Natural Science Forum / Biology / Paleontology / September 2004

This is simply not true. If Neandertals interbred with humans
the loci were one would _expect_ to see clear evidence is in the
HLA loci, given the other separations one would expect to see
very 'unusual' non-african haplotypes and alleles in europeans.
One does not see anything to this kind. There are no funky
northern eurasian haplotypes.
 Secondarily the collective of X-linked loci concur with mtDNA
in suggesting the population size and all are in agreement with
a obligate african radiation.  

I am convinced by the evidence I see, the evidence that
Neandertals were replaced, from a genetic point of view is 99.9%
convincing.

I am not convinved also by the lack of good evidence. Apriori, I
would argue that Neandertals were more likely to have interbred
relative to asiatics. However the evidence that asiatic
erectoids could not have interbred with humans is less
convincing, both from a morphological point of view and from a
genetic point of view.

From the genetic point of view:
1. MX1 locus. Hap 4 and Hap 5 are a minority even in asia.
2. HLA, many two component plots cannot join east asia to
africa, even though they join european lines directly to the
most genetically deep parts of africa. This might be explained
by a long term contribution and expansion of certain erectoid
haplotypes (selective in those regions) as well as gene
conversion and recombination to mix them up. In particular, one
group that has been difficult to reconcile are the Indonesian
highlanders. The MX1 and HLA 'hot spots' overly each other.
3. mtDNA undertyping in the region.
4. No mtDNA sequences from Erectus and undertyping of tribes in
australia and indonesia.

Even so the prospect of intermixing in south east asia, by all
these loci would present a scenario of a few individuals, 1 to
100 intermixing in the context of 1000s to 100,000s of humans.

We can contrast this with the work done in europe.

1. 1000s of mtDNA typed
2. 10,000s of HLA typed (13,000 typed in germany similar number
in denmark), all consistent with recent african origins.
3. Only one MX1 type in italy, which could be explained by rare
recent mutation.
4. 1000s of Y chromosomes typed.

The basic question here is if the mtDNA representing female
lines is african, it the Y lines representing males is all
african and if >100,000 HLA lines are africa. Where did this
neandertal contribution come go to. I am not unfair on this, I
can and have dissected peoples HLA, like Japan and Europe
scraping off layers of migration and examining that which is
left behind. The most genetically distinct people in europe, by
far, are the sardinians. The most genetically diverse group of
people are the iberians and the greeks and anatolians. In
essence everyone else in europe is a recent serial expansion
product of these two peoples.
 For example I scraped off layers of recent migration in europe
to show a specific allelotype connection between the french,
germans and koreans/orochon/ainu/japanese. And while I could
have stopped there I further found evidence for intermixing in
the middleeast. I also traced the origins of these early mixings
back to africa, I showed the proportion that likely came from
the east, and the proportion that likely came from the west
(iberia). This population would have migrated out of and fixed
patterns that would be later replaced in europe, essentially
making them a snapshot of the population of southern europe >10
kya. By migrating as a people and scattering themselves in asia
they in essense protected that material from wholescale
replacements. And yet where are the non-african alleles in these
peoples? In addition who did the replacing in france, and
germany. The replacement was not largely from outside, it came
from all directions. From Ireland, from the basque, from
austria, from greece, from iberia, from sardinia and from
africa. IOW there was a vacuum that sucked new peoples into a
largely evacuated region. Thus there is no great evidence that
humans in europe were replaced by all kinds of waves from
africa. It looks more like the waves reached europe, expanded in
europe and then the populations were devastated (Irish HLA,
France, German and Italian HLA makes this evident). The
protoIrish, protoBasque, protoaustrian were in much better
situations than the people in germany and france at the end of
the last ice age and these groups re-expanded.
 Nor am I fixated on this hypothesis. I traced the immigration
of several african haplotypes in the last few thousand years
into europe. However, I also at the same time detemined, that
most of the european geographic expansion had occurred before
these new haplotypes reached europe. Therefore it is quite clear
the demic diffusion and multiple sweeps do not explain the
makeup of europeans. These models argue for single discrete
early waves that expanded and largely blocked later waves.
Nor can a model be placed which says the early hybrids were
swept out, in essence the Basque, Iberians, Tuscans are what
became of the early hybrids, and the hybridization is between
older european from the east and west africans.

