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Biotech Science

Have Humans Come Close To Extinction? 206

Posted by timothy from the closer-than-today-that-is dept.
waytoomuchcoffee writes "According to a new study, our virtually identical DNA indicates humans were close to extinction about 70,000 years ago. Another take on the same study tells how being lactose intolerant in adulthood was normal, and being able to digest lactose became a survival advantage after dairy farming was invented."
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Have Humans Come Close To Extinction? More

Have Humans Come Close To Extinction?

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  • Diversity in a small group (Score:4, Interesting)

    by Inexile2002 ( 540368 ) on Monday June 09, 2003 @10:09PM (#6157611) Homepage Journal
    Unlike our close genetic relatives - chimps - all humans have virtually identical DNA. In fact, one group of chimps can have more genetic diversity than all of the six billion humans alive today.
    Something about that struck me. If the natural state of affairs is for a wide genetic diversity even in a small group - such as the chimps, then why wasn't there a similar diversity in the 2000 people who went on to sire the rest of us.

    Think about it. A chimp troop can consist of up to 60-70 chimps for a big troop. Assume all but around 30 troops are killed off leaving around 2000 chimps. If a single troop of those chimps could have more genetic diversity than all of humanity - ie. more than the 2000 people who sired us then 2000 chimps would have around 30 times more diversity. (Or more than that depending on how much more diversity in a chimp troop than there is in humanity.)

    So, either humanity dwindled down by chance to 2000 people who happened to have little genetic diversity, or there was some common genetic trait that selected for those specific people. Or something. But then who knows... maybe chimps are just naturally genetically diverse and we're not... or maybe I just missed something that the writer thought was too technical for the article.

    Still, the numbers bothered me.

    • Additional Comments on reflection (Score:5, Interesting)

      by Inexile2002 ( 540368 ) on Monday June 09, 2003 @10:20PM (#6157688) Homepage Journal
      Thinking about that, I didn't make myself clear on something. What I was trying to say was that if a single troop of 60 to 70 chimps can have X diversity, shouldn't a group of 60 to 70 humans - a close relative of the chimp - also have X diversity. What struck me about the article is that their implication is that those 2000 people they say sired us had less diversity than 60 to 70 chimps.

      Makes you wonder if it has something to do with human females being fertile year round. If I recall, chimp females are not. Because chimps can only mate at certain times, there is less oppurtunity for one male to sire all the children in a troop. In a human harem type social group, this could be easily accomplished which would cut down the genetic diversity considerably. Do this for a couple of generations and you might end up with a population with a depressed gene pool. Anyway, just arm chair theorizing off the top of my head. (Gotta use that anth degree for something.)

      • Re:Additional Comments on reflection (Score:4, Interesting)

        by zenyu ( 248067 ) on Monday June 09, 2003 @10:37PM (#6157785)
        Makes you wonder if it has something to do with human females being fertile year round. If I recall, chimp females are not. Because chimps can only mate at certain times, there is less oppurtunity for one male to sire all the children in a troop.

        I think the article isn't specific enough to judge whether sexual practices have anything to do with it. Pygmy Chimps (Bonobos) always look like they are in heat and like humans who never look like they are fertive have sex with anything that moves. But most chimps have a stratified society where only one male at a time has sex with all the females. The females do cheat on him, but I don't know how common those children are. Even the Amish have plenty of out of 'falsely fathered' children so I don't think humans should be less diverse due to sexual exclusivity.

        More likely there where several rounds of near human extinction and just the latest one was sometime in the last 100,000 years. We also have this nasty habit as a species to eat those that aren't 100% human...perhaps our competitors had similar tastes ;) (JK! -- no homo erectus, homo neanderthalis hate mail pls)

        • Re:Additional Comments on reflection (Score:4, Insightful)

          by Inexile2002 ( 540368 ) on Monday June 09, 2003 @11:06PM (#6157939) Homepage Journal
          You're right of course, the article is too vague. It was really just musing onto the keyboard. I'm not advancing a theory or anything. There could be many explanations for the low genetic diversity including subsequent death of lineages, genetic advantages of a sub-group (the whole scikle cell anemia - malaria connection) etc. Also, there was some genetic bottlenecking, where an even smaller group populates most of the world and the remainder stays behind in Africa.

          I remember reading that if you took any world wide sample non-Africans - ANY sample no matter how diverse - and an equal number of randomly sampled Africans from the same villiage, you'd find more genetic diversity in the African villiage. The argument being that there was some genetic bottneck on the way out of Africa and only a tiny minority of the gene pool actually left.

          Oh, and if us Neaderthals were still cheesed about that whole cannibalism thing, we'd let you know. We're over it. We ate you guys too. It's all good.
        • Wear uranium underwear!

