You Are a Giant Tongue! The Five Key Adaptive Traits That Made Us Human

File:Da Vinci Vitruve Luc Viatour.jpg

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Leonardo da Vinci’s famous Vitruvian Man and its variants (such as that done by William Blake) present human beings as the pinnacle of creation, unusually beautiful beings of perfect proportions obviously arising to their impressive stature in the cosmos from a blueprint drawn up by the supreme architect, God.

And yet God, if God exists, surely didn’t create humans as the ancient Roman architect Vitruvius created buildings. And God certainly didn’t make humans instantaneously, like a magician pulling a rabbit out of a hat. Instead, God used history to make humans; most specifically, evolution.

And that’s exactly what anthropologists have discovered–that humans evolved from (and alongside of) earlier primate and Homo species that are now extinct. Australopithecus is gone; Homo habilis is gone; The Neanderthals are gone. But Homo sapiens are still here; we are the last representatives of the genus Homo that are still standing.

Here are the five key evolutionary developments that made us the globally dominant species we are today:

  • We ceased knuckle walking. By leaving the trees and walking upright, a whole host of other adaptive changes were set in motion. To begin with, we went from being round and short to skinny and tall (as compared with forest-dwelling apes). Upright walking is also a game changer in terms of energy use when travelling. Researchers have shown that knuckle walking for any extended length of time is exhausting for primates. If you’re a primate under environmental pressure to be on the move, upright walking is a huge advantage.
  • Our bodies became giant tongues. Walking and running for extended periods of time in the heat of the day meant that we had to cool off efficiently–and our early ancestors did this by losing their body hair (beginning about three million years ago). Where other mammals cool off by panting, we sweat through our skin. Our bodies are basically akin to giant and panting tongues. (Talk about being polymorphously perverse!) Harvard’s Daniel Lieberman, a professor of human evolutionary biology, puts it this way: “Quadrapeds can gallop for about ten to fifteen minutes, and then they overheat, but hominids can cool down by sweating. They use their entire bodies like a dog’s tongue.” (Quote source: NOVA documentary, “The Birth of Humanity,” 27:00 mark, embedded at the bottom of this page.)
  • Those in the genus Homo became mid-day hunters. Instead of being tree-dwelling–and largely fruit and leaf eating–primates, our ancestors, not long after leaving the trees, jumped into a very particular savanna survival niche: the hunter that hunts, not at night, but in the heat of the day. Our ancestors’ evolutionary strategy was to use our “giant tongues” (our naked and sweating skin surfaces), and our ability to run long distances, to wear down the panting animals we pursued. In hunting, our ancestors became the proverbial tortoise to the hare. Even and steady progress, as opposed to quick bursts of energy followed by abrupt stops to rest, was our ancestors’ method for winning races with their prey. It’s a brilliant strategy for survival, and it made use of key Homo adaptations (upright walking, naked sweating, tracking, and forethought). This meant that our ancestors could pursue game for hours at a time, and their “hands free” lifestyle–which initially evolved to groom those in their packs, navigate trees, and pluck leaves and fruit–could now be used to bring down panting and tuckered-out big game animals by the throwing of stones, and ultimately spears, at them. Hands could also be used to make stone tools for cutting game open (to substitute for the fact that our ancestors didn’t have the sharp teeth of other predators). Increasingly sophisticated tool use, of course, favored the evolution of bigger brains.
  • Our ancestors made fires at night. All that daytime hunting meant that our ancestors had to get sleep at night, and anthropologists believe that the discovery of fire helped them do this (it kept predators at bay). The fire circle also gave our ancestors a place to cook game, making the meat won easier to digest. From meat they could get the kinds of calories needed for their intensively mobile lifestyle. It also gave them the calories necessary to support larger brains (which consume a lot of calories). Fire also facilitated socializing and group cohesion. It was at the fire circle that early Homos gathered in groups at night and communicated (thereby putting additional evolutionary pressure on the development of larger brains and ever more acrobatic usages of language).
  • The brains of our ancestors had most of their growth outside the womb. To achieve large brains, the problem of primate mothers’ narrow birth canals had to be solved. Evolution thus favored in the genus Homo extremely delayed development, which meant long childhoods for extended learning and growing big brains. Big brains through the creation of dependent children is an expensive and time consuming species adaptation, but it pays off big time in the long run. In contemporary humans, our brains aren’t fully developed until we reach the age of twenty. Throughout childhood we are essentially tag-teaming with our mothers, finishing her pregnancy by bringing to term, in the womb of our skulls, the most essential part of ourselves–our brains. (Thus it seems that human success is, in yet another respect, about running a marathon; about making a long run gambit that promises a big payoff to those with the stamina, patience, and cunning to endure.)

