The great anatomically modern human leap


There is a debate in paleoanthropology, well, there are lots of them. But this one has to do with behavior that doesn’t fossilize well, and which suggest the presence or lack of modern cognition. The ancestors of the San, pictured above, are a great source of data for that question. A new find pushes back the date when San Bushmen behaved like any other modern people right down to symbology and sophisticated subsistence strategies:

WaPo– Poisoned-tipped arrows and jewelry made of ostrich egg beads found in South Africa show modern culture may have emerged about 30,000 years earlier in the area than previously thought, according to two articles published on Monday.

The findings published in the journal “Proceedings of the National Academy of Sciences” show that the 44,000-year-old artifacts are characteristic of the San hunter-gatherers. The descendants of San people live today in southern Africa, so the items can clearly be traced forward to modern culture, unlike other archaeological finds, researchers said.

Anatomically modern humans appear in the fossil record in Africa about 150,000 to 200,000 years ago. But the first inkling of so-called modern behavior this find represents seems to spring almost out of nowhere about 50,000 to 75,000 years ago. The date is imprecise in part because the evidence is sparse and in part because it’s a bit arbitrary — what really counts as modern behavior?

There is some evidence that our direct ancestors were a relatively small group, one kind of human among many, that underwent a trial by fire. In fact we do know a relatively average super volcano erupted in Sumatra about 72,000 years ago and may have caused a disruption in climate and associated ecology that affected that population, our population. Some anthropologists and geneticist think our numbers may have shrunk to as few as a few thousand adults scattered over thousands of square miles in a single part of Africa.

Whatever the cause, and bearing in mind our proclivity to laud our own specific greatness over rivals, there does seem to be a jump in human behavior circa 50 – 70 KYA as demonstrated by the emergence of art, technology, and diversity shortly after the Sumatran eruption. Modern people lived for tens of thosands of years in Africa. Then, in the space of a few thousand years, Hsap culture bloomed, we flowed over the panet like a human tsunami. People walked out of Africa into the Middle East, some turned north and west into Europe, others stayed east, shot across the coasts of southern Asia developing better technology the entire way until they could sail across the Pacific to colonize the virgin lands of Australia; they were so good at navigating and boat buiding that they eventually reached Hawaii, Easter Island, and may have even set foot on the west coast of South America. Other groups took on Siberia — in a brutal Ice Age mind you — and would one day walk over the top of the frozen world into North America.

By the time the two great branches of the human family, east and west, reunited in the European Age of Exploration, those hunter-gatherer pioneers had successfully expanded down through the Great Plains and Central America, tamed the mighty Amazon basin, and were living comfortably clear down to the tip of Argentina and as far east into both new world continents as they could go. And, for the first time in millions of years, there was only one kind of human alive in all the world. Our archaic hominid peers, as rich in subspecies a mere 100,000 years ago as anytime in hominid natural history, had all disappeared completely.

Trying to understand what it was that allowed our ancestors to flourish so dramatically while others living side by side went into the sweet night of extinction is a big deal in anthropology. There have been many ideas, resistance to disease, a common language stemming from that limited geographical beginning, insular culture with a powerful touch of xenophobia. But whatever it was, it’s hard to look at the evidence and not conclude our anatomically modern human ancestors simply had something going for them intellectually that our close cousins at the time lacked.

Comments

  1. jakc says

    Have to disagree with you here. Our archaic cousins haven’t disappeared. Some of them are our ancestors. Whether Neandertal or Denisovan culture disappeared is an interesting question, but the people didn’t. Modern humans share genes with them

  2. ShowMetheData says

    I’ve looked at the varied pre-super-volcanic population GROUPS as having a range(bell-curve) of “modern human” abilities

    Our ancestor population group existed but was hemmed in by other “superior” humans. But the “superior” humans were only “superior” in the pre-super-volcanic context.

    Sometimes in talking about evolution, we are content to have Darwin as our easy-access icon, but I think it should be a bell- or normal distribution-curve. Always a range of possibilities in a population – that is what allows an origin of species

  3. F says

    By the time the two great branches of the human family, east and west, reunited in the European Age of Exploration,

    Radical Euro-centric oversimplification. Arguably, this is likely somewhat true of pre-Columbian Americas with respect to everywhere else, but I can’t feature “two branches of humanity” in any form being delineated by New world/Old world. This is so fractally weird it’s making my head hurt just thinking about it.

    (Sorry if I’m just being a drag.)

  4. lsamaknight says

    Sailed across the Pacific/i> to reach Australia? Wrong ocean for starters unless you’re taking the long route. And I thought gene mapping had confirmed that the ancient Aboriginal Australians island hopped through their way down through South-East Asia before getting here which represented the end of the road for that particular branch of human migration.