      • Not clear (Score:5, Insightful)

        by GCP ( 122438 ) on Monday June 09, 2003 @11:07PM (#6157950)
        The thing that should have bothered you is the utter ambiguity of such a claim. This is just one of those "newspaper statistics" that sound as though they mean something but don't.

        What is the diversity of all humans? Is it more than the diversity between the two most different humans? What is the means of quantifying difference? Is there some standard, or are there lots of standards, or are there just countless ways, each of which yields a different answer?

        What about the diversity in a group of chimps? Is that a family of chimps, or a small group randomly chosen from all chimps, such as one might find at some zoos?

        I'm just not sure how to interpret the comparison of diversity between a small group (of chimps) and a large group (all humans). Size of group wouldn't have been mentioned, presumably, if it weren't part of the equation. What part?

        Unless you know what it is they really mean, I'm not sure it makes much sense to go looking for deeper meaning.

      • Re:Additional Comments on reflection (Score:4, Interesting)

        by maxume ( 22995 ) on Tuesday June 10, 2003 @12:08AM (#6158258)
        One thing that might be a factor that you don't seem to have mentioned is that most chimps are probably under considerably higher environmental pressure than the average human. The genetic makeup of todays typical human doesn't really have all that much to do with the continuation of his genetic line. It seems like the increased pressure for selection in the chimps would cause them to evolve faster than humans do. I don't really mean evolve in the sense of becoming greater as a species, but in the sense of becoming better suited to a particular environment.

        If two sub groups of chimps each evolved under rather disparate conditions, and then crossbred, it would seem that their genetic diversity would increase. Considering that we as humans don't really evolve to any particlar environment anymore(we move around way to much), and we crossbreed pretty much constantly, perhaps the chimps are just doing a good job of playing survival of the fittest?

        • Re:Additional Comments on reflection (Score:4, Insightful)

          by Madcapjack ( 635982 ) on Tuesday June 10, 2003 @08:10AM (#6159599)
          Since evolution is a two step process: first mutation, then selection, we wouldn't expect selection to increase diversity. mutation is responsible for increasing diversity. selection decreases diversity. diversity might be a selective advantageous property of populations, and in some cases there might evolve (by selection) functions that increase diversity. sexual reproduction is one such thing.
      • Your first post was pretty clear and interesting question.

        A prolonged & extreme selective pressure is a cause of reduced diversity. An obvious candidate must be the last Ice-Age which also fits nicely into the time frame. This issue has recently been covered in a excellent BBC documentary series Walking with Cavemen [bbc.co.uk], which also featured a figure of 2000 females in a significantly reduced human population. I suspect the last programme was based at least partly on this research.

        The programme suggeste

      • Re:Additional Comments on reflection (Score:4, Insightful)

        by JanneM ( 7445 ) on Tuesday June 10, 2003 @09:42AM (#6160224) Homepage
        Well, there are other factors as well. Normally, that troop will outbreed quite a lot with other troops, which will keep it diverse and smother out much of the randomness.

        But if there are only on the order of hundreds of individuals available, small random effects will start to have an impact. Not every individual will reproduce equally effectively, even if they are genetically equally viable - due to accidents, and other random effects, you will tend to get an inverse power-law like distribution with small numbers oif individuals. So, in that troupe of 2k individuals, maybe twenty to fifty of them will in reality be the progenitors of the majority of the offspring - others will have caught a disease, or be infertile, or have their children all die early, or have a falling out with their partner or whatever.

        By the time the population is large enough that individual chance is smothered out, the individuals will in practice all stem from a small subpopulation of those that were available at that earlier time.

    • Re:Diversity in a small group (Score:2, Insightful)

      by Anonymous Coward
      > So, either humanity dwindled down by chance to
      > 2000 people who happened to have little genetic
      > diversity, or there was some common genetic
      > trait that selected for those specific people.
      > Or something. But then who knows... maybe
      > chimps are just naturally genetically diverse
      > and we're not... or maybe I just missed
      > something that the writer thought was too
      > technical for the article.

      Nah, there's no extra explanation needed .. its a well known phenomena, called the 'founder
    • That or they started out different, then screwed like mad until the gene pool wasn't all that drastically different anymore... much like they would have to do to go from 2000 to 4 billion. Just a thought. Makes me wish I was there *sighs*
      • Just look in the Bible. (I'm a secularist myself, but the old testimate is an entertaining folk tale.) How many Son's did Abraham have? You have Lot who had a lot of kids by his daughters. I mean incest, polygamy on a mass scale, all the makings of a really shallow gene pool.

        Then you have Kings from other cultures who would spread their seed wide and far. You see the same behavior in rock stars and sports figures today. How many kids did Jim Morrison sire? How about Wilt Chamberlin? Hell even Ben Franklin

        • That's not exactly a followable story... it doesn't get very far. Adam and Eve had two children, One killed the other then left got married and founded a city. Who did he marry if the only humans in existance were he, his mother, and father?
          • Like I said, an entertaining Folk Tale.