AMH or anatomically modern human is the morphology of Cromagnon.
THe word cromagnon is used primarily to describe the 'human'
associated cultures of france and spain. When one wants to
describe the morphology of cromagnon, AMH is used to separately
distinquish this. From the beginning the argument over cromagnon
resolved around the culture, were these paleolithic or neolithic
peoples, by artifacts both found in the caves and in caves in
the region, and while it was generally concluded these people
had qualities of what we now call a race, it was later noticed
that the racial qualities did not disappear but later blended
into modern humans and these qualities are still seen in many
moderns although not in a single individual. As I had reported
previously I felt that humans entered europe about the same
time, or even before via iberia and sardinian, and that hence
these peoples mixed. Less modern qualities are seen in both
sardinians and berbers, two suspect populations, and a wide
range of morphology exist in africa from short, stout robust
people like such as in Nigeria, to very tall people, like the
Mandenka of Senegal. This treatment of cromagnon as a special
race is interesting because genetics has basically dissolved all
racial lines as meaningless, and greater morphological extremes
exist in africa, just not the same traits. The morphological
diversity of humans changes over time in two ways.

1. People evolve in response to environment, or have an
environmentally induced response within development.

2. People change in abundance and intermix. There is nothing
spectacular about cromagnon AMHs in the context of all human
kind.

3. The traits that become subject to selection change.

And on top off this Knight determine that 'races' may have
appeared in africa, but later dissolved into each other as they
have appeared to have done all over the world. Therefore it is
nothing spectacular that non-'modern' looking races appear or
that they disappear. What is important is that while these
'human' races appear in europe, the Neandertals do not melt into
the human races, that morphology simply dissappears. This is not
true in asia, where it appears there could have been blending,
but as stated above this doesn't have to have occurred, and fine
analysis of erectus and similar looking humans refutes this, the
blending products do not neccesarily have to have the same fine
qualities as the starting materials. In fact in europe, as
humans appear on the eurasian scene Neandertals continue to
derive as classic neandertals, they are anti-blending. IOW, not
only do Neandertals show qualities of a completely different
grouping of humans, both morphologically and genetically, when
tested with a migration their morphology indicates evolution of
more distinguishing traits, possibly as a means of species
identity and xbreeding restriction, a pariah effect. (which for
the soothing of Annes Neanderhysteria, humans would have been
the Pariahs). The timing of Neandertal mtDNA coalescence roughly
coincides with human appearance in levant and implicit in
LiuJIang and other asian sites. This suggest that neandertals
underwent reexpansion and this possibly explains the greater
derivation of their morphology, with more human looking
Neandertals dying out and more distinquished surviving. lol.  

I can give you the two papers dealing with 10,000s of europeans
HLA if you want to find evidence of Neandertal, be my guest.

Have fun.

Philip and Dar:

I would have to take DAr's side on this one.  What the mtDNA evidence seems
to suggest is, that *most* of the ancestry of "modern" humans derives from
Africa. But, as several prominent geneticists and biological anthropologists
have suggested, it doesn't either prove or disprove the possibility of
interbreeding between various distinct human populations.  FWIW, Alan
Templeton's latest foray into this area, back in 2002, seems to suggest
three major migration OoA, with subsequent spread of "African" genes to
"indigenous" populations in Eurasia. The "modern human" migration, or
whatever it was, which took place around 150 kyr ago, was only the latest of
these.  Certainly people like Templeton are in the "minority", but I
personally also happen to think that the "dominant" interpretation of the
genetic evidence simply can't be ether proven or disproven, and neither can
one say, for sure, that interbreeding between various groups of humans
*never* took place.  It certainly seems to take place between closely
related species when barriers which had previously separated them, break
down.
Anne G

