Exam 2

Human Evolution

Shared common ancestor with
Apes ~6.5 mya

Ardipithecus
(Bipedal)
over 5 mya

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. Afarensis (Lucy)
common ancestor

A. ganhi

Homo habilis
2-1.8mya

First signs of greater encephalization:
(more intelligent beings
had more offspring- thus, larger brains
continued to be passed down)

Homo erectus
1.8mya-350,000
moved out of Africa to
Middle East, Asia...

(Archaic) Homo sapiens
evolved 350,000
years ago

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.

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.

Traveled to Asia and Australia
60,000 years ago

Traveled to
New World
25,000 years ago

Later reached
South Americas

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!

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

No major extinctions in Africa
(people were already residing there
from the beginning, thus there was
no major change)

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).

Later developed into
present day apes

Adaptive Radiation

development of several new SPECIES from a common ancestor due to adaptations to different environments.

Form of
Divergent Evolution?

Is a result of natural selection

Character
Displacement

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

Adaptive Differentiation

development of different PHENOTYPES from a common ancestor due to adaptations to different environments