            While you are at it, where did the notion of a Virgin Birth come from. Go back to the Gospel. The only notes (where mentioned) about Jesus' beginnings was that his mother became Pregant our of wedlock. The "Holy Spirit" could have been anything from pathenogesis to Joseph being particularly randy one night. His reaction was shame and embarrasment, recall, not jealosy.

            Also note the Bible refers to Christ being rejected by his brothers and sisters.

            And yes I have re

    • Re:Diversity in a small group (Score:5, Insightful)

      by zaad ( 255863 ) on Tuesday June 10, 2003 @02:35AM (#6158820)
      Something about that struck me. If the natural state of affairs is for a wide genetic diversity even in a small group - such as the chimps, then why wasn't there a similar diversity in the 2000 people who went on to sire the rest of us.

      IANAG(eneticist), but I would say that this is most likely due to a concept known as founder's effect in population genetics. There looks like there's an interesting page curtesy of googlecache [216.239.53.100].

      Think of it in these terms. Whatever your genetic diversity happens to be, if you reduce a population from two million down for two thousand, you're going to lose a lot of diversity. Further, especially that population reduction was due to some selection pressure (may immunity to some disease), you're going to target a very select subset of the population (known as hard selection). So what happens is that you end up with much less genetic diversity than you would have otherwise (diversity takes time to build up).

      In the case of the chimps, if they've not gone through a recent "extinction" scare, and have had a long, long time for their genome to diverge and mutate, even if you just sample a small group of 60 or so chimps, they're going to exhibit much more diversity simply because they've had so much more time for their genome to wander or drift.

      Does that make more sense?
      • And moreover, when that little group discovers something like the hatchet, they suddenly outcompete everything that eats the same food as them, but isn't in the tribe and isn't told the secret. Time and again, one tribe wipes out all the tribes nearby with a new weapon or other new technology, thinning the gene pool.

        In the 1300s, there certainly weren't a billion people of European descent. There were more like 50 million. That's barely thirty generations ago. This sort of thing happened in pre-history a

    • Don't panic! It can all be explained Mr Gorilla (Score:4, Insightful)

      by madmarcel ( 610409 ) on Tuesday June 10, 2003 @04:03AM (#6159065)
      (Without reading the article...)

      I don't know much about genetics but....

      IIRC genetic diversity also indicates how
      old a 'species' is.

      Hence, given the widespread genetic diversity in chimpansees and the low genetic diversity in humans, you can deduce that chimpansees have been around much longer than humans.

      The other explanation could be that a single group of humans were so succesfull at some point in the past that we are all descendants of that group.
      (oops, thats the same as coming close to extinction - just phrased a different way :)

      There are groups of people in the world that are very much genetically distinct from the rest of us. (Eh, Read "The Naked Ape" by whatshisname...)
      ( Isolated pockets of genetic diversity...stuff like that )

      Another explanation could be the life span of chimpansees...anyone know how long they life in the wild? Short lifespan? Females are almost constantly pregnant. Now compare that to humans...long lifespan...relatively low pregnancy rate ( welll...) That could also explain the difference in genetic diversity?
      Phrased another way - for an equivalent period of time there might have simply been more generations of chimpansees compared to generations of humans.

      Could that account for the difference in genetic diversity (as well)?
    • What you are missing, I think, is that diversity reduces in small total populations.

      Chimps, can and do change troops, interbreed with other troops, exist as lone males, etc. If they were reduced to 2000 or so then they would not maintain their current level of genetic diversity as, for example, fewer males would have the opportunity of siring offspring.

      Hence it is not a like-for-like comparison. You are comparing pre-small-pool chimps with post-small-pool humans. Although given the state of the world


    • Unlike our close genetic relatives - chimps - all humans have virtually identical DNA. In fact, one group of chimps can have more genetic diversity than all of the six billion humans alive today.

      Why doesn't such impressive genetic diversity in the chimp world translate to more obvious facial/structural diversity as is seen in the wildly differing appearances of humans?

      To put it another way, if they're so genetically diverse, why do they all look alike? I'm sure Jane Goodall, et al, can tell different troo

    • I teach this data (prior studies) as part of my lecture on Race in Politics (I like to disabuse my students of the notion that race is a useful biological marker or indicator of genetic variance). Here are the answers from my reading of other studies:

      1. Chimps have remained a distinct species filling their ecological niche for far, far longer than homo sapiens. Genetic changes have had more time to accumulate.

      2. The 2000 indidivuals from whom we all descend didn't have kids that continued in isolation

  • What a liability for humans! (Score:5, Funny)

    by 1nv4d3r ( 642775 ) on Monday June 09, 2003 @10:14PM (#6157656)
    So do your part to ensure diversity, and make sweet love with someone genetically different (read: hot) under some power lines near a microwave running with the door open. "For the sake of the species" never made a better pick-up line.

