Chapter 10 Flashcards
What are the major trends in hominid evolution?
Bipedalism
Expansion of the Brain
Reduction of Face, Teeth and Jaws
Other Evolved Traits: Neoteny, Loss of body hair, Fine motor control
What are the theories for bipedalism?
Habitual upright locomotion. Theories: Adaptation to life in savannahs Better dispersion of body heat Freeing of hands to carry food or make tools
Describe Darwin’s hunting hypothesis
That Hominins evolved in Africa
Hunting meat = tool use = large brain + small canine•Tool use = free hands = bipedalism
Describe the patchy forest hypothesis
Peter Rodman andHenry McHenry
African savanna
bipedalism arose because it was more energy-efficient in certain environments, especially those with few trees
Describe the bipedal skeleton
Foramen magnum centered at the base of the skull
Changes to the pelvis becoming more bowl shaped
Legs angle inward at the knee
Enlarged ankle bones and arch in the foot
Describe the provisioning hypothesis
Owen Lovejoy More food supports more infants, lower interbirth interval (IBI) Suite of anatomies and behaviors coevolve Food provisioning Pair-bonding Reduced canine size Cooperation Bipedalism
What is different about humans?
Upright walking Nonhoning chewing Material culture + Speech Hunting and cooperation Domestication of plants and animal
Describe Non-Honing chewing
Honing vs. apical wear
Shearing vs. grinding
Male–male aggression
Smaller teeth = less comp. + more group stuff
What is the effect of tooth enamel and masticatory muscles on evolution?
Humans have thicker enamel than chimps
Chimps = sharp teeth, slicing even w/ little enamel. Ripping.
Human = grinding + crushing, processing + chewing
Thin enamel = tooth decay = starvation = death
Better chewing = more nutrients
Size + where muscles attach (smaller masticatory muscles = brains get bigger)
Describe the East African Rift Valley sites
Good dates, good preservation of fossils, good diversity
Past: African savannah landscapes, Now:
Olduvai Gorge - Lewis and Mary Leakey
Olorgesaillie, Tanzania Mary Leakey, Henry Bunn and Ellen Kroll
Describe the South African sites
Vertical shaft caves - lotsa fossils, but all mixed, hard to date
Swartkrans, Sterkfontein
Taung child - Raymond Dart - 1st hominin fossil found in Africa (1920)
Late Miocene-Pliocene Proto-hominids
Sahelanthropus tchadensis 7mya (Position of the foramen magnum indicates a more upright posture=bipedalism?) Orrorin tugenensis 6.1 - 5.7 mya (Small, human-like teeth Femur = bipedalism) Ardipithecus ramidus (foot bones divergent large toe combined with rigid foot –• unclear concerning bipedal behavior. pelvis = adaptations tree-climbing + bipedal activity
Describe the issue of the multiple species of pliocene-pleistocene australopithecenes
Things usually consolidate, we think they’re separate but maybe same, but we also could have had that many.
Very many hominins using tools, interbreeding + eating varied diets.
Describe Australopithecus anamensis
Kenya and Ethiopia, Africa ~4 million years old
Woodland
M. Leakey and T. White
Anatomies: Bipedal = Based on shin bone, Nonhoning canines - pretty good adaptation to dispensary tree climbing
Describe Australopithecus afarensis
Fossils from east Africa (Hadar + Laetoli) 4-3 mya
‘Lucy’ – a juvenile called her baby was also found. Donald Johanson. 40 % complete, from about 3.2 mya - Good jaw, complete femur + rotating pelvis
Angled knee (valgus) = easy to walk + give birth
Bipedal (some climbing?); Nonhoning, small canine, Large molars, No language
Describe the Taung child and its discovery
1920 in South African quarry site, Raymond Dart
1925 = 5-7 yr old child (new studies indicate probably was 3-4 yrs old)
named Australopithecus africanus – “Southern ape of Africa”
Describe Australopithecus Africanus
3-2 mya Cranial capacity ~450 cc (1/2 L) Large, chinless jaws Broad, bowl shaped pelvis, Walked erect S-shaped spinal column Southern Africa ~ 3 + 2 mya
Describe the robust Australopithecenes
Au. robustus: South Africa, 1.8 - 1 mya (Dart)
1.5–2 mya. Small, nonhoning canines; very large premolars + molars
Au. boisei: East Africa 2.2 to 1.3 mya. (M. Leaky)
Thicker jaws, larger molars and premolars. Massive muscle attachments for chewing. Larger cranial capacity ~490-530 cc
Both bipedal
Describe Australopithecus Sediba
2 million years old (Malapa cave), South Africa Forest and grassland, Eating C3 foods Anatomy: Small brain, small teeth. Human-like hand and pelvis, Mosaic foot Lee Berger
Describe Au. Aethiopicus
East Africa
Small brain, big cranial crest
Small teeth, lots of masticatory muscles
Face in front of brain
Describe early hominid tool culture
Earliest identifiable tools East Africa ~2.5 mya
Yes soft tissue stuff too, but it decomposed!
Homo habilis associated w/ Oldowan tool tradition
Hominid tool culture Raymond Dart, proposed a culture for Australopithecines : Osteodontokeratic (Bone-tooth-horn)
Describe Oldowan tool making
smashing two rocks against each other where pieces are picked off to make tools
1 harder rock and 1 softer
Describe Lomekwi stone tool making
3 mya
Australopithecus or Kenyanthropus
Simple - smashing one stone against another on the ground
