Paleoanthropology

The study of human and primate evolution. The study of human ancestors. The study of ancient populations. In order to determine how and when this evolution happens, we will need to look at dating methods used in archaeology.

Dating Methods Stratigraphy Carbon-14 dating Dendrochronology Relative Dating: comparative method which determines the sequence in time by showing which specimen is older, but not an exact date. Chronometric Dating: determines an “exact” date for a specimen or site.

Stratigraphy Is a relative dating tool The older something is, the deeper it is in the ground. Situations where using this method might be difficult?

Dendrochronology Chronometric dating method Trees tend to create one growth ring per year. By counting the rings on the tree, we know how old it is. Width of the ring depends on the moisture in the air during the year it formed. Ex: thicker rings = lots of rainfall.

Carbon-14 Chronometric method Is based on the “half-life” of carbon-14 that can be applied to organic remains. 12C is absorbed through plants, cosmic radiation causes 14C. When an organism dies the 14C begins to decay, the rate of decay (5,730 years for ½) is measured to determine how old the remains are. Oy5Ehttp:// Oy5E

Other Dating Methods Thermoluminescence: Radiometric decay; materials which were heated in the past and that release stored energy as light once reheated. Obsidian Hydration Dating Biostratigraphy: dating a site based on presence of certain fossil species.

Geologic Time The earth is 4.6 BILLION years old. The first primates evolved about 50 million years ago. The first hominins evolved about 6 million years ago. Geologically speaking, these last two dates are relatively recent events.

Carl Sagan’s Cosmic Calendar Big bang: January 1 Origin of the Milky Way: May 1 Origin of the solar system: September 9 Formation of Earth: September 14 Origin of life on earth: ~ September 25 Oldest fossils (bacteria and blue-green algae: October 9 First cells with nuclei: November 15th

Carl Sagan’s Cosmic Calendar

Geologic Time Eons: a major subdivision of geologic time. The history of earth is divided into 4 eons. Era: a subdivision of an eon. Period: a subdivision of an era. Epoch: a subdivision of a period.

Geologic Time Precambrian: contains 3 of the 4 eons. 90% of the earth’s history. –Hadean eon: 4,300-3,800 Ma. Origin of the earth prior to any fossil evidence of life. –Archean eon: 3,800-2,500 Ma. Fossils of first forms of life. Single-celled organisms. –Proterozoic eon: 2, Ma. Oxygen in the atmosphere, first multicelled organisms.

Geologic Time Phanerozoic eon: 542 million years ago to the present. –Rapid speciation –Divided into three geologic eras: the Paleozoic, Mesozoic, and Cenozoic.

Geologic Time: Paleozoic Era The first era of the Phanerozic eon Ma, First vertebrates (early fish to tetrapods). First reptiles = first land dwellers. Therapsids: “mammal-like reptiles.” Ancestors of early mammals.

Geologic Time: Mesozoic Era Ma. Triassic, Jurassic, and Cretaceous Periods “Age of Dinosaurs” First mammals (~200 Ma) Bird-like reptiles End of the Cretaceous period = mass extinction of the dinosaurs and many other organisms.

Geologic Time: Cenozoic Era 65.5 Ma to present. Primate and humans evolve. “Age of mammals.” Earliest primates = 50 Ma. Earliest primitive apes = 20 Ma. First hominins = 6 Ma

Fossils Paleospecies: Species identified in the fossil record. Identified based on physical similarities and differences to other species. Variation within species: sexual dimorphism, age, etc.

Paleoecology Paleoecology: the study of past environments. Palynology: the study of fossil pollen. Plays a large role within paleoecology.

Past Behavior In order to evaluate the behavioral patterns of human ancestors, paleoanthropologists use comparative data from nonhuman primates to make analogies regarding past populations. –Early studies: baboons: due to their savanna habitat.

Past Behavior Today, the chimpanzee is most often used, because it is the primate most related to us. The bonobo has also been used, it is equally related to us, because these two species split from each other AFTER the hominin line had already diverged from them.

Key Terms Sites: Locations of discoveries; both in paleontology and archaeology. Artifacts: Objects made or modified by hominins.

Experimental Archaeology A subfield of archeology: the study of manufacture and use of tools in order to learn how they were made and used. The only tools once used by human ancestors which are still preserved are stone (lithic) tools. –How did they use these tools? Experimental archaeology can help tell us!

Paleoanthropologists

Paleoanthropologists: Louis Leakey His idea to look for evidence of human ancestors in Africa was revolutionary. Most famous discoveries were in northern Tanzania at Olduvai Gorge.

Paleoanthropologists: Louis Leakey Proconsul Aficanus: likely a common ancestor for both humans and other primate species. Homo Habilis: “handy man.”

Paleoanthropologists: Mary Leakey Married to Luis Leakey. Australopithecus Boisei: (used to be known as Zinjanthropus boisei) Laetoli Footprints (belonging to Australopithecus afarensis).

Paleoanthropologists: Richard Leakey 1944-present Homo erectus, “Nariokotome Boy” (or “Turkana Boy”) Director of the National Museums of Kenya Head of Kenya Wildlife Services (KWS) Conversationalist: elephants and rhinos

Paleoanthropologists: Donald Johanson 1943-present Worked mostly in Ethiopia. With grad student Tom Gray, discovered the partial skeleton of Australopithecus afarensis, “Lucy” (1974) Homo Habilis

Paleoanthropologists: Tim White 1950-present Teaches at Berkeley. Ardipithecus Ramidus (Ardi) Worked with D. Johanson on Lucy.

Additional Resources “Lucy’s Legacy,” Donald Johanson “One Life,” Richard Leakey “Origins,” Louis Leakey /time/health/article/0,8599, ,00.htmlhttp:// /time/health/article/0,8599, ,00.html