The Replacement and Cosntinuity Models Essay
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Paleonthropologists generally use the following 2 models to explain the origins of modern humans.
- The replacement model
- The continuity model
Each of these models has its basis that could be traced back to hundred of years ago. The two models would be discussed explicitly with the use of examples for easy understanding.
The Replacement Model
This model was founded by Christopher Stringer and Peter Andrews. They proposed that modern humans evolved from archaic Homo Sapiens 200,000 – 150,000 ( 2000 centuries ago) only in Africa and then some of them migrated into the rest of the world due to one reason or the other replacing all of the Neanderthals and other late archaic Homo Sapiens beginning around 1000 centuries ago.
Since the interpretation of this fossil record is accepted by some people, it means all people today or modern humans share a relatively modern African ancestry which simply means we are all Africans. All other lines of humans that had descended from Homo erectus presumably became extinct.
As we can see, the regional anatomical differences that we can among humans today are recent growths evolving mostly in the last 400 centuries.
This hypothesis is also referred to as the Noah’s ark or African replacement model.
The accepted view of the out of Africa model is that Africa exchanged genes with Eurasia, which shared genes with East and Southeast Asia and there are two evidences supporting the replacement model: the fossil record and DNA. So far, the earliest form of modern Homo sapiens skeletons came from Africa. This simply means that there are no homo sapiens existing today that would not be traced back to Africa.
Though John Relethford and other critics of the replacement model have had the greatest diversity in DNA simply because there were more people living in Africa during the last several years and this would lead us to the explanation of continuity or multi-regional model.
The Continuity Model
This model was advocated by Milford Wolpoff, of the University of Michigan, he proposed that modern humans evolved more or less simultaneously or at the same time in all major regions of the old world from local archaic homo sapiens. Which means that homo erectus were available in all regions of the earth ever since inception. The hypothesis of this model states that modern homo sapiens had multiple origins from existing local populations. Each local population of archaic humans gave rise to a population of modern humans. This model was formulated around 1992 at University of Michigan. ( Turnbaugh, et. al# 323) . They advance their claim by stating that through gene flow, the archaic Homo sapiens gene was given greater variability thus enabling it to produce greater adaptations. By this process, they assume that we modern humans materialized.
From a personal perspective, it is the continuity model that makes more sense. Because it claims that modern human came into existence through Homo erectus that was available in all region of the earth. This means that each region has its founding homo erectus.
Example I to support personal view
Modern Chinese are seen as having evolved from Chinese archaic Homo sapiens and Homo erectus. This means that the Chinese and some other people in the world have great antiquity in place.
Example II to support personal view
Medley of cranial features is used to argue that modern aborigines are descended from Javanese Homo erectus. The traits that were familiar between the Javanese Homo erectus
and the modern humans living in Indonesia and Australia regions include:
Jorgen Holm in Human evolution