ANT: Module 4 Discussion
McNeilx2
UTF-8Module-4-Hominin-Evolution.pptxModule 4
Hominin Evolution
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When it Happened
30 million years ago – New World Monkeys and Old World monkeys diverged
Same time Old World Monkeys and Apes diverged
5-8 million years ago humans and apes diverged
Where it happened
Why it Happened
Anthropoid ancestors were still tree dwellers
20 m.y.a, climate became drier; forests contracted; grassland habitat increased
Monkeys new world: 1) volcanic islands connecting south America and south Africa, 2) rafting
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How are we similar to Apes?
Forward facing eyes
No tails
Long gestation and dependency
Dental arrangement
Hands
What makes us Human?
Bipedal Locomotion
Big Brains
Use of tools
Language
Elephants 650 days gestation; cats and dogs 60 days, monkeys around 160, apes around 190, humans 280; chimps 240; 257
Estimates should that gestation would have to be around 21 months for humans to give birth to a baby with the neurological and cognitive skill of a chimp
Other Animals
Vancouver island lizard, jerboa rodent of Arabic north Africa deserts, kangroos, birds
Locomotive Differences
By comparison to apes, humans have:
a foramen magnum that points down
a curved lumbar spine
a short, flared (versus long and thin) ilium
a strong, robust talus (ankle bone)
a strong, non-opposable big toe
a complex arch system in the foot
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Humans have a curved lumbar spine
Humans have a downward pointing foramen magnum
Locomotive Differences
Spinal column
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Hips
Humans have a short and flared ilium versus the long and thin ilium in apes
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Chimp
Lucy
Human
Pelvis
Humans have an angled knee joint, apes have much less of an angle
Knee Comparisons
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Humans have smaller brow ridges, no post-orbital constriction
Larger brains (Humans: 1200 cc., Gorillas: 475 cc)
Human versus Gorilla cranial differences
Humans have flatter faces, no sagittal crest
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Humans have small incisors, large molars
Humans have parabolic dental arcade, Apes have U-shaped
Humans have relatively thick molar enamel
Humans have bicuspid lower premolars, not sectorial
Humans have smaller canines
Upper Diastema or gap between canine and premolar
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Bovine Teeth
Major Evolutionary Trends in Hominid Evolution
Bipedalism
Brain Size
Jaw Shape
Prognathic jaws
Flatter face with more pronounced chins
Reduced canines and diastema
Increasing reliance on tools
Australopithecus afarensis East Africa
~ 3-4 million years
Ape-like face with small brain
Bipedal with long arms
Scavengers not hunters
Highly sexually dimorphic
Within the range of a chimp, ¼ of modern humans
Most human like primate at that time – direct ancestors to homo sapiens?
Lucy
3’6” tall 60 lb
New date - 2.9 mya
Laetoli footprints
3.6 million year old volcanic tuff
Bipedal footprints of 2 or 3 hominids
Hyenas, wild cats, baboons, wild boar, giraffes, gazelles, rhinos, several kinds of antelope, buffalo, elephants, hare, birds, and rainprints
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Homo habilis
2.3-1.6 million years ago
Bigger brain
Less facial protrusion
No sagittal crest
Smaller molars and premolars
Weighted ~90 lbs, still a scavenger
Tools
Homo habilis
In 196 a more advanced ancestor skull was found—a much bigger brain. Homo habilis or “handy man.” How did Homo habilis live? In the man the hunter film, contemporary society was used as a model. It was absurd, why? Because it focused only on male activity. There was a shift to man as an intelligent hunter, not a vicious killer.
Hunting as a tempting explanation for how we became human. Where they really hunters? Homo habilis was only 90 pounds. He was a little guy, not likely to be a hunter.
There was a cluster of animal bones and tools found around an ancient lake front. But Louis Binford asked: Would our ancestors really have set up camp on the waterfront, where all of the predators came to drink? So how are the clusters of stones and bones explained? Collecting bones---scavenging! And processing bones. Scavenging is very different from hunting! Why supplement veg diet with meat from scavenging? Scavenging experiment in dry season.
After stone tools came there was a change in appearance in bone assembleges. Was there then a behavioral change at the time that stone tools evolved? Climate change provided new challenges and opportunities. Herded animals became more abundant but hunting dogs were also around at this time. Living in an environment with lions too—intelligence becomes key. Need calories to keep that big brain working=scavenging for meat.
Homo erectus/ergaster
2m – 300k year ago (Longest Hominin)
India, China, Java
Bigger Brain (75% modern humans)
Flatter Face; smaller canines
Taller (Modern Proportions – Barrel Chest)
Stone technology – Acheulian
Cooperative Hunters
New Technologies
Use of Fire
Decrease mortality, enter into colder climates, protect from predators, and defrost/tenderize food, kill parasites
Rafts
Explore new areas
Neanderthals
Approx. 200,000 – 50,000 /30,000
Big Brains
Rock shelters in Europe, west and central Asia
More robust bodies
Massive brow ridges with protruding nose and jaw
Heavily muscled
Variety of stone tools (Mousterian)
A hyoid bone discovered indicates that language was possible
Evidence to support burial their dead – grave goods and pollen
Homo neandertalensis
Hey, What Happened?
Extinct 40,000 years
New research suggests lack of clothing other than primitive caps
Competition with humans
Volcano
Parasites and pathogens
Division of labor
The fossil record does not show simply a progression of species leading to a modern species
Instead, more like a branching tree with many “transitional” forms between early and modern species
H. Florensis
Anatomically Modern Homo Sapiens (AMHS)
Earliest AMHS fossils 190,000 years old (Africa)
Cranial Capacity = 1,000 – 2,000 cc
Europe and Australia much later 50,000-35,000 years ago
Today there are more than 6 billion Homo sapiens
When the bones of two early humans were found in 1967 near Kibish, Ethiopia, they were thought to be 130,000 years old. A few years ago, researchers found 154,000- to 160,000-year-old human bones at Herto, Ethiopia. Now, a new study of the 1967 fossil site indicates the earliest known members of our species, Homo sapiens, roamed Africa about 195,000 years ago
A 195,000 year old fossil from the Omo 1 site in Ethiopia shows the beginnings of the skull changes that we associate with modern people, including a rounded skull case and possibly a projecting chin.
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Modern Human Migration
Summary
Environmental changes lead to first human characteristic – Bipedalism
After bipedalism, increasing brain size, less prognathism, and tools
These changes are recognizable in fossil record
Start as scavengers but become hunters
Modern humans evolved in Africa 200,000+ years ago and spread throughout the rest of the world
