Key steps in human evolution Flashcards
when did chimps and human diverge
5-6mya
what has occured to climate in homo evolution
6-4.5mya - stable and slightly warmer than today
4.5-1mya - increasingly unstable and fluctuations
when did the current ice age begin and the last glacial maximum
- 58mya
11. 7kya
what are the period called before and after the last glacial maximum
before - Pleistocene
after- holocene
what are hominids
member of hominidae (great apes)
what are hominins
bipedal hominids
the lineage that leaads to homo sapiens
when did anatomically modern homo sap arise
200kya
what are premodern homo
pleistocene homo that lack modern human cranium and post cranial skeleton
inc N
H.heidelbergensis
what is the transitional homo
H.habilis (fingers could grasp)
what are the archaic Homo and when were they pressent
Australopithecus africanus (3-2.4mya) Australopithecus afarensis (3.7-3mya )
what is some of the main difficulties in the field
rarity of fossils
what are en route to H.sap
homoplasy
why is there a rarity of fossils
up until 2mya on African plane - scavenged
low population and frequent bottlenecks
what is homoplasy
shared characteristics that aren’t inherited from LCA
what is unusual about earth now
only one hominin
up until 13kya always at least two
what hominins were present 60kya
N
D
H.floresiensis
what is the earliest bipedal hominin
Ardipithecus ramidus
- 2m heght
- 4.mya
what interesting about A.ramidus fossil
opposoble thumbs - like Chimp - evidence spent time in trees
suggets transitional phase
what do A.afarensis fossils show about bipedalism
lucy - 3.6mya
same height as A.ramidus nut pelvis and muscle =
modern features = walk as we do
Laetoli footprint - suggets a gait and speed of walk sim
modern human
what are some eamples of theories for the evolution of bipedalism
hands free -but this not sel pressure
thermoreg on savanna - but A.ramidus in forest
incr energy efficiency - especially over long distance/pot competitive adv over other hominins
aquatic ape theory
what were the firt hominins to use tools
H. habilis
2.2mya
what is the first tool culture
olduwan
split flakes from surface of pebbles - scavenging meat not hunting
how is hommo tool use different from other animals
ability to improve/modify
what are the tools used by H.erectus
Achuelean tools 1.6mya -150kya little change well balanced some shaped for hand axes for hunting more sophisticated
what is speech and what does it require
ability for sound
anatomy inc low larynx/distorted tongue/large windpipe
what is language
system for communication
what do fossils of H.erectus show us about their ability for speech
similar windpipe to h.sap
threfore speech probs ev
what do N fossils suggest about their ability for speech
probs lacked lower larynx- less ability/limits no of sounds
what does cranial capactiy of hominins suggets about the evolution of language
in A.afarensis - 375-550cm^3
in H.habilis 650cm^3 and evidence of Broca area
after this all more than 1000cm^3
what is the problem with looking at brocas area on fossils
not human specific
not solely language role
what gene has genetics studied for the ev of language
FOXP2
assoc with diseases in which language affected
what subsitutions present in H.sap of FOXP2 and what hominins present in
T303N
N325S
both in N and some studies suggest in Erectus
what the effect of incr FOXP2 in zebra finch
incr dev of song = pot inv in reg song syst
what the phenotype shown by mouse with the FOXP2 homo subs
incr neuron growth in forebrain
altered patterns of ultrasonic vocalisations
incr dendrite length and synaptic plastcity
decr in dopamine conc
comparison of genes in human and chimp
incr nerual gene in homo
what evidence does tool use suggest about language
oldowan - tech stasis inconsitent with presence of language
pot a coev relationship would expect
what have studies on the social transmission of tool use shown
imporve when laguage to teach
not by imitation
suggest pot a sel for language
