ANCIENT DE-POPULATIONS: Genetic study reveals that populations of ancient humans were surprisingly small.
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New genetic findings suggest that early humans living about one million years ago were extremely close to extinction.
The genetic evidence suggests that the effective population—an indicator of genetic diversity—of early human species back then, including Homo erectus, H. ergaster and archaic H. sapiens, was about 18,500 individuals (it is thought that modern humans evolved from H. erectus), says Lynn Jorde, a human geneticist at the University of Utah in Salt Lake City. That figure translates into a total population of 55,500 individuals, tops.
One might assume that hominin numbers were expanding at that time as fossil evidence shows that members of our Homo genus were spreading across Africa, Asia and Europe, Jorde says. But the current study by Jorde and his colleagues suggests instead that the population and, thus its genetic diversity, faced a major setback about one million years ago. The finding is detailed in the January 18 issue of Proceedings of the National Academy of Sciences.
To make these estimates, Jorde's group scanned two completely sequenced modern human genomes for a type of mobile element called Alu sequences. Alu sequences are short snippets of DNA that move between regions of the genome, though with such low frequency that their presence in a region suggests it is quite ancient. Because older Alu-containing regions have had time to accumulate more mutations, the team was also able to estimate the age of a region based on its nucleotide diversity. The team then compared the nucleotides in these old regions with the overall diversity in the two genomes to estimate differences in effective population size, and thus genetic diversity between modern and early humans.
"This is an original approach because they show that you can use mobile elements…to flag a region of the genome," says Cédric Feschotte, an evolutionary geneticist at the University of Texas Arlington.
The effective population researchers estimate at about 18,500 reveals that the extent of genetic diversity among hominins living one million years ago was between 1.7 and 2.9 times greater than among humans today. (Other studies have shown that the present-day effective population is around 10,000.) Jorde says the reason the modern effective population is so much smaller than the current number of people (nearly seven billion) is that a population explosion occurred, probably due to the development of agriculture about 10,000 years ago. He does not expect that there would have been such a staggering difference between the effective and actual populations of early humans.
Jorde thinks that the diminished genetic diversity one million years ago suggests human ancestors experienced a catastrophic event at that time as devastating as a purported supervolcano thought to have nearly annihilated humans 70,000 years ago. "We've gone through these cycles where we've had large population size but also where our population has been very, very small," he says.
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49 Comments
Add CommentI don't get it... How is "effective population" defined? Why should it have decreased?
Reply | Report Abuse | Link to thisIf only there were a resource available to everyone in the world. A digital encyclopedia of sorts... ;-)
Reply | Report Abuse | Link to thishttp://en.wikipedia.org/wiki/Effective_population_size
The critical element is the number of individuals that successfully passed their genes through to the current population. For example, a social organization found in many species, in which a dominant male provides the greatest contribution to genetic diversity, would affect the outcome of this population estimate.
Reply | Report Abuse | Link to thisAlso, a catastrophic event is not necessarily a global catastrophe: it could also be a devastating disease or, for what was expected to have been a somewhat geographically contained species, gradually changing local or regional conditions, such as desertification.
ribosome-"Effective population" refers to the genetic diversity among a population...not how many individuals exist in a population, but how much genetic diversity that group has. Genetic diversity has decreased, according to the article, because of a genetic "bottleneck" that occurred around 1 million years ago, decreasing the number of people in the world drastically, probably due to some natural disaster. Fewer individuals leads to less genetic diversity in later populations. Hence, the decreased effective population we see today (not to mention the other genetic bottle necks that have occurred since then).
Reply | Report Abuse | Link to thisribosome-"Effective population" refers to the genetic diversity among a population...not how many individuals exist in a population, but how much genetic diversity that group has. Genetic diversity has decreased, according to the article, because of a genetic "bottleneck" that occurred around 1 million years ago, decreasing the number of people in the world drastically, probably due to some natural disaster. Fewer individuals leads to less genetic diversity in later populations. Hence, the decreased effective population we see today (not to mention the other genetic bottle necks that have occurred since then).
Reply | Report Abuse | Link to this"We've gone through these cycles where we've had large population size but also where our population has been very, very small..."
Reply | Report Abuse | Link to thisAnyone who thinks that the human population cannot get much smaller again very fast is foolish.
There's a large contingent of people who are desperate to make that happen ASAP.
Reply | Report Abuse | Link to thisHowever successful a species is in their survival and propagation techniques, there's still a whole lot of luck involved.
