Human evolution

The grasping hands and feet of primates are adaptations for

hanging on to tree branches

all modern primates, except what, have a big toe that is widely separated from the other toes

Homo

The thumb is relatively mobile and separate from the fingers in all primates, but a what is found only in anthropoid primates

opposable thumb

two subgroups of primates

prosimii and anthropoidea

prosimii vs anthropoidea

probably resemble early arboreal primates and include the lemurs of Madagascar and the lorises, pottos, and tarsiers of tropical Africa and southern Asia vs. moneys, apes, and humans

Humans belong to the same clade as

the African Great Apes

first hominids came about

5 mya

our ancestors were not chimpanzees or any other modern apes but

Chimpanzees and humans represent two divergent branches of the hominoid tree that evolved from a common ancestor that was neither a chimpanzee nor a human

human evolution did not occur as a ladder with a series of steps leading directly from an ancestral hominoid to Homo sapiens but

Human phylogeny is more like a multibranched bush with our species as the tip of the only surviving twig

the various human characteristics, such as upright posture and an enlarged brain, did not evolved in

unison

mosaic evolution

Different features evolved at different rates

There are at least how many different hominid forms found in the fossil record

20

by how much have the brain size of hominids grown over 6 mil yrs

Based on skull measurements, researchers have estimated that brain size in hominoids tripled over the past 6 million years

jaw size of hominoids vs humans

Our hominoid ancestors had longer jaws - prognathic jaws - than those of modern humans

what resulted in flatter face with more pronounced chin for humans

the prognathic jaws/longer jaws

major homo changes

origin of homo sapiens

Homo habilis; a specific species of hominin, which are a group of primates including modern humans and all extinct human species

H. habilis vs. H. erectus

H. erectus was considerably taller and had a larger brain than H. habilis

tools of hominids

main reason for success of homo erectus

homo neanderthals found in

neander valley

later remains show decrease in robustness of the front teeth for homo neanderthals and face, suggesting

use of tools replaced teeth

homesites

In caves, also in the open (near rivers, framed with wood and covered with skins)

what happened to homo neanderthals

they interbred with homosapiens and were killed off by them maybe due to disease or competition

are neanderthals and modern humans separate monophyletic groups?

yes

Denisovans

close relatives of Neanderthals also interbred with humans

hypothesis for expansion out of africa in order

archaic vs modern homo sapiens

early shelter and tool progression

started gathering rather than hunting; shelters made of mammoth bones and wool and tools got sharper

Venuses art

why did archaic homo sapiens not draw other humans

last place colonized by hominids