Lecture 30 Flashcards
What is the evolutionary relationship of living great apes and humans?
Humans sometimes given their own family -Hominidae -but difference between chimps and humans is very small
In what way do humans differ in locomotion from other great apes?
-Bipedalism-humans walk upright habitually -great apes typically “knuckle walk” -human foot become less grasping -big toe straightened
What are the skeletal differences associated with upright walking?
-big toe reduced -pelvis shortened, more bowl-like than blade-like(helps support base of spine) -femur bends inwards , patella central to joint -connection with spinal column (foramen magnum) on underside of skull -less robust arms
What are the consequences of upright walking?
-freed hands for other purposes -humans have greater manual dexterity -greater tool use -ability to throw accurately (important in hunting)
Why did upright walking evolve?
possible explanations: -improved foraging capacity in grass lands (seeing above the grass) -improved thermoregulation under hot savanna sun(less sun on body) -enabled greater home range size, and hence foraging success -increased ability to use tools effectively (eg hunting) -most energetically way of getting around between food patches
How do humans differ from other apes= 3 things?
-locomotion -diet -brain size
How does human diet differ from other apes?
-humans are highly omnivorous but with much higher meat intake than other apes -aslo eat higher amountes of processed food (cooked…) -chimpanzees are omnivorous but not as much meat consumed
How does brain size differ between humans and other apes?
-human much larger -cranial capacity= volume inside the skull -adult chimps- 400ml -adult humans=1400ml -we start at almost the same way but then the difference changes at around 6 months=
What are the consequences of increased brain size?
-profile flattens -jaw size becomes relatively smaller -more complex behaviours -capability to manipulate environment -more complex relationships, and manipulating environment
What are the world populations of apes?
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Where did hominids originate?
-majority of fossils found in East Africa -most of these in sites in the Rift Valley -lots of lakes,and human fossils found in the same deposits as lake dwelling creatures eg. fossil hippos -early hominids must have spent some time around water
Describe the hominid evolutionary tree:
-about 20 species 3 main genera- australopithecus(about 7 species) -Paranthropus (3 species) -Homo (about 7 species)
What was the first hominid?
-discovered 2001 in Chad -nicknamed Toumai -6 to 7 million yrs old -chimps and humans may have common ancestor earlier than thought -skull only -location of foramen magnum on base of skull suggests it was bipedal -not certain it is a hominid
What is Ardipithecus ramidus- Ardi?
-location? Afar, Middle Awash Etiopia -dated 4.4 million years old -remarkably complete early hominid skeleton -cranial capacity= chimp size -shape of foot and hand suggest an intermediate level of bipedal walking (opposable large big toe but relatively delicate hands) -surrounding fossils indicate it lived in a woodland environment, probably spent much time in trees
What is Australopithecus afarensis- Lucy?
-lived 3-4 million yrs ago -skeleton includes jawbone, part of pelvis and entire femur =first solid evidence for the transition from four to two legs= bipedalism
What is the evidence that A.afarensis (lucy) walkked upright?
-shape of the pelvis very similar to modern humans -angle of femur and articulation with knee joint indicates bipedalism -bones suggest A.afarensis only 1.2m tall -discovery of tracks in volcanic ash (3.5Mya)=walking on two feet -A.afarensis jaw found nearby -footprints are heel to toe- walking like humans -two individuals (parents and child?) walking by side -animal walking next to them?
Was Australopithecus brainy?
-facial features more champ-like -complete juvenile skull - 3.3 MYO suggests more human appearance but chimp dentition -adult cranial capacity= 440 mls comparable with a chimp -no increase in brain size in Australopithecus
What were the earliest humans and where were they found etc.?
-earliest Homo species were Homo habilis (handy man) or Homo rudolfensis -H.habilis lived from 2.5-1.5 million yrs ago –H. habilis found in Olduvai Gorge, Tanzania -often found with simple stone tools (Oldowan tools) -cranial capacity 600ml (larger than chimps and Australopithecus but still much smaller than modern humans)
Who were the Homo erectus?
-live 1.8MY-300 000 years ago -specimens found in Africa, Europe and Asia (even in Indonesia) -more complex “Acheulean” tools -increased cranial capacity 900ml= early specimens 1100ml= late specimens
Who was the Turkana boy?
-the most complete fossil hominid -Homo erectus -found at lake Turkana, Kenya -1.5 million years old -12 year old boy -height= 1.6 m =therefore adults must have been similar height to modern humans
When did Homo sapiens appear?
-first fossils appeared between 190-160 000 years ago -nickname Omo, found by the Omo river in Ethiopia -cranial capacity= 1300ml
What is surprising in cranial capacities of the homonids?
-neanderthals had larger brain than us!
What are the characteristics of Homo neanderthalis?
-the nearest relative of Homo sapiens -lived between 130 000- 30 000 yrs ago -found in Europe and Middle East -very similar societies to Homo sapiens(hunter/gatherers) -may have been outcompeted by Homo sapiens or maybe interbred? -shared up to 99.5% genes -could higher infant mortality during childbirth have contributed to their extinction?
What is Homo floresiensis?
-discovered in 2004 on Flores, Indonesia -Very recent (18 000 years old) -though to have evolved from Homo erectus ancestors -the skull and skeleton since nicknamed= hobbit -controversy! as only had cranial capacity 400mls -sone argue reduction would be unlikely -may be a dwarf or diseased Homo sapiens…eg. microcephaly…. not clear!
What are the key futures and themes in this lecture?
