Early Homo

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Early Homo

• 1. Homo habilis
• 2. Homo rudolfensis
• 2.4 -- 1.6 mya
• contemporaneous with A. boisei and
• A. robustus for 1 million years, then
• 1. all australopithecines became extinct
• 2. New species of Homo evolved

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Homo erectus

• Fossils 1.8 mya -- 300,000 Africa (1.7 in Asia)
• Pleistocene
• Alternation of warm and cold climates
• With glacial advances - lowering of sea level -
• land bridges
• Facilitated dispersal of Homo out of Africa

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Differences in brain size and skull
characteristics

• Cranial capacity
• early Homo species (500 - 800 cc)
• Homo erectus (750 - 1,250 cc), averaging about
  900 cc
• Skull was thick
• Large, solid brow ridges
• Occipital bun
• Reduction in relative tooth size

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Homo erectus
Turkana boy
Kenya, Africa 1.6 mya c. 12 years old 56
tall would have been 6 had he survived
to maturity
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800,000-400,000 yBP Europe
Fossil sites for Homo erectus
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Regional variation
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A basic tool of Homo erectus Acheulian
biface hand axe
1.4 mya - 400,000 ya entire stone
flaked Acheulian technique
controlled use of fire
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Early Homo sapiens

• Classification complex unresolved
• Archaic H. sapiens appears c. 350,000 yBP
• Found throughout the Old World (except far north)
• Brow ridges still prominent - but less dense
• Later forms have higher cranial vault and reduced
  tooth size.
• Mean cranial capacity increased to 1,410 cc in
  Neandertals but. . .greater body mass

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archaic Homo sapiens sites
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early Homo sapiens showing erectus-like features
Petralona, Greece Bodo, Ethiopia
Dali, China
Oldest 500,000 yr, Bodo, Ethiopia heidelbergensi
s 700,000 yr.
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Neandertals archaic Homo

• Lived in a time-range 130,000 - 24,000 ya
• Shared Europe with modern H. sapiens for c.
  12,000 yrs.
• Brain was, on average, larger than that of modern
  humans 1410 vs. 1350 cc
• Height 4.9 - 5.6 ft.
• Weight 110 - 143 lb.
• Heavier bones, more muscular
• Short extremities reduction of surface area
  adaptation for cold climates?
• Intentionally buried their dead.
• Homo neanderthalensis (DNA evidence)

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Neandertal vs. modern human Skull shape may hinge
on one bone
Sphenoid bone (20-30 shorter)




Contacts 17 of the 22 bones
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Neandertal sites Note not in Africa
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Origin of modern Homo sapiens
Two competing hypotheses 1. Regional
continuity model
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• 2. African replacement model

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53 individuals complete sequence of mtDNA
Common ancestor of all modern mtDNAs lived in
Africa
B

• Most recent common
• ancestor of all modern mtDNA
• Most recent common
• ancestor of Africans and
• non-Africans

A
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Phylogeny of 14 populations based on allele
frequenciesat 30 microsatellite loci and genetic
distances

• Geographically neighboring populations cluster
  together
• Basal branch separates African and non-African
  groups
• Split estimated from this data 75,000 to
  287,000 ya
• Consistent with African Replacement Model

Bowcock, Ruiz-Linares, Tomfohrde, Minch, Kidd,
and Cavalli-Sforza (1994)
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• Genetic diversity at a single locus in chromosome
  12 among people of 7 geographic regions 12
  different alleles of TTTTC repeat
• Each graph shows the frequencies of the various
  alleles for a sample from a particular region.
• Arranged by travel distance from sub-Sahara
  Africa north.
• If non-African populations were founded
  sequentially by small bands of people migrating
  from one population to the next, then non-African
  populations should show a pattern of reduced
  genetic diversity.
• Conclusions
• 1. African populations show much greater allelic
  diversity than non-African populations
• 2. Consistent with African replacement model.