Humans Nearly Went Extinct 70,000 Years Ago 777
Josh Fink brings us a CNN story discussing evidence found by researchers which indicates that humans came close to extinction roughly 70,000 years ago. A similar study by Stanford scientists suggests that droughts reduced the population to as few as 2,000 humans, who were scattered in small, isolated groups. Quoting:
"'This study illustrates the extraordinary power of genetics to reveal insights into some of the key events in our species' history,' said Spencer Wells, National Geographic Society explorer in residence. 'Tiny bands of early humans, forced apart by harsh environmental conditions, coming back from the brink to reunite and populate the world. Truly an epic drama, written in our DNA.'"
The way things are going (Score:5, Insightful)
Environmental damage here we come!
Re:The way things are going (Score:5, Funny)
it all sounds like a lame plot from a porno (Score:5, Funny)
Re:it all sounds like a lame plot from a porno (Score:5, Funny)
Re:it all sounds like a lame plot from a porno (Score:5, Funny)
General "Buck" Turgidson: Doctor, you mentioned the ratio of ten women to each man. Now, wouldn't that necessitate the abandonment of the so-called monogamous sexual relationship, I mean, as far as men were concerned?
Dr. Strangelove: Regrettably, yes. But it is, you know, a sacrifice required for the future of the human race. I hasten to add that since each man will be required to do prodigious... service along these lines, the women will have to be selected for their sexual characteristics which will have to be of a highly stimulating nature.
Ambassador de Sadesky: I must confess, you have an astonishingly good idea there, Doctor.
Re:it all sounds like a lame plot from a porno (Score:5, Funny)
Re:it all sounds like a lame plot from a porno (Score:4, Funny)
(One way or another.)
Re:The way things are going (Score:4, Insightful)
we will actually reach that population level again. Environmental damage here we come!
I knew someone would say this. Alright, I'll bite. Name one plausible environmental damage scenario (other than full-out nuclear war) that would cause a significant proportion of human extinction.
The most extreme predictions of global warming will hardly slow down human population growth, much less actually reduce populations, much less threaten us with extinction. (Of course, predictions are that human population growth will naturally slow and even stop over the next 50 years, but that's another subject).
Re:The way things are going (Score:5, Interesting)
Good old fashion starvation and disease. For reference, see the current food prices and how these are liked in the developing world. Biofuel mania has something to do with it, but increased consumption by people and animals people eat is the major problem.
Yes, it's entirely possible to get crop failures leading to starvation. But how many deaths? 1M? 10M? Not even a small dent in human population.
The flaw in your thinking is very common -- it assumes a static world that does not adjust. If people are dying by the millions, then things will adjust. Hunger is by far a distribution problem, not a food production problem.
Re:The way things are going (Score:5, Insightful)
I've read this sentiment many times, and although I agree with the latter statement, I can't agree with the former. In my view, it's not a distribution problem, it's an economic problem. We could distribute enormous amounts of food anywhere on the globe, but we don't. Why? It's too expensive. Hungry people are often poor people, and poor people can't pay enough to meet our expectations of a return (or even no loss) on labor, fuel, vehicles, storage, and other distribution resources. So, we make this choice: they're just not valuable enough to us to bear the cost of sending food (of course, aid agencies disagree and do exactly this).
Re:The way things are going (Score:5, Insightful)
As for diseases, there is no earthly disease that kills 100% of its victims, (because such a disease would then itself become extinct).
I think you've been watching too much Science Fiction.
You are not legend.
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Maybe something like an airborne or mosquito-borne variant of HIV?
It's certainly possible to get killer diseases, but that's not an environmental damage scenario. That can happen anytime.
Re:The way things are going (Score:5, Interesting)
Volcanism. With global warming, the melting of the polar ice will result in a major redistribution of mass. The planet will want to conserve angular momentum. Something will have to give.
Huh? I suggest going to look up the mass of the earth, compared to the mass of all the water. The mass of ALL the water is proportionally tiny, much less the mass of just the ice. Then try and remember that the world goes through periodic ice ages that redistribute water mass all the time.
