LM3 in Paleoanthropology

Great Debates
1

The now dry Lake Mungo in Australia has yielded many fossil specimens. The current favorite is LM3 (dubbed “Mungo Man” by the newspapers and not to be confused with “MM” Millenium Man or Marilyn Monroe.) The LM3 fossils were discovered in 1974.

LM3 was described as gracile and within the range of living aborigines and dated at 60,000 (60 kya) . While there has been some debate whether or not LM3 was male or female, it would definitely have to be a modern human since it was capable of making the boat trip to Australia.

LM3 has been left out of the bickering surrounding the OoA and MERH camps until just recently, that is. Now LM3 has been dragged into the limelight because an Australian group has applied mtDNA methods to a piece of the fossil and find it is different than all living humans and our sister or cousins, the Neanderthals.

I’m sure OaA allows for variant mtDNA to slip out of Africa and travel the coastlines to Australia and go extinct. How about MREH?

http://www-personal.une.edu.au/~pbrown3/palaeo.html
Might be helpful if you are short of references.

The mtDNa was published in PNAS, January 16, 2001/vol 38. #2, pp537-542, Adcock et al., Mitochondrial DNA sequences in ancient Australians: Implications for modern human origins.

Jois

2

[scratching head in a manner uncannily reminiscent of the earliest hominids]

Um–I flatter myself that I’m no slouch when it comes to talking about paleontology and archaeology and paleoarchaeology and all those “-ologies”, but, “huh?”

Is there a debate topic here, or shall we just share fruit and copulate randomly?

:smiley:

[sub]I gather you want to talk about Mungo Man? Your link just goes to a bewildering array of other links. Are you talking about the challenge to the “Out of Africa” theory of human origins?

Link from http://boards.straightdope.com/sdmb/showthread.php?threadid=54574

Mungo Man: the last of his kind?

Is this what you’re talking about? [/sub]

:confused:

3

Wow, you guys have gotten boring!

4

No, Jois, your OP is just full of jargon. I read quite a bit on paleoanthropology too, and while I can figure out your OoA refers to the “Out of Africa” hypothesis (although you also have it as OaA), I’m having trouble figuring out what MERH stands for - although I realize it must be the alternative hypothesis. I’m sure I can figure it out with time, but how about telling us?

Do yourself and the rest of us a favor and restate the OP with a little more clarity, huh?

5

MERH = Man Evolved Right Here?

[sub]::Ice Wolf getting ready to d&r any second now::[/sub]

6

MREH is short hand for Multi Regional Evolution Hypothesis whose main supporter is Dr. Wolpoff – at Michigan I think, yes Jois?

Posits that man evolved seperately more or less in place on each continent, which of course inflows to maintain species. Has run into serious trouble given genetic evidence (per all that crap I have posted in the race threads).

Re MREH allowing varient MtDNA – I have understood this is the very heart of their claim.

But if the MM stuff doesn’t show up in modern populations we have a number of explanations:
(1) Simply a dead OoA lineage
(2) A earlier OoA lineage perhaps diverged and then displaced.
(3) evolved seperately per MREH, but then this flies in the face of other evidence.

I’m sure Phil will have extensive and caustic comments.

7

Got some questions about this:

  1. How many theories are there about human evolution? Is OoA divided into OoA Part 1, and then OaA The Sequel, that is two seperate migrations out of Africa during the evolution.

  2. If MREH has any credence, could man have evolved from different ancestors? Because, to my way of thinking here, if not there’d have to be a common ancestor. Which was darn near global in distribution. And we’re right back with: where the heck did the CA come from? Out of Africa? Asia? Europe? What?

I look forward to the answers. For some reason, this kind of stuff is fascinating.

8

Jois, spot me if I mess up here.

Generally speaking there are two main theories. MREH and OoA.

MREH has been steadily losing ground as diverse genetic evidence has come in. MREH supporters have attempted to revise the theory (which initially postulated independant evolution of Homo Sapiens from Homo Erectus in place on each of the continents with gene flow to allow for non-speciation) but the results (IMHO) begin to look like desperate attempts to save a dead theory. Frankly, I think there’s no reason to give credence to MREH: the recent Neandertal DNA analysis pretty much excluding contribution to modern humanity for example is yet another data point in the coffin. The game has moved to what form OoA took – which is a pretty complex issue.

OoA has perhaps two main flavors, a rather simplistic one wave out and more complex multi-wave with backflows, etc. Then of course, there are probably as many versions of OoA II as there are postulators. Just my opinion, but I think there won’t be much clarity until we begin to understand what the different stories that different parts of the genome are telling mean. To my understanding we don’t yet have a full enough understanding to ressolve some contradictions – some of the materials I’ve posted re race touch on contraditory estimates on divergences etc.

