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