Re:The way things are going (Score:5, Funny)
"Darn it, that was close, I'll get them next time!"
Re:The way things are going (Score:4, Funny)
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Re:The way things are going (Score:5, Interesting)
#1 it is unequally balanced..the temp changes more at the poles where the ecosystem is more sensitive to temperature. Therefore a small global change will mean dramatic changes in isolated areas.
#2 if you look through history, the average GLOBAL temperature over a one year period has typically hovered around 0 deg C for most of history. I hear that is an important temperature for something..... Anytime the temperature strays from freezing dramatic changes happen to the global environment.
#3 Consistency. So much of our modern society is based an the extremly mild conditions the earth has experienced over the last 20,000 years. Most of Europe is inhabitable ONLY because of the gulf stream and atlantic currents. Agriculture is ONLY possible because the temperature has been consistant year to year. We are in a sweet spot environmentally that is very unusual in earths history. screwing with the temperature is not going to help.
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Re:The way things are going (Score:5, Insightful)
Be careful saying that. You're likely to get yourself harassed, blacklisted, and shunned for such politically incorrect remarks.
I fully believe that the greenhouse effect is a simple matter of physics. I also believe that the effects, as we know them, do not occur rapidly. I also know that, historically, the climate is NOT stable - whoever said that it's been stable for most of history simply does not know history (Nineteen-hundred-and-froze-to-death being one example, the total environmental collapse of mesoamerica and the middle east, the sudden shift that made Europe more habitable and helped lead to the Rennaisance, etc etc etc).
In other words, yes our pollutants will have a very real effect on our climate. There is no free lunch. But, those effects belong to our children and grandchildren - what you see today is the normal cycle of change - but in a highly connected world prone to panic and fantasy, and overly willing to lay blame anywhere it can.
It may not be all bad though... it might scare us into actually controlling ourselves - before the bill actually shows up.
Re:The way things are going (Score:5, Informative)
So yeah, maybe there is some input that we haven't yet discovered that explains the warming trend. Lord, that would be nice. But until some evidence of that is uncovered, I'm going to trust the nice, testable, repeatable climate models over people's thought experiments, untestable claims, and "what-ifs".
P.S. - why don't ordered and unordered lists work anymore?
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Ever wonder why the word "coincidence" often has the phrase "just happens to" associated with it? Have you ever wondered why it matches when we *started* figuring this out and were barely using it versus when we were/are at peak usage? Seeing as how volcanoes have more of a measurable and directly observable impact than anything we've ever done, I'm not rea
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Ever wonder why the word "coincidence" often has the phrase "just happens to" associated with it?
If, like you just did, that fact was stripped of context and taken alone - then yeah, I would probably be skeptical and write it off as a coincidence.
However, along with this big temperature increase we ALSO have an entire body of scientists with models that seem to describe past events really, really well - and even have a pretty decent track record over the last 10 years. These models ALSO implicate man-released CO2 in the warming.
So now the word "coincide" and the phrase "just happens to" look less and
Re:The way things are going (Score:5, Insightful)
Do you really think that ? I don't.
Considering human acts the main cause of global warming (or whatever other catastrophe you want) is very comforting. Why ? Because we can do something about it.
On the other hand, if humans are not the cause, we have a really big problem. Imagine it is some kind of change on the sun. How do we handle that ?
These days, I take a great deal of comfort on the idea we are destroying out planet, our "natural" disaster are due to humans doing this or that.
Re:The way things are going (Score:5, Interesting)
http://www.rollingstone.com/news/story/12343892/can_dr_evil_save_the_world/print [rollingstone.com]
Scientists routinely use such computer models to test the effects of various climate-related scenarios, from rising CO2 levels to the impact of deforestation on global warming. After several weeks of running a climate simulation on Stanford's superfast computer network, Caldeira concluded that shading the sunlight directly over the polar ice cap by less than twenty-five percent would maintain the "natural" level of ice in the Arctic, even with a doubling of atmospheric CO2 levels. Push the shading up to fifty percent, and the ice grows. Even better, the restoration happens fast: Within five years, the temperature would drop by almost two degrees.
