A 1400-year-old volcanic or other induced "winter" likely spurred the divergence possibly even later than 150,000 years ago, brought about by an explosion of Toba in Sumatra. The elimination of this bottleneck 10, 000 years later allowed another wave of emigration from Africa. Volcanic winter may have succeeded in the reductions of populations to levels low enough for founder effects, genetic drift and local adaptations to produce rapid population differentiation (Ambrose 623 -- 651) .
This new research posits new assumptions about evolutionary rates, anagenesis, gene flow and population stability. Most biological evolution consists of the following two processes: anagenesis and cladogenesis. Anagenesis describes the transformations that occur within a single lineage, that is, as a population develops new characteristics. Cladogenesis, describes the splitting of a single species into two or more groups that later subsequently diverge in their individual traits through the anagenetic process. Gene flow and population stability are now seen as being much more relative. Also, the perceptions of the genetic basis of anatomical differences between human populations has also changed dramatically. The assumptions about gene flow for interpreting fossil species as grades and clades has been radically altered (including assumptions of relative and absolute ages of fossils, and the implications of revised ages). The fact that the human evolution was influenced by bottlenecks and rapid evolution has changed the entire perception of the continuity of the human clade as the Australopithecines, Homo Erectus and Neanderthal are not seen as part of the human lineage, but rather as possible marginal contributors of DNA if the other species interbred with Homo Sapiens
(Washburn 76).
In this short essay, the author has illustrated the very startling similarity in relation religious fundamentalists, in their continued dogged resistance and almost religious conviction that the human family tree began much earlier., that is, millions...
Ironically both are based upon a dogma that has been set up and a community's agenda, existence (and usually careers) have been based upon an established orthodoxy whose overthrow will jeopardize an established order. The only difference between the two is that the early evolutionary orthodoxy which overthrew the creationist orthodoxy is now paradoxically in the same position battling the forces of analysis in evolutionary change. In addition, this most recent biological evolution is not propelled as much by an agenda other than the one to gather data. Largely, it has been allowing the data itself to frame the debate and to define the agenda by not defining it at all. It is truly a pursuit of scientific truth via the scientific method at its best. Certainly, if the old scientists had their way, we would need something like a modern scopes trial to liberate the story of human origins from supposition to one of fact. We should be happy that it has not and that stubborn resistors to change for resistance sake can now take up their place along the sidelines of the game of knowledge and warm the benches beside the creationists. They will always represent a booing minority, but they now do not command the high ground of pure intellectual pursuit and plumbing of the origins of humanity as a distinct species.
Works Cited
Ambrose, Stephen H. "Late Pleistocene human population bottlenecks, volcanic winter, and differentiation of modern humans." Journal of Human Evolution. 34. (1998): 623 -- 651. Print.
Johanson, Donald. "Origins of Modern Humans: Multiregional or Out of Africa?" Action
Bioscience.org. 2011. Web. 6 May 2011.
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Tierney, John. "The Search for Adam and Eve." Newsweek . 11 Nov. 1988: 46-52.. Print.
Washburn, Sherwood L. Classification and Human Evolution By Sherwood L. Washburn. London, UK:
Routledge, 2004. 76. Print. Washburn, Sherwood L. Classification and Human Evolution By
Sherwood…
