Two chimps walked into a bar …

… and made a real mess of the place when one of them spotted the jar of pickles on the counter. They fought over it until one of them had almost all the pickles and the other one had a number of bruises and a tiny fragment of one pickle that the other chimp dropped by accident.

That would be the way it would happen if two chimps walked into a bar. Or imagine two chimps, and each finds a nice juicy bit of fruit out in the forest. And instead of eating the fruit, because they are not hungry, they carry it around for a while (this would never happen, but pretend) and then accidentally run into each other. What would happen? Same thing. Event though neither chimp actually needed the fruit and each chimp had its own fruit, the dominant chimp (between the two) would end up with both pieces of fruit.

This is why chimps could not possibly cooperate in any effort to scour the forest for various edible items, bring them all back to a central place, share and then cooperatively process the food items, and ultimately produce a meal that is eaten by all of the chimps on an as needed basis. Humans do that but chimps can’t. Explain this and you explain one of the major features of human evolution…

Some of us think that about two million years ago, an ape-like hominid ancestral population for humans gave rise to individuals with the novel capacity to do the following:

1) Make and control fire;

2) Cook food on this fire; and

3) Cooperate enough that individuals could in fact bring food morsels to a central place for processing and sharing.

The consequences of this nexus of novelties would be significant. There would be much more energy in the environment available for consumption because cooking converts a lot of inedible biomass into edible biomass. This could supply the necessary nutrients for bodies to grow larger and be maintained at larger sizes, which might be useful in the predator-rich environment of Africa. Note that where we can determine cause of death for australopiths, or at least guess reasonably what it might have been, predators are typically involved. This seems to stop happening with the larger bodied Homo erectus following this transition.

Another consequence is the extra nutrition to support the growth and maintenance of a large, costly brain.

These early human ancestors would have to have a way of cooperating rather than (almost) always competing over things like food. This could result in behaviors supportive of more complex and sophisticated technologies being regularly used, as we in fact see in the archeological record. The novel food sources plus the additional technology together would support this species’ movement into additional habitats previously not occupied by hominids. We also see this happening just at this time in the archaeological record.

For various reasons I won’t go into here, this would also have surely changed the overall social organization among these hominids, and we suggest that this may have been the origins of something not entirely different from modern (more or less monogamous) marriage.

(Here is a copy of a paper that discusses this idea in some detail.)

Comments

  1. #1 Stacy
    February 12, 2009

    It’s simple. The female hominid discovered fire and how to use it. Filing in the blanks becomes easy now.;-)

  2. #2 Greg Laden
    February 12, 2009

    Most likely exactly that. Female primates generally are the technology savvy where there is technology being used by a species. Mother to daughter transmission is key in all of these species . With CPF (Central Place Foraging) Mo-Da transmission may become less relatively important, but it would be key early on.

    It would be later in prehistory that males would start bonding with each other across time using various phallic artifacts like spear points and such.

  3. #3 skyotter
    February 12, 2009

    Explain this and you explain one of the major features of human evolution…

    impulse control. chimps don’t have it, and humans may have developed it through a filter of symbols. this NOVA had a good breakdown:

    http://www.pbs.org/wgbh/nova/apegenius/

    a chimp is given a choice of two candy dishes with different amounts of candy. the one that the chimp chooses is given to a *second* chimp, while the chimp-chooser gets the other dish. the chimp-chooser invariably *always* reaches for the dish with more candy, no matter how many times it learns that by trying to pick more, it gets less

    repeated with symbols (numbers representing candy, instead of candy), the chimp-chooser “gets” the game, and starts picking the lower number, thus getting more candy

    i probably explained that badly. Happy Monkey anyway!

  4. #4 Pierce R. Butler
    February 12, 2009

    Do mother chimps bring “home” edibles for weaning/post-weaning chimplets?

  5. #5 Greg Laden
    February 12, 2009

    No, they don’t bring stuff ‘home’ .. the weannies attempt to take the food from mom (right out of her mouth often) and mom tolerates it to varying degrees.

  6. #6 Lou FCD
    February 12, 2009

    No, they don’t bring stuff ‘home’ .. the weannies attempt to take the food from mom (right out of her mouth often) and mom tolerates it to varying degrees.

    ..and in a broader sense, this differs from Homo sapiens weenies, how?

    Damned weenies.

  7. #7 jay
    February 12, 2009

    and we suggest that this may have been the origins of something not entirely different from modern (more or less monogamous) marriage.

    consider that in most mammals, the female stops being sexually receptive as soon as she becomes pregnant. This does not happen like that in humans.

