Chapter 3 Flashcards
Evolution
change over time and space
Two major aspects of evolution
- descent with modification
- natural selection
Decent with modification and natural selection
over very long periods explaining the vast variety of life on earth
Species
a group of organisms that can produce fertile offspring
Genus
a grouping of similar species
Hominoids
humans, orangutans, gorillas, chimpanzees, and gibbons
Primates
hominoids, monkeys, and prosimians
Primary Characteristics of primates
mostly tree-dwelling, rely heavily on sight, highly social, and live in groups
Phylogeny
the evolutionary history of a species based on fossils and genetics
Ontogeny
the growth and development of an individual organism (a single human)
Genetics
our growth and development results from the interaction of our genetics and the environment
Nuclear DNA
located in the cell nucleus that is a combination of genes inherited from our parents
Mitochondrial DNA
located outside of the cell nucleus and inherited only from the maternal lineage
Fossil Record
provide direct evidence of evolutionary change, but there are significant gaps in the fossil record (we still are missing many fossils)
Paleoanthropologists
specifically, study hominoid lineage
Hominins
all members of the human lineage after the split with the chimpanzee lineage (7 million years ago from today)
Sahelanthropus tchadensis
the oldest fossils of the hominin lineage (found in levels dating to 7 mya) but only found a complete skull that was badly deformed (could be an ape ancestor and not hominin)
Ardipithecus ramidus
early hominin (lived 4.5 mya in an area of Ethiopia) with a nearly complete female skeleton found who is nicknamed “Arid”
- had a large opposable toe (ideal for tree-climbing)
- clearly bipedal (walked upright)
- lacked pronounced canines found in great apes
Radiation of hominin species
4 million to 2 million years ago
Radiation
a period in which there is a rapid increase in the diversity of a single species lineage
Lineage split into 3 groups
Kenyanthropus, Australopithecus, and Paranthropus (all walked upright, lacked large canines, had slightly larger brains, and had larger molars)
Australopithecines
lived 4 mya to 1.8 mya and Laetoli footprints further prove bipedal
Homo Habilis
lived 2.5-1.6 mya in East Africa, had bulky chewing muscles, had large teeth, and had a massive brain
Homo Erectus
lived 1.9-1.5 mya in East and South Africa, as well as Europe and Asia, had an even larger brain and lived inside and outside Africa
East African Rift Valley
from Malawi in Southern Africa to Turkey and Syria in the Middle East
3 Important Characteristics of Rift Valley
- it’s a trough that has filled up with sediments (preserved sites
- it’s tectonically active (leading to erosion that exposes long-buried sites)
- it’s volcanically active (levels of volcanic ash can be dated using the argon method
Lower Paleolithic
stone tools found on the early hominin sites in the East African Rift Valley
2 major stones Tool Industries (types of toolmaking)
- oldowan (1.9-1.7 mya) located in the Olduvai Gorge, could be old as 3.3 mya, consists of flaskes (silvers of rock struck off stone may be used to butcher) or cores (the pieces off of which flakes were struck), known mostly for the chopper (tools used to smash bone or was wasted)
- Acheulian (1.7 mya-200,000 years) associated with Homo Erectus, known for bifaces (hand ax or cleaver), much more sophisticated tools, also could have been used of woodworking
Stone tool technology
marks an important points inhuman evolution and offers some of the earliest known archaeological artifacts
Examination of the surface of animal bones may reveal
- gnawing by carnivores (pit marks and striations)
- butchery with stone tools (identifiable cut marks)
- smashing bones to get marrow (fracture patterns
Base Camps
evidence of a circle of lava blocks and high concentration of animal bones and stone tools suggests and shared food continuously at the site
Palimpsest
a site that was revisited on several occasions possibly by the same group of different groups
Evidence of fire
a concentration of traces of wood ash burnt artifacts and burnt bones reveal possible hearths
Homo Erectus
- 1.4 mya only the genus Homo survived and there was just one single species with the genus
- began to expand its geographical range and the range of ecological niches it inhabited in what is called a dispersal event that occured 1.8 mya
- found in Dmanisi (Republic of Georgia) dates between 1.85-1.77 mya, making it the earliest evidence of human occupation outside of Africa
Hominin activity at Dmanisi is unclear
- none of the animal bones have signs of cut marks (so likely no interaction with hominins)
- stone tools found widely dispersed on the site and not associated with hominid and animal fossils
- fossils and stone tools come from irregularly shaped pits in the stone (water may have created pits bones tumbled into or could have been dens of carnivores)
- Tools found are mostly simple flakes (no Acheulian style tools found)