Reply | Report Abuse | Link to thisThat early hominid populations have existed near to the brink, our own included, is nothing new. The study how ever is, and lends credence to the record.
Reply | Report Abuse | Link to thisI find it a compelling exercise to imagine our ancestors struggling for limited resources in the face of disaster and within their genes are held everything that we now are. How close had we come to not being here. That's some selective force to be sure.
Thanks everybody for the explanation of the concept of the effective population...
Reply | Report Abuse | Link to this... especially for the wikipedia link full of easily comprehensible formulas. ;-/
So, 1,000,000 years die not yield enough genetic diversity to compensate for the genetic loss experienced.
Very interesting. Just out of curiosity: Is there any mammal with effective population size much bigger than the human's one?
Cheetahs also underwent an genetic bottleneck some 1000 years ago. Their effective population size according to this definition might be pretty close to zero.
Let's face it - humans breed like bunnies.
Reply | Report Abuse | Link to thisWere there as few as a dozen, as long as 8 were females, the species would bounce back.
could it be a result of the "flood" that exists in so many culture's ancient mythologies?
Reply | Report Abuse | Link to this@Lloydster, With hominids distributed across Africa, Europe and Asia it is not possible for a single flood event to have caused it. There simply is not enough water. Even if we liberate all landlocked ice we would only raise global sea levels by about 60-75 meters (200-250 feet). Also, a flood of that magnitude would have left other markers in the geological record. Floods certainly have plagued humanity as we like to live near water and to anyone experiencing a flood I'm sure it is like the whole world has flooded, but floods of biblical proportions are just myths.
Reply | Report Abuse | Link to this@ Lloydster: Robert makes excellent points. While a lot mythologies have a grain of truth, the fact is it's impossible to discern the grain in the sandbox. Also keep in mind that mythologies borrow. The Judeo-Christian flood myth, for example, is practically a word-for-word copy of the legend of Gilgamesh, which predates the JC myth. In such an instance, you have one myth that's retold, not two myths providing "corroboration".
Reply | Report Abuse | Link to this@candide Just wait till 2012 foolish humans them aztecs will learn you good.
Reply | Report Abuse | Link to thisThe Story of Noah's Ark is hardly a "word for word copy of the Legend of Gilgamesh." Aside from different names, and many different details, Noah's Ark is written from a perspective of Mono-Theism where as the Legend of Gilgamesh is written from a perspective of Poly-Theism.
Reply | Report Abuse | Link to thisNo one claims that Moses' story of the Ark was an original idea of his. It is most likely that both stories come from a much earlier account, as do all of the other legends of Flood and near human extinction.
Now we have genitic evidence (had it for some years now) that humans nearly became extinct early in our existence as a species. Almost universely there is a legend of a Flood that accounts for this. Something happened, and almost all cultures say it was a flood. Even if such were not geologically universal, it was at least anthropologically universal.
Now, the comment that there is not enough water to account for such a flood is a valid argument, if one makes the (almost universal) assumption that the account calls for a uniform flood that covered the whole earth to a uniform depth of several miles. This would be a semetrical flood.
My point is, who ever said that the Flood had to be a semetrical Flood? If it was assemetrical, that is not a uniform depth over the entire surface of the earth at the same point in time, there would be no extra water needed to do so.
What I mean is that what if something caused the water of the earth to move over the surface to one side of the earth, and then the other? Think this is rediculous? It is happening now to a lesser extent. It is called the tides.
If a large planet (a rogue planet), or a small black hole came close enough to the earth, it could account for the Flood.
An objection to this would be, "If such happened, there would be terrible geologic upheval as well." Maybe that is what is meant by, "The fountains of the great deep burst forth."
Just some food for thought.
Yah, I think we should all try as hard a possible to imagine how bibilical myths might actually have possibly happened... if we click our heels together 3 times while doing so, who knows what might occur?
Reply | Report Abuse | Link to thisIf a black hole came close to the planet we'd have much more serious things to worry about than the water rising a few dozen meters.
Reply | Report Abuse | Link to thisI am only offering a thought for discussion, I have no intention of trying to defend the idea.
Reply | Report Abuse | Link to thisHowever, the effects of the Black Hole would depend entirely upon it's proximity to the earth, and it's own mass.
Yes, there would be other effects, and their severity would depend on the two factors I have mentioned above. Do you have any idea what these effects would be? (I mentioned one of them already.)