In Wood's view, this was a no-brainer. You could stabilize the ice, save the polar bears and demonstrate the virtues of planetary engineering for less money than it takes to feed and clothe the soldiers in Iraq for a year. Because the aerosols are launched only over the Arctic, there is little danger of directly impacting humans. And best of all, you can try it for a few years and see if it works. If something goes wrong, you can quit, and within a year or so, all the particles will have dissipated, returning the region to its "natural" state.
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How do you think scientists got that information on the length of ice ages, but can't get a decent grasp on average temperature for more than 2000 years? Your sentences directly contradict each other.
Have you ever actually talked to a geologist? (Score:5, Interesting)
You're also wrong if you think that recorded human history is the only record of past climate that we can reference. There are numerous natural records of past climate that go back much further into the past. And by the way, the best estimate for an average global surface temp is actually about 14 degrees C, not 0. I have no idea where the grandparent got that number. Maybe they mistook temp anamoly for absolute temp.
Finally, it may surprise you to learn that many researchers of past and current climate do in fact hold geology degrees.
Re:The way things are going (Score:5, Interesting)
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Re:The way things are going (Score:5, Informative)
Which might explain why the GP said that records from the Roman Kingdom were over 2500 years old and that after that they had the Roman Republic. You should have kept reading after you saw the phrase Roman Kingdom.
Re:The way things are going (Score:5, Funny)
Hey, look everyone! We've got a postcard from IGNORANT WORLD.
Re:The way things are going (Score:5, Interesting)
In addition, there are several thousand years worth of recorded events before that, but by historians living long after (although still ancient by our perspective) they supposedly occured. Many such cases can be considered the "historical" myths of their time, although in other cases historians mention the titles of prior works now unknown to us (thus indicating that these were written, rather than oral, legends).
Re:The way things are going (Score:5, Insightful)
How about the people who busily insist that can't possibly be anything other than a wholly human-caused phenomenon, and that we can definitely stop it. What if we can't? Plans, anyone?
Seriously, I want my interstellar settler permit and associated vehicle already...oh, wait...we can't even go to the moon anymore.
Re:The way things are going (Score:5, Insightful)
Might as well give up now and save a few billion dollars.
I'm of the opinion that GW is natural and we are just giving it a teeny tiny push.
Next they'll blame the next ice age on human activity as well.
It bothers me (Score:4, Insightful)
Where's the beef? Why are people saying that we're going to see cataclysmic changes in our environment, when no appreciable changes have occured so far. What is the basis for all these predictions?
Re:It bothers me (Score:5, Informative)
Re:It bothers me (Score:5, Interesting)
Re:It bothers me (Score:5, Informative)
Famine: Well, there's a lot of Africans who still don't get enough to eat.
Floods: Might as well include storms, so think about the number of hurricanes in the last couple of years, and many people in Europe have been experiencing SOME flooding.
Rising water: that's a really slow effect. Mind you, eroding shore lines are a sure sign of this phenomena.
Just because you don't see it happen instanteously doesn't mean its not happening.
AND you should be GLAD its not happening instanteously!
Re:It bothers me (Score:5, Interesting)
The other thing I'd like to mention is that there really are more things to consider than just CO2 levels in terms of global warming. I don't think that human carbon dioxide emissions will be the end of us, but it could trigger the chain of events that leaves our planet much less hospitable to us. Have you heard of the methane hydrates in the cold sea bed?** It's possible that a small shift caused by our increasing carbon dioxide emissions - even if they have to increase by another 30% or maybe more - will push the temperature over a critical threshold and trigger a cascade which will again cause all hell to break loose.
So in a way, you are right. Except in climates which are around a sensitive temperature (e.g. Those areas where the temperature hovers near 0 degrees C) there is very little change right now. That could be that CO2 emissions are having a very minimal effect on the temperature, or more likely IMO, that's just that we haven't quite overwhelmed the checks that are in place.
