One branch of anthropoids is the New World monkeys. New World monkeys:
live almost entirely in trees.
have long, flexible arms to swing from branches.
have a prehensile tail, which is a tail that can coil around a branch to serve as a “fifth hand.”
Copyright Pearson Prentice Hall

17. Copyright Pearson Prentice Hall
Evolution of Primates
The other group of anthropoids includes Old World monkeys and great apes.
Old World monkeys live in trees but lack prehensile tails.
Great apes, also called hominoids, include gibbons, orangutans, gorillas, chimpanzees, and humans.
Copyright Pearson Prentice Hall

18. Copyright Pearson Prentice Hall
Hominid Evolution
Hominid Evolution
Between 6 and 7 million years ago, the hominoid line gave rise to hominids. The hominid family includes modern humans.
As hominids evolved, they began to walk upright and developed thumbs adapted for grasping.
They also developed large brains.
Copyright Pearson Prentice Hall

19. Copyright Pearson Prentice Hall
Hominid Evolution
Modern human
Copyright Pearson Prentice Hall

20. Copyright Pearson Prentice Hall
Hominid Evolution
Copyright Pearson Prentice Hall

21. Copyright Pearson Prentice Hall
Hominid Evolution
The skull, neck, spinal column, hipbones, and leg bones of early hominid species changed shape in ways that enabled later hominid species to walk upright.
Evolution of this bipedal, or two-foot, locomotion freed both hands to use tools.
Hominids evolved an opposable thumb that enabled grasping objects and using tools.
Copyright Pearson Prentice Hall

22. Copyright Pearson Prentice Hall
Hominid Evolution
Hominids displayed a remarkable increase in brain size, especially in an expanded cerebrum—the “thinking” area of the brain.
Copyright Pearson Prentice Hall

23. Copyright Pearson Prentice Hall
Hominid Evolution
Early Hominids 
At present, the hominid fossil record includes these genera:
Ardipithecus
Australopithecus
Paranthropus
Kenyanthropus
Homo
Copyright Pearson Prentice Hall

24. Copyright Pearson Prentice Hall
Hominid Evolution
There are as many as 20 separate hominid species.
This diverse group of hominid fossils covers roughly 6 million years.
All are relatives of modern humans, but not all are human ancestors.
Questions remain about how fossil hominids are related to one another and to humans.
Copyright Pearson Prentice Hall

25. Copyright Pearson Prentice Hall
Hominid Evolution
Australopithecus 
An early hominid species, Australopithecus, lived from about 4 million to 1 million years ago.
The structure of Australopithecus teeth suggests a diet rich in fruit.
Copyright Pearson Prentice Hall

26. Copyright Pearson Prentice Hall
Hominid Evolution
The best known species is Australopithecus afarensis—based on a female skeleton named Lucy, who was 1 meter tall.
Members of the Australopithecus species were bipedal and spent some time in trees.
Copyright Pearson Prentice Hall

27. Copyright Pearson Prentice Hall
Hominid Evolution
Paranthropus 
The Paranthropus species had huge, grinding back teeth.
Their diets probably included coarse and fibrous plant foods.
Copyright Pearson Prentice Hall

28. Copyright Pearson Prentice Hall
Hominid Evolution
Recent Hominid Discoveries 
In 2001, a team had discovered a skull in Kenya.
Its ear resembled a chimpanzee’s.
Its brain was small.
Its facial features resembled those of Homo fossils.
It was put in a new genus, Kenyanthropus, which lived at the same time as A. afarensis.
Copyright Pearson Prentice Hall

29. Copyright Pearson Prentice Hall
Hominid Evolution
Photo Credit: left: Fred Spoor, copyright National Museum of Kenya; right: Animals Animals/©E.R. Degginger
Kenyanthropus platyops
Homo erectus
Copyright Pearson Prentice Hall

30. Copyright Pearson Prentice Hall
Hominid Evolution
In 2002, paleontologists working in the desert in north-central Africa discovered another skull.
Called Sahelanthropus, it is nearly 7 million years old.
If it is a hominid, it would be a million years older than any hominid previously known.
It had a brain like a modern chimp and a flat face like a human.
Copyright Pearson Prentice Hall

31. Sahelanthropus tchadensis
Hominid Evolution
Photo Credit: copyright M.P.F.T.
Sahelanthropus tchadensis
Copyright Pearson Prentice Hall

32. Copyright Pearson Prentice Hall
Hominid Evolution
What is the current scientific thinking about hominid evolution?
Copyright Pearson Prentice Hall

33. Copyright Pearson Prentice Hall
Hominid Evolution
Rethinking Early Hominid Evolution 
Researchers once thought that human evolution took place in steps, in which hominid species became gradually more humanlike.
Copyright Pearson Prentice Hall

34. Copyright Pearson Prentice Hall
Hominid Evolution
Hominid evolution did not proceed by the simple, straight-line transformation of one species into another.
Rather, a series of complex adaptive radiations produced a large number of species whose relationships are difficult to determine.
Copyright Pearson Prentice Hall