Your answer only demonstrates a closed mindedness on your part. I am pointing out that almost all cultures have a flood story, and this genetic research indicates (not proves) that at one time our species almost did become extinct. Those who were there claimed it was a universal flood. These legends were started before the Books of Moses were writen (as I also pointed out), so don't start with it only being a Bliblical Flood.
Reply | Report Abuse | Link to thisIf a large rogue planet, or a black hole came close enough to the earth would it not raise the tides? Possibly enough to account for a legend of a Great Flood?
Carl, let me paraphrase your thinking and then you can tell me where I’ve misrepresented you. The genetic research indicates that something caused a drastic reduction in human population around one million years ago. The cause of that reduction could have been a flood that was initiated by a black hole or a rogue planet. The best reason for thinking this is that there are flood legends found in various texts that were written two or three thousand years ago, which could have been preserved through oral tradition for about one million years.
Reply | Report Abuse | Link to thisIs this your position?
Potato Chip;
Reply | Report Abuse | Link to thisYou are pretty close, but you may have a misconception here. I am not taking a specific position. I have one, but I am trying to follow a line of logic here, based on what we do know, but I am not going to "fight" for or even defend a position.
The next thing is the order of the logic train.
1. This research indicates (not proves) that at one time the human race faced extinction.
2. Very many legends have come about describing such a time, and almost all of them blame it on some type of Flood.
3. One objection to a world wide flood is that there is not enough water to have covered the whole earth to a uniform level of several miles. Even if something could be evoked to make this amount of water available, then the next objection would be, "Where did it go?" These are valid objections.
4. The reason for the problem in #3 is that everyone assumes a symetrical flood is being talked about. That the legends are saying that the water level somehow rose to a uniform level of several miles. I am challenging this assumption with the idea that maybe there was an assymetrical flood. One where the water level was not a uniform depth throughout the world.
5. I am not saying that a black hole or a rouge planet caused such. I am saying that a black hole or a rouge planet could have caused an assymetrical flood by the same mechanism that the moon causes tides today.
6. If such were the case, it could explain the fact that we have many legends of near extinction (most claiming a flood), and this genetic research that claims that mankind did almost become extinct. I am NOT saying this is the explanation, but that it could explain the situation.
I am not trying to prove anything. I am trying to initiate a discussion.
I have already mentioned one objection to this line of thought. That being that such an encounter would have geological upheavals as well. IF this is the explanation, then we know where the Biblical phrase came from whereby "the fountains of the great deep burst forth.", or that one legend(at least) does mention such an upheaval.
If you have followed my line of logic, then you should be able to come up with the next objection. I am waiting to see if someone does.
Please remember, I am not trying to prove a position. I am trying to provoke a thoughtful discussion.
Thanks for your thoughtful response.
Carl - I think we should all chip in and buy you a spell-checker!
Reply | Report Abuse | Link to thisAll Agreed?
PeterT
Carl, the most important issue I was hoping you would address is the one thing you didn't. That is whether you think that such a flood legend could be preserved through oral tradition for about one million years.
Reply | Report Abuse | Link to thisIf the legends originate from actual floods that occurred in the last five or ten thousand years (or even fifty thousand), then we are only talking about floods with local effects, since there is no evidence of dramatic population reduction during that time frame. If there was a flood that occurred one million years ago, it wouldn’t have been passed down through oral tradition and it couldn’t be the source of the legends.
I know you said that you are not trying to prove anything, but you also said that you are trying to follow a line of logic. Please explain why you think that a near-extinction event that took place one million years ago has some connection with flood legends that were written in the last few thousand years.
Carl,
Reply | Report Abuse | Link to thisThe next objection? Moon, moon where art thou moon? is that the one you mean?
Our current population may well have its origin in mutations in a very few individuals, after which gradual change occurred. If that is the case, how can one determine whether a small population represents "almost extinct" and a new line just getting started?
Reply | Report Abuse | Link to thisThe diversity in the science community confounds logical reasoning of the human brain.
Reply | Report Abuse | Link to thisThere no evidence for this "Endangered Species: Humans Might Have Faced Extinction 1 Million Years Ago" using genetic evidence diversity.
These libertarianism always use the words "might, assume, suggests, and estimate" and others words.... to defined their liberally reasonings.
They get a lot of undereducated people believing in this genetic evidence.
On thing about genetic evidence, if people can not explain things logically they blame on genetics. In other words they blame the evidence
or problems on YOU.
Not exactly sure what you mean. Please explain.
Reply | Report Abuse | Link to thisPeter T said;
Reply | Report Abuse | Link to thisCarl - I think we should all chip in and buy you a spell-checker!