* (IANA Environmental Scientist, so there may be a margin of error in the direness of my predictions)
** http://dsc.discovery.com/news/2008/02/26/methane-global-warming.html [discovery.com]
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It bothers me that people keep talking about the hypothetical effects of global warming without any real data. CO2 levels have risen by 30%, and surface temperature have not shown enough of a trend that we can really say the temperature is even rising.
Um, remember phase changes, heat of liquefaction and heat of vapourization? What is happening to glaciers and arctic ice again? Are the specific heats of water and ice relatively high or low compared to most materials?
If you put some cold water with some ice cubes in a glass, how fast does the temperature of the water change while the ice is melting? How fast does the temperature change after all the ice is melted?
Re:It bothers me (Score:5, Insightful)
The biggest short term impact of northern cap melting away is albedo. The caps radiate away a far amount of energy because of the snow and ice. Less snow and ice, means more darker surfaces which means more energy is retained. This becomes a feedback loop that rapidly (relatively speaking) ends up warming the northern hemisphere.
You're writing like you don't understand how significant even small changes in global temperatures can have large impacts. Do yourself a favor and read the IPCC reports. Better yet, go enroll yourself in a university and major in climatology. Then you will understand exactly how much energy a 1 degree rise in temperature world-wide can have, and why it should be a concern.
And stop confusing climatology with meteorology. The climate doesn't shift over the course of a week. The changes people are concerned about will be happening over the coming decades and centuries. We only have a hope of preparing for it if we start early.
~X~
Re:It bothers me (Score:4, Insightful)
"(over population is so much more of a threat)"
It is impossible to go extinct due to overpopulation. It is the secondary effects of overpopulation (such as global warming) that cause problems.
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That's definitely a problem I have (Score:5, Insightful)
1) What if even though we are the source, we can't stop it? What if it turns out there's just no way now to turn things around, we are too far down the road? What then?
2) Assuming historical extrapolations are right, the world has been much hotter and colder than it is now. Thus it is likely that will happen again. Thus no matter what we do, we are probably in for a big temperature change at some point.
So then if we assume it is true that a temperature shift of a few degrees will really screw us over, then we need to be preparing for it and figuring out how to deal with it. It really seems like a case of not if but when. Even if we are the cause and have the power to prevent this current change, a change that we can't will happen at some point. Also, just because we are the cause, doesn't mean we can prevent it.
Either way, the most sensible thing would seem to be to figure out what we need to do to be able to survive a temperature shift, not concern ourselves with what the cause is because unless we are extremely incorrect about past temperature, it is not a static function over any time period, and thus is not likely to remain so, regardless of what we do or don't do.
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1. CO2 is a very minor greenhouse gas
2. The amount of CO2 re release into the atmosphere is pathetic compared to the other gases - a mere 0.28% 3. The hottest years on record predate the industrial revolution
4. There are a number of other factors such as the above that you can't/don't give an explaination for (solar activity being one), and you simply resort to either the "your workin for
Re:The way things are going (Score:5, Insightful)
B: Yes. The era of planet formation was pretty hot. Your point?
C: The industrial revolution predated worldwide temperature monitoring. The "record", such as it goes, it incomplete.
I'll have to beg your forgiveness; the "global warming isn't a threat / is not our fault" line has been embraced by the same slice of the body politic that claims DDT doesn't hurt baby eagles, smoking doesn't cause cancer, and you can cut taxes forever and still pay for a war.
If when you argue on the same side of an issue as those who have long since ceded any claims to credibility to the scientific method, you get associated with their tactics until argued otherwise. "Silence implies consent", and all.
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Incorrect. Aside from water vapor, carbon dioxide has the largest radiative forcing of the green house gases in our atmosphere. The others, in order, are methane, nitrous oxide, and CFC-12. To add to this, the lifetime of carbon dioxide in the atmosphere is quite long, unlike gases sucha as methane.
