Archaeologica.org

American Journal of Physical Anthropology
Volume 128, Issue S41 , Pages 33 - 59

Haplotype Trees and Modern Human Origins (p 33-59)

Alan R. Templeton

Abstract

A haplotype is a multisite haploid genotype at two or more polymorphic sites on the same chromosome in a defined DNA region. An evolutionary tree of the haplotypes can be estimated if the DNA region had little to no recombination. Haplotype trees can be used to reconstruct past human gene-flow patterns and historical events, but any single tree captures only a small portion of evolutionary history, and is subject to error. A fuller view of human evolution requires multiple DNA regions, and errors can be minimized by cross-validating inferences across loci. An analysis of 25 DNA regions reveals an out-of-Africa expansion event at 1.9 million years ago. Gene flow with isolation by distance was established between African and Eurasian populations by about 1.5 million years ago, with no detectable interruptions since. A second out-of-Africa expansion occurred about 700,000 years ago, and involved interbreeding with at least some Eurasian populations. A third out-of-Africa event occurred around 100,000 years ago, and was also characterized by interbreeding, with the hypothesis of a total Eurasian replacement strongly rejected (P < 10-17). This does not preclude the possibility that some Eurasian populations could have been replaced, and the status of Neanderthals is indecisive. Demographic inferences from haplotype trees have been inconsistent, so few definitive conclusions can be made at this time. Haplotype trees from human parasites offer additional insights into human evolution and raise the possibility of an Asian isolate of humanity, but once again not in a definitive fashion. Haplotype trees can also indicate which genes were subject to positive selection in the lineage leading to modern humans. Genetics provides many insights into human evolution, but those insights need to be integrated with fossil and archaeological data to yield a fuller picture of the origin of modern humans.

Multiregional theory: homo erectus left Africa 2 mya to become homo sapiens in different parts of the world

Out of Africa theory: homo sapiens arose in Africa and migrated to other parts of the world to replace other hominid species, including homo erectus.

SYDNEY (Reuters) Australian and Chinese scientists have dated China's Nanjing Man as 580,000 to 620,000 years old, further supporting a multiregional theory of human evolution that argues Asians evolved locally and not out of Africa.

The scientists said Nanjing Man (Homo erectus), a male and female skull discovered in 1993 in Tangshan Cave near Shanghai, shows that humans evolved in isolation in China and much earlier than previously thought.

"We can confidently say the Nanjing Man fossils are older than 580,000 years and probably at least 620,000 years old," said Zhao Jianxin from the University of Queensland.

Scientists had previously estimated Nanjing Man to be about 400,000 years old. The "Out of Africa" theory of evolution argues that Homo erectus in Asia was replaced by Homo sapiens newly arrived out of Africa about 100,000 to 200,000 years ago.

"The Nanjing Man finding supports the multiregional evolution model that argues modern Asian populations evolved directly from Asian Homo erectus, rather than evolving from populations out of Africa," Zhao said.

"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."

French archaeologists said the corpses dated back 2,100 years according to C14 dating, and the four people belonged to the Caucasoid group of the Caucasian race. However, they could not explain where the people were from.

Generally speaking, the Caucasoid group mainly live in Europe, West Asia and northern Africa.