    (Just don't give her your name--she might expect you to help raise your special freak).

  • Close to Extinction? (Score:4, Interesting)

    by Sunlighter ( 177996 ) on Monday June 09, 2003 @10:25PM (#6157710)

    Arguably, in spite of our numbers, we're close to extinction now.

    Hey, good to know we got out of it last time.

  • More Info & complete paper (Score:5, Informative)

    by MonkeyBoyo ( 630427 ) on Monday June 09, 2003 @10:28PM (#6157731)
    Here is the abstract [uchicago.edu] from the The American Society of Human Genetics article, and here is Stanford's press release [stanford.edu] on the story.

    And are the web pages of Marcus W. Feldman [stanford.edu] and Noah Rosenberg [usc.edu] From Rosenberg's research page [usc.edu], here is access to a PDF of the journal article [usc.edu].

  • advantages (Score:5, Funny)

    by larry bagina ( 561269 ) on Monday June 09, 2003 @10:39PM (#6157796) Journal
    being able to digest lactose became a survival advantage after dairy farming was invented."

    But being lactose intolerant was an advantage once fart-lighting was invented.

  • invention of dairy farming (Score:5, Funny)

    by alonsoac ( 180192 ) * on Monday June 09, 2003 @11:08PM (#6157951) Homepage Journal
    being able to digest lactose became a survival advantage after dairy farming was invented.

    So at some point some humans said:

    "Hey lets invent dairy farming!"
    "Hmm, but we're all lactose intolerant..."
    "What the heck, if we take this crap every day we'll eventually mutate and some generations down they will be thanking us."

    Nice long-term thinking there, thanks!
  • Within the next 50 years, about half of us will be dead!

  • Alternative Interpretation (Score:4, Insightful)

    by Iainuki ( 537456 ) on Monday June 09, 2003 @11:53PM (#6158196)
    I'm not sure I buy the article's argument that "humans" came close to extinction. I think another possibility is that what they're looking at is a speciation event: that's the point that homo sapiens sapiens branched off from immediate predecessors. If that group had been killed, we wouldn't be here, but I'm not sure the homo genus would have died off.
    • The gene study only suggests that we all have common ancestors from a small group (perhaps only few thousand) which was pretty geneticaly homogennous and lived maybe 70 000 years ago.

      There are many possible scenarios: one possibility is that tribes originating from an isolated small group of individuals got lucky for some random reason, while the other prehistoric people did not make it to the current gene pool. But it does not necesserily follow that everybody other must have died at once, exactly around

  • Dogs (Score:3, Interesting)

    by Beryllium Sphere(tm) ( 193358 ) on Tuesday June 10, 2003 @12:40AM (#6158397) Journal
    Robert K. Wayne of UCLA has estimated that we may have domesticated wolves as much as 100,000 years ago.

    What if it was 70,00 years ago? Did our partnership with dogs save our species?

    • Re:Dogs (Score:3, Funny)

      by Scaba ( 183684 )

      I think it is, in fact, the wolves who domesticated us; well, domesticated our chimpanzee ancestors. Through careful breeding they were able to create an entirely new species which they called "Aaaaooooooooooooooo!!!!!" (which is also their name for everything else). But they quickly became bored with us, sniffed one another's asses, and then chased down a gazelle for an early supper.

    • (In the prehistort past...)

      Lassi: Woof Woof

      Timmy: Ug, what Lassie? Mass extinction coming.

      Lassi: Woof Woof

      Timmy: Ug, If me survive me eat Lobster and mate many times.

      Lassi: Ruff, Woof, Woof

      Timmy: Oh, nevermind, Oggg being chased by tiger. Me gettem beer and watchum show.

    • Cats domesticated us.

      Think about it. We build structures and pile food in there to draw the mice for them to eat!

      We have all seen cat owners. Every house has a little shrine for the kitty cat. They reserve the best seats in the house and the better windows for the cat. And all for what? So the cat can ignore our existance except when it needs to be petted, or just mess with our minds.

  • Lactose intolerace (Score:5, Informative)

    by Nice2Cats ( 557310 ) on Tuesday June 10, 2003 @01:37AM (#6158635)
    The ability to digest milk after puberty is still only widespread in Caucasians and some parts of Africa, as I happen to know because I am one of the Caucasians who is not a mutant and had to give up my ice cream orgies with puberty (puberty did have its compensations). This is why lactase pills (which contain the emzyme required to break down the milk sugar lactose into glucose and (I believe) galactose) are selling like mad.

    The BBC had one of their unevitably brilliant documentations about the rise of mankind a few weeks again on German television where they pointed out that humanity must have been really, really close to the gutter before it exploded. Then this big, black rectangle came and showed them how to use the thigh bone of a pig to kill...oh, never mind...