"The amount of CO2 re release into the atmosphere is pathetic compared to the other gases - a mere 0.28%"
Incorrect. CO2 currently makes up over 72% of greenhouse gas emissions from
Garbage magazine (Score:4, Interesting)
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I know that the GW alarmists are very vocal and can and often do get very vitriolic in their attacks with those who don't agree with their agenda. This especially true when facts and figures are brought to the public's attention that contradict their loudly trumpeted propaganda.
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The most common argument against any questioning of global warming is to claim that the questioner is somehow not intelligent enough to understand. It's second only to immediately accusing any questions of being paid for by Big Oil.
Disregarding GM-Hath-Come theories as preposterous isn't a wise move, but blind acceptance of what the media tells you
Re:The way things are going (Score:5, Insightful)
The global cooling issue was a 1 time tabloid issue. It was never in the science world other than 1 article. Only idiots point to that.
In the 80's, it was reagan trying to roll back the environmental changes (interestingly, the majority of the environmental laws esp EPA was from the pubs). It was the beginning of the ozone issue.
In the 90's, it was solving the Ozone issue. And just all the other ones was a problem. Fortunately, it is being saved because the freon was stopped. But we still have a hole in the south pole, that is slowly receding.
And since the 90's, global warming has been an issue. Back in the mid 90's, the neo-cons said that the earth is not warming. Now they say that man can not be behind the warming.
Do not buy it. Just quit polluting and forcing your shit on me and mine.
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The global cooling issue was a 1 time tabloid issue. It was never in the science world other than 1 article. Only idiots point to that.
My middle school science text in the early 80s presented both global cooling igloo effect and global warming. I guess they were covering their bets...
I really don't think global cooling was a 1 time tabloid issue. Looking at the always reliable wikipedia, looks like more than a single 1970s article...
http://en.wikipedia.org/wiki/Global_cooling [wikipedia.org]
So I am a skeptic. Stick with some theory for more than a couple of decades and I will buy in.
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Is Newsweek [denisdutton.com] a tabloid? How about Time Magazine? [businessandmedia.org] How about the NY Times [newsbusters.org]?
Actually, yes. All three are "town-crier" style publications, focused mostly on reporting what other people in the world say and do. None of them are a scientific journal.
The pollution from my four-banger car is not causing people in underdeveloped countries to starve to death. Over reactions from GW Doomsday predictions are.
The $120 a barrel crude oil has little if anything to do with present-day reactions to Global Warming. And that's what's causing the widest and sharpest increase in the cost of food, not the redeployment of farmland to create biofuel.
And that's ignoring that the loudest reactions to Global Warming have never been ethanol, but conserva
Re:The way things are going (Score:5, Insightful)
I presume that you love America? And perhaps by extension that you love our national symbol, the bald eagle? Well the only reason you can see them in the wild today is because of the DDT ban. They are one of the few species to ever come back after being placed on the endangered species list, and it's directly due to environmental action. So I'd hope you'd show a little gratitude.
I've heard convincing arguments that an outright ban on DDT went too far, and allowing small-scale controlled usage would have been beneficial. However the large scale cause-and-effect of spewing tremendous amounts of DDT everywhere -> bald eagle populations dropping, and banning DDT -> bald eagle populations recovering is indisputable. We know it was the DDT; we could measure it in the corpses of their prematurely dead young.
Other than that... Global Cooling was not actually a mainstream theory. Pollution/Smog was a serious problem, ask anyone who lived in L.A. in the 80s and now compared to now thanks to their emissions regulations. The ban of CFCs has had a demonstrably positive effect on the condition of the ozone layer.
So you're basing your decision to not believe in Global Warming based on a series of things which mostly turned out to be completely true?
Good job!
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The DDT ban was one of the most successful examples of environmental policy in our history.
I presume that you love America? And perhaps by extension that you love our national symbol, the bald eagle? Well the only reason you can see them in the wild today is because of the DDT ban. They are one of the few species to ever come back after being placed on the endangered species list, and it's directly due to environmental action. So I'd hope you'd show a little gratitude.
The worldwide DDT ban has caused the deaths of millions worldwide. Even if DDT were to make the bald eagle extinct, which is highly doubtful, the lives of millions of men, women, and children is more important to me.