9

Soory to post and run. I’d expected to continue on but got into technical difficulties, but LOL at Ice Wolf’s MREH, I’ll try to keep up with the posts.

All sorts of different methods have been attempted to name the fossil specimens, now they are named by location and in the order in which they were found. LM3’s fossils look as modern as yours or mine would. LM55’s fossils might be quite different. At least you know that LM is Lake Mungo and from now on no matter what is discovered about his age or body type or genes, LM3 will be identified as LM3.

In the OP I tried to introduce LM3 and explain (quickly) why a 25 plus year old fossil discover should right now be a topic of discussion (well, heated debate) in the anthropology and paleoanthropology world and tie it to what I thought was the very well known debate between MREH and OoA. (Sometimes written MRE and OOA and even OOA1 and OOA2.)

These ideas deal with the evolution of humans and probably have a lot to do with looked at the available materials and did the best they could with what they had. Some thought that “Man Evolved Right Here” and there was a “regional continuity” between what they found in the fossils and the humans living in that area. Others favored a replacement theory. What these theories have boiled down to in the end are currently known as MREH (MRE) or OOA (OoA/OOA2). IIRC MREH as the longer history, going back to the 1930s with several revisions over the years. OOA (in some form) may be every bit as old but the thread is more difficult for me to find. It, too, has has revisions over the years.

So, Collounsbury is right. MREH has man evolving separately in various places but not becoming separate species because of gene flow between the various groups. Dr Wolpoff(Michigan, I think) is the main supporter, Dr Brace is another as is Dr Thorne. Early on they had included Neanderthal as part of anotomically modern humans’ lineage, that Neanderthals evolved into modern Europeans. It seems to me that this positition is softening, that now MERH is saying that the Neanderthals shared genes with us, I’m reading that much more than before.

OOA was doing well as a theory proposing that modern humans became modern humans in Africa and then moved out of Africa to cover the world and replace any other earlier forms of Homo. Dr Stringer is the voice heard most often for this camp and various studies seem to point to Africa as the place where modern humans first appeared and where aspects of modern behavior first appeared.

I do not know how hot the debate was before the first Neanderthal mtDNA studies were published, but it has been thunder and lightening ever since. The studies seemed to land squarely on the side of OOA. Our mtDNA seems to say we appeared 150,000 years agoo and Neaderthals’ mtDNA is not enought like ours to be us. Three different studies of three different Neanderthal mtDNA samples have confirmed these results.

Now can you see how important LM3 has become? It’s dated to 60,000, is a modern human and his mtDNA is not like ours either. I think OOA can allow for variant mtDNAto slip out of Africa, travel the coastlines to Autsralia and go extinct. I had hoped that some of you had read enough of what MREH has had to say about this new development to offer some discussion.

I think MREH will have to do some re-inventing to remain viable - if that is even possible. I think OOA is missing a lot of detail, but still makes more sense to me.

Ice Wolf, this fascinates me, too. I’ve got to re-read your questions and my current reply, then I’ll try to answer whatever is missing, OK?

Jois

10

Well, I don’t think any major researchers these days dispute that the ancestors of all modern humans migrated out of Africa at some point. The question is whether they were already H. sapiens-type when they emigrated, or whether they were of some earlier type and then evolved in place into modern forms. Homo erectus (Java Man, Peking Man, and their ilk) is believed to be the first member of the genus to have emigrated, and spread through south and east Asia (but not to Oceania, the Americas, or Europe, at least AFAIK). The MREH hypothesis depends on the parallel evolution of sapiens-type humans from various different groups of erectus throughout its range, while simultaneously retaining cohesion through gene-flow. This sort of thing is quite difficult to buy according to the most common models of speciation and how evolution generally occurs in lineages.

It seems to me that the discovery of any sapiens type fossil with mtDNA more different from modern humans than that of Neandertals, whether in Australia or elsewhere, presents a lot more problems for OoA than MREH, in that it implies that the sapiens-type skeletal morphology is paraphyletic (present in two or more lineages that are not sister-groups) - just what MREH would predict.

What I’m curious about is the state of the play regarding nuclear DNA. I believe most of the data to date is on mtDNA - reasonable, since it evolves faster than nuclear DNA and hence has finer resolution for the relatively short periods of time we are talking about here. But mtDNA is inherited matrilinearly only, so that something quite different could be going on with nuclear DNA.

Jois, I am familiar with the debate between the two hypotheses, just not with the shorthand you used. And you confused the issue just a little by referring to MERH, MREH, OoA, and OaA in the OP! :wink:

11

Still not sure what you’re getting at, Jois. Are you just asking how the Mungo Man discovery affects current viewpoints on MREH and OoA?

