Origin of Modern Humans: Out of Africa or Otherwise

[cmacq]

This is another of my most favorite topics.


CmacQ

[LittleGrizzly]

I have always heard it was out of Africa we came ? this is disputed ?

[Samurai Waki]

I have always heard it was out of Africa we came ? this is disputed ?

Yep. Boba Fett came in and shot all the dinosaurs with his Remington 30.06, then the Mandalorians settled on Earth, but lost communication during the War with the Republic, and then Jesus came and made everyone Christians, and we've all been happily living together since.

[cmacq]

Wakizashi I do understand your point.

Basically, someone in a position of authority, say the chairman of a department at a prestigious university, makes a pronouncement based on an assumption, that was in turn based on a somewhat related group of evidence, and there are always people more than willing to be true-believers. I think this may have something to do with the troupe/pack mentality thing.

This to get the ball rolling..

But no, actually it is another one of those great unproven theories with so many problems they are untenable, yet somehow like Jason, continues to keep-on-tickin. Still the Out of Africa Theory (OAT) is taught as fact, at all the finest institutions of higher learning world-wide, without reservation. Remember the title of this topic was Origin of Modern Humans. So what does the evidence of early Modern Humans in Africa actually suggest, pro and con?


CmacQ

[Mediolanicus]

It is but a side note, but it is a question that fits into this discussion.

When did modern humans appear in the Americas and Australia?
the mainstream theory is that for the former they've crossed the Bering straits during the last ice age. However, human fossils have been found dating 30000 prior to the last ice age.
Same thing with Australia... They give us a date and then discover a fossil that's much older...

[cmacq]

However, human fossils have been found dating 30000 prior to the last ice age.

I believe the earliest evidence for Humans in the Americas is dated after 10000 BC.



CmacQ

[PBI]

An interesting question. Is there an alternative theory?

As with the Big Bang, I was under the impression that there was a scientific consensus (as much as there ever is) on this. Anyone care to present any contradictory evidence?

[cmacq]

One important piece of this puzzle is very evident. However, one quick question first. The physical manifestation of natural selection is due to; a) nature, or b) the human will?



have to run


CmacQ

[macsen rufus]

The physical manifestation of natural selection is due to; a) nature, or b) the human will?

Well, by definition it is (a), if (b) is involved it's no longer natural selection but selective breeding, but semantics aside I'm sure you have something interesting in mind

I believe the earliest evidence for Humans in the Americas is dated after 10000 BC.

Here I must disagree - the 10,000BC date applies to what is commonly referred to as the Clovis Civilization, and had been an orthodoxy for quite some while, however finds over the last 5 years or so have earthed up some very good candidates for pre-Clovis peoples, pushing first Americans back to 25-20,000 yrs BP. A bit politically sensitive as it may endanger some native American claims to indigenousness.

Someone (I believe it was Adrian II) posted up an excellent link to a "human origins" interactive a while back, though like a fool I didn't bookmark it, nor can I remember the URL now... but well worth a look. Anyway there are strong genetic grounds for at least one wave of asiatic migration prior to the last glaciation.

As to the general concept of the OAT, though, I think it's as close to the truth as we can get. Clearly there was a genetic bottleneck from which all modern humans descended, in Africa, although there are still some doubts over how many waves of migration occured or the precise timing and routing of specific populations (again see the interactive for which I can't offer a link...)

The only other serious contender would be separate hominid populations independently evolving into Hom sap independently, and this seems extremely unlikely given the remarkably narrow base of the human genome - we are a distinctly un-diverse species compared to most, which again is down to the bottleneck

[Kagemusha]

Modern Genetics and specially Haplogroups can give us a clear answer to this. If i recall right, it has been already been some years when "Eva" the first female was traced back to Africa.

[cmacq]

Sorry if I don’t address the topic of ‘the peopling of the western hemisphere’ as this a very complex subject in itself. I’m not married to the Clovis First Theory, yet I would want to see a lot more evidence for a Pre-Clovis occupation. Still please, that sounds like an excellent title for a thread.

Yes, very good Macsen Rufus you are quite correct, as the answer to my rather elementary question: the physical manifestation of natural selection is due to [of course] (a) nature. Yet, this leads to another simple question. The survival of physical manifestations within a given population is largely due to their interactive suitability to the attributes of a specific natural setting; a) true, b) false?