Other than that... Global Cooling was not actually a mainstream theory. Pollution/Smog was a serious problem, ask anyone who lived in L.A. in the 80s and now compared to now thanks to their emissions regulations. The ban of CFCs has had a demonstrably positive effect on the condition of the ozone layer.
The Global Cooling theory was actually fairly accurate. It just came at the end of a cold spell. But much like the GW theories of today, people look at a graph and see it going in a particular direction and draw a straight line in that same direction to predict the future. Today, it's call
Re:The way things are going (Score:5, Informative)
The global outright ban was an overreaction, but we were just spraying the stuff willy nilly and it was spreading throughout the environment. The stuff is carcinogenic. In the US, where a person is more likely to die of cancer than malaria, it doesn't make sense to use it.
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Damn those Cylons (Score:5, Funny)
The concept of races (Score:5, Interesting)
I look forward to the day when people stop saying "I'm X race" and instead say "I carry the genetic markers for A, B, and C." Well, perhaps it's unlikely, but an ex-biologist can dream, can't he?
Re:The concept of races (Score:5, Insightful)
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Re:The concept of races (Score:5, Insightful)
Conversation with government clerk.... (Score:5, Funny)
Clerk: Full name please?
Me: Allen Dale Douglas
Clerk: Date of Birth?
Me: June 12th, 1981
Clerk: Place of birth?
Me: In a hospital.
Clerk: Which city and state, Einstein?
Me: Oh, Dallas TX, Presbyterian Hospital
Clerk: Sex?
Me: Sometimes.
Clerk: (rolls eyes ) Sex?
Me: Male.
Clerk: Race?
Me: Human.
Clerk: No, I mean what ethnicity are you?
Me: Texan.
Clerk: (rolls eyes again, tosses pencil up into the air and walks away)
Re:The concept of races (Score:5, Funny)
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Re:The concept of races (Score:5, Informative)
The rest of humanity spread out across the globe, the Genography project has some nice maps of how the genetic markers show humanity to have moved. They do make one error when it comes to Europe. Europe was settled at least twice - once by a long-headed hunter-gatherer people and then later by a rounder-headed farming people. The long-headed people are the ones who developed lactose tolerence and anyone who can digest cheese or milk in any quantity is descended from the long-heads. In order for that to make sense, the long-heads must have migrated with cattle or goats, much as many nomadic tribes do today. The Iron age "Ice Man" (central Europeans give them such boring names - at least Britain's bogman was called Pete Marsh) was, if I remember the description correctly, one of the round-headed people. He was also left-handed, but that probably doesn't signify anything of interest. He was either a trader or a trapper and there can't have been many tools in either trade that were designed with a specific hand in mind.
Re:The concept of races (Score:5, Insightful)
Also, keep in mind that the genetic evidence is just one line of evidence, and that's it's difficult to interpret. If their conclusions are correct, then other lines of evidence should corroborate their story. In particular, if humans nearly went extinct 70,000 years ago, then shouldn't we expect to see that in the archeological evidence, with stone tools becoming less common for a period?
Re:The concept of races (Score:5, Interesting)
This newer claim must be treated with caution, because it involves humans that have spread out (less likely to find remains, less likely the humans would have been affected catastrophically) and it's much harder to calculate numbers, because it's much harder to determine what would have been available to whom and what level of trade would have existed when levels of critical resources differed between human-inhabited areas.
DNA is also a dangerous thing to go by. We know there was a mitochondrial Eve, and we know a date but not whether it was the date of the event horizon (the point at which all surviving humans were descendents of Eve, within a timeframe in which differences in mtDNA would not yet be significant in the only regions we have really mapped for such purposes) or the point of singularity itself (when Eve lived). We also don't know why homogenious mtDNA occured - unless it conveyed such dramatic advantage as to be always selected (mtDNA handles energy conversion in cells), there's nothing that makes it obviously preferential, so all mtDNA lines should have survived on a completely random distribution.