I'm no expert on the nuclear DNA but what reading I've done makes it clear
that some population outside of Africa who bleeping well weren't moderns
have genes in the population. The Y chromosome and the mtDNA can tell you a
lot about some recent population movements but they make clear that some AMH
who must have bred with our ancestors don't have mtDNA or Y chromosomes in
the present population. I think that if human DNA can be recovered from hair
as was claimed in a recent article it can be dertermined if any genes for
Hsn are still to be found in the current population at some point in the
future. It will take a lot more work to make sure they weren't ancestors
whose genes got selected out.

No I do not think they were major contributers to the current population.
Evolution was moving toward Hs and the genes to be Hs were flowing out of
Africa alone or in clusters.

Yup, you will always get it from Phil, but Phil is not the whole sum of
anthropological thinking on the matter, so dont worry : )

Some of the above strikes me as being very smart. I may be wrong but it
strikes me that moderns replaced archaics because they had a set of features
that had survival value. Hsn had a suit of features that compute as cold
adaptions and I keep reading make them poor athletes in a dozen different
ways no matter how strong or agile they were. Any features that caused
problems would get selected out of a population.

In my observation tropic people tend to be much more disease ridden than
cold climate people.

Once a gene becomes rare in a population the most likely thing for it to do
is vanish unless it provides a fairly decent increase in reproductive
success and isn't linked to something that does the opposite.

Hsn might have been a different species. Unless we get a look at Hsn genes
that is going to be hard to prove and mtDNA and the Y chromosome are more or
less beside the point here. They can only tell you whose lines are now found
in the population not whose lines were once part of the same population.

Europe might have undergone a substantial population replacement with active
selection occuring for non archaic features. Remove the might. No matter
which point of view discussed is right that is what happened.

There is at least one gene found in non Africans that must have come out of
Africa some time that isn't found there now. I believe it related to vision.
I'm not sure what it has to say expect the more I read about nuclear DNA the
more I think every little piece that can be inherited separately is going to
have its own unique story to tell.