35. Copyright Pearson Prentice Hall
Hominid Evolution
The diagram shows fossil hominids and the time ranges during which they may have existed. The time ranges are likely to change as paleontologists gather new data. The question mark after Sahelanthropus tchadensis indicates that scientists are not yet certain that this species is a hominid. Paleontologists do not yet have enough information to know how hominid species are related. It is now clear that hominid evolution did not proceed by the simple, straight-line transformation of one species into another. Current hypotheses about early stages of human evolution recognize the incompleteness of the data.
Millions of years ago
Copyright Pearson Prentice Hall

36. Copyright Pearson Prentice Hall
Hominid Evolution
The hominid fossil record dates back 7 million years, close to the time that DNA studies suggest for the split between hominids and the ancestors of modern chimpanzees.
Copyright Pearson Prentice Hall

37. The Road to Modern Humans
Paleontologists still do not completely understand the history and relationships of species within our own genus.
Other species in the genus Homo existed before Homo sapiens.
Copyright Pearson Prentice Hall

38. The Road to Modern Humans
The Genus Homo
The first fossils in the genus Homo are about 2.5 million years old.
These fossils were found with tools, so researchers called the species Homo habilis, which means “handy man.”
Copyright Pearson Prentice Hall

39. The Road to Modern Humans
2 million years ago, a species called Homo ergaster appeared. It had a bigger brain and downward-facing nostrils that resembled those of modern humans.
At some point, either H. ergaster or a related species named Homo erectus began migrating out of Africa through the Middle East.
Copyright Pearson Prentice Hall

40. The Road to Modern Humans
Out of Africa—But Who and When?
Evidence suggests that hominids left Africa in several waves, as shown in the following diagram.
Copyright Pearson Prentice Hall

41. The Road to Modern Humans
Data show that relatives and ancestors of modern humans left Africa several different times. But when did early hominids leave Africa, and how far did they travel? By comparing the mitochondrial DNA of human populations around the world and by continuing to study the fossil record, scientists hope to improve our understanding of the complex history of Homo sapiens.
Copyright Pearson Prentice Hall

42. The Road to Modern Humans
It is not certain where and when Homo sapiens arose.
One hypothesis, the multi-regional model, suggests that modern humans evolved independently in several parts of the world from widely separated populations of H. erectus.
Copyright Pearson Prentice Hall

43. The Road to Modern Humans
Another hypothesis, the out-of-Africa model, proposes that modern humans evolved in Africa between 200,000–150,000 years ago, migrated out to colonize the world, and replaced the descendants of earlier hominid species.
Copyright Pearson Prentice Hall

44. Copyright Pearson Prentice Hall
Modern Homo sapiens
Modern Homo sapiens
The story of modern humans over the past 500,000 years involves two main groups.
Copyright Pearson Prentice Hall

45. Copyright Pearson Prentice Hall
Modern Homo sapiens
The earliest of these species is called Homo neanderthalensis.
Neanderthals lived in Europe and Asia 200,000–30,000 years ago.
They made stone tools and lived in organized social groups.
The other group is Homo sapiens—people whose skeletons look like those of modern humans.
Copyright Pearson Prentice Hall

46. Copyright Pearson Prentice Hall
Modern Homo sapiens
50,000–40,000 years ago some populations of H. sapiens seem to have changed their way of life:
They made more sophisticated stone blades and elaborately worked tools from bones and antlers.
They produced cave paintings.
They buried their dead with elaborate rituals.
Copyright Pearson Prentice Hall

47. Copyright Pearson Prentice Hall
Modern Homo sapiens
About 40,000 years ago, a group known as Cro-Magnons appeared in Europe.
By 30,000 years ago, Neanderthals had disappeared from Europe and the Middle East.
Since that time, our species has been Earth’s only hominid.
Copyright Pearson Prentice Hall

48. Copyright Pearson Prentice Hall
32-3
Copyright Pearson Prentice Hall

49. Copyright Pearson Prentice Hall
32-3
The ability to merge visual images from both eyes is called
monocular vision.
binocular vision.
overlapping vision.
color vision.
Copyright Pearson Prentice Hall

50. Copyright Pearson Prentice Hall
32-3
Which of the following is true about hominid evolution?
The development of a large brain happened before bipedal locomotion.
There is a straight line of descent from the earliest hominid species to Homo sapiens.
The genus Homo appeared before the genus Australopithecus.
Hominid evolution took place as a series of adaptive radiations that produced a large number of species.
Copyright Pearson Prentice Hall

51. Copyright Pearson Prentice Hall
32-3
The evolution of bipedal locomotion was important because it
increased brain size.
made it easier to see.
freed both hands to use tools.
allowed easier escape from predators.
Copyright Pearson Prentice Hall

52. Copyright Pearson Prentice Hall
32-3
The multi-regional model hypothesizes that
a. Homo sapiens evolved independently in several parts of the world.
b. Modern humans evolved in Africa, then migrated to various parts of the world.
c. Neanderthals produced cave drawings.
d. Homo habilis descended from Homo erectus.
Copyright Pearson Prentice Hall

53. Copyright Pearson Prentice Hall
32-3
The oldest known Homo sapiens skeletons are about
6,000 years old.
100,000 years old.
3 million years old.
30 million years old.
Copyright Pearson Prentice Hall

54. END OF SECTION