    • Yeah, it's interesting as I'm one of the few adult Asians I know who *isn't* lactose intolerant.

      Ice cream, milk, cheese... I love them all.
    • I'm really curious about why digesting milk is such a big deal? Until the 20th century we had absolutely no way of storing milk long enough to consume it.

      Before that it was either right out of the cow, or in the form of cheese where the lactose is nicely broken down by fermentation.

      Like all points, there are exceptions. I do recall one culture in Africa subsists on a food product made by mixing the blood of the cattle with the milk. But they are nomads who maintain too small a cattle population to affor

      • And on the subject of the Masai, cattle are sacred to them, a gift from the god(s), and they generally don't kill them. In fact, they gave the USA fourteen cows in the wake of 9/11- a collective donation from many tribes, and (for them) a priceless gift. Our ambassador refused to accept it.

        I don't know what happened to the cows. I do know that the Masai do, indeed, drink blood and milk mixtures. Having lived with a Jewish roommate, i can remember the look of horror on her face as she tried to interpret it into kosher food concepts.

        Lactose Intolerance is not the only intolerance out there... Gluten intolerance hits 7% of the population (including me.) More women than men, mostly northern european descent. Me with my scottish pale skin and my german grey eyes, it's got my grandmum, my mum, my sister, and me. Skipped both brothers.

        Part of my point being - there are genetic variations that are gender specific, there are genetic variations that are region-specific, and there are genetic variations that we're only just discovering. Another part of my point being- Lactose intolerance is unbelievably common. And i miss ice cream and milk. Lactase tablets aren't enough for a lot of people out there, that's how severe we're talking... I think maybe there are a number of changes that happened regionally, and now we're seeing the results as cultures blend. My dentist talked about it all the time, how asian teeth and african teeth and european teeth are similar but jawlines differ, and when you get different genes kicking in for jawbone and teeth it sometimes leads to really good combinations and sometimes leads to surgical correction so that the kid can chew. He said this in a completely nonracist way; he thought it was a great idea to blend genetic and cultural groups together, so he was more than happy to help correct the results of problem combinations, because they could usually be helped and their appearance meant that new combinations were always being created.

        Oh, and about the Masai. Don't mess with a people who kill lions by hand. These are the people from the movie the ghost and the darkness- flushing out lions by shouting and beating the brush...

        • Thank you, it was the Masai I was thinking about. I just was too lazy to google around and find it. I've got a mind that remembers really off the wall facts, and can call them up on demand. Details... well, they don't seem to store quite as well.

          For my part, I react rather violently to a protein generated by dust mites, and my immune system is not too fond of mold and mildew either. Wherever my ancestors came from, they must not have kept a lot of food in the fridge, and if the stayed indoors must have ke

    • how being lactose intolerant in adulthood was normal, and being able to digest lactose became a survival advantage after dairy farming was invented.

      Preceding the domestication of cattle; for lactose intolerant to arrise, it must have offered some survival advantage.

      • Re:Lactose intolerace (Score:4, Funny)

        by arkane1234 ( 457605 ) on Tuesday June 10, 2003 @11:24AM (#6161211) Journal
        I'm just trying to imagine how milk was harvested before the domestication of cattle...

        I'm picturing a mass army of hunters, with painted bodies to blend in to the environment, silently stalking the herd of cows. Suddenly, a violent explosion of activity occurs, and thousands of hunters bolt towards the herd with bucket in hand, tackling the slower cows and draining the milk from their teets.

        That, my friend, is Darwin in action =)

        • LOL. Though I was actually thinking more along the lines of "souring the mothers breast milk" allowing the mother to suckle another infant.
      • "Preceding the domestication of cattle; for lactose intolerant to arrise, it must have offered some survival advantage."

        Makes sense. If mother's milk is inedible to all but the infant, its a lot more likely the infant will get fed when the parents are hungry.

    • Milk is not very common or popular in China, and the government there has been making a big push to get the people drinking it for health reasons. But they also had to set up a special hotline to handle all the cases of lactose intolerant people drinking it for the first time. And that'd be most of them.

      http://www.fb.com/issues/analysis/China_Briefing_I ssue19.pdf [fb.com]

      I read the original Wall Street Journal article referenced, but don't have reg at wsj.com so can't link to it. It was quite interesting.

  • Noah's ark (Score:4, Interesting)

    by DJ Rubbie ( 621940 ) on Tuesday June 10, 2003 @02:15AM (#6158761) Homepage Journal
    Could the biblical story of Noah's ark explain this, as a worldwide flood leaving only a single family of eight alive will achieve this effect of everyone having similar genes.

    Before you mod me down into oblivion for sounding like a self-righteous Creationist, do note that other cultures have references to a catastrophical flood (such as the Chinese, apparently the character for ship is that story).