Brace has his reasoning. Afterall MREH was not a stong theory in
the 80's for no reason, the problem is that they were
overzealous in suppressing the views of the opposition.
I think that there is a certain romanticism in the european
origin that stems back to the biases of the 19th century. I
could use this as an antithesis of ANNEs argument. People
beleived that Neandertals were intermediate to humans, a
prespecies it was kind of rascist because they beleived that
superior humans must have come from superior victorian europe.
 The other issues I think brace has resolves around, what I
think are the critical misteps that the OoA camp has made. Even
I don't beleive Paabo's or even Vigilant's timings. These I
think are radically late. Anyone who is probably familiar with
the paleontology of humans outside of africa will question the
late dates. If these dates were relaxed to suggest humans
expanded earlier and left earlier from africa, then some of the
evidence against OoA becomes evidence for OoA. Prime examples
are liuJiang and LM3. Notice that both of these are in that
critical period between which the OoA camp claims is way to
early 'fight'fight'fight' and the period which would OoA
paradigms way too late. The problem with OoA of course is they
screwed up their calibration.
 The second issue is that morphological variation in africa and
between africa and the levant is consistent with a continuoum of
hominids. THe basic problem I have is that very specific
patterns of humans in africa shared with human evidence in
distal points, such as LM3 and Liujiang reflect in my opinion
the migration of Negrito morphology and negrito-like morphology
and not every morphology that was in africa. So those specific
early morphologies in asia and the morphology of isolated groups
like the Andaman islanders is a telltale to the prelude to the
migration. Why is it that we see these morphologies in primative
african groups, now, and in asia then, but the mtDNA says these
all groups came from africa, but the morphology of africans then
was robust and generally much taller. Combine this with the
Xlinked and the mtDNA and the depth of diversty in pygmies
versus non-pygmies in africa and one comes to the base
conclusion that what probably happened is a pygmy population
expanded from a marginal constriction, and as it did so its
technologies allowed the increase in growth with some odd
initial consequences based on environment. As growth then became
the norm and desired outside of africa, particularly in cold
climates these morphologies refined and some expected convergent
evolution took place. These other african groups were not
specifically human, but quasi human. Then the molecular data
makes perfect sense.
 Thus the continuoum was not specific but generic in nature. I
have to say what is confident and what is unlikely and I have to
say it was unlikely that a single concise populations that
throws pygmy like peoples into depths of asia was not the same
population whose morphology currently is somehow substantially
different relatively speaking to these asian extracts. This is
troublesome and with the small population it is downright
bothersome.
 While ANNE tries to devinate the nature of the exact modern
humans relationship with Neandertals I personally think that is
the wrong question to ask. It might be a question to ask if
there was evidence, but you don't ask a question when there is
no evidence for that. The right question to ask is this. Let us
suppose that some rare intermixing with asiatics occurred, and
let us also argue that based on mountains of genetic evidence as
humans expanded they generally did not mix close to the source
of the expansion (otherwise the X-linked and mtDNA would have
been all over the place). What types of barrier testing patterns
are available. The one I keep swirling around with is the same
one I presented here 10 years ago, are the barriers of 'natural'
(uncontrolled, sh.t happens) origin or were they of selective
nature.
 And the answer I come up with is a selective nature of
population segregation (eurphemistally called the mad ape or
cannibalistic ape theory for maximum entertainment value). This
is the only way to explain why recent splits like N and H have
no genetic evidence where as distal mixes that were not being
continually mate tested might have relaxed or have selected
along different lines that were not deleterious to OoA
human/East asian derivative mixing. It may have been true that
during the course of the last 500,000 years that technology and
culture was closely tuned to cranial evolution with so many
marked variations in behavior, language capacity etc that
culture became proprietary with respect to kind, and thus
competition between groups became particularly intense. I think
that humans may have been the big but not extinct losers in
africa, early, but that they turned this disadvantage into
advantage. How many pygmies are found in the african
paleontological record from 90 to 500 kya? None. Of course with
a pop size of 8800 would you expect find such groups? And where
are the majority of pygmy tribes found. In general we find
evidenc of hominids were we find also archaeology and if Japan
is any example the archaeology is tell tale of the luxorousness
of the habitat. So what if the habitat is not luxorious, what if
it highly marginal and sparce, or resources are hard to extract.
Will there be a preponderance of archaeological evidence, or
will that nature of the habitat include conservative habits such
as tool recycling, tool minimization or even corporeal
recycling.
 There is the kung but the other tribes live around the central
african region. The most productive environs in africa are to
the west and south of this.   So my guess is that at a certain
rapid point in hominid evolution it became a race to the finish
line, specifically in africa, this was probably triggered
initially by the changes in brain size in erectus, but as
improvements began so did the competition and specifically
competition of culture as a extension and consequence of these
improvements. Humans appear to have gotten the shaft and were
delegated to marginal forests deep in the heart of africa or in
desrt wastelands to the south. While more luxorious habitats
probably supported larger populations they probably did not
breed the type of efficient, innovative and wise qualities
living in a sparse climate promotes.  Small size coupled with
the need for competitive brain power also means scaler bigger
brains in times of plenty with facilitative growth spurts. The
!kung show us why they might have delayed maturity. In such a
marginal climate the 'fast' guy is going to burn up reserves
before they have accumulated, the slow guy is going to have
enough to get through the drought as well as get that baby born.
This I think focused humans into an older and wiser group. My
modeling of neandertals with !kung birth rate came up with some
pretty outstanding conclusions, some Neandertal women would have
to have and produced children ( 8 to 10) into their forties even
though everyone else they knew from childhood would be dead and
who would raise their children. More likely is the new
predictions of Neandertal birth cycles and maturity. This fits
far better the model. MY guess is those neandertal females had
the capability to nurse a child while at the same time carrying
another to term. So now we have a true discrepancy between Ns
and human culture, or at least up until the agrarian period
begins.  
 This focusing of humans however probably made it difficult for
them to mate with other groups and particularly Neandertals,
when they finally run into the groups that have similar
selective constraints on maturation (sparse climates favoring
conservation over rapid breeding) then they find more relaxed
barriers for interbreeding. I don't think the barriers were
mental, I think that groups that had barriers form between
adjacent groups while this rapid evolution was taking place may
have been more successful than those that didn't possibly
because some of the evolved traits couldn't mix and possibly
because 2 traits accomplished the same result and there was no
benefit to admixing inorder to gain this particular trait. It
may have been a genetic detente that developed. Of course the
human language genes may have spoiled everything.

