Compare and contrast the multiregional and replacement models for human origins in the table below. If you are struggling with this, see the PowerPoint on the origins and dispersal of modern humans and review the tutorial: https://www2.palomar.edu/anthro/homo2/mod_homo_4.htm Multiregional ModelReplacementMain argument of this model Evidence that supports this model Based on the evidence, which model of human origins is best supported? Replacement Model ArgumentsThere are two sources of evidence supporting the replacement model--the fossil record and DNA. So far, the earliest finds of modern Homo sapiens skeletons comefrom Africa. They date to nearly 200,000 years ago on that continent. They appear in Southwest Asia around 100,000 years ago and elsewhere in the Old World by60,000-40,000 years ago. Unless modern human remains dating to 200,000 years ago or earlier are found in Europe or East Asia, it would seem that thereplacement model better explains the fossil data for those regions. However, the DNA data supporting a replacement are more problematical.Beginning in the 1980's, Rebecca Cann, at the University of California, argued that the geographic region in which modern people have lived the longest should havethe greatest amount of genetic diversity today. Through comparisons of mitochondrial DNA sequences from living people throughout the world, she concluded thatAfrica has the greatest genetic diversity and, therefore, must be the homeland of all modern humans. Assuming a specific, constant rate of mutation, she furtherconcluded that the common ancestor of modern people was a woman living about 200,000 years ago in Africa. This supposed predecessor was dubbed"mitochondrial Eve". More recent genetic research at the University of Chicago and Yale University lends support to the replacement model. It has shown thatvariations in the DNA of the Y chromosome and chromosome 12 also have the greatest diversity among Africans today. John Relethford and other critics of thereplacement model have pointed out that Africa could have had the greatest diversity in DNA simply because there were more people living there during the lastseveral hundred thousand years. This would leave open the possibility that Africa was not necessarily the only homeland of modern humans.Critics of the genetic argument for the replacement model also point out that the rate of mutation used for the "molecular clock" is not necessarily constant, whichmakes the 200,000 year date for "mitochondrial Eve" unreliable. The rate of inheritable mutations for a species or a population can vary due to a number of factorsincluding generation time, the efficiency of DNA repair within cells, ambient temperature, and varying amounts of natural environmental mutagens. In addition, somekinds of DNA molecules are known to be more subject to mutation than others, resulting in faster mutation rates. This seems to be the case with the Y chromosomein human males.Further criticism of the genetic argument for the replacement model has come from geneticists at Oxford University. They found that the human betaglobin gene iswidely distributed in Asia but not in Africa. Since this gene is thought to have originated more than 200,000 years ago, it undercuts the claim that an Africanpopulation of modern Homo sapiens replaced East Asian archaic humans less than 60,000 years ago. Regional Continuity Model ArgumentsFossil evidence also is used to support the regional continuity model. Its advocates claim that there has been a continuity of some anatomical traits from archaichumans to modern humans in Europe and Asia. In other words, the Asian and European physical characteristics have antiquity in these regions going back over100,000 years. They point to the fact that many Europeans have relatively heavy brow ridges and a high angle of their noses reminiscent of Neandertals. Similarly,it is claimed that some Chinese facial characteristics can be seen in an Asian archaic human fossil from Jinniushan dating to 200,000 years ago. Like Homo erectus,East Asians today commonly have shovel-shaped incisors while Africans and Europeans rarely do. This supports the contention of direct genetic links betweenAsian Homo erectus and modern Asians. Alan Thorne of the Australian National University believes that Australian aborigines share key skeletal and dental traitswith pre-modern people who inhabited Indonesia at least 100,000 years ago. The implication is that there was no replacement by modern humans from Africa60,000-40,000 years ago. However, the evidence does not rule out gene flow from African populations to Europe and Asia at that time and before. David Frayer, ofthe University of Kansas, believes that a number of European fossils from the last 50,000 years have characteristics that are the result of archaic and modernhumans interbreeding.

Human evolution is how humans and their ancient relatives changed over a very long time from early…

Answered: Compare and contrast the multiregional…

11th Edition

ISBN:9780134580999

Author:Elaine N. Marieb, Katja N. Hoehn

Publisher:Elaine N. Marieb, Katja N. Hoehn

Chapter1: The Human Body: An Orientation

Section: Chapter Questions

Problem 1RQ: The correct sequence of levels forming the structural hierarchy is A. (a) organ, organ system,...