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Hi Nancy, Sylvia and all, 1) Without any polemics, one can invent innumerable hypotheses on something. However, a new (although perhaps not really new here) scientifically sound and acceptable hypothesis needs to accomodate (explain) facts and observations in a better way than the one it pretends to substitute. 2) Let's define ingression (not mine): "incorporation of genes of one species into a gene pool of another species". This is known from e.g., bacteria (though species definition is different here), plants, invertebrates, not sure about amphibians. Correct me, but I am unaware of any example from Mammalia (tiger-lyon?). Examples of cross fertilisation between mammalian species are known (e.g., donkey x horse = mule) but these hybrids are not fertile and therefore cannot reproduce to give a new species. In theory, it might exist in humans (or hominoids) but in the absence of the slightest indication of its existence (e.g. cross fertilisation of ape species and reproducibility between these hybrids), the biological species concept (hypothesis) fits human evolution better then the hypothesis of reticulate speciation (in humans). In addition, the fact that the genetic differences between today living humans are so extremely minimal strongly supports a common origin. 3) Geographic isolation: the common house mouse is the same in China and Europe (and probably the Americas) even though one would expect little gene flow between these populations. I would think that humans are/were at least as mobile as mice. 4) According to current knowledge, Homo sapiens neandertalensis is not our ancestor. If it really was a subspecies of Homo sapiens this would be an example of evolution within (not of) separate populations of Homo sapiens. However, not even here is a sign (I am not aware of any) of intermingling between H. s. sapiens and H. s. neandertalensis although the latter also has a wide geographic distribution (Europe, Asia, Africa). All in all, at present I fail to see how introgression between human species could be a "reasonable scenario" (scientifically sound hypothesis). Cheers, Niko ----- >evolution of separate populations of Homo sapiens could have happened if > H. > erectus and H. sapiens populations experienced introgression in more than > one > place. This seems like a reasonable scenario. - SH > > I agree that H.s. could spread after evolving from one > group of H.e. I just don't think that Homo erectus in > different isolated groups could have evolved into the same > species everywhere. I have read about that theory in > several places, for instance, in The Real Eve; I'll have to > get youthe name of the author. I should probably add that > I am not a scientific professional; i'm a criminal defense > lawyer, but I often wish I had stayed with paleontology > instead. If I've mistaken what I read I hope someone will > email me and let me know. > --- Bill Chaisson/Deirdre Cunningham <chaisson@netacc.net> > wrote: > > >I'm not convinced that it's racist, but I still don't > > agree > > >with it. -And my grandfather was from Alabama, so we > > could > > >be cousins! I'm just a few miles away from Dayton, Tn, > > >home of the Scopes trial. > > > > Isn't this issue something that can be settled with DNA > > evidence? > > > > I also don't understand why it seems unlikely that a > > large highly > > mobile and highly adaptable organism like Homo sapiens > > could not > > become globally distributed after originating from a > > single > > population of H. erectus. > > > > Please provide a reference where the multi-origins > > evidence is presented. > > > > Thanks, > > Bill > > -- > > --------------------------------------------------- > > William P. Chaisson > > Adjunct Assistant Professor > > Department of Earth and Environmental Sciences > > University of Rochester > > Rochester, NY 14627 > > 607-387-3892 > > "The United States is in no sense founded upon the Christian religion." - > George Washington > > > > __________________________________ > Do you Yahoo!? > Yahoo! Small Business - Try our new resources site! > http://smallbusiness.yahoo.com/resources/ > > > > > -- --- ADDRESS: Dept. de Geologia/Unitat Paleontologia, Universitat Autònoma de Barcelona, Campus, Edifici Cs, 08193 Bellaterra (Cerdanyola del Vallès), Catalunya, SPAIN --- Tel xx34-93-581-1464/Fax -1263 --- n.malchus@gmx.net (admits larger attachments) nikolaus.malchus@uab.es (max. 2MB for attachments) ---
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