Review List the two major groups of primates Review Which early hominine bones changed shape over time allowing for walking upright Apply Concepts Pick three characteristics of primates and explain how it benefits them

Ch 26 Animal Evolution and Diversity 26.3 Primate Evolution

What Is a Primate? Mammal that has Relatively long fingers and toes with nails instead of claws Arms that can rotate around shoulder joints Strong clavicle Binocular vision Well-developed cerebrum.

Fingers, Toes, and Shoulders Typically have five flexible fingers and toes on each hand or foot that can grip objects firmly and precisely.

Fingers, Toes, and Shoulders Most have opposable thumbs and big toes Move against the other digits, allowing them to hold objects firmly in their hands or feet.

Fingers, Toes, and Shoulders Arms can rotate in broad circles around a strong shoulder joint attached to a strong clavicle, or collar bone, making them well suited for climbing.

Binocular Vision Ability to combine visual images from both eyes, providing depth perception and a three- dimensional view of the world.

Well-Developed Cerebrum Cerebrum is large and intricate Enables more-complex behaviors than are found in many other mammals Many primate species create elaborate social systems that include extended families, adoption of orphans, and even warfare between rival troops.

Evolution of Primates

Lemurs and Lorises Small, nocturnal primates with large eyes adapted to seeing in the dark Bush babies of Africa, the lemurs of Madagascar, and the lorises of Asia.

Tarsiers Broad faces Widely separated nostrils More like “monkeys” than a lemur.

Anthropoids Humanlike primates Include monkeys, great apes, and humans.

New World Monkeys Found in Central and South America Live almost entirely in trees Long, flexible arms that enable them to swing from branches Prehensile tail Long tail that can coil tightly around a branch.

Old World Monkeys and Great Apes Spend time in trees but lack prehensile tails.

Hominoids Include gibbons, orangutans, gorillas, chimpanzees, and humans DNA analyses confirm that chimpanzees are humans’ closest relatives.

Hominines Split from lineage that led to chimpanzees 6 and 7 million years ago Include modern humans and all other species more closely related to us than to chimpanzees.

Hominine Evolution Ability to walk upright, grasping thumbs, and large brains.

Walking Upright Skull, neck, spinal column, hip bones, and leg bones of early hominine species changed to allow to walk upright.

Adaptations Bipedal Opposable thumb Much larger brains. Two-footed locomotion Freed both hands to use tools Opposable thumb Thumb could touch the tips of the fingers Allowed grasping of objects and the use of tools Much larger brains.

Australopithecus Lived from about 4 million to about 1.5 million years ago Were bipedal but skeletons suggest they probably spent some time in trees Teeth structure suggests diet rich in fruit Bipedal came before larger brains.

The Genus Homo About 2 million years ago, a new group of hominine species appeared.

At least three other Homo species existed at the same time as early humans.

Out of Africa

Hominines began migrating out of Africa at least 1.8 million years ago Fossil and molecular evidence suggest that some hominines left Africa long before Homo sapiens evolved and that more than one Homo species made the trip in waves.

Homo erectus traveled across India and through China to Southeast Asia Some of the oldest fossils found in Java.

“Out-of-Africa” model Multiregional model Modern humans evolved in several parts of the world independently from widely separated populations of H. erectus “Out-of-Africa” model Modern humans evolved in Africa about 200,000 years ago, migrated through the Middle East, and replaced the descendants of earlier hominine species.

Mitochondrial DNA analysis from living humans around the world determined the last shared common ancestor between 200,000 and 150,000 years ago.

DNA data suggest that a small subset of those African ancestors left northeastern Africa between 65,000 and 50,000 years ago to colonize the world, supporting the out-of-Africa hypothesis.

Homo neanderthalensis Began about 200,000 years ago Made stone tools, lived in complex social groups, had controlled use of fire, were excellent hunters, and performed simple burial rituals Survived until about 28,000–24,000.

Modern Homo sapiens Arrived in the Middle East from Africa about 100,000 years ago 50,000 years ago making more sophisticated stone blades and were making tools from bones and antlers Produced spectacular cave paintings and buried their dead with elaborate rituals.

Neanderthals and H. sapiens lived side by side in the Middle East for about 50,000 years Both groups moved into Europe, where they coexisted for several thousand years Neanderthals disappeared 24,000 years ago What happened?

Binocular Vision Throw a paper ball to your partner who should try to catch it with one hand- record if it was caught- do this 5 times Now have your partner close one eye and repeat step 1 Switch roles with your partner and repeat the process.