Human Evolution

1. Human Evolution

2. Paleoanthropologists- individuals who study fossil evidence of human evolution (also known as biological anthropologists) • Much of information established by these scientists have come from the fossils of early Hominids (humans and their immediate ancestors) • The fossils speak to these scientists about how they walked, how large the brain of an organism, an organism’s diet, etc. • The immediate surroundings of a fossil, such as tools, bones of prey, the plant remains, and pollen grains.

3. Hominids belong to the Order Primates. • 2 large divisions of modern Primates: • Anthropoid Primates: marmosets, monkeys, apes, humans. • Prosimian Primates: lemurs, lorises, tarsiers. • Pygmy Marmoset Lemur Tarsier

4. Characteristics of Primates: • They have movable fingers and toes. • Flat nails not claws. • Prehensile hands and in most species feet. • Prehensile- grasping. • Color vision- unlike most mammals. • Binocular vision- helps w/ depth perception. • Characteristics of Anthropoids: • Opposable thumbs- helps in the grasping aspect and efficiency of hand usage. • In non-human species opposable big toes which aide in climbing. • Large brains- relative to body size.

5. Characteristics of Humans • Bipedalism- the ability to walk primarily on two legs. • Smaller toes that are aligned w/ each other. • Humans are the only primate w/ this foot structure. • Enlarged brain which results in a more vertical face. • Extensive areas devoted to speech recognition and production.

6. Australopithecus afarensis, one of the earliest human species, lived between 4 million and 3 million years ago. This skull cast is a composite of bone fragments from different individuals of this species. The lighter portions represent bone fragments, and the missing pieces are filled in to reveal what an entire skull probably looked like. F. Schneidermeyer/Oxford Scientific Films http://encarta.msn.com/media_461516621_761566394_-1_1/Australopithecus_afarensis.html

7. In 1974 American paleoanthropologist Donald Johanson discovered the skeleton of “Lucy,” a 3.2-million-year-old female of the early human species Australopithecus afarensis, at Hadar, Ethiopia. Until the late 1990s, Lucy’s was the most complete skeleton of an australopithecine ever found. Australopithecines were primitive humans that first evolved over 4.4 million years ago. Lucy’s pelvis and leg bones, similar to those of modern humans, indicate that she regularly walked upright. John Reader/Science Photo Library/Photo Researchers, Inc. http://encarta.msn.com/media_461542649_761566394_-1_1/Lucy.html

8. Australopithecus afarensis (A. afarensis) means “southern ape of the Afar Valley” • Those fossils similar to Lucy have been designated australopithecines from the genus Australopithecus. • Australopithecus africanus dates from about 2.3 – 3 mya; probably descended from A. afaranesis. • taller and heavier than Lucy; larger cranial capacity. • Australopithecus robustus and A. boisei date from 1 – 2.6 mya. • heavier skulls,larger teeth than Lucy; larger cranial capacity than A. africanus. • Not thought to be ancestral to modern humans.

9. The genus Homo was established after paleoanthropologists discovered a skull, in the early 1960’s, w/ a much larger brain case than the australopithecines. • Homo habilis- means “handy human” • found along w/ stone tools. • fossils found in southern and eastern Africa. • 1.6-2.5 million years old (myo). • research indicates the region of the brain responsible for speech existed in this species. • thought to have ate meat due to tool marks on animal bones.

10. Homo erectus- means “upright human”; found as early as 1891. • Originally found on Pacific island of Java, since in China, Europe, and Africa. • thought to be 1st hominid to travel outside of Africa. • 1.8 million-50,000 years old. • thicker skull than modern humans. • Traces of charred bones indicate H. erectus were hunters who used fires for cooking and probably warmth. • It is believed, due to the climates in Europe and northern Asia, most lived in caves.

11. Homo sapiens- said to be an early form of our species that is now extinct. • Arose about 800,000 years ago until about 50-35,000 years ago. • Scientists believe H. sapiens and H. erectus coexisted about 700,000 years. • Neanderthals- belongs to H. sapiens • 230,000-30,000 years ago. • Heavy bones, thick brow ridges, protruding teeth. • Slightly larger cranial capacity of modern humans. • Stood about 5 ft tall. • Lived in caves and stone shelters. • It is speculated they wore clothing made of animal skins. • Scientists do not believe they were ancestral to modern humans.

12. H. sapiens sapiens- modern humans • 1st fossils w/ distinguished features of modern humans found in caves in southwestern France. • About 100,000 years old; coexisted w/ Neanderthals about 70,000 years and w/ H. erectus about 50,000. • Early modern humans known as Cro-Magnons, named for the caves for where the fossils were found. • About 6 ft tall. • Many phenotypic differences w/ in species but all able to interbreed and produce offspring.

13. 1 1 1 A. africanus Homo habilis Australopithecus  afarensis 1. (Source: Larry Williams sculptures, http://www.landofskulls.com/) http://www.ecotao.com/holism/hu_habilis.htm 2 2 3 Homo erectus Neanderthal Homo sapiens 3. http://www.boneclones.com/bh-032.htm 2. http://cogweb.ucla.edu/ep/Homininae_skulls.html