 This is how I reconcile the facts. Whereas Wolpoff, Brace and
trinkhaus like to see these intermediates where they look, none
of these intermediates explain the closely shelled and long term
population in africa, in fact they make nonsense explanations to
explain this. Whereas in a model where speciation could have had
a 'sh.t happens' component and selective component then species
models revolve around the number of populations one could have
of about the same size as humans or larger. As we see today
humans have great capacity to move around, erectoids also but I
suspect more slowly, and some of these advanced africans also
can move, particularly if pushed by expansive humans into places
like Iberian and Romania and Isreal. Indeed while ANNE makes
these complaints about the thoroughness of the molecular she
herself does not come up with good alternative explanations,
neither Brace. It is very easy to say there is no proof of
recent origins assume that neandertals and human freely
intermixed and stick your fingers in your ears.
 This is were I think I split with many paleontologist, I
personally think that modern humans are overgrown pygmies. The
trial of evolution was surviving as a pygmy when all your
competitors are twice your size and several times your strength.
This I think is an accord for wisdom, resourcefulness and
efficiency. Something that is in great abundance in most of
these pygmy tribes.

1. You may not be able to birth every season, or even every
other season, infact females might, at bad times be blocked for
six or more years. Longer lived females may not have a problem.
Short lived females would go extinct. If a neandertal female
forstalled pregnancy for 6 years based on the current idea, she
has effective aborted the chance of being a mother, consider the
age to maturity of 11 years stalling 6 would mean she would give
birth at 18 or 19 years and by 23 to 26 years she is dead, she
would not have raised her children, at most with luck she would
have a single child.

2. Well this makes it convenient for humans to travel and
expand, if they can arbritrarily stop breeding for several
seasons to move and get established, then they can get a foot in
the door. Alternatively if body plan can shift in resonse to
resources such as the gracile robust (so far only seen in humans
relative to hominids, every neandertal was robust). In fact
given some of the anecdotes I think that human females could be
remarkably resilient on the move and is probably attributable to
their ability to store weight for the next pregnancy and to
conserve weight during times of scarcity.

3. Small size, small scale, slow growth may have allowed humans
to live on places, islands and that Neandertals ignored because
of the lack of sufficient resources. This may have allowed
humans to move to other islands that were more distal that had
more resources or that connected with other lands.

4. Its easy for a few genes to shift when plenty becomes
perpetual, one sees it in plants and other species. Even the
pygmies will grow better and taller on a western diet. Its not
so easy if your obligately robust to revert to a more efficient
body plan. Secondary issue is that expensive brain. the smaller
the human the smaller the brain, the less energy the brain
draws. For neandertal their obgligately large bodies effectively
mean that come heat or cold their expensive brain is still
pumping along. This markedly limits their ability to travel into
warmer and marginal climates.

So to address the issue, i think that the selection would be
bidirectional. There were probably talents humans had that Ns
did not, and there are probably talents Neandertals had the
unfortunately were more situation specific.