Re: mtDNA Eve and the determination of humanity

From: jack syme <>
Date: Sat Feb 25 2006 - 14:27:43 EST

I have been thinking about this some over the past few days. I was thinking that the MRH could be an example of convergent evolution. That is, the selection pressure on the archaic homo sapiens in Africa, Asia, and Europe, simultaneously selected for the same adaptation independantly in these areas. I was speculating that the adaptation that evolved simultaneously could have been the ability to communicate. Perhaps related to a structural change in the frontal lobes.

In some ways I have tried to come up with an argument that "the image of God" is our ability to communicate in abstract language. I know animals display some language abilities, and archaic homo species had some language abilitiies. But if there is anything that seperates modern homo sapiens from animals, and from archaic homo species, it seems to me, would be our sophisticated language.

I was going to ask here if anyone else was familiar with a similar example of convergent evolution. Has anyone ever documented that a single species (or a species and subspecies) isolated by geography or some other means of reproductive isolation, has ever evolved in these seperate regions into the same new species simultaneously? That would seem very unlikely. However, if the strategy to survive is the same in each region, i.e. improved communication, I suspect that it could be convergent evolution in these seperate regions.

But then I thought that these seperate geographic regions are not completely isolated from each other and there is interbreeding. So, it seems more likely that modern homo sapiens emerged out of africa soley, but there was interbreeding with the archaic homo species in these areas that accounts for the autosomal genetic findings. The OOA would be wrong in the sense that the modern homo sapiens did not displace the archaic homo species without interbreeding, but mostly displaced them with some interbreeding. If I had to choose between three geographic regions evolving into modern homo sapiens simultaneously and a modern homo sapiens emerging out of Africa but interbreeding with all of the other geographic regions, I would say that via Ockham's razor the latter is more likely.

Whether or not OOA or MRH, or some combination of the two turns out to be the accepted mechanism of human origin, the recent data still disproves the RTB model, because the RTB model requires genetic isolation of the modern human from archaic homo species. Templeton's latest data clearly refutes that.
  ----- Original Message -----
  From: Dick Fischer
  To: ASA
  Sent: Saturday, February 25, 2006 1:46 PM
  Subject: RE: mtDNA Eve and the determination of humanity

  Hey Guys and Gals:


  Before we jump from one horse to the other, we need to look at the horse we want to ride. According to Donald Johanson (Remember, Lucy?), the Multiregional Continuity model (MRH) has the following characteristics.


  The Multiregional Continuity Model15 contends that after Homo erectus left Africa and dispersed into other portions of the Old World, regional populations slowly evolved into modern humans. This model contains the following components:

    a.. some level of gene flow between geographically separated populations prevented speciation, after the dispersal
    b.. all living humans derive from the species Homo erectus that left Africa nearly two million-years-ago
    c.. natural selection in regional populations, ever since their original dispersal, is responsible for the regional variants (sometimes called races) we see today
    d.. the emergence of Homo sapiens was not restricted to any one area, but was a phenomenon that occurred throughout the entire geographic range where humans lived
  Now the counter intuitive part is the idea that H erectus in Europe and H erectus in Africa developed in situ to become H sapiens in both locations. This would be like putting zebras in Australia and zebras in Africa and a million years later finding horses grazing on both continents with only fossils of zebras to be found. And this ignores the second wave out of Africa that occurred around 100,000 years ago with both displacement and interbreeding combined.


  So let's take another look at the Out of Africa approach. Again, quoting Johanson:


  In contrast, the Out of Africa Model asserts that modern humans evolved relatively recently in Africa, migrated into Eurasia and replaced all populations which had descended from Homo erectus. Critical to this model are the following tenets:

    a.. after Homo erectus migrated out of Africa the different populations became reproductively isolated, evolving independently, and in some cases like the Neanderthals, into separate species
    b.. Homo sapiens arose in one place, probably Africa (geographically this includes the Middle East)
    c.. Homo sapiens ultimately migrated out of Africa and replaced all other human populations, without interbreeding
    d.. modern human variation is a relatively recent phenomenon
  Aha, here is the fly in the ointment. Thanks to Templeton we know there was interbreeding. Egad! Are there logical inconsistencies in both arguments? Is it going to be left up to ASA to solve this one? Mouses at the ready . Get set . Click!


  Dick Fischer

  ~Dick Fischer~ Genesis Proclaimed Association

  Finding Harmony in Bible, Science, and History
Received on Sat Feb 25 14:29:27 2006

This archive was generated by hypermail 2.1.8 : Sat Feb 25 2006 - 14:29:27 EST