All Agreed?
Great!!!! I have some real expensive ones in mind. Just send the money to my bank account.
Seriously, I ususally do not have a lot of time to write these posts, and while I do proof read them, sometimes I misspell words. Sorry about that, but I overlook when others do this, and I hope people will extend me that same courtesy.
Carl
About the possiblility of an oral traditon being passed down for 1 million years...
Reply | Report Abuse | Link to thisI did not address this for the very reason I am not trying to "prove" something. Also, I do not have an oppinion on the subject, so why try and BS someone who is giving me a thoughtful discussion. Wont do that.
Also, the subject involves to many assumptions, and side arguments to treat well. One of these assumptions is the estimate of the time period given in this article. There is another genetic study (done on Mitochondrial DNA) that estimates a near extinction event at 80,000 years. Is this the same event, but given different dates due to different assumptions in the rate of mutation? Are these 2 different events. I do not believe the science is quite up to definatively answering either question.
There are many other side avenues of this line of argument, but on this thread I do not have the time to do all of them..
Carl, you keep saying that you're not trying to prove anything, but you did outline a set of premises that make an argument for a flood. Specifically, regarding a black hole or rouge planet causing an asymmetrical flood, you said this:
Reply | Report Abuse | Link to this"it could explain the fact that we have many legends of near extinction".
But here’s the problem. Even if the event happened 80,000 years ago, clearly it could NOT explain the written legends.
The idea of an oral tradition being carried down for a million years seems unlikely in the extreme. The exsistance of an oral language that could be passed down 1 million years ago is doubtful. I am not saying impossible..........just highly unlikely. If there was a oral capability of that degree at that time.....why would it have taken so so long to develop to where the race was 990, 000 years later.
Reply | Report Abuse | Link to thisCarl,
Reply | Report Abuse | Link to thisWhat I mean is simply that such an event would have raised havoc with the Lunar orbit and would quite likely have stolen the moon from us entirely.
Why not?
Reply | Report Abuse | Link to thisWe assume that writting was a "recent" development, but we don't really know. We have written records written on stone and clay tablets, but it would seem logical that before man learned how to use these elements for records, he probably used imlements that did not last nearly as long. Like a charred stick on wood, or stone on wood, or the charred stick on animal skins.
You also underestimate the power that such an event would have on the racial memory.
The last thing is that these two genetic studies that demonstrate that humans were nearly wiped out give 2 very widely different dates. It may be there were two events, or it may mean that the estimates of such a great age (derived from the genome) are not that accurate.
So, for this debate, I am sticking with the idea that genetic research has shown that mankinds memories of a near extinction event are accurate, and the witnesses said it was a flood.
That is what I thought you meant, but I wanted to make sure first. Not quite what I meant, but close enough for me to work with.
Reply | Report Abuse | Link to thisYes, such an event would have an effect on the shape of the Moon's orbit. One that could raise the tides far enough to account for the legends of floods (that almost all cultures have) would definately effect the Moon's orbit.
However, no one knows what the Moon's orbit was at that time. We believe it was similiar to what it is now, just a little closer, based on how we think the moon was formed, how long ago we think it was formed, and where we think the original orbit was. These are assumptions based on a logical argument, but since no one was there keeping accurate astronomical records at the time, no one can prove what the orbit was at the time in question. Not me, not you, nor anyone else.
No, the last paragraph does not mean I am right. Not going to make that claim.
As well as having an impact on the orbit of the moon, such an event (a large planed, or a black hole raising the tides to a worldwide flood) would have an impact on the orbit of the earth. However, the same reasoning I applied to the moon would apply to the earth. We would have no idea what that impact was, simply because there is no way we can know what the original orbit of the earth looked like.
Now before I go any further, let me remind you that I am NOT saying that the earths orbit is different than it was in the time in question. I have no way of proving it was, any more than someone else can prove that there was no change. I will say that it would take a lot less gravitational energy to raise the tides than it would to move the orbit of a planet. That is, that the effect on the tides would be greater than the effect it would have on the orbit of the earth (or moon), In order to have enough energy to greatly change the orbit of the earth, it would have ripped the oceans right off of this planet.
So it would appear that we could neither prove that such an event happened by it's effect on our orbit, nor can we disprove it.
However, there is an interesting astronomical anomally that is worth considering. Since I am running out of character space, I will have to write another post to explain what I mean.
