The first homo sapiens

Discussion in 'Biology & Genetics' started by Jenyar, May 21, 2003.

  1. Jenyar Solar flair Valued Senior Member

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    I just came across an interesting bit of information:

    It took from the beginning of our species until 1804 to reach 1 billion, but it only took 12 years for the world's population to rise from 5 to 6 billion.

    Isn't it mathematically possible to project the population increase backwards and see when the the population count was close to 1? Just for interest's sake, can someone do the maths on this?
     
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  3. Dr Lou Natic Unnecessary Surgeon Registered Senior Member

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    At first I thought this was a really good question, and it still is a good question but the answer is no.
    Reason being the population would have stayed the same low number for a long time because man would have been living like an animal. There would have been a steady population count that balanced around the same number for god knows how long. Only once we got over the hump and started travelling and making civilisations would our numbers have started to increase.
    Perhaps there would be a way to figure out what the human population was while they were hunting and gathering in africa.
    It would have been in the thousands(maybe a hundred thousand or so) for a long time without any changes because people would been dying at the same rate as they were being born.
    There is no way by using this method to figure out the time of the dawn of man.
     
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  5. ElectricFetus Sanity going, going, gone Valued Senior Member

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    Jenyar,

    I think you could but it would not be very accurate. Just get a couple of more coordinates of pop growth and chart them on excel or minitab then fit it to a logarithmic curve, you'll get your answer.
     
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  7. Jenyar Solar flair Valued Senior Member

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    At least it should be interesting to see - as accurate as the data we have would make it - when population started growing exponentially.

    I'm sure I'm not the first person who thought of this, so I'll have a look around first. It's been a while since I've done anything in Excel so I'd like to save myself some embarassment

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    Please let me know if anybody else finds anything...
     
  8. Buckaroo Banzai Mentat Registered Senior Member

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    Estimates from the 90s say that human population couldn't ever have been fewer than 100-200 thousand individuals. This population is/was thought to be necessary to account for the genetic polymorphisms found in living humans. The narrower is the genetic bottleneck, the smaller is the possible future genetic diversity. In the last years, however, there has been this finding or theory that human genetic variation has increased acceleratedly, due to technology (not "high-tech" sort, just primitive technology does it to some degree) possibiliting larger population growth, and buffering of natural selection. I don't know if these estimates were recalculated taking into account these new perspectives.

    Something like it wouldn't lead to an estimate of the "first homo sapiens", however, because it's not like it arose from nowhere, being literally the first. Nearly every speciation (specially in animals like mammals) is at some degree a chronospeciation, that is, a population of a species gradually evolving into a different form over generations. This happens with virtually the entire population leaving offspring and so nearly all individuals of this population being ancestors of the descendant species. There's no such thing as the "first of the new species" being offspring of only two individuals of the "previous" species, and being completely endogamic afterwards (that is, mating only with their "new species" siblings, not back-crossing with other individuals of the "parent" species). In other words, it's "blurry", not a single generation/birth leap.
     
  9. exchemist Valued Senior Member

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    Excellent point. So much for Adam and Eve, eh? Funny how we often subconsciously assume there must have been a "first" pair of human ancestors, rather than an ancestor population. Perhaps it comes from things such as family trees, which of course ignore all the people who "marry in" to the family being described at each generation.
     
  10. Fraggle Rocker Staff Member

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    Not so easily. The population has not been growing at a steady rate. Prehistory and history have been punctuated by events that caused enormous changes in human population dymanics.

    The first was the Agricultural Revolution 12KYA. Until then humans were nomadic hunter-gatherers, chasing their food across the landscape. During a bad year there simply was not enough food so some would die, either by starvation or in a battle with the tribe in the next valley who wanted to encroach on their hunting and gathering territory.

    Population growth was very slow from the emergence of our species around 200KYA until this Paradigm Shift. For the first time ever, there was a food surplus. Death by starvation became rare. Furthermore, the twin technologies of farming and animal husbanrdy, which comprise agriculture, both permitted and required people to settle in one place. Staying in a familiar place, surrounded by other people, made them somewhat safer from predators. The domestication of the dog, which happened precisely at that time (they thought the tasty garbage piles around our villages were gifts from heaven), made them even safer, since dogs can see at night and will give their lives to protect their loved ones.

    Population began to increase more quickly than it had been, as a steady stream of new technologies (like iron plows) provided even more food.

    The current population explosion is also the byproduct of technology. Up until the end of the 19th century, the infant mortality rate was around 80%. Every cemetery on earth was full of tiny gravestones. Suddenly two developments happened. One was the public health campaign; highlights were covered sewers, wrapped food and a reliable supply of fresh clean water. The other was modern scientific medicine. Asepsis alone (keeping a wound or a surgery site clean--President Garfield was not killed by a bullet, but by the infection caused by doctors sticking their fingers into the hole) saved millions of lives. The first antibiotics toppled pneumonia and diarrhea as the world's top two killers. Vaccines conquered smallpox and other scourges.

    Ironically enough, the automobile improved public health. The streets of a big city like New York were ankle-deep in horse manure!

    As a result, today parents confidently expect all of their children to grow up. When they live to childbearing age, it causes a dramatic spike in the population growth rate.

    BTW, even in the distant past, population growth has not been constant. I can't track this down right now, but at some point before the migration out of Africa 60KYA, there was a population crash. No one knows what caused it; perhaps a plague. It reduced the population of our species to about ten thousand.
     
  11. iceaura Valued Senior Member

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    If we are talking about world wide human population, there were two booms that we know of for sure - sudden large and permanent increases in the number of homo sapiens on the planet. One was subsequent to the colonization of Australia, the other subsequent to the colonization of the Americas, in both of which technology developed elsewhere was presented with virgin landscapes for its employment, while diseases and parasites and other ills were left behind temporarily.