    • Could the biblical story of Noah's ark explain this, as a worldwide flood leaving only a single family of eight alive will achieve this effect of everyone having similar genes.

      You'd want to pick your eight very carefully, and only five of them would count anyway (unless Shem, Ham and Japheth were adopted sons). There are ancient rumours that Shem looked Caucasian, Ham was black (weird discussion here [aaronc.com]) and Japheth was basically Asian, I don't know how much credence to give them.

      I'd be interested in seei

    • No.

      Because.

      Because.

      Oh all right, because...

      1) The Noah story isn't set that long ago. According to the ages listed in the pentateuch, that only happened about five thousand years ago.

      2) All the other animals would also have small diversities, unless it was a special wacky kind of flood that only drowned humans.

      J.

    • Re:Noah's ark (Score:3, Interesting)

      by MonkeyDluffy ( 577002 )
      No.

      There is no evidence whatsoever that there was a worldwide flood - and a disaster of that magnitude would leave lots of evidence. And nobody told the Egyptians and Chinese about it - their civilizations were going strong before, during, and after when the flood supposedly occurred.

      Many cultures have flood stories, because towns are usually located near good water supplies such as lakes and rivers. Which flood on occasion.

      -MDL

    • One other point:

      Ever population has a magic number that determine the minimum number of individuals required to maintain its existance. For birds this number is about 4,000. We witnessed one population recently dip below the magic number and cease to exist: the Carrier Pidgeon. There were some pretty heroic attempts on the part of humans to get the population back on its feet, but all for naught.

      Giving the benefit of the doubt that the bible simply didn't count women, you have 9 breeding pairs. (Noah, h

      • > Giving the benefit of the doubt that the bible simply didn't count women, you have 9 breeding pairs. (Noah, his wife, 8 sons, 8 wives.)

        Actually, the standard version of the story says 3 sons and 3 wives; thus only three breeding pairs. The story in Genesis clearly states that the three sons repopulated the whole earth, so Noah and his wife cannot be counted as a fourth breeding pair.

        And of course you get a genetic bottleneck of a mere 5 people (Noah, Mrs. Noah, and the three daughters in law) unle

    • Gilgamesh [grtbooks.com].

      Every civilization that can trace its culture back to Mesopotamia has its own version of the epic.

    • Re: Noah's ark (Score:5, Insightful)

      by Black Parrot ( 19622 ) on Tuesday June 10, 2003 @10:06AM (#6160433)


      > Could the biblical story of Noah's ark explain this, as a worldwide flood leaving only a single family of eight alive will achieve this effect of everyone having similar genes.

      No. As others have already pointed out, (a) the biblical flood supposedly happened 4000-5000 years ago, not 70,000 years ago, and (b) geology soundly refutes any and all claims of a global flood (this being realized by the parsons who invented geology, already by 1820), and (c) all animals would also have to have genetic bottlenecks at the same time (or more recent, due to other causes), and (d) there are a very large number of additional problems with the flood yarn, which we can go into if you wish.

      Of course, you could always sweep everything under the rug by claiming that God patched everything up with miracles afterward, to make it look like the flood never happened. But theology is no more capable of investigating such bizarre claims than science is.

      > Before you mod me down into oblivion for sounding like a self-righteous Creationist, do note that other cultures have references to a catastrophical flood

      And lots of cultures have references to multiple gods. Do you put the same weight on those traditions, or do you just pick the ones that you think supports your own position?

      > (such as the Chinese, apparently the character for ship is that story).

      I think that particular claim is that the character is the composition of the characters for "8" and "mouth". Extraordinarily weak evidence for a flood, even if the claim about the symbols is true. Basically someone has noticed that out of all the writing systems in the world they can find one symbol that has a very weak association with one story in their favorite mythology. This is nothing more than a posteriori data scumming.[*] Given the amount of data they have to work with, the only surprise is that they haven't found a better match with the target mythology.

      [*] I use the roguelike term "scumming", since the obvious "data mining" has a very different connotation.

      • The actual article (not the headline) said sometime within the last 100,000 years, not 70,000 years. The 70,000 year figure was given for the theorized split between hunters and gatherers.

        Also I see people quoting as fact that animals do not have a similar genetic bottleneck. Where are you getting this information? When this story was posted on Slashdot sometime last year, I looked for similar research on animals and could not find any.

        The story I read last year was much more detailed in the methodology u

        • And I'd still like to see the evidence that "animals" do not show any signs of a recent bottleneck, since everyone seems to be generalizing "animals" from the briefly mentioned (and not explicitly studied) chimps.

          Well, if you believe that animals show signs of having a recent genetic bottleneck, then the onus of proof rests with you. Not the other way around.

          JP

  • Perhaps humans haven't always lived here. Think about it, most cultures have an Atlantis-like legend, and a Flood/Migration legend.

