Question

Three models of human evolution

Answer 1

Replacement Model

• The replacement model is also called the “Out of Africa” model.
• According to this model, modern humans evolved from archaic humans only in Africa around 200 thousand years ago.
• Some of them then migrated to the rest of the Old World.
• This model suggests that all modern humans today share a relatively recent African ancestry.
• It also suggests that any physical differences now found between modern human populations must have evolved within the past 40 thousand years or so.

Regional Continuity Model

• modern humans evolved more or less simultaneously from local archaic human populations in many places in the Old World.
• Modern European people, for example, are thought to have evolved from European Neanderthals.
• It says that the common ancestor of all modern humans was Homo erectus,who lived in Africa 1.8 million years ago or earlier.
• They also think that intermittent contact and gene flow among evolving human populations throughout the Old World prevented any of the local populations from evolving into different species.

Assimilation Model

• The assimilation model takes into account data that cannot be explained by either the replacement model or the regional continuity model.
• It is also a compromise between these other two models.
• According to the assimilation model, the first modern humans evolved in Africa, and later migrated into other parts of the Old World.
• Rather than simply replacing the local archaic human populations they encountered, the modern human migrants interbred with them, at least to a limited degree.
• The local archaic populations were partly absorbed and partly replaced by the modern human populations.
• In some cases, the archaic and modern human populations may have lived side by side for long periods of time, perhaps for thousands of years.
• assimilation model seems to be the best fit for the evidence, especially the DNA evidence