By the way, I thank you people for the intelligent objections forming an intelligent discussion, rather that the name calling and character assination that I have seen on other blogs (in Sci. American) when someone says something going against the "norm".
PS
Reply | Report Abuse | Link to thisI have run out of time right now, so I will have to finish this discussion after I get out of work tonight. Sorry.
ktulu,
Reply | Report Abuse | Link to thisNot that I believe any part of it, but don't you mean the Mayans?
Carl, I just wanted to hear you commit to the requirement that in order for the event to have spawned the legends we know of today, the stories would have to have been retained culturally. You seem to accept the absurdity of the notion that these stories could have been retained orally for 80,000 years, since you haven’t tried to defend that stance (no one could, as the retelling of the story would have to be reliably preserved through at least 3,000 generations, without interruption).
Reply | Report Abuse | Link to thisInstead, your position obligates you to posit a new argument, which is that humans have had some form of writing throughout this entire timeframe. And not just any form of writing, but a form that was sophisticated enough to convey the stories in question, and one that could preserve the story uninterrupted. This is a point that is at least as sticky as the original. Since it’s essential to your logic, I wonder why you didn’t address it at the start. I’m guessing that you didn’t realize that it was a necessary premise, and equally problematic.
So the challenge of defending your logic has now doubled. Before, you were only suggesting that a black hole or rogue planet caused a cataclysmic flood 80,000 years ago. But now you have been forced into arguing (in addition) that humans had some form of written language at least that far back. I hope you can see that the more you try to defend your argument, the more difficult it gets. You’ve dug a huge hole for yourself, and when your thinking is submitted to scrutiny, you’ve had to dig another equally absurd hole. I suggest that you climb out.
You seem to forget that I have also questioned the time frame set by the two genetic researches that were done. One said 80,000 years, the other said a million years. If they were the same event, then the descrepancy in the two different ages would indicate that we do not know enough to say it happened a million years ago, or 80,000. It could have been much greater, or much less. If they were two different near extinction events, it would seem to me that each genetic study would have found 2 events, not just one for each. So, despite the amazing findings of these two studies, there is still an awful lot that has to be answered.
Reply | Report Abuse | Link to thisAs far as if it were possible that oral (or semi written) traditions could have been passed down for such a long time, you said it might be possible, but was not likely. I am not trying to prove any of the things I have said on the subject. I am willing to admit a difficulty, but I am actually driving to a different path, one which I am still not trying to prove something, but to share an amazing (I think) possibility that might be worth someone looking into.
So, if you don't mind, I would like to leave this part of the discussion admitting that your objection is legitimate, but it might still be possilbe that the traditons were handed down for so long a time, or for a lesser time considering the descrepancies I have mentioned. I don't know the anwer to this, and I am more interested in the other part of the discussion I have been driving at.
Ok, this morning I said that if such a rogue planet or black hole came close enough to the Earth to raise the tides it would have an effect on the orbit of the Earth. I also said that since no one really knows what the orbit of the earth looked like 1 million years ago, there would be no way of proving that such an event actually happened. I also said that there was an interestion astronomical anomally that comes up at this point.
Reply | Report Abuse | Link to thisWhat I am referring to is called Bodes Law (or Rule). This is a simple mathematical relationship dealing with the mean distance from the sun that all of the planets of the Solar System share. If you do not know what Bodes Law (or Rule) is, just look it up on Wikipedia.
The point is that all of the planets follow this relationship to a very large degree. No one knows why this is so, most assume it is just a coincidence. I should say that all of the planets follow this rule to a very high degree except for Neptune.
Again, no one knows why Neptune is so different, but it is.
Now, I have suggested that a large rogue planet or a black hole came close enough to the earth to raise the tides to a point of making an assymetrical flood on the earth. If such happened it probably did affect the orbit of the earth to some small degree, but we can not prove it one way or another.
What if said hypothetical object came close enough to Neptune to chage it's orbit from a Bodes Law arangement into the orbit it is now? I am not saying this definately did happen, but that it might have happened. 7/8 of our Solar System follow Bodes Law, 1/8 does not. Now we have two events that may have been caused (I did not say "were caused") by the same thing.
There are other anomallies. Another one is the tilt of Uranus axis of rotation. 7/8 of the planets axis of rotation are approximatley perpendicular to the plane of their orbit. Earth's is approximately 23 Degrees tilted.
Uranus on the other hand is tilted almost 90 degrees . Again, no one knows why. Some theorize that there was a collision with a large body, and this knocked Uranus over.
