"Out of Africa" theory revised

[Ahknaton]

It looks like the commonly accepted wisdom that all human populations come from a single gene pool that only recently diverged has been disproven.

New analysis shows three human migrations out of Africa

http://news-info.wustl.edu/tips/page/normal/6349.html

Replacement theory 'demolished'

By Tony Fitzpatrick

Feb. 2, 2006 — A new, more robust analysis of recently derived human gene trees by Alan R. Templeton, Ph.D, of Washington University in St Louis, shows three distinct major waves of human migration out of Africa instead of just two, and statistically refutes — strongly — the 'Out of Africa' replacement theory.

That theory holds that populations of Homo sapiens left Africa 100,000 years ago and wiped out existing populations of humans. Templeton has shown that the African populations interbred with the Eurasian populations — thus, making love, not war.
*Homo sapiens*: 'Out of Africa' three distinct times, new analysis shows
Homo sapiens: 'Out of Africa' three distinct times, new analysis shows

"The 'Out of Africa' replacement theory has always been a big controversy," Templeton said. "I set up a null hypothesis and the program rejected that hypothesis using the new data with a probability level of 10 to the minus 17th. In science, you don't get any more conclusive than that. It says that the hypothesis of no interbreeding is so grossly incompatible with the data, that you can reject it."

Templeton's analysis is considered to be the only definitive statistical test to refute the theory, dominant in human evolution science for more than two decades.

"Not only does the new analysis reject the theory, it demolishes it," Templeton said.

Templeton published his results in the Yearbook of Physical Anthropology, 2005.

A trellis, not a tree

He used a computer program called GEODIS, which he created in 1995 and later modified with the help of David Posada, Ph.D., and Keith Crandall, Ph.D. at Brigham Young University, to determine genetic relationships among and within populations based on an examination of specific haplotypes, clusters of genes that are inherited as a unit.

In 2002, Templeton analyzed ten different haplotype trees and performed phylogeographic analyses that reconstructed the history of the species through space and time.

Three years later, he had 25 regions to analyze and the data provided molecular evidence of a third migration, this one the oldest, back to 1.9 million years ago.

"This time frame corresponds extremely well with the fossil record, which shows Homo erectus expanding out of Africa then," Templeton said.

Another novel find is that populations of Homo erectus in Eurasia had recurrent genetic interchange with African populations 1.5 million years ago, much earlier than previously thought, and that these populations persisted instead of going extinct, which some human evolution researchers thought had occurred.

The new data confirm an expansion out of Africa to 700,000 years ago that was detected in the 2002 analysis.

"Both (the 1.9 million and 700,000 year) expansions coincide with recent paleoclimatic data that indicate periods of very high rainfall in eastern Africa, making what is now the Sahara Desert a savannah," Templeton said. "That makes the timing very amenable for movements of large populations through the area."

Templeton said that the fossil record indicates a significant change in brain size for modern humans at 700,000 years ago as well as the adaptation and expansion of a new stone tool culture first found in Africa and later at 700,000 years expanded throughout Eurasia.

"By the time you're done with this phase you can be 99 percent confident that there was recurrent genetic interchange between African and Eurasian populations," he said. "So the idea of pure, distinct races in humans does not exist. We humans don't have a tree relationship, rather a trellis. We're intertwined."

[Anima Eternae]

I like how he added the mandatory nonsense about race not existing.

[Ahknaton]

I like how he added the mandatory nonsense about race not existing.
Yeah, that tweaked my nose too. It was going great up to that point.

[Petr]

Evolutionists change their fairytales all the time.


Internal evolutionary squabbles overlooked

As shown later, this program advocates what is called the ‘Out of Africa’ model, without saying so. This is where modern humans came out of Africa and replaced less evolved hominids that had emerged from Africa much earlier. But there is another evolutionary idea, called the ‘multi-regional’ or ‘regional-continuity’ hypothesis, where the hominids that emerged from Africa 2 Ma evolved into modern humans in many parts of the world. This is one of the most vitriolic debates among paleoanthropologists, yet this episode presents only one side. The acrimony between the proponents of these rival theories is due, according to the anthropologist Peter Underhill of Stanford University, to: ‘Egos, egos, egos. Scientists are human.’ We think both sides are right—in their criticisms of each other, because humans did not evolve at all!

http://www.answersingenesis.org/pbs_nova/0930ep6.asp


Petr

[Professor John Frink]

Objections to Templeton's theory:

While acknowledging that mtDNA supports replacement, Templeton (2002) argues that several nuclear DNA polymorphisms are much older than the expansion of modern humans out of Africa and must therefore reflect intermixture with Neanderthals and other archaic humans. Templeton’s analysis suffers, however, from two flaws: (1) a wide margin of error in the time estimates based on nuclear DNA polymorphisms, combined with a bias in favour of polymorphisms that look older than they really are; and (2) a disregard for selection pressures that would inflate the variability of these polymorphisms and thereby inflate the time estimates.

As Templeton himself concedes, nuclear DNA accumulates variability at a slower rate than does mtDNA, so any time estimates would suffer from a wider margin of error. Although this may explain why some polymorphisms yield very old dates (oldest = 1.9 million BP), it is not readily apparent why none yield very young ones (youngest = 230,000 BP). Keep in mind that if a polymorphism looks much younger than its real age it would also have much less variability. A significant proportion would have none at all or not enough to attract the interest of population geneticists. Templeton is thus using a biased sample that includes polymorphisms that have much more variability than they should for their age but excludes many that have much less.

The second flaw is that all but one of Templeton’s nine nuclear DNA loci produce proteins of one sort or another. They are thus exposed to selection pressures that may inflate genetic variability, i.e., through heterozygote advantage, frequency-dependent sexual selection, disease-resistance polymorphisms, and other balanced polymorphisms. Templeton uses the hemoglobin β-chain locus in his analysis, yet many of its alleles (e.g., β-Thalassemia) are clearly balanced polymorphisms that provide some protection against malaria. The MC1R locus is used even though its alleles code for highly visible differences in hair colour that may have been maintained through sexual selection (Rana et al. 1999). The PDHA1 locus is used, yet different portions of the PDHA1 region have evolved at different rates, a strong indication of natural selection (Disotell 1999). The MX1 locus is used even though one of its alleles causes alopecia areata in the homozygous state and is likely maintained through some form of heterozygote advantage (Tazi-Ahnini R et al. 2000).

http://human-nature.com/nibbs/02/frost.html