    Could it be possible that we are the decendents from a crashed spacecraft? Maybe I played Homeworld too often, but doesn't it seem funny that we are the only primates that can:

    • Swim
    • Choke to death on food (Apes and monkeys can breathe and drink at the same time.)
    • Lose our Virginity.
    • Cry

    (A great site that goes into more detail is: Here [synearth.net].)

    At times we have more anatomically i

    • First; Sorry some idiot modded you flamebait because he thought your a kook.

      Second; The features you mention are (I think) quite well explained be Dessmond Morris's 'Aquatic Ape' hypothesis. This says that modern humans are descended from a bunch'o'monkeys that were forced out from the trees/savahna of Africa and found a niche in a reef that existed off the east coast of Africa much like the great barrier reef. I'm not sure about the virginity thing, but the others fit well. It also explains our webbed han

      • Second; The features you mention are (I think) quite well explained be Dessmond Morris's 'Aquatic Ape' hypothesis.

        Actually it was Alister Hardy who first coined the hypothesis. Desmond Morris mentions it in passing in 'The Naked Ape' and it was picked up by Elaine Morgan as an alternative to what she called 'The Mighty Hunter' narrative of human origins in her 1972 pop feminism book 'The Descent Of Woman'. It is Morgan who is the published writer most identified with Aquatic Ape Hypothesis.

        Pro/anti flamef

      • Now you have to ask yourself: how?

        I realize that all of these traits are probably dormant in all mammals, and were simply re-expressed in humans through mutation. The enlarged forehead of humans is actually a common feature of infant apes, our forehead simply doesn't receed during maturity. (Though you wouldn't know it looking at the behavior of some people.)

        But there is a big problem. We somehow successfully mutated several major features in our Genome in the blink of an eye. To boot, we did it with a

    • The problem with this is the similarity of the human method of design, the commonality of DNA, etc. Evolutionists use this as an argument of common ancestor, creationists use it as an argument of common designer. Either way, it eliminates the extra-terrestrial option, UNLESS the aliens too originated from earth (or all life on earth from them), but diverged at some point then rejoined.

    • Swimming (Score:3, Insightful)

      by TamMan2000 ( 578899 )
      In 1959 Koshima macaque monkeys learned to swim, ever since then the entire group can swim...

      Also in American colonial times the only human swimmers were witches...

      The other arguments are interesting, but the swimming one is weak.
    • For a possible (rather reasonable) explanation, read "The descent of woman" by Elaine Morgan. She theorizes that human beings are part acuatic, that part of our evolution happened at sea, or rather at the coast making extensive use of the sea. That explains the biped position (to walk into sea as far as possible), the hairlessness (you drop hair as a thermo insulator and get fat instead if you know what's good for you, when you are at sea), the big nose with downward-pointing holes, the crying (eliminates

  • BBC's writer clearly didn't do his homework (Score:5, Informative)

    by zaad ( 255863 ) on Tuesday June 10, 2003 @02:45AM (#6158854)
    It's shocking how much better the San Francisco Chronicle article [sfgate.com] is to the BBC article [bbc.co.uk].

    Clearly both writers had the same source [usc.edu] to work with, but the sfgate article was much more researched, thought-out, and nicely tied together. Even when I had only read the BBC article, I was shocked at how poorly structured the article was.

    If you're only going to read one of the two, read the sfgate piece.
  • ...we have kept trying.

  • Genetic Lactose Intolerance (Score:5, Informative)

    by MonkeyBoyo ( 630427 ) on Tuesday June 10, 2003 @03:52AM (#6159034)
    What triggered the writeup was the The American Society of Human Genetics journal article [uchicago.edu]. For some reason the SFGate link [sfgate.com] also discussed the genetics of lactose intolerance, and here I will give some references and discuss how this is relevant to early human evolution and perhaps bottlenecks.

    Genetic lactose intolerance (= hypolactasia = non-production of lactase enzymes past weaning) has a hereditary component (Sahi 1994) [nih.gov]
    It is assumed that thousands of years ago all people had hypolactasia in the same way as most mammals do today. At that time in cultures where milk consumption was started after childhood, lactase persistence had a selective advantage. Those people with lactase persistence were healthier and had more children than people with hypolactasia, and the frequency of the lactase persistence gene started to increase.
    The Cambridge World History of Food (2000) [cup.org] has a good article [cup.org] on the science and geography of lactose intolerance. This problem is not caused by the gene that creates lactase but instead by another gene (LAC*R (lactase restriction)) that kicks in later and ramps down the primary gene. (The other allele LAC*P allows lactase production to persist) However that article says:
    it seems most likely that the European and Arabia-Sahara centers of LAC*P prevalence, and the Uganda-Rwanda center (if it in fact exists), arose independently. Population movement and gene flow can be very extensive and, no doubt, have played a substantial role around the centers. Despite the efforts of some authors to find a common origin in the ancient Middle East, it is simpler to suggest independent origins than to postulate gene flow from the Middle East to Scandinavia and to the interior of East Africa. The problem might be resolved in the future if gene sequencing could show that the LAC*P alleles in Sweden and Saudi Arabia are, in fact, the same or are distinct forms of the gene with a similar function.
    â¦
    Finally, the LAC*P and LAC*R genes are interesting far beyond their biomedical significance. Along with linguistics, archaeology, and physical anthropology, further research on lactase genes and other genetic markers will provide clues to the prehistory of peoples, their migrations and interminglings, and the origins and development of major language families.
    However in 2002 the LAC*P gene was identified and sequenced within a Finnish population [nature.com] and was found to be the same as those in the rest of the world. This means that genetic adaptation for adult milk drinking evolved early and all milk-drinkers have ancestors in some early population in the middle-east or Africa.

