I have been reading some posts wondering about the content of the recent "Neandertals Revisited" conference. Of course the most pertinent questions have come from those who have looked at the participant list and wondered whether much new information could result. Of course we all have a research record, and I cannot think of many surprises that came up over the course of the meeting. Indeed, there was probably an overrepresentation of Neandertals-as-separate-species advocates among the senior scientists.
I will admit that as I started my own presentation, I had the distinct sensation that I was to play the role of Neandertal defense attorney before a stacked jury. And there was a moment when Bernard Wood (George Washington University) told the crowd he thought I made a case for gene flow with the same slim evidence that Dick Cheney made the case for weapons of mass destruction (My response: we have to send in the troops!).
But I the story emerging from the conference is the great level of interaction and common ground among the junior scientists. I experienced more rational discussion with this group than I have ever seen at a conference before. Maybe all the good food made us more mellow than usual, but I tend to think that the younger scientists are really reaching out to each other in collaborative ways. Moreover, people like me--studying the evolutionary dynamics of traits--are paying much more attention to people studying other parts of the problem and vice-versa. I find it exciting to be able to use new information on Neandertal adaptations to give an estimate of the actual importance of those characteristics to Neandertal survival and reproduction. I find it very useful to be able to examine the ontogenetic differences between Neandertals and recent humans to assess when these changes may have taken place during life, and to formulate hypotheses about the kinds of developmental and structural genes that may have been involved.
We aren't there yet on these ideas. The field is just beginning to be able to pose these questions, and is far from answering them. But the fact that we can see the essential questions rising out of our data is tremendously encouraging.
It would of course be unfair to say that we all agree on anything. My own interpretation of the Neandertal mtDNA pattern could not be further at variance from that of the Leipzig group, for example. And I would say there is a deeper epistemological divide concerning the nature of comparisons in our research. Ultimately this divide reflects different assumptions about the level of difference represented by comparisons between Neandertals and recent humans. Some researchers think the level of difference can be meaningfully quantified and used as a test of phylogenetic hypotheses. Others think that the level of difference measured in such ways ultimately derives from arbitrary assumptions, and that the pattern of variation rather than its level is the appropriate test of phylogeny. It is easier to quantify a difference, and takes a much smaller fossil sample to do so, than to study the pattern of change over time and space.
I don't expect this divide to disappear soon, if at all. I think it may get worse, especially as those of us most concerned with questions of Neandertal phylogeny continue to advocate for our methods and data. I readily admit the possibility that I am completely wrong, and when I become convinced of it I will let everyone know it. But for the moment I think that the accurate measurement of difference is simply unimportant, because it is ultimately impossible. And I think that the examination of differences between Neandertals and recent people without full consideration of the temporal aspect of the samples is misleading. And I think that the idea that selection has been less than the most overwhelmingly powerful force in our evolution is simply not worth considering.
But I'm excited to think that probably most of my colleagues ultimately agree with these premises, although they may differ on their implications. And I'm gratified to have been included in a small number of scientists who will be making fundamental progress on Neandertal studies in upcoming years.
I have written some thoughts on the main topics coming out of the conference also.