So that’s how Leonardo’s Vitruvian Man evolved. What makes us distinctively human–upright walking; hairlessness; our love of competition, exploration, and steak; our Promethean habit of stealing fire (technology) from heaven; our smarts, speech, forethought, and tribal sociality–comes from a key set of historically contingent adaptations that, when combined, took on a powerful synergy.

Perhaps, in light of this story of human adaptation, the better visual representative of our species is not Leonardo’s Vitruvian Man, but John Pasche’s 1971 tongue logo done for The Rolling Stones (image source: Wikipedia):

File:The Rolling Stones Tongue Logo.png

We are a species, after all, that has succeeded by regulating an even temper and temperature. Slow and steady progress wins the race (both in hunting and socializing). Our evolutionary strategy as a species really has been all about keeping cool–and all that implies, both in terms of resource acquisition and attracting mates. The rule is: be energetic even as you are also patient, observant, and strategic in your planning. To talk, cut up, and dance around the campfire together, you’ve got to be nice (or at least appear to be nice). And to hunt down an animal, you’ve got to get sweaty.

To quote from Pulp Fiction, it’s all about being “little Fonzies” (or little Mick Jaggers). That is, about keeping cool (nice, clever in your talk, energetically sweaty). It’s a winning evolutionary strategy.

And speaking of Mick Jagger, the lyrics he sings below, in “Start Me Up,” are curiously suggestive of key aspects of our evolutionary history. (Who knew The Rolling Stones could be so educational?) And notice that Jagger starts off with a Vitruvian Man pose. I wonder if he meant to do that.

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SOURCE: The evolutionary story I’ve outlined above is simply a summary of an exceptional NOVA documentary, The Birth of Humanity, which is on YouTube and can be seen below. It provides the details. How wonderful it is that physical anthropologists have been able to piece this human story together. Who needs myths when you’ve got science? The truth is stranger than the fiction.

About Santi Tafarella

I teach writing and literature at Antelope Valley College in California.
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5 Responses to You Are a Giant Tongue! The Five Key Adaptive Traits That Made Us Human

  1. I am not a giant tongue! I am livid. I am in fact a very articulated tube of which a tongue is a simple flapper thingy at the top end. I am not a body part, I am a body plan. I’ll thank you to remember this in the future and ask that you ensure that you correct this misconception post haste.

    • Santi Tafarella says:

      Keep cool, Arthur Fonzerelli, keep cool.

    • Santi Tafarella says:

      By the way, I’m not making up the idea. It comes from Harvard’s Daniel Lieberman, a professor of human evolutionary biology, who puts it this way: “Quadrapeds can gallop for about ten to fifteen minutes, and then they overheat, but hominids can cool down by sweating. They use their entire bodies like a dog’s tongue.” (Quote source: NOVA documentary, “The Birth of Humanity,” embedded on this page.)

  2. Staffan says:

    “Who needs myths when you’ve got science? The truth is stranger than the fiction.”

    Yes, but somehow fiction always beats the truth. It’s what the audience wants. And there is probably a scientific explanation for that too. You find archetypal patterns in stories all over the world, among peoples who have never been in contact with each other. We have evolved a certain way of thinking and understanding things, and fiction caters to that in a way science can’t.

    And what about the social environment which many believe creates the strongest selective pressures for humans? That’s when it get really interesting, but also more controversial and political. Some people are clannish, others just a bit tribal, yet others are highly individualistic. Some use guilt as social control while others depend more on shame. Is this just a matter of choice? Given that the social environment has changed at an extraordinary rate the last 10K years it stands to reason that there has been changes. But the most likely candidates are traits that differ between peoples.

    If you avoid those topics and only select that which you find personally rewarding, then you are essentially using science to create fiction.

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