    Several others are presumed, following certain technological gains such as agricultural practices (saving seeds, tilling equipment, clearing orchards), although it is not certain exactly what the key factors were and thus when - or even whether - the population boomed. It is possible (for example) that the key innovation in the neighborhood of grain agriculture was not the creation of a food surplus - there have been human cultures with large food surpluses since the invention of the fishing net and the tended orchard - but the ability to store it for more than a year, to ride out a supply failure. Grains keep. But grains are not good food, in general, and the people who relied on them early were not robust and healthy, so whether the populations of grain-eaters boomed in consequence of (presumably) not busting in bad years is not really known.

    Meanwhile there has been one major planetary bust that we know of, coincident with and often blamed on a large explosive sulphur volcano in Indonesia a few tens of thousands of years ago, and several fairly large but not planetary long term minor bust and minor boom overall plateaus all (as far as I have ever heard) blamed on disease.

    You cannot simply project back from any current population dynamics and conclude anything valid.
     
  12. Jenyar Solar flair Valued Senior Member

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    Damn, how I miss this place!
     
  13. Buckaroo Banzai Mentat Registered Senior Member

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    I only replied because it came on "related topics" with a thread I had just created, and for a moment I confused 2003 with 2013. Not that I'm against topic "necromancy" as it's called, I find actually a good thing, even though usually I prefer to avoid it in order to not bother the seemingly majority of people who are for some reason weirded out with old threads coming back. Funny to think that there are 10 year old discussion threads on the internet, often I have this feeling that on the internet it's all new and ephemerous, with sites coming and going in a much shorter time span.
     
  14. Fraggle Rocker Staff Member

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    Grains were not the first cultivated plants. The oldest evidence of agriculture (unnaturally hybridized species or varieties) is fig trees in the Old World ca. 12KYA and pepper plants in the New a couple of millennia later. The tended orchard was indeed the first Neolithic technology, although without domesticated meat animals they still had to do a lot of hunting. One reason for the relatively late timelines of the paradigm shifts to permanent villages and then to cities in Mesoamerica was, in fact, the complete absence of large herbivores to domesticate for food and traction. The largest domesticated animal was the turkey and the only animal that could barely be used for traction was a dog dragging a travois. I have often expressed my wonder at the determination of the Olmecs (or whoever came first), who built their cities without the help of donkeys, oxen, goats, horses, etc.

    As for fishing, there is indeed evidence of permanent villages established on the shores of rivers and seacoasts, where fishing was abundant. Some of these communities experimented with farming, although they had no reason to invent animal husbandry. These communities were certainly Neolithic culturally, even though they don't quite satisfy the textbook definition of the word. However, there's no evidence that any of them made the next Paradigm Shifting transition from villages to cities. I haven't come across a good discussion of this, but my guess is that since there's a limit on the number of fish that can be taken from a single location, this put a limit on the size of the villages. Inviting another tribe to join them and enlarge the population would be disastrous, whereas in a true Neolithic village with both farming and animal husbandry, increasing the population resulted in greater prosperity due to division of labor and economies of scale.

    Storing food was very difficult with Paleolithic technology. The invention of the technology of pottery in the Neolithic Era was the first step toward solving that problem. There was no reason that Paleolithic people could not have discovered the technique earlier (and perhaps they did and used it for ornamentation, although I haven't seen any articles about that), but since pottery is heavy, bulky and fragile, it would be of little use to nomads with neither wheeled vehicles nor domesticated herbivores to pull them.

    As I've noted in other threads, in the late Paleolithic Era the life expectancy of an adult who had managed to survive childhood was in the low 50s. Fast forward 15,000 years to the Roman Empire. Huge populations needed massive food supplies, which required vast swaths of land devoted to agriculture. Furthermore, the agricultural land had to be outside the city where land prices were cheaper. With only draft animals as a power source, food had to be very sloooowly carted in from those areas. Now meat doesn't keep well (in an era before the invention of refrigeration), and furthermore pasture for meat animals is a very inefficient use of farmland. (Dairy cattle are ten times more efficient as a source of food than beef cattle, but milk spoils even faster than meat.)

    As a result, only the aristocrats had a significant ration of meat in their diet. The peasants and slaves had to get by on bread, baked in the city from wheat (with its long shelf life) grown in the countryside, plus a bit of cheese, eggs, nuts and/or seeds that barely gave their diet a proper balance of amino acids. These people did not understand vitamins and minerals. So the life expectancy of the average peasant in the glory days of the Roman Empire was about 23 years!

    Is that what caused the dieback and near extinction of Homo sapiens while our ancestors were all still in Africa? Do you have a more precise date?
     
  15. Jenyar Solar flair Valued Senior Member

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    Nothing dies on the internet; it just becomes legend

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  16. Trooper Secular Sanity Valued Senior Member

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    Michael Petraglia, from the University of Cambridge has cast doubt on the Toba catastrophe theory.

    http://www.nature.com/news/2007/070702/full/news070702-15.html

    I thought this was interesting.

    Human Line Nearly Split in Two

    “We don't know how long it takes for hominids to fission off into separate species, but clearly they were separated for a very long time.”
    --Dr Spencer Wells, Genographic Project
     
  17. iceaura Valued Senior Member

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    All that establishes is that some people unexpectedly survived Toba, - the suggestion that survival was easy, or the survivors numerous, is not established.

    Dunno. Apparently sufficient precision to decide the matter is not yet available: http://en.wikipedia.org/wiki/Toba_catastrophe_theory
     
  18. Trooper Secular Sanity Valued Senior Member

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    Well, before this project, they weren't even sure if humans had reached India as part of the ‘Out of Africa’ dispersal by 74,000 years ago.
     

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