Frankly, I don’t think it has any effect on either. All it means is that a human being got to Australia 10,000 years earlier than first thought, and left no modern descendants. The same sort of failed colonization has no doubt happened at least hundreds of times in human history. All it means is that we have to revise backward (slightly) our estimates of when people began crossing large bodies of water into Austronesia. (Personally, I’m already amazed that humans made it there 50,000 years ago…60,000 years is only slightly more of a leap, not a real revolution.)

And as for MREH vs. OoA… I don’t see how it matters which theory you belive. Whether you think human beings arose in Africa or in Africa/Europe/Asia, they still had to sail to Australia.

Is Mungo Man’s origins and identity a mystery? Sure. A world-shattering mystery? No.

12

Eh, how so? We are concerned with contribution to Hs. If we have similar morphology but no contribution to Hs I still don’t see a MREH scenario refuting OoA. But I’m tired, perhaps not thinking really clearly.

13

'S beyond my expertise.

But not my wife’s.

I’m printing out the thread for her to review.

I’ll post her response tomorrow or the next day.

(OaA = Out-a Africa? :D)

14

Anyone with sufficient paleoanthro backgrounding and some time on your hands, please describe and/or post links to the processes by which we have a handle on the mitochondrial DNA of your basic Neanderthal.

Fascinating…

15

I’m not saying that LM3 refutes either hypothesis. In fact I don’t think it has a direct bearing on either one. The results are more in line with MREH, but MREH fails on other evidence.

If modern humans are genetically distinct from Neadertals, in my book that pretty much shoots down MREH right there, since some of it is based on supposed skeletal similarities between modern Europeans and Neandertals. (Also IIRC dental similarities between ancient Asian populations and present ones). My main question is whether nuclear DNA could tell a different story than mtDNA. I think it’s unlikely, but that’s the main loophole still available for MREH to wriggle through.

My point was only that the situation with LM3 is more in line with what you would expect under MREH than OoA. MREH says the H-sap morphology evolved more or less independently in different areas. Under this view European H-sap could be more closely related to Neadertals than they were to populations with H-sap morphology elsewhere, e.g. LM3. But as all living humans are closer to Neadertals than they are to LM3, this is irrelevant to MREH itself as it concerns the ancestry of present humans. LM3 would merely demonstrate that is possible for two populations to evolve an H-sap mophology independently, as MREH requires.

16

I guess I shouldn’t have said that LM3 “causes problems” for OoA - It doesn’t, really.

17

Back to Ice Wolf:

While there may be many theories about human evolution, these two, with some minor variations, are the main two.

I don’t think many would say OOA1 and OOA2 are two different theories and most commonly people just use OOA. It does seem sure that early Homo species left Africa early and spread over Europe and Asia. It’s the “second” OOA that is debated by MREH.

Could man have evolved from different ancestors? It does seem to be the sticking point. It involves several tough issues one of which is the length of time it takes for a new species to form from an existing one. In primates the suggested time seems to be about a million years. That is, the population would have to split and not interbreed and take up variations for about a million years. Then, they would (maybe) not be able to breed and have fertile offspring - that is the bare bones definition of species: breed and have fertile offspring.

Additionally, there is the problem of having a large enough population to continue go back and forth and keep our DNA nearly identical world wide.

Speciation is another great topic all by itself.

Jois

18

Colibri: “It seems to me that the discovery of any sapiens type fossil with mtDNA more different from modern humans than that of Neandertals, whether in Australia or elsewhere, presents a lot more problems for OoA than MREH, in that it implies that the sapiens-type skeletal morphology is paraphyletic (present in two or more lineages that are not sister-groups) - just what MREH would predict.”

I can see a problem here, too. I can almost argue the MREH side. Here’s the abstract:

Proc. Natl. Acad. Sci. USA, Vol. 98, Issue 2, 537-542, January 16, 2001

Mitochondrial DNA sequences in ancient Australians: Implications for modern human origins

Gregory J. Adcock*, Elizabeth S. Dennis, Simon Easteal§, Gavin A. Huttley§, Lars S. Jermiin§,¶, W. James Peacock, and Alan Thorne*

  • Research School of Pacific and Asian Studies and § John Curtin School of Medical Research, Australian National University, Canberra ACT 0200, Australia; Commonwealth Scientific and International Research Organization Division of Plant Industry, Canberra ACT 2601, Australia; and ¶ Australian Genomic Information Centre and School of Biological Sciences, University of Sydney, New South Wales 2006, Australia