    Two things strike me as very different in humans: 1) the aforementioned ability cooperate effectively and 2) very long period of dependency for the young.

    Whereas in a non social but intelligent mammal (racoon for instance) having the male around would just be more resources required, and the mother can survive reduced food intake long enough to get the young mobile, with humans, keeping the male around can inprove reproductive success. Perhaps then, females who did not ‘turn off’ had a reproductive advantage over those that did. Bingo ‘long term mating’

    Darwin had noticed that while in most animals males competed for females, there seems to be some female competition in humans. My understanding is that he seemed to think of it as a reversal, but in essence it is a parallel competition. Males compete for the scarce resource (a fertile female) females compete for a scarce resource (a male who will actually stick around and provide resources for the young). This would suggest that makup, hair dressing, jewelry and killer heels are actually an indirect byproduct of this long term mating strategy.

  8. #8 Azkyroth
    February 12, 2009

    Or, more precisely, that this mating strategy produces impulses that purveyors of Overpriced Crap can hijack to sell people things they don’t need and didn’t want.

  9. #9 Gerry L
    February 12, 2009

    I spend a lot of time with captive chimps. Sharing, as Greg noted, is not often practiced. And fights can break out over food. But one thing I have noticed is that they don’t fight over non-food “stuff.”

    They get non-food enrichment items (blankets, clothing, stuffed animals) and one of the girls might carry an item around for hours or even days. But when she puts it down and another chimp picks it up … nothing. No reaction. No trying to get it back. I’ve never seen them get emotional about stuff.

  10. #10 Greg Laden
    February 12, 2009

    Gerry. Obviously you have not given them a Nintendo.

    But seriously, interesting point.

  11. #11 Mike Haubrich, FCD
    February 13, 2009

    One of the things that occurred to me during your presentation last night was that in addition to providing more energy with less food through cooking (shifting resource allocation from the gut to the brain,) waiting for the dinner grew into an opportunity for greater socialization among the group at “dinner time.”

    This may venture a bit deeply into evolutionary psychology; but here goes.

    With the increased time of socialization, the small group developed more complex communication tools over time. I’m thinking language here. Would it have also created the sort of mechanical solidarity that engenders the growth of larger groups into tribes and bands?

    Do we know enough about neandertals to say whether or not they cooked their food? If not, would that help explain the ascendancy of the cro-magnons?

  12. #12 Stephanie Z
    February 13, 2009

    I did feel a little sorry for the people last night who didn’t know this was available here. You did well, but the time for talking about any part of this was so short.

  13. #13 Greg Laden
    February 13, 2009

    But Lynne did a great job telling people to get to this blog, so hopefully people will look around.

  14. #14 AK
    February 13, 2009

    AFAIK male chimps in the wild bring back meat from hunting trips and share it out among some of those (especially females) who didn’t go on the trip. (See many books and articles on chimp behavior in the wild.)

    My impression is that they are very Machiavellian in their choice of recipients and “cuts” of meat involved, however that may be the bias of the particular authors I read on the subject.

    I know Goodall was probably over-enthusiastic in her early conclusions regarding meat-sharing (“chimps always share meat while never sharing anything else”; paraphrase), but there is much evidence for meat sharing and a good deal of speculation (and debate) regarding the origins/motivations.

    A quick search located The Predatory Behavior and Ecology of Wild Chimpanzees, as well as Meat sharing among the Gombe chimpanzees: harassment and reciprocal exchange. The latter attempts to demonstrate that meat sharing is primarily in response to harassment.

    While searching, I also discovered Chimpanzees Share Forbidden Fruit, which documents sharing of plant food by males. This appears to be limited to human crops “raided” by parties of males, who clearly take risks and know it in making these raids.

    Somewhat in line with the article’s conclusions, I would suggest that in general food is shared when its acquisition involves status-enhancing activity, as a means of trading individual demonstrations of prowess for enhanced status within the community. This is roughly parallel with similar food-sharing by human hunters (no time to find links, but see various descriptions of San lifestyles). Indeed, one description I read of responses to successful hunters involved verbal harassment to encourage sharing that was very analogous to that described by Gilby (see link above).

    My suggestion, then, is that chimpanzees (and bonobos) posses the same Machiavellian sharing impulses as humans, including the recognition that contributions to the group welfare can be traded for enhanced status within the group.