по Danielle Coffey 11 лет назад
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development of several new SPECIES from a common ancestor due to adaptations to different environments.
development of different PHENOTYPES from a common ancestor due to adaptations to different environments
selection working in opposite directions. There is compeition at the mean so phenotypes diverge in order to reduce competition.
ex) Galapagos Finches Beak Size: separately they are similar, over time beak size diverged to reduce competition in eating the same food.
**also: Competitive Exclusion
Bipedalism was more beneficial seeing as the African Rift Valley was changing from a tropical to a savannah landscape. Standing upright allowed our ancestors to see above the tall grasses, reach food on trees, cool more efficiently from the sun, and most notably: conserve more energy (as this was more energy efficient than walking long distances on four legs).
Australopithecus over 4mya
Extinctions caused by ENVIRONMENTAL CHANGES.
A. ganhi
Homo erectus 1.8mya-350,000 moved out of Africa to Middle East, Asia...
Adaptations such as endurance running, sweating, and less body hair were seen here.
lead to "Persistence Hunting" (needed bigger meaty foods to support larger bodies and brains).
(Archaic) Homo sapiens evolved 350,000 years ago
H. sapiens sapiens (move from Africa and Middle East)
H. sapiens sapiens have ~3% neandertal DNA in us.
Outlived neandertals due to taller slimmer bodies which require less energy to sustain, more advanced hunting tools (such as throwing spears) allowed them to get food without putting themselves in harm's way.
No major extinctions in Africa (people were already residing there from the beginning, thus there was no major change)
Traveled to Asia and Australia 60,000 years ago
Reached South Pacific Islands moving from SE Asia
islands that are much closer geographically have residents that are closer related genetically as well, when compared to islands that are further apart
Traveled to New World 25,000 years ago
North America: extinction of many animals 14,000-6,000 years ago bc hunted to extinction
Presence of humans increases the probability of extinction for animals in the area. Major BIODIVERSITY effect!
Later reached South Americas
H. sapiens neandertals (goes to Europe and Middle East)
FoxP2 gene found in neandertal DNA led scientists to believe neandertals could has possibly had a language.
DIES OUT
Possible causes of extinction:
-Not advanced enough technology to catch food in order to sustain and maintain food requirements for large bodies.
-Lived in cold climates
-H. sapiens sapiens were better adapted to enviornment, started out competeing neandertals, leading to their demise.
Homo habilis 2-1.8mya
First signs of greater encephalization: (more intelligent beings had more offspring- thus, larger brains continued to be passed down)
A. Afarensis (Lucy) common ancestor