  5. KG says

    I’d say these finds, while significant, have been considerably hyped, as is customary in paleoanthropology. Shells pierced presumably for use in necklaces found at Blombos cave in South Africa date from around 75,000 years ago, and there is evidence of ochre mining (presumably for cosmetic use) more than 100,000 years ago. See McBrearty, S. and Brooks, A.S. (2000) “The revolution that wasn’t: A new interpretation of the origin of modern human behavior” Journal of Human Evolution 39:453-63.

  6. Paul W., OM says

    Trying to understand what it was that allowed our ancestors to flourish so dramatically while others living side by side went into the sweet night of extinction is a big deal in anthropology. There have been many ideas, resistance to disease, a common language stemming from that limited geographical beginning, insular culture with a powerful touch of xenophobia. But whatever it was, it’s hard to look at the evidence and not conclude our anatomically modern human ancestors simply had something going for them intellectually that our close cousins at the time lacked.

    The last sentence here makes me think maybe you didn’t really absorb the stuff discussed in the previous two.

    I think it’s fairly likely that what ended up setting our ancestors apart from the other groups was not anything we’d recognize as any kind of intellectual superiority. It may have been nothing intellectual at all, and may even have been an intellectual inferiority that led those people to blunder into a lifestyle that eventually worked out well for them.

    That may be why the population dwindled to maybe a few thousand before taking off again.

    Suppose, just as one of many examples, that our ancestors were vulnerable to a parasite that altered their behavior, e.g., to make them more gregarious, even somewhat foolishly gregarious, just by turning down a big “fear of strangers” or “fear of the unknown” knob. (Rather like what was selected for in the Russian experiment that bred for docile foxes over many generations. They ended up with something with a variety of remarkable similarities to domestic dogs, with floppy ears and a variety of coats and such. All those things were a side effect of turning one big “knob.”)

    Making humans more gregarious is a pretty plausible thing for a parasite to do, to enhance its own propagation at the expense of its host. There are a lot of parasites that do similar things, like the toxoplasmosis bug making rats less fearful of cats. Making humans less standoffish could easily make it much easier for a bug to spread from human to human, despite there being a variety of good reasons for being more standoffish than that.

    If you simply made humans more gregarious, that would make it easier to transmit culture, because there would be more opportunities for communication, imitation, and so on. More things would be successfully transmitted from generation to generation—not necessarily better or smarter things, in themselves, just more things.

    That in turn, would enable them to eventually stumble on a combination of winning cultural tricks, with no “intellectual” brain evolution necessary—just the turning of one emotional knob.

    That’s how anthropology and evolution often work out—the obvious explanation is quite often wrong, and the right explanation is just offbeat and weird and accidental.

    For example, it seemed obvious for a long time that we must have evolved big smart brains before we evolved to walk upright and have little body hair.

    But we didn’t. We evolved upright walking and little body hair before we had brains any bigger than our cousins of the time, and there’s no evidence we were smarter.

    Nowadays, it’s more plausible that we evolved those things to give us better stamina for doing things we could do with our little not-much-better-than-chimps’ brains—especially patiently walking after prey for a very long time, keeping them from resting and making them overheat before we did, so that they were prostrate and vulnerable when we finally caught up to them. (Most predators are sprinters, so most prey animals are sorta sprinters too, to stay ahead of them in a short-duration race. We evolved a different predation strategy of being slow and steady, and making it a long race.)

    That not-very-smart hunting strategy may have ended up freeing our hands to carry more stuff, communicate with gestures, etc., and foster eventual brain evolution to be smarter and take more advantage of those things.

    But what made us evolve that hunting strategy in the first place It may have been purely situational—the climate changed and that was the only strategy that worked well on the plains that used to be jungles, so we did it. (Maybe we’d used that strategy for some animals before, but we then ended up specializing in it because other strategies mostly stopped working.)

    Or maybe it was stupidity that made us do it. Maybe the hunters that developed that strategy were just cussedly determined not to let that fucking animal get away, because they were pissed off, when wiser people said “let it go.”

    It’s likely that nobody really understood the issues or could make a good guess as to what would turn out to be a successful strategy, so a somewhat “dumber” strategy was about as likely to work as a “smarter” one.

    When things are very poorly understood, “dumber” guesses are almost as likely to turn out to be right as “smarter” ones, so you’d expect the smarter guys to win a little more often, on average, but you would not expect the winners to usually be the smartest guys. Luck counts for a whole lot, even dumb luck.

    That is the kind of situation our ancestors were perpetually in. They were always faced with a complicated world that they had a very poor handle on. So luck mattered a whole lot.

    Our ancestors were probably not the dumbest, but my guess is that they weren’t the smartest either—they were just passably smart, maybe a bit above average but maybe not, and lucky that what they did eventually worked out well.

    I’m not an anthropologist and I don’t know which of the above stories are right, but what anthropology I know suggests that roughly similar non-obvious things are very common.

  7. jakc says

    Plus, there is still the possibility of a Neandertal triumph in the future when a lost population of Neandertals finds a bill sapien willing to lead them … Though holo sapiens will undoubtedly declare an overwhelmning loss to be a draw

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