    The problem with equating lactose intolerance with genetics is that people will see this as an either/or situation â" either you can eat it or you can't. The fact is that most intolerant people can consume small to medium amounts of lactose with no problem. Major milk problems are more often the result of allergies.

    Eventually there is the issue of culture. Fermented milk products (e.g. yoghurt and cheese) may be easier to digest than raw milk. Do the cheese/yoghurt eaters have a cultural advantage? Or have they disadvantaged other cultures? [google.com]

  • BBC should check it's own archives... (Score:5, Interesting)

    by EvilSuggestions ( 582414 ) on Tuesday June 10, 2003 @04:57AM (#6159214)

    I don't expect the BBC to do an exhaustive search of all the peer review journals every time they do a science story, but they should at least check their own archives to help explain an curious conundrum like this one.

    The date given for the bottleneck, ~70,000 years ago, coincides perfectly with the largest volcanic explosion in the last half million years. One that spewed thousands of times as much ash as produced in the 1980 Mt. St. Helens eruption.

    The explosion of Toba in Indonedia around 74,000 years ago probably caused a greater than 5 degree drop in average global temperature that lasted over 6 years. 5 degrees may not seem like much but that global average may translate to over a 15C drop in the summertime temperatures in the temperate regions and would have devestating effects on many of the plants we relied on for food.

    Point is that most of what I just mentioned (and much more) can be found in a few articles on their own web site:

  • Big Volcanic blast ~70K yrs. ago? (Score:4, Interesting)

    by budalite ( 454527 ) on Tuesday June 10, 2003 @07:52AM (#6159556)
    This "news" is pretty old. There was even a Learning Channel (or Discovery) show a couple of years ago about the idea of "supervolcanoes", one of which could rest beneath Yellowstone [slashdot.org] and one (Toba [nodak.edu]) that, they think, blasted ~70K years ago, causing global average temperatures to drop and nearly causing our species to become extinct. Interesting stuff.

  • Toba (Score:5, Interesting)

    by 4of12 ( 97621 ) on Tuesday June 10, 2003 @09:38AM (#6160187) Homepage Journal

    I'm surprised that article didn't pick up on the theory that the bottleneck in the genetic line about 70K years ago might well have been due to the eruption of the Toba supervolcano [bbc.co.uk] that was regarded as one of the most significant eruptions in the last 2 million years. That kind of climatic change from such an eruption could well be responsible.


    • > I'm surprised that article didn't pick up on the theory that the bottleneck in the genetic line about 70K years ago might well have been due to the eruption of the Toba supervolcano that was regarded as one of the most significant eruptions in the last 2 million years.

      Yeah, this "news" is pretty old. I've heard the exact hypothesis that you suggest scores of times on talk.origins over the past several years.

  • As I remember from high school biology, doesn't only a small percentage of our DNA code for useful information? The reset was just junk that is cut out during protein synthesis (introns? extrons? I forget the terms...) Is this included in the study? Could it be that chimps are also extremely genetically uniform in the areas that matter, but they have more diverse "junk" material than us? Then again, I seem to remember someone saying that the "junk" DNA plays a vital part in evolution? Argh, guess I shouldn
    • they don't mention "junk" DNA, and I couldn't even find the original article (why in the hell wouldn't the BBC reference it?). What is called junk DNA makes up the vast amount of our 3 billion base pairs, but junk DNA is different than intron DNA (and exon), and there is increasing evidence that Junk DNA may actually be very important. As far as diversity, that usually refers to differences within coding DNA, not junk DNA.

  • Goats, not cows (Score:3, Interesting)

    by Tablizer ( 95088 ) on Tuesday June 10, 2003 @01:27PM (#6162482) Journal
    Why didn't they domesticate goats for milk production instead of cows? Goats don't produce lactose in their milk. We can't easily switch now because goat milk tastes too different from cow's milk. We are too used to the taste. Cow milk is kind of like the QWERTY of milk.

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