Hominin Evolution (based on R. Klein, B. Wood), compiled by Charles J. Vella, 9/2012



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Milestones

Time































Split from Chimpanzees

5-7 M

Split from

Gorillas


10 M







Bipedalism

4 M













Transformation of the canine
















Stone tools

3.3M/2.6M

Hadar, A. afar.










Handaxe

1-3 M













Spear points

1 M













Fire

800 T

Gesher Benot Ya’aqov, Israel

Stone Hearths, 300T







Symbolic Thought

35 T













Art

35 T






























Coexistence circa 1.8M: Paranthropus boisei, Homo rudolfensis, H. habilis and H. ergaster foraged in the same area around Lake Turkana.


In Africa, H. erectus may have evolved into H. heidelbergensis, but in Asia a dead end.

Migrations:

Morphological traits typical of Neanderthals began to appear in European hominids at least 400,000 years ago and about 150,000 years ago in western Asia.

Neanderthal sites: at least 30 (Neander Valley, Germany, 1856; Sipka, Moravia 1880; Spy, Belgium 1886; Krapina, Croatia, 1899-1906; Ehringsdorf, Germany 1908-1925; Le Moustier, France 1908; St. Brelade, Channel Islands, 1911; Kiik-Koba, Crimea, 1924; Mount Carmel, Palestine, 1929; Teskhik-Tash, central Asia, 1938; Saccopastore, Italy, 1929; Guattari/Circeo, Italy, 1939; Shanidar, Iraq, 1953; Amud, Israel, 1961; Kebara, Israel, 1964; Dederiych, Syria, 1993; St. Cesaire, France 1979; Zaffaraya, Spain, 1983; Lakonia, Greece, 1999)

All modern human genes originated in Africa; in past 2 MYA, Africa was source of emigration of a H. ergaster hominin, then a H. heidelbergensis hominin, then several waves of modern humans; modern humans are derived from relatively recent, ca. 50-45 kya migration out of East Africa.

Homo sapiens sites: Pestera cu Oase, Romania, c. 35 kya; Kent’s Cavern, England, c 30 kya; Bacho Kiro & Temnata, Bulgaria 43-40 kya; Papua New Guinea, Australia, Tasmania, 40 kya; Oceania, 35-30 kya; Arctic Circle, 27 kya; preClovis culture, Texas, 15 kya, Monte Verde, Chile, 12.5 kya; Clovis culture, before 11 kya

Homo sapiens: migration out of Africa, then interbreeding with Neanderthals in Western Asia (65,000–90,000 years ago); (contributed 1-4% of their DNA to Homo sapiens); then a move to Southeast Asia; ancestors of East Asians and Western Indonesia arrived later, between 38-25TYA

2 migrations into Asia from Africa

1 - Denisovans: a common ancestor with anatomically modern human and Neanderthal mtDNAs about 1.0 million years ago. This indicates that it derives from a hominin migration out of Africa distinct from that of the ancestors of Neanderthals and of modern humans; 4-6% DNA to New Guinea, Melanesia, Aborigines by 44 TYA; human migration to SE Asia between 75 and 62TYA

2 – No Denisovan DNA: To East Mainland Asia (Han Chinese) and Western Indonesia

Sources:

Bernard Wood – Human Evolution, 2011

Richard Klein – Richard G. Klein, 2009

Modern Human vs. Chimpanzee Skeleton (after B. Wood):






Human

Chimpanzee

Forehead

Steep

Low

Face

Flat

Projecting, snout-like

Cranial vault

Widest higher up

Widest at base

Skull

High, globular, rounded

Smaller

Brain size

Large (1350cc)

Small (300cc)

Foramen magnum

Forward in skull

Backward in skull

Canine teeth

Small; smaller,

more incisor like canines that occlude tip to tip



Large, wear on sides; large

upper canines are honed against the first lower premolars, producing

a sharp edge in back of the canines.


Dentation

Rectangular arcade; small front teeth

Curved arcade; large front teeth

Base of skull

Angled

Straighter

External Ear Canal

Large

Small

Thorax

Straight sides; cone-shaped

Conical, barrel-shaped rib cage

Lumbar vertebrae

5

3-4

Limb bones

Straight

Curved

Limb proportions

Lower limb long

Arms longer than legs;

Lower limb short



Thigh Bone

Straight

Angled toward knee

Wrist

Less mobile

More mobile

Fingers

Straight, & long, opposable thumb

Curved, long fingers, & short thumb

Hand

Cup-shaped

Flat

Foot

Arched & big toe straight

Flat & big toe angled

Pelvis

Basin shaped;

Neonatal head is tight fit



Long, narrow;

Neonatal head has ++ room



Development –

Bones and teeth



Slow

Fast

Locomotion

Bipedal

Knuckle walker

Chin

Present

None

More typical of hominin than ape:

Large molars

Small canines

Thicker mandible

Large brow ridge

Canine worn at tip



Hip joint: outer/cortical bone is thickest at top and bottom of neck



The Toba catastrophe theory suggests that a bottleneck of the human population occurred c. 70,000 years ago, proposing that the human population was reduced to perhaps 15,000 individuals[3] when the Toba supervolcano in Indonesia erupted and triggered a major environmental change. The theory is based on geological evidences of sudden climate change and on coalescence evidences of some genes (including mitochondrial DNA, Y-chromosome and some nuclear genes)[4] and the relatively low level of genetic variation with humans.[3]

However, such coalescence is genetically expected and does not, in itself, indicate a population bottleneck, because mitochondrial DNA and Y-chromosome DNA are only a small part of the entire genome, and are atypical in that they are inherited exclusively through the mother or through the father, respectively. Most genes in the genome are inherited from either father or mother, and thus can be traced back in time via either matrilineal or patrilineal ancestry.[5] Research on many genes finds different coalescence points from 2 million years ago to 60,000 years ago when different genes are considered, thus disproving the existence of more recent extreme bottlenecks (i.e., a single breeding pair).[3][6]

On the other hand, in 2000, a Molecular Biology and Evolution paper suggested a transplanting model or a 'long bottleneck' to account for the limited genetic variation, rather than a catastrophic environmental change.[7] This would be consistent with suggestions that in sub-Saharan Africa numbers could have dropped at times as low as 2,000, for perhaps as long as 100,000 years, before numbers began to expand again in the Late Stone Age.[8]




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