Primates and Human Origins Chapter 32-3 Primates and Human Origins

Carolus Linnaeus named our order Primates, which means __ In Latin? What is a Primate? All Primates have: Binocular vision Well-Developed Cerebrum Relatively long fingers and toes Arms that can rotate around their shoulder joints

Binocular Vision Is the ability to merge visual images from both eyes, thereby providing depth perception and a three-dimensional view of the world. Many primates have a flat face, so both eyes face forward with overlapping fields of view.

Well-Developed Cerebrum The large and intricate cerebrum of primates – including a well-developed cerebral cortex – enables them to display more complex behaviors than many other mammals. Many primate species have elaborate social behaviors that include adoption of orphans and even warfare between rival primate troops.

Fingers and Toes Primates normally have five flexible fingers that can curl around objects, most also have flexible toes. These flexible digits enable many primates to run along tree limbs and swing from branch to branch with ease. In most primates the thumb and the big toe can move against the other digits (called an opposable thumb), this adaptation allows many primates to hold objects firmly in their hands or feet.

Shoulders Primates are well adapted to climbing because they can rotate in broad circles around a strong shoulder joint.

Evolution of Primates It is hypothesized that humans and other primates evolved from a common ancestor that lived more than 65 million years ago. Primates that evolved from two of the earliest branches look very little like typical monkeys and are called prosimians (lemurs, tarsiers, lorises, and bush babies)

1.) Prosimians Most prosimians alive today are small, nocturnal primates with large eyes that are adapted to seeing in the dark. Many have doglike snouts. Examples (living today): Bush babies of Africa, Lemurs of Madagascar Lorises and Tarsiers of Asia

2.) Anthropoids Members of the primate group that includes monkeys, apes, and humans. This group split very early into two major branches. One branch, found today in Central and South America, is called the New World monkeys Ex: spider and squirrel monkeys These monkeys have long, flexible arms that enable them to swing from branch to branch. They also have a prehensile tail, which is a tail that can coil tightly enough around a branch to serve as a “fifth hand”.

2.) Anthropoids continued The other anthropoid group, which evolved in Africa and Asia, includes the Old World Monkeys and the Great Apes. Old world monkeys, such as langurs and macaques, spend time in trees but lack prehensile tails. Great apes, also called hominoids, include gibbons, orangutans, gorillas, chimpanzees, and humans.

Hominid Evolution Between 6 and 7 million years ago, the hominoid line gave rise to a branch that ultimately let to the ancestors and closest relatives of modern humans, the hominid family. The hominids displayed several distinct evolutionary trends. Over millions of years, they became able to walk upright and developed opposable thumbs, and large brains. The skull, neck, spinal column, hipbones, and leg bones of early hominid species changed shape in ways that enabled later species to be bipedal, walk upright, this freed both hands to use tools.

Early Hominids At present, most paleontologists agree that the hominid fossil record includes at least these genera: Ardipithecus, Australopithecus, Paranthropus, Kenyanthropus, and Homo (as many as 20 separate species. This diverse group of hominid fossils covers roughly 6 million years. All these species are relatives of modern humans, but not all of them are human ancestors.

Australopithecus Early group of hominids, lived from about 4 million to 1 million years ago. They were bipedal apes that spent at least some time in trees. Structure of their teeth suggest a diet rich in fruit. Small brains Lucy

Paranthropus Grew to the size of well-fed linebackers. Huge, grinding back teeth. Diet probably included coarse and fibrous plant foods. All died out.

Kenyanthropus and Sahelanthropus Kenyanthropus skull was discovered in Kenya by Meave Leakey in 2001. Ear structure resembled those of chimpanzees, and its brain was rather small. Existed at the same time as the A. afarensis. Sahelanthropus skull was found in 2002 in West Africa. Brain size of a modern chimp, yet it has a short, flat face more like that of a human. Lived about 7 million years ago, there is debate about whether it is a hominid or not.

Genus Homo Homo habilis “handy man” lived about 2.5 million years ago, used stone and bone tools. Homo ergaster had a larger brain and downward-facing nostrils lived about 2 million years ago. Homo erectus lived from .2 to 1.8 million years ago, migrated out of Africa and through the middle east into china.

Migration Patterns

The Road To Modern Humans Homo neanderthalsis – named after the Neander Valley in Germany where their remains were found. Made stone tools and lived in organized social groups. Lived 200,000 to 30,000 years ago. Homo sapiens – Lived 100,000 years ago to present. Sometime around 40 – 50 thousand years ago they began using new technology to make more sophisticated tools and changed their way of life. One group of Homo sapiens called Cro-Magnons lived in Europe about 40,000 years ago and are thought to be the ancestors of modern humans.