Only twelve descendent lines exist in the whole of Europe and Asia. Another eight pretty much covers the rest of the planet. I say "only", but remember at least one actual catastrophic drought and this supposed one happened much later than mtDNA Eve. If a uniform, homogenous strain was preferential, we should not be getting such divergence now. It's not a simple picture.
(Also, dating an event by mutations is dangerous, since mutations can revert, not all markers mutate at the same rate, and all kinds of other factors make such calculations extremely messy. On the DNA mailing list, people often point out that the margins of error on last common ancestor calculations are so broad as to make the calculation worthless.)
It's a Douglas Adams kind of situation: even if we knew for certain, we wouldn't really know what it was we were certain about, or indeed that we were even certain about it.
So...the Neanderthals could have wiped us out (Score:4, Interesting)
Re:So...the Neanderthals could have wiped us out (Score:5, Insightful)
The problem with these studies is that there isn't any DNA record of the humans that didn't make it. The only evidence we could hope to find of the humans that have died out is fossilized remains, which are few and far between.
Re:So...the Neanderthals could have wiped us out (Score:4, Interesting)
Re:So...the Neanderthals could have wiped us out (Score:5, Insightful)
People don't "intermingle", they have children. If the children die, or all the children's children die (or all the children's children's children die, ad inifinitum), then your unique genetic code is erased (except the portion of your genetic code that you shared with other individuals who got it through a different path in the graph).
In fact, it's slightly more complicated than that because when you have children you only pass on (an essentially random) half of your genetic code. You might have the dumb luck that none of the unique mutations in your code gets passed on to your children because they never land in your children's 50%. You therefore might have had a unique mutation that cannot ever be detected in the future genetic record because by chance you passed on the "common" portion of your DNA code and not the unique mutation.
So yes, branches of this DAG can and do die off. Nothing "points" to them, so they die. In fact, this is the very mechanism by which natural selection and speciation occurs.
The arguments they use in the article are statistical and even though they account for many factors, in the end they can only work on information available from surviving DNA.
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Of course what I'm really saying is that in all probability we would have struck first, catching the Neanderthals by surprise. And without any concept of a
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Re:So...the Neanderthals could have wiped us out (Score:5, Insightful)
What a difference 70,000 years makes!
Supervolcanic event at Lake Toba, on Sumatra (Score:3, Interesting)
one arkload (Score:5, Funny)
Just saying...
If by 70,000 years ago (Score:5, Funny)
Seems a bit shaky to me (Score:5, Interesting)
It stands to reason that the tests on mitochondrial DNA of a group in Africa is only useful if you assume everyone left Africa sometime after 60,000 years ago.
Given there are numerous sites in Australia that claim to have artefacts stretching back at least that far (and possibly 176,000 years ago) it is very likely there were pockets of humans in other parts of the world much earlier than 60,000 years.
This research actually only shows that there is evidence of a population crash in Africa. Not that homo sapiens across the world had a population crash.
70,000 is co-incidental with another event... (Score:5, Interesting)
Across the world the last eruption of a super volcano was the Toba volcano in Indonesia. This erupted around 75,000 years ago spewing out tremendous quantities of rock and ash and is thought to have reduced global temperatures by up to 21 degrees centigrade.
Where can I get more information about this? (Score:3)
Does intelligence have survival value? (Score:4, Insightful)
Are we going to find life on other planets but discover that high intelligence is rare?
CNN article is a complete mischaracterization (Score:5, Informative)
http://www.ajhg.org/AJHG/abstract/S0002-9297(08)00255-3 [ajhg.org]
The actual study contrasts two complex hypotheses on early human populations in Africa. The major points are:
1. (Presented as the current consensus). Early humans lived in a one population in eastern or southern Africa. Around 90,000 years ago, this population splits. One of the daughter groups is the primary source of the Khoisan (a South African ethnic group with many "early" maternal lineages). The other is the source of the out-of-Africa migration 60-70,000 years ago. After the out-of-Africans leave, there is renewed migration between the two African groups.