Right, now we’ll have at the infamous analytical bottleneck. But, beforehand one more simple, yet Socratic question. Given the nature of the genetic data, and remembering the results of termination analysis, how exactly, or by what mechanical means would a genetic researcher be able to 1) perceive a genetic bottleneck; and 2) perceive the geographic origin of a genetic bottleneck?

In all truth I’m not opposed to a bottleneck, per se. In fact, in a biological sense, it may prove a mathematical imperative. I just want to see the evidence and the method of how the bottleneck theory was derived. Regardless, how would a bottleneck theory support the OAT as opposed to an Out of Center Theory (OCT) proposal, for example. For Center in OCT, please see Asia. And please, don't mix genetic studies up with Paleoarchaeology, as we'll get to the dating of Blombos Cave and the actual physical evidence of Modern Humans therein, much later.

Right, just to touch base, also what exactly are the attributes of a Modern Human?

Have other work to do…

CmacQ

[woad&fangs]

Macsen Rufus, is this(http://www.dnai.org/d/index.html) the interactive you are talking about?

[macsen rufus]

@Woad&Fangs -- it's not the same one, but thanks for the link anyway

The survival of physical manifestations within a given population is largely due to their interactive suitability to the attributes of a specific natural setting; a) true, b) false?

GENERALLY speaking, true, but in the PARTICULAR case of modern humans we have evolved sufficient intelligence to both alter our environments and the selective pressures within them, and also to shield individuals from threats, thereby allowing traits to persist in the genepool that nature "red in tooth and claw" would have eliminated, or at least severely attenuated.

Quick bit of pre-Clovis evidence (sorry, I couldn't resist it with this title )
Faeces hint at first Americans

how exactly, or by what mechanical means would a genetic researcher be able to 1) perceive a genetic bottleneck; and 2) perceive the geographic origin of a genetic bottleneck?

That would be down to various genetic markers - haplogroups, mitochondrial DNA (ie matrilineal), population distributions, comparisons with other near relatives, known rates of mutation for specific markers etc.

Regardless, how would a bottleneck theory support the OAT as opposed to an Out of Center Theory (OCT) proposal, for example.

I'd generally accept Mitochondrial Eve as being African, and the divergence represented by the Koi/San bushmen of the Kalahari would be very difficult to reconcile with an OCT model.

Right, just to touch base, also what exactly are the attributes of a Modern Human?

Go ask the Human Genome Project But for now, I'll go with the species Homo sapiens sapiens, and not include Neanderthals, H. erectus, H. heidelburgensis, H. antecessor, et al, but I'd really argue that "exact attributes of a species" is an impossible ask...

[cmacq]

Right,

'haplogroups, mitochondrial DNA (ie matrilineal), population distributions, comparisons with other near relatives'

Thats what's said...
but this data, as impressive as it may seem on the surface, only goes back a couble of generations. And, the 'known' rates of mutation for specific markers etc,' are in fact not actually known. These are based on rank specuation as again our ablity to accurately backtrack only goes a few generations. Also, genetic studies alone can in no way provide support for the OAT, in a geographic sense.

I'm not really sure what you mean by the Sandawe people? It seems just as plasable that these are a festigual expression of the first Modern Humans to have entered Africa from Asia. This could be very much akin to the Ainuesque expression as seen in east Asia (and possibly Pre-Clovis North America???).

There are two aspects of the Modern Human; the anatomical aspect and the behavioral. It seems that most researchers recognize that the anatomical aspect predates the behavioral aspect. Thus, the bottleneck theory together with the physical manifestation due to natural selection of anatomical Modern Humans indicates the final stage of development occurred within one specific geographic setting; a) true, b) false?



work awaits

CmacQ

[macsen rufus]

This is an interesting overview of the debate

Also, genetic studies alone can in no way provide support for the OAT, in a geographic sense.

Strongly disagree -- refer to the above link:

No matter what criticism is leveled at any one of these genetic test, the fact remains that all genetic testing on the subject has 100% unanimously supported the “out of Africa” hypothesis.

There is room for some doubt and error on the genetics -- but only on the chronology. The geography is unequivocal. See especially the chromosome 12 CTTTT mutation (M16b???), which clearly shows "the rest of the world" as a subset of the African population.

this data, as impressive as it may seem on the surface, only goes back a couble of generations

Again, strongly disagree - the significance of mitochondrial DNA is that it is NOT part of the genome. It is passed down directly from mother to child UNALTERED, except for random mutations/copy errors. It does not recombine like nuclear DNA. I'm not sure how far back mitochondria go (evolutionarily speaking), but it should be able to trace common ancestry way back to before we even had backbones.