Contributed by W. James Peacock, October 30, 2000

DNA from ancient human remains provides perspectives on the origin of our species and the relationship between molecular and morphological variation. We report analysis of mtDNA from the remains of 10 ancient Australians. These include the morphologically gracile Lake Mungo 3 [60 thousand years (ka) before present] and three other gracile individuals from Holocene deposits at Willandra Lakes (<10 ka), all within the skeletal range of living Australians, and six Pleistocene/early Holocene individuals (15 to <8 ka) from Kow Swamp with robust morphologies outside the skeletal range of contemporary indigenous Australians. Lake Mungo 3 is the oldest (Pleistocene) “anatomically modern” human from whom DNA has been recovered. His mtDNA belonged to a lineage that only survives as a segment inserted into chromosome 11 of the nuclear genome, which is now widespread among human populations. This lineage probably diverged before the most recent common ancestor of contemporary human mitochondrial genomes. This timing of divergence implies that the deepest known mtDNA lineage from an anatomically modern human occurred in Australia; analysis restricted to living humans places the deepest branches in East Africa. The other ancient Australian individuals we examined have mtDNA sequences descended from the most recent common ancestor of living humans. Our results indicate that anatomically modern humans were present in Australia before the complete fixation of the mtDNA lineage now found in all living people. Sequences from additional ancient humans may further challenge current concepts of modern human origins.

I’m bothered by this study, Colibri, it isn’t just the question of the morphology being paraphyletic - to me that is resolved by recalling that our mtDNA goes back to the most recent common ancestor of all living humans. What does it say about the individuals that were robust? How meaningful is this whole business of the LM3 and “His mtDNA belonged to a lineage that only survives as a segment inserted into chromosome 11 of the nuclear genome…?”

You might have to try PNAS and see if you can pull up the entire article.
Colibri: “What I’m curious about is the state of the play regarding nuclear DNA. I believe most of the data to date is on mtDNA - reasonable, since it evolves faster than nuclear DNA and hence has finer resolution for the relatively short periods of time we are talking about here. But mtDNA is inherited matrilinearly only, so that something quite different could be going on with nuclear DNA.”

There has been a lot of work on chimp mtDNA and nuclear DNA and it might bring us back to the problem of chimps not having been separated long enough for true speciation to occur. Bonobos (the “share fuit and copulate randomly” group of the great ape line) may not even be truly a separate species from the chimps. Unresolved.

I might be able to find someone to discuss some of these very tough areas if you are interested but he’s less patient than Collounsbury and his typing is worse than mine.

Jois

19

Thank you, Polycarp, I hope she doesn’t mind. This whole business of mtDNA and it’s implications might not strike her fancy at all. Email me if she’d like to hook up with people who enjoy discussing the austropiwhatsies and oreopithwhozies. They are on another planet as far as I’m concerned.

BTW: Out-a Africa is perfect!

AHunter3, if your email works, I’ll send you links for the basic Neanderthal mtDNA articles.

Jois

20

My wife, who has chosen the name Skulldigger for when we finally get home access and she can post under her own name, wrote out a detailed post, about half of which has been covered above in material posted between when I printed out the thread for her and now.

But the gist of the observation she wished to make is that OoA and MREH are not so far apart as might be observed. Effectively what is going on is that the earliest hominids evolved in Africa, from Ardipithecus up through Homo habilis, and that Homo erectus was the first species to leave that continent. Sporadic evidence across most of the Old World shows H. erectus giving way, very gradually, to archaic H. sapiens. (Note that it needs to be stressed that these are archaic, not modern, forms of our own species – or, if you choose to be a splitter, species related closely to us and the Neandertals.) Effectively the question becomes whether the transition from H. erectus to H. sapiens “archaic-subspecies-ensis” occurred once in Africa followed by replacement, or was a gradualist transition throughout the range H. erectus was occupying at the time. Evidence can point both ways. She notes, “There is a site in northern africa where fossils of H. erectus and archaic sapiens were found around the same campfire site. It’s dated to just about a hundred thousand years ago.” So effectively the disagreement comes down to whether the actual ancestors of modern man made the transition from H. erectus to H. sapiens before or after they migrated outside Africa. There is no doubt that there are erectus fossils elsewhere; there is no doubt that there are archaic sapiens fossils occurring in what appears to be a replacement-species mode, evolutionarily speaking. It’s a tempest in a teapot, for all practical purposes. (She herself buys into the MREH hypothesis, seeing the species line as rather broad and gray rather than a single point of transition, and allowing that some interfoliation between what we would call archaic sapiens and erectus did occur. But this gets beyond paleoanthropology into population genetics, and evidence is pretty nebulous to say the least.)

She further notes that culturally-based claims can skew the picture. There is a Chinese paleoanthropologist who is firm in his claim that the Chinese people evolved in situ from the local H. erectus (=sinensis) population. And certainly the Mungo Swamp fossils in Australia have led Thorne and others to make extravagant claims for Australian evolution.

In short, she and I feel that far too much theoretical superstructure is being built on too little factual evidence, that conclusions are going to be exceedingly difficult to substantiate, though easy to create as speculation.