Download What is Generally Agreed Upon?

What is Generally Agreed Upon?
The
earliest hominids are all from Africa
The first to move out of Africa was H. erectus
(ca. 1.7 mya)
H. erectus found its was to Asia and Europe
relatively quickly
Modern Human Origins:
Eve or Everywhere?
From which ancient population is modern
humanity (H. sapiens) descended?
Two main theories today address this:


1.
2.
Multiregional Evolution, or Regional
Continuity Model
Out of Africa, Mitochondrial Evem Recent
African Origin, or Complete Replacement
Model
The Basics of Each Model
Regional Continuity
•Associated today with Milford
Wolpoff
•Been around since 1930’s,
originating with Franz
Weidenrich
•Based on morphology of
ancient modern Old World
people
Complete Replacement
•Associated with Allan Wilson,
Rebecca Cann, and Mark
Stoneking
•Been around since 1987
•Based on tracking mutations
and modern genetic diversity in
mtDNA (mitochondrial DNA) of
147 individuals from Africa,
Asia, Europe, Australia, and
New Guinea
The Particulars of Each Model
Regional Continuity
•Continuance of physical traits
from regional populations of H.
erectus to Homo sapiens.
Examples:
Australian aboriginals and
Indonesian H. erectus have
similar row and other traits
•Modern east Asians and Asian
H. erectus commonly share
shoveled incisors, absence of
third molars, and flat faces
•
•Archaeology
suggests a
timeframe of 1.6-1.7 mya to
begin the process
Complete Replacement
•Great diversity in mtDNA
exists in modern Africans
compared to other populations
suggesting this is the root of
the human tree
•Molecular clock suggests a
timeframe of perhaps 200,000
years back to a few common
ancestors of all modern
humans
The Implications of Each Model
Regional Continuity
•Modern traits (e.g. huge
forehead. Rounded skull, chin)
arise at the same time
everywhere
•Gene flow between
populations keep them from
diverging too much
•Predicts modern traits should
occur in a mosaic
•Transitional forms should be
seen in each region
Complete Replacement
•Modern traits appeared once
(in Africa) and recently
•Carriers of modern traits
moved out and replaced
archaic humans
•Predicts all modern traits will
be seen in Africa first
•No transitional forms should
be seen
The Bottom Line of Each Model
Regional Continuity
•Archaeologically inconsistent
•Ignores genetic evidence
•Explains morphological
continuity parsimoniously
•Has been used to support
dangerous ideas about race
•Requires lots of gene flow
•Implies need for total
taxonomic simplification
Complete Replacement
•Achaeologically consisten
•Recognizes genetic evidence
•Lacks a parsimonious
explanation of trait continuity
•Consistent with a polytypic,
single species concept
•Little gene flow required
•No taxonomic change required