The Koi-San peoples are the earliest divergence from the Hom sap sap common ancestor, and represent a haplotype that NEVER LEFT AFRICA (L1) - all groups outside Africa descend from L3. To explain the Koi-San haplotype and location by an OCT theory would entail early hominids leaving Africa, going to the "centre", then speciating to modern humans, and returning to the remotest corner of Africa without leaving any descendents in the centre, without migrating in any other direction, and without "dropping off" any descendents between the centre and south-western Africa. Possible, maybe, but significantly less convincing than the "OAT" explanation.

Thus, the bottleneck theory together with the physical manifestation due to natural selection of anatomical Modern Humans indicates the final stage of development occurred within one specific geographic setting; a) true, b) false?

I hold to (a), based on the evidence I've seen so far (which is, of course, not exhaustive....), and given that I trust genetics more than archaeology.

work awaits

same here

[TevashSzat]

Wow, macsen, thats some very thorough explanations regarding to the current scientific consensus

[cmacq]

Again, strongly disagree - the significance of mitochondrial DNA is that it is NOT part of the genome. It is passed down directly from mother to child UNALTERED, except for random mutations/copy errors. It does not recombine like nuclear DNA. I'm not sure how far back mitochondria go (evolutionarily speaking), but it should be able to trace common ancestry way back to before we even had backbones.

Macsen Rufus I think you may have misunderstood. I meant the data based on the sample population, can be gathered only from several recent or current generations. Again, everything else is based on still another theory which can not be adequately tested over extremely long periods of time. Regardless, the genetic data may be used to demonstrate a biological relationship between x and y modern populations. But the genetic data alone can simply not be used to dictate where x and y modern populations lived 20000 or 70000 yrs ago.

The assumption here is that the current genetic populations of Modern Humans currently residing in Africa have always done so. As even the most casual observer will note the modern population of Africa is anything but homogeneous. Here, within a more recent context intrusive elements abound for a variety of reasons. Thus, what the OAT actually implies is that Modern Humans descended from a specific African population that was tied to a specific geographic setting. Africa is a big and diverse place so, what is this specific population and where is this specific setting, so that we may more closely explore this rather unique biome?

I also think it’s very important at this juncture to point out that a necessary element of the OAT, is the replacement theory. In a nutshell the replacement theory holds that after untold millions of yrs of evolution within Africa, a wave of Modern Humans emerged to sweep across the globe replacing all earlier forms. The replacement theory is not, I repeat not, the same as the bottleneck theory. The later proposes that from a much larger Paleo-Human population, only an incredibly small subgroup thereof actually contributed their genes to the current Modern Human population. The reason for this remains unclear.

I’ll address the other points soon.

It was 113 yesterday and 114 today and my bloody AC is out

Have to go now…


CmacQ

[cmacq]

I hold to (a), based on the evidence I've seen so far (which is, of course, not exhaustive....), and given that I trust genetics more than archaeology.

Again, I believe that logic and the evidence indicate that Macsen Rufus' answer to the question is quite correct. Right, the question was; The bottleneck theory together with the physical manifestation due to natural selection of anatomical Modern Humans indicates the final stage of development occurred within one specific geographic setting, true or false? As Macsen Rufus noted above the answer appears to be; 'true.' Although this is a very subtle yet important distiction, one will note that this statement was designed to apply only to anatomical Modern Humans. This is because, as Macsen Rufus so appropriately noted above that after the behavioral aspect was achieved, and we have true Modern Humans, environmental impacts on our species' genetics became increasingly less pronounced.

I think the answers to the series of question I'm asking are critical to understand this topic. I promise the reasoning for why I’m posing these questions as an argumentitive framework will soon become clear, if one has not deduced my modus operandi already. I also assure that my argument against the OAT will be innovative, objective, to some convincing if not interesting, and at the very least entertaining for all.

As my time is very limited and this topic (Origin of Modern Humans) is not my specific area of expertise, I’m still digesting the Billings paper and will thereafter comment on its relevance to the current topic, forthwith. However, after a quick review I will say I've noted several pertinent problems, which will be addressed.




later all

CmacQ

[macsen rufus]

Macsen Rufus I think you may have misunderstood. I meant the data based on the sample population, can be gathered only from several recent or current generations. Again, everything else is based on still another theory which can not be adequately tested over extremely long periods of time. Regardless, the genetic data may be used to demonstrate a biological relationship between x and y modern populations. But the genetic data alone can simply not be used to dictate where x and y modern populations lived 20000 or 70000 yrs ago.

