About whether single origin is about homo or homo sapiens sapies: I can believe it has two meanings, or that the former meaning has been replaced by the second (which would be metaphorically fitting). I was sure I had heard "African Eve" in contexts about the ancestor of Java man and Peking man. But I searched "African Eve" in the Gale electronic bibliography of articles and couldn't find any use predating Wilson's mitochondrial DNA study. So now African Eve seems to mean only mitochondrial Eve. Perhaps the same fate befell "single origin." In any event, the refs for this article and the links to it from other wiki articles require that it talk about the Out-of-Africa or "replacement" model, which says Peking man and Neanderthal et al were supplanted, without interbreeding, by the descendants of recent African migrants. So it will need rewriting and probably splitting in two and changes to the links to it if "single origin" indeed refers to an African exodus of early homo. 168... 20:43 17 Jun 2003 (UTC)
From Science News, May 17, 2003 "Mark Stoneking of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, an advocate of this **single-origin model** of human evolution, nonetheless regards the new evidence with caution. He hasn't seen the report but worries that the Cro-Magnon DNA is contaminated. However, mitochondrial DNA analyses of living people align with the single-origin, or **out-of-Africa,** scenario, Stoneking says. "
"Adherents of the contrasting **multiregional-origin** theory..." 168... 21:15 17 Jun 2003 (UTC)
Here's the earliest reference I can find to "single origin." It's a news article written by a science journalist, which appeared in Science magazine in 1987, on the heels of Stoneking and Wilson's first evidence for a "mitochondrial Eve." Note that the usage of terms in this excerpt implies that if one applies "single origin" to the million-odd-year old exodus, one will be speaking about what many people nowadays call the multi-regional origin model--i.e. the very opposite of what most people nowadays seem to mean by "single origin."
"The first, termed the candelabra model by Harvard University's William Howells, proposes that ancestral populations--specifically, Homo erectus--throughout the Old World each independently evolved first to archaic Homo sapiens, then to fully modern humans. This model, which has also been called the Neandertal phase hypothesis, therefore envisages multiple origins of Homo sapiens sapiens, and no necessary migrations. One consequence would be that modern geographic populations would have very deep roots, having been separated from each other for a very long time, perhaps as much as a million years.
"The second, which Howells called the Noah's Ark model, envisages a geographically discrete origin, followed by migration throughout the rest of the Old World. In this model, populations of Archaic sapiens might be completely replaced by the newcomers. So, by contrast with the candelabra model, here we have a single origin and extensive migration. Moreover, modern geographic populations would have relatively shallow roots, having derived from a single source in relatively recent times. "
It seems "Noah's Ark" didn't stick and "Out-of-Africa" or "African Eve model" are what researhers use.168... 21:31 17 Jun 2003 (UTC)
Re: "(anatomically modern humans)...evolved in Africa about 250,000 years ago", can you cite a source for this, SLR? Nothing I've read gives a number like this. I think the only people who speculate on this number are the Out-of-Africanists, who base their guesses on DNA evidence. In my readings, I most often see the date of the exodus and the date of the emergence of the species alike reckoned as "100 to 200 000 years ago"; i.e. separate dates aren't attached to the era of the common ancestor and the African exodus. 168... 20:07 19 Jun 2003 (UTC)
- It is just a number I got out of a textbook -- if you have better dating, yes please change it. I just think that we need some estimate/approximate date for the emergence of Homo sapiens. I'll check other sources, but like I said, if you know of some recent consensus among paleoanthropologists, please by all means put it in (but I would expect the date for the speciation and the date for the movement out of Africa to be different) Slrubenstein
"The age of the most recent common ancestor (MRCA) for mtDNA, on the basis of the maximum distance between two humans...is estimated to be 171,500 +/- 50,000 yr. We can also estimate the age of the MRCA for the youngest clade that contains both African and non-African sequences from the mean distance of all members of that clade to their common node as 52, 000 yr. **Because genetic divergence is expected to precede the divergence of populations, this date can be considered as the lower bound for an exodus from Africa. " From "Mitochondrial genome variation and the origin of modern humans" Ingman, Paabo and others, NATURE VOL 408 7 DECEMBER 2000
So actually, with respect to my earlier comment, actually there is some basis for distinguishing the dates of the migration and the evolution from the DNA data, and some people are trying to do so. I read this excerpt before but forgot about it.
The only place I know to look for consensus or controversy in news stories and encyclopedia articles, where I don't recall seening argument about when H sapiens evolved _in Africa_. I figure the multiregionalists don't often have cause to argue that particular point, b/c events in Africa aren't central to them. 168... 20:29 19 Jun 2003 (UTC)
- I am sure you are right on this last place. I have misplaced my most recent textbooks; earlier ones date the emergence of Hs to the middle pleistocene but I am sure the date can be pushed further back. I also suspect that fossil evidence will suggest that Hs emerged before the MRCA. Well, every article is a work in progress. For what it is worth, though, I wanted to tell you that I think this is sha[ing into a very good article. I feel like you have been more respectful of my changes, and I appreciate that -- but I want to emphasize that I also value many of your own changes and additions. Slrubenstein
I appreciate your cooperativeness too, and am glad for the signs that we might be able to work together in the future without antagonism. That's certainly my hope. Also, just in your capacity as an anthropologist, I'm glad you approve of the shape the article is taking and of contributions I've made to it.
One point about consensus that may not need making, but which I wish I had: For the paragraph in question, of course, we only need the consensus of the Out-of-Africansts, b/c this paragraph is about their contention. That's why I felt quoting Paabo's words alone established at least something. I ended up characterizing the dates as the BBC and other news sources have done. 168... 21:01 19 Jun 2003 (UTC)
- I'm glad to see you share my feelings about working together. I also think you are quite right that for dating, it is only a consensus among the Single Origin people that need concern us. In lieu of any other information, I think the change you made to the date (the rather broad range) is good -- appropriate and well-stated. I do not know if this article is the appropriate place for a more polemical discussion of evolution, but I do think it is important that readers understand that the issue iiat hand really is whether Homo sapiens evolved in only one place or many -- not whether we all share an ancestor, for no matter where H. sapiens evolved, as long as you go back far enough evolutionary theory argues that all human beings have a common ancestor (I mean, multi-regionalists too think we have a common ancestor, it is just that our common ancestor, they argue, was H. erectus or some other species), as indeed all living organisms are descended from a common ancestor. I think this claim is something most people do not understand, or have a hostile reaction to -- and so it is important to explain it clearly. But perhaps such a general explanation belongs in the evolution article, not here (I am just musing out loud, as it were). Anyway, for the moment I think it is a fine article, Slrubenstein