lecture 4 Flashcards
What fundamental features do humans share with all living organisms?
Inheritance based on nucleic acids (DNA & RNA),
genetic code,
proteins composed of amino acids
What two species are humans’ closest living relatives?
Pan troglodytes and Pan paniscus
Around what time did the human lineage diverge from the chimpanzee lineage?
around 7 Mya
Describe some general characteristics of human’s closest living relatives.
opposable big toe, longer arms than legs, a projecting lower face, large canine teeth, plentiful body hair, a relatively small brain
Describe characteristics that distinguish humans from chimpanzee?
-Feet: facing forwards and thumb no longer opposable b/c thumb would get in way of walking and we have an arch for pushing us forward and upward
- foramen magnum is more forward on head so we an look forwards
- reduced body hair so we can sweat when we run
- small dentition
- large brain
-Pelvis: more bowl shaped to hold organs
- legs: bipedal now to walk long distances and grab shit, legs angled inward to keep them under center of gravity so don’t sway
Name four features that the common ancestor of humans and chimpanzees shared with living chimpanzees.
may be Ardipithecus ramidus dating to 4.4 M ago with apelike small brain and adaptations for climbing like opposable big toe and had hominin features such as small canine and pelvis adapted for walking.
What are the three major groupings of fossils in the human lineage?
Early Hominins: apelike traits like smaller cranial capacity, but small canines like humans for eating
Australopithecines: apelike traits but changes in skull, spine and legs indicated bipedalism
Homo: 2 Mya to now, distinctly more human with growing cranial capacity, sophisticated stone technology, control fire, left Africa
What is the estimated age of Ardipithecus ramidus? List the apelike and humanlike characteristics of A. ramidus (an early hominid)?
A Ramidus dates back to about 4.4 Mya with apelike features of chimp sized brain and opposable thumbs for climbing and human like features of small canine teeth and pelvis adapted for walking (bowl shaped)
What is the estimated age of Australopithecus afarensis? List the apelike and humanlike characteristics of A. afarensis?
About 3.5 Mya A. afarensis was alive and had apelike features of projecting lower face far beyond the eyes, large canines, long arms relative to legs, small and had humanlike traits too like bipedalism.
What is the estimated age of Homo habilis? List the humanlike characteristics of H. habilis?
H. habilis is about 2.5 Mya and had a greater resemblance to modern humans than past Homo with features like flatter face, shorter teeth row, humanlike hands, increased brain size
What is the estimated age of Homo erectus? List the humanlike characteristics of H. erectus? H. erectus also made evolutionary history by being the first known hominid to do this. What did H. erectus do? H. erectus may have been the ancestor of what other species?
From about 1.9 to 0.2 Mya homo erectus lived and had human like features of rounded skull, its face projected less than earlier species, smaller teeth, larger brain capacity. H. erectus was the first hominid to leave Africa about 2 Mya (spread into middle east) and may be an ancestor of H. floresiensis which lived on a small Indonesian island.
Homo heidelbergensis left Africa and is believed to have given rise to what two species? Please list four characteristics of one of these species.
Neanderthals and Denisovans
Neanderthals: dense bones, projecting brow ridge, larger brain, thick skull
What is the geographic origin of modern humans?
africa
Around what time did modern humans leave Africa? Describe two genetic consequences of this migration from Africa
about 2 Mya
Genetic load: intense genetic drift fell on the humans that left Africa leading to the fact that the farther humans stray from Africa the more deleterious mutations there are through genetic hitchhiking.
Genetic admixture: the mixing of different populations with different genetics that could not previously breed