The strength of DNA studies lies in that it takes an overview of large populations - it might not be able to say exactly where a given population was at a given date, but it will show that say this population branched from that one so many mutations ago, and their geographic range is limited, and both are related to another population with a different range, and diverged earlier/later, whatever. No-one is saying the evidence is simple. It is definitely a four-dimensional jigsaw, and archaeology, culture, language etc all add pieces to it.

The assumption here is that the current genetic populations of Modern Humans currently residing in Africa have always done so. As even the most casual observer will note the modern population of Africa is anything but homogeneous. Here, within a more recent context intrusive elements abound for a variety of reasons. Thus, what the OAT actually implies is that Modern Humans descended from a specific African population that was tied to a specific geographic setting. Africa is a big and diverse place so, what is this specific population and where is this specific setting, so that we may more closely explore this rather unique biome?

I would contest that it is an assumption. What the genetic evidence shows is that (a) current African populations are more genetically diverse than "the rest of the world", (b) many current "African" haplotypes do not occur outside Africa, (c) these African haplotypes branched earlier from the common ancestor than the "rest of the world". Taken together that is strong evidence that the majority of African populations have remained there at least since Hom sap speciation. And of course there are plenty of "rest of world" haplotypes that have diverged outside Africa and are not represented there on a "population" scale. We do have the benefits of both genomic and mitochondrial DNA so can trace both matrilinear and patrilinear descent independently.

I also think it’s very important at this juncture to point out that a necessary element of the OAT, is the replacement theory. In a nutshell the replacement theory holds that after untold millions of yrs of evolution within Africa, a wave of Modern Humans emerged to sweep across the globe replacing all earlier forms. The replacement theory is not, I repeat not, the same as the bottleneck theory.

I'm less decided on the replacement theory - the "strong" form, that all "pre-modern" populations were wiped out has problems. However, the weaker form seems most reasonable to me - that there might have been some geneflow between archaic and modern populations. I cannot accept the strong multi-regional hypothesis that Hom sap sap speciated independently from seperate archaic populations though. That is just not the way evolution works. Isolated populations diverge, they do not converge. Now you may think "convergent evolution" - but that's a red herring - different species can evolve similar characteristics in adapting to a given environment, but it doesn't make them evolve into the same species.

The bottleneck implies that all "rest of world" modern populations are descended from a single group of approx 150 individuals. Geneflow theories seem to have been knocked back a bit now that Neanderthal remains have had some DNA extracted, and found them significantly different to Hom sap - but that's probably not so surprising - they are the other branch of the divergence from H. heidelburgensis. That would seem to make it even less likely that H. erectus would contribute much in the way of interbreeding, and it is H. erectus distributions that multiregionalism seems to depend upon. I simply don't believe it, and it also has dodgy roots in 19th century nationalism and attempts to "prove" racial purity (yes, even anthropology has its political bias/agendas ) It also depends for a lot of its evidence on morphology from a very sparse fossil record, some of which, on review, hasn't held up. Our genetic map is much more complete than our fossil record.

The later proposes that from a much larger Paleo-Human population, only an incredibly small subgroup thereof actually contributed their genes to the current Modern Human population. The reason for this remains unclear.

I would suggest that migrating populations would have necessarily been small - an extended family or hunting group, maybe. Routes "out of Africa" would have been few and perilous (across the Sinai, or across the Red Sea). Compared to H. erectus and Neanderthals, Hom sap has a HUGE brain, and developed language, and therefore the ability to transmit material culture - Europe is notable for the rapidity with which improved tool design spread, and with a remarkable degree of similarity - just at the point Neanderthal was going extinct. Neanderthal culture was notably localised, Hom sap culture widely distributed. Greater intelligence, ability to communicate and retention of a material culture would all confer a huge selective advantage to the newer species. Now the big question, to my mind, would be "what mechanism extincted the Neanderthals?"

There are three obvious scenarios, and probably more:

1) Hom sap and Neanderthals in contact, possibly interbreeding (but I doubt this aspect), Hom sap genes dominate over generations
2) Hom sap and Neanderthals in contact, but in direct conflict (ie warfare/genocide)
3) Ham sap and Neanderthals not interacting directly, but competing ecologically, and guess who fit the niche better???

