Hi again DBlevins,
It seemed to me that the dominant thoughts about Human evolution were that it was much more 'linear' and it hasn't been until recently that studies have shed some more light onto the complexity of our lineage.
People like to think of species as linear, however when you look at subspecies and variations between populations, it is self evident (imho) that a bushier arrangement is appropriate, maybe even more of a weave when subspecies interbreed and produce hybrids.
Personally I think there will always be an impetus to branch away from the parent lineage, particularly when new eco-systems are involved that cause variation on the selection process. Until such branching reaches speciation, the picture will be shrubby rather than linear.
Certainly the biggest objection I had had with the identification of some individual hominin fossils as separate species has been the geologically recent bottleneck effect on our variation, which to my mind created a more narrow interpretation of what constituted H. Sapiens.
Because it happened during the time
H.sapiens was already established as a species. Don't know how it affected the
H.neanders (anyone know?) ...
With the inclusion of these recents finds, others in West Africa and the recent findings concerning hybridization among Neanderthals and Denisovians, it appears that there is a stronger multi-regional facet to the OOA hypothesis.
Be careful here. Multi-regional, IIRC, was originally about
H.sapiens arising independently in several locations (an aspect I have always had trouble with -- such a scenario should result in different species or subspecies not the same one), whereas what we have here is some rather limited hybridization between hominid populations. I would expect that many hybrid offspring may have been infertile, thus reducing the impact of such individuals on the overall populations. After all some mules are fertile and can produce offspring with horses and donkeys.
Mule - Wikipedia
quote:
here are no recorded cases of fertile mule stallions.[citation needed] A few female mules have produced offspring when mated with a purebred horse or donkey.[9][10] Since 1527 there have been more than 60 documented cases of foals born to female mules around the world.[9] There are reports that a mule in China produced a foal in 1984.[11][12] In Morocco, in early 2002, a mare mule produced a rare foal.[9] In 2007 a mule named Kate gave birth to a mule son in Colorado.[13][14] Blood and hair samples were tested verifying that the mother was a mule and the colt was indeed her offspring.
So I would not be surprised to see similar small numbers of offspring from hybrids when the genetic divergence had almost reached isolation levels.
Enjoy