2. (The new hypothesis proposed in this paper). Early humans split into two largely separate African groups starting around 150,000 years ago. Again, one of these is the primary source of the Khoisan and the other is the source of the out-of-Africans. Again, there is renewed migration between these groups after the out-of-Africans leave. (Also, this second hypothesis requires some limited migration from the Khoisan ancestors to the other group around 90,000 years ago to make the patterning of genetic variation work out).
The data which these hypotheses are trying to account for - in part - is that there is significantly more diversity in maternal lineages in Africa than out. In fact, all of the maternal lineages outside of Africa are a subset of *one* of the African lineages. So any explanation of this has to somehow derive a non-diverse population (the rest of the world) from a very diverse source population (Africans). Both of these hypotheses try to do this in fundamentally the same way (population splits in Africa), but the new paper argues that in order for the pattern to be as it is, a longer time of separation of populations in Africa is required.
There are no new population size estimates in the paper whatsoever. There is no discussion (other than an off-hand mention or two) of population sizes in the paper.
The CNN/Associated Press article is sensationalistic at best and misleading at worst.
And as an aside, whatever the "separate study by researchers at Stanford University" is - I couldn't figure out which one it was in the reference list - it is certainly about *effective* population size, which is _very_ different than census population size. For instance, the long-term effective population size of the entire human species is generally estimated to be around 10,000 *effective* individuals.
They don't really know what forced them apart (Score:3, Interesting)
If you don't like Genesis, there is a Hungarian Myth that tells the story of the Huns (one of the language groups) beginning with the tower of Babel (the Genesis story above). The best telling, IMO, is The White Stag [amazon.com], by Kate Seredy.
Mt Toba explosion 70,000 years ago... (Score:4, Interesting)
The Mt Toba explosion is believed to have been so huge (vastly larger than Krakatoa) that it plunged the whole earth into a "nuclear winter"-like period (just look up "Mount Toba" or "Toba catastrophe theory" in Wikipedia).
In any event, we already knew that there was a genetic bottleneck about 70,000 years ago, as those Wikipedia articles indicate. What's the real genetics news here?
Mitochondrial DNA (Score:5, Insightful)
Re: (Score:3, Funny)
What will make us nearly extinct the next time will be a lack of breeding due to an overuse of the Internet in the general population.
Re:Are we SO sure? (Score:5, Insightful)
I think that this is actually plausible. Things to mull over that could make this an interesting topic:
1) What evidence, 70000 years later, would decisively display the difference between a flood and a drought?
2) Could the Noah story be an allegory written after the fact to describe this event, with only the details mixed up? If so, what does that tell us about this story?
3) What remnants of an Ark would one expect to find 70000, or even 5000 years after the fact? Conversely, what evidence could be shown that would decisively PROVE OR DISPROVE that the event happened? And I'm talking about scientific evidence here. Not anecdotal faith-based cruft. Not even science-based faith-based cruft, if you please...
Love these topics. Go people, go!!
Re: (Score:3, Insightful)
Re:Are we SO sure? (Score:5, Funny)
Re: (Score:3, Funny)
actually the whole almost dieing out thing just reeks of a total lack of intelligent design
Might have been just a bit of tweaking. You go for bipedalism and bigger brain with high hopes of something great emerging, and all you get is bipedal apes with big brains shrieking at each other and throwing feces. So you wipe out all but the brightest of them hoping to push the brainy thing, and lo, complex behaviours emerge shortly after, like art, and religion, and stuff, which seems like progress until you realize that now you have bipedal, big brained apes with art and religion and state level civ
Re: (Score:3, Interesting)
The same book where we may read about the (almost) extinction of humanity by water, informs us that the next time God will use fire!
2Peter 3:6
According to that book, Universe was stretched out (Big Bang) at the Beg
Population bottleneck, and his name is Noah (Score:3, Insightful)
Re:Old News (Score:5, Informative)
The end of this article [nationalgeographic.com] seems to cover that. Basically, this is a completely independent set of data (taken from the Genographic Project) that further confirms a theory that's been kicking around for a while.
Re:The flood! (Score:5, Interesting)
Re:The flood! (Score:4, Informative)
You too can do basic research in just minutes!