Obviously in some parts of the world replace Neanderthals with H. erectus (notably Asia), but the same issues occur.

The other point that I have in mind that I don't think has really been represented, concerns the nature of migrations. We are necessarily looking back over 200,000 years or so, and see where everyone ended up. This makes it easy to think of a "long walk" migration out of Africa. What I propose is a "short walk" process - people don't set out from a continent, they leave the area their tribe dominates, and go over the next hill looking for new territory to inhabit. Then their children do the same (assuming a broadly settled pattern - even nomads have a 'range', generally). In this way populations, over time, will appear to have moved from one end of the earth to the other. But our timescale makes it look a lot more deliberate and organised than was the case.

One last note, I spotted that the Billings paper is from 1999, so there is likely new data that may alter some of what he says

[cmacq]

One last note, I spotted that the Billings paper is from 1999, so there is likely new data that may alter some of what he says

Right, I believe OCT (Out of Center [Asia] Theory) based on the genetic data was first proposed in the late 90s and early 2000s. For more recent work on the OCT please see Dennell, of the U of Sheffield, England, and Roebroeks, Leiden U, Netherlands. However, I may add I've long held this view because of an extremely prominent feature (its form and intended function) of the Modern Human anatomy. This also ties into the global distribution of most nonhuman primates and provides an extremely plausible forth Neanderthal/Modern Human scenario.


I'll address more late, have to run...



CmacQ

[cmacq]

First, the Billings paper cites the recovery of remains diagnostic of anatomical Modern Human from the Jebel Qafzeh and Skhul sites. He uses these examples because they are the best cases; both sites were rock shelters with stable contexts, the data recovery was conducted with a relatively high standard of control for the day, the excavations were well documented, and the dating of the remains was established by their association with a Levallois-Mousterian chipped-stone assemblages.

Somehow the Billings paper, incorrectly inferred that the Qafzeh and Skhul remains were classified as Homo sapiens sapiens. This is not the case as they are considered either Archaic Humans and/or a subpopulation of Neanderthals. Strangely, the Billings paper also uses these sites as evidence that supports an Africa origin for Modern Humans, however both are located in Israel, which is of course in Asia.

The Billings paper also failed to mention that the Omo I and Ngaloba (LH 18) remains were also those of Archaic Humans, the context of these sites are extremely poor, the recoveries were very poorly documented, the field methods remain unclear, and the methods of dating remains extremely suspect.

CmacQ

[macsen rufus]

Right, I believe OCT (Out of Center [Asia] Theory) based on the genetic data was first proposed in the late 90s and early 2000s. For more recent work on the OCT please see Dennell, of the U of Sheffield, England, and Roebroeks, Leiden U, Netherlands. However, I may add I've long held this view because of an extremely prominent feature (its form and intended function) of the Modern Human anatomy. This also ties into the global distribution of most nonhuman primates and provides an extremely plausible forth Neanderthal/Modern Human scenario.

I've been looking for the original Dennell & Roebroeks article, but it seems to be available by subscription only ... and there's a worrying number of search results that go directly to creationist bloggers (not a scientific objection, I know... ) Needle in a haystack trying to find rational responses to their work!

As far as I can tell though they do depend entirely on archaeological, and not genetic, data, or more to the point, they've taken archaeological evidence and made genetic conclusions. Our genome is incontrovertible - we KNOW it has survived from our ancestors (with alterations, sub-divisions etc). But fossils do not tell us whether they were in our line of descent or not, whether they are ancestors or evolutionary dead-ends, or even their species - we judge mostly by morphology, but if archaic humans were (as some suggest) highly polymorphic it muddies the waters even further. And there is the eternal conundrum with fossil records - absence of evidence is not evidence of absence. It is widely accepted that Asia has an extremely sparse record which can be interpreted in a number of ways: low population densities, inadequate research, poor retention etc. Therein lies the danger of interpolation and extrapolation. But as Billings points out, 1.5 million years over a 6000km range without a single recovered fossil is a very big objection to large-scale geneflow amongst Homo erectus populations.

Somehow the Billings paper, incorrectly inferred that the Qafzeh and Skhul remains were classified as Homo sapiens sapiens. This is not the case as they are considered either Archaic Humans and/or a subpopulation of Neanderthals. Strangely, the Billings paper also uses these sites as evidence that supports an Africa origin for Modern Humans, however both are located in Israel, which is of course in Asia.