If the object I have hypothesized did exist, and do what I have suggested, could it have passed over one of the poles of Uranus, and changed it's tilt? I am not saying it did. I am suggesting that it is a possibility.
There are other anomallies. Time and space prevent me from going into this further. But here are now 3 things that COULD POSSIBLY be explained by a rogue planet or black hole.
Just trying to suggest a facinating possiblity.
It’s not fascinating. It’s what people call tortured logic. When I said your challenge had gotten twice as difficult to defend, I was wrong. It’s three times as difficult. You’ve proposed a flood, for which there’s no evidence, written history dating back about 80,000 years, for which there’s no evidence, and a rogue planet that altered Neptune’s orbit to make it conform to a long-since discredited idea, for which there’s no evidence. This is neither induction nor deduction.
Reply | Report Abuse | Link to thisLook for fields of boulders or layers of large stones. They are all over the place.
Reply | Report Abuse | Link to thisThat is the question. The modern human species is about 200 thousand years old. It took the hunter/gatherers that cross the Bering Straits about 12 thousand years to go from stone tools to pyramids so what were we doing 188 thousand years. The best answer is that the earth has had many natural disasters over the last 200 thousands years and maybe many before that has kept the human population down. The last 12 thousand years maybe the longest period of peace that the human race has ever known. I hope it will last at least another thousand years to give us time to spread to space.
Reply | Report Abuse | Link to thisI think most astronomers will tell you Bode's "Law" is a convenient, but flawed explanation for planetary placement. Mind you, I'm basing this off of 10 year old data, back when I was trying to use Bode to do planetary placement in a computer simulation and was laughed at by hard core astronomers, but I'm inclined to listen to the advice of the directors of two major observatories rather than a guy trying to advance a flood theory that (pardon me here) doesn't hold water.
Reply | Report Abuse | Link to thisIt seems a lot more likely to me that the catastrophic event was viral, neatly explaining how such a small Effective Population survived-- they shared a common genetic immunity that the rest didn't. While there's a lot of holes to this theory, (chief among them, a global vector that could cover the Earth in the Paleolithic era), but it beats the heck out of changing planetary orbits and making up an imaginary written record.
Amazing that we don't put animals, plants, ect as endangered unless they are almost extinct. I would say any species that has less than 10,000 would be almost extinct, but not according to humans. Humans are the invasive species, and they are out of control!
Reply | Report Abuse | Link to thisan off the wall thought has bugged me for some time, I may as well offer it here. Our species, and a mere handful of others, once suffered a devastating mutation in our germ plasm (passed on to all future generations) -- we no longer make our own ascorbic acid, an absolutely essential substance. There is no possible way this can be accounted for by classic evolutionary theory as it is anti-survival, and even less can the theists claim a benevolent god did this to us. But what if it was a retroviral plague? Many affected species would have died out completely and very quickly, while those few that already lived mostly on fresh produce managed to survive.
Reply | Report Abuse | Link to thisI wonder if you would see evidence of genetic bottlenecks in those other few species that share our disability.
It is not necessary to posit a worldwide simultaneous flood to account for the variety of legends. During the meltdown of the last ice age there would have been many huge, devastating floods in different places, enough to imprint themselves in folk memory for all time. (And don't think oral history isn't passed down without the need of writing.) Floods are everywhere in the geological record. In my area it was an ice dam that let a giant inland sea flow to the ocean when it let go, and the scouring action of that mass of water is quite visible to trained eyes.
Reply | Report Abuse | Link to thisAnother suspected cause of the Near East legends is a comet or asteroid strike in the Red Sea or Indian Ocean, driving huge walls of water inland and vaporizing sea and sea bed, for weeks of muddy rain thereafter. There are some evidences of craters.
Where are these 2 people from ? Our greatest diversity is in Africa . should we ask if that country is represented ? If not how can All humanity be accounted for ? we may have come out of Africa but some people remained. Time frame is the question on out of Africa.
Reply | Report Abuse | Link to thison the topic of oral tradition -- Troy
Reply | Report Abuse | Link to thisAlso, the epic of Gilgamesh one of oldest surviving works of literature, so I do not get where we got on the oral tradition train in the first place.
1 million years ago we were in a magnetic reversal with a brief sudden positive reversal (http://en.wikipedia.org/wiki/Jaramillo_reversal
)
our magnetic field of course comes from the Earth's core. Some theories hold that a sudden magnetic shift is caused externally. I agree with the person who said some of the local large and sudden flooding would have made it into that culture's oral or written tradition.