Convoluted human evolution: Tattersall's take (Introduction)

by David Turell @, Sunday, February 14, 2016, 19:45 (1073 days ago) @ David Turell

My favorite paleoanthropologist's take on the confusion in human fossil ancestry:

"You might thus be tempted to imagine that, in the century and a half since Charles Darwin pointed out that we are joined to the rest of nature by common ancestry, science might have begun to make some progress toward a biological definition of the human genus. But if so, you would be doomed to disappointment. Scientists are still arguing vehemently over which ancient fossil human relatives should be included in the genus Homo. And they are doing so in the absence of any coherent idea of what the genus that includes our species Homo sapiens might reasonably be presumed to contain.


"But in practice there is a problem: the splitting of lineages that produces those groups of species also produces a branching system of relationships. In other words, the descendants of the ancestral species themselves divide, to produce ever-larger groupings of descendants that are increasingly remotely related. As a result, not all species in any genus will be equally closely related by descent. This means that how inclusive you want your genus to be is an entirely arbitrary matter about which there may be legitimate disagreement. Species have a reasonably objective biological reality that is grounded in the dynamic that exists among their members. Genera, on the other hand, are purely historical constructs.


"The fossil record, mainly consisting of mineralized bones and teeth, is a very pale reflection of the once-living world it represents, and it is rare indeed to find an articulated skeleton that will reliably tell you which elements of the individual go together. Worse yet, the fossil bones themselves are more often than not broken and incomplete. As a result, attributing fossils to a species or to a genus can often be an extremely tricky matter involving a lot of subjective judgment. This fairly harsh reality provides much of the background against which attempts to recognize fossil members of the genus Homo need to be understood.


"Yet if there is one lesson that we can very clearly derive from a mushrooming fossil record, it is that the history of the hominid family is very much like that of any other successful family of mammals, among which diversification has always been the rule. The history of the hominids has been one of vigorous evolutionary experimentation with the hominid potential. Numerous species, whose relationships can only be clarified by recognizing several genera, have been thrown out onto an ever-changing ecological stage to compete and to flourish, or face extinction.


"If we can adopt a more realistic notion of what our genus Homo is, we will at the same time open the way not only to a better understanding of the process that produced us, but also to a more accurate perspective about the kind of creature we happen to be."

Comment: Just a smattering of a great essay, from the bony standpoint, not from the DNA studies. The bush is still a bush.

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