As I read it he was saying the Skhul remains were Neanderthal, likely migrated from Europe/a cooler area (ie not morphologically adapted to the more arid environment yet), but also points out that some Hom sap remains in the region pre-dated these Neanderthals. He also is taking a middle-ground between strict RSOH and multi-regionalism, and seems to support an "Africa and/or Middle-East" homeland. Under certain climatic conditions the arid zone from north Africa right across to the asian steppes could be considered one contiguous biome, yet even this doesn't really counter objections to the difficulty of crossing Sinai.

Here's one response to the "Savannahstan" theory

I could really do with not being at work, as there's a lot of stuff in there and I can't give it full attention. It does sound an interesting alternative hypothesis, though An interesting topic all round

[cmacq]

I'm sorry;

I find I don't understand the purpose of the Derricourt paper? Whatever side of this debate one assumes, the evidence is clear that this barrier was breached, one way or another and both ways, not only by Modern Humans and a variety of nonhuman primates, but by other terrestrial mammals, as well. I also find this review fairly conflicted, as on the one hand it expounds the difficulties of a Sinai-NE Africa passage by known populations of Archaic Humans in central Africa, yet did not consider the possibility that fully Modern Humans staged in southwestern Asia, immediately adjacent to the Sinai could have easily moved into Africa at a later date. If anything I think the Derricourt paper actually underscores the server difficulties of a non-Modern Human populations move from central Africa into Asia. In fact, if one removes the critical assumption that Modern Humans originated in central Africa, by Derricourt’s own logic, the paper seems to actually support the OCT, rather than the OAT.

Still, the Derricourt paper proposes several excellent points. First, the paper indicates that the OAT proposed point of origin for Modern Humans was a relatively narrow strip of central Africa, not the entire continent. Second, this paper outlines the difficulties of moving from central to northern Africa. Third, Derricourt seems to have correctly concluded that any movement into or out of Africa was via the Sinai, and these moves most likely occurred for only relatively short periods of time. Overall, based on these points this paper seems to draw the distinction between an African and Asian origin for Modern Humans in sharp relief.




CmacQ

[macsen rufus]

Good point.

I will ponder over the weekend, no posting from home, alas.

[cmacq]

As plain as…

To move the ball foreward, while cutting to the chase.

I’ve given some time to let the above debate sink in a bit. An important point from the above discussion, affirmed by macsen rufus was that the bottleneck theory together with the physical manifestation due to natural selection of Anatomical Modern Humans (AMH) indicates the final stage of evolutionary development occurred within one specific geographic setting. In other words, for the most part all fully modern humans are directly descended from an extremely small breeding population, and the final evolutionary stage which characterizes this population, and all members share, occurred in, and was possibly inspired by, a specific environment. Of course, the OAT proposes that this specific environment was the relatively narrow ban of sub-Sahara Africa north of the Kalahari. So then, what can geography, climate, environment, and anatomy tell us about the origin of fully modern humans?

Collectively, the environment of this narrow ban of sub-Sahara Africa north of the Kalahari includes jungle, woodlands, tropical rainforests; as well as tropical and subtropical grasslands, savannas, and shrublands. However, it is more or less bordered on both the north and south by large deserts, which are in turn edged by semi-arid tropical steppe transitional zones. The climate of this region, restricted to those settings inhabitable year round by populations with a relative low level of technology, is somewhat variable, and ranges from tropical, subtropical, temperate, semi-arid, and arid. Over time, the geographic extent and intensity of these climatic and environmental settings has certainly changed, yet in a very general sense these characteristics have typified the region for several million years.



As far as anatomy is concerned the fully modern human nose is of some interest. Clearly, it is rather more pronounced, with the notable exception of Nasalis larvatus, than those exhibited by monkeys and Apes. In a larger context, this is due to the recession of the jaw and expansion of the cranium and brain. Of course, this flattened the overall facial anatomy and provided only a small area for a nasal cavity. To a lesser extent, this process is also evident among Apes, However, in modern humans it’s even more remarkable, as the olfactory eqithelium encompasses about 2.5 cm2 of the cavity’s lining. Thus the relatively unique structure and design of the modern human nose, when compared to other primates, suggests that its primary function was something other than simply respiration or acquiring scent.



One will note the skeletal morphology above, formed by the two nasale, two maxilla, and ethmoidale bones. However this view actually shrouds its interior complexity. The moist mucous membrane act to humidify inspired air, as it secretes as much as one liter of water per day. Interestingly, at normal body temperature the modern human nose maintains the relative humidity of inspired air at approximately 95%. Why? Right, clearly one of the fully modern human nose's primary functions was to protect the inner lining of the nasal and oral passageways and lungs from desiccation. Of course, one may naturally suppose that this type of evolutionary adaptation would at some point be manifested in a population that occupied either a semi-arid and/or arid climatic setting. As the proposed geography is bounded by semi-arid and/or arid climatic settings, one might easily think this observation supports the OAT. However there are two additional aspects or adaptations of the fully modern human nose that appear to suggest a far different, and more probable environmental and climatic setting.


More to follow.



CmacQ

[cmacq]

Before we continue, a brief examination of a recent study of Neanderthal nasal anatomy may prove useful. I’ll explain why a study of Neanderthal anatomy pertains to that of fully modern humans, below. Ian Tattersall (paleoanthropologists, American Museum of Natural History NY), Jeffrey Schwartz (University of Pittsburgh), with commentary by Jeffrey Laitman (anatomist, Mount Sinai Medical Center, NY), conducted a study of the nasal anatomy of 20 Neanderthal skulls. Of these, 8 specimens exhibited most of the nasal bones relatively intact. Due to the fragile and somewhat spongy nature of the interior nasal bones, these features are not typically preserved in the fossil record. For example most of the nasal bones are missing from the Neanderthal skull on the left, while they can be seen in the example on the right.

Schwartz and Tattersall identified two bony projections jutting into the front of the nasal cavity from either side. Now I’m not sure if these were significant modifications of the Ethmoid bone. However, the Tattersall-Schwartz study claims that they did not find these features in any modern humans or in other ancient human ancestors. Laitman adds that these bony structures probably helped Neanderthals breathe the cold air of Ice Age Europe. The jutting projections may have provided additional surface area on which mucosal coverings designed to warm and humidify extremely cold, very dry air before it reached the throat and lungs. Previous studies have suggested that overall the very large sinus cavities of Neanderthals served a similar function.

The rationale for offering this particular post was to demonstrate that as both hominid and hominin species exited Africa, for one reason or another, these either occupied similar environments with like climates, or conversely there were evolutionary adaptations. The alternative was of course, extinction. In this respect the Neanderthal is extremely instructive, as one will note the general hominan anatomy was clearly well established long before this species' entry onto the stage. Yet the Neanderthal also demonstrates that as hominans occupied increasingly more marginal environments with correspondingly less hospitable climates, sweeping evolutionary adaptation continued unabated, although these expressions on the surface may appear subtle. In this respect the Neanderthal can be viewed as one attempt to mitigate a less than favorable environmental and climatic impact on biology. As it is extremely self evident, that this of course doesn’t preclude, that there were other similar biological responses.


cheers

CmacQ

[General SupaCrunk]

No, we come from Atlantis, Mu (Also known as Lemuria), Lyra, Pleiadia and more. Atlantis and Mu comes from Berndard's star. Pleiadia 450 light years away, Lyra milions of light years far. Life didn't started in Africa, our scientists are wrong.

[cmacq]

Please, do you have a working knowledge of Lettish.


CmacQ

[Philippus Flavius Homovallumus]

I can't offer anything on the biological front, but I am privilaged to study at the same university as Dr Bruce Bradley. Prior to leaving the States, Docter Bradley demonstrated that the ealierest sttlers in America used a proto-European type of stone tool technology, which involved the reduction of a piece of flint or other material into the desired object by removing the excess. By contrast Asian, and therfore Native American, technology involved removing blades from a stone core and fitting them into a wodden or bone weapon or tool.

The first type of technology dissapears rapidly after the modern Native Americans appear on the scene. The conclusion was that Native Americans were not the aborigonal people of America.

Doctor Bradley is now working in Britain, I will leave you to draw your own conclusions about why that is.

[Sigurd]

It is not my intention to derail this topic but I read once in a scientific magazine that the first Americans were Australians.
A bit flippant, but they found sculls that were identical to Australian aborigine sculls.
I searched the Internet and found this article:

http://news.bbc.co.uk/1/hi/sci/tech/430944.stm