New evidence that humans developed big brains to cope with society

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For the past several decades, scientists have been fascinated by the "social brain theory" — the idea that certain animals evolved big, powerful brains to cope with the complexities of social life. A new computer simulation has now shown that this assertion is likely correct.


Our bulbous brains require a lot of energy to function. Like, a lot of energy. That one organ alone requires 25% of our body's total fuel stores. So from an energy allocation perspective — and thus from an evolutionary perspective — it sure as hell better be worth it.

Other animals haven’t had to make these sorts of Darwinian adjustments. Herd animals and insect swarms, while social, take on loose social arrangements that are typically based on short-term advantages.

But other animals, like primates, whales, dolphins, and elephants, have social lives that are far more dynamic, often involving intense coordination with multiple group members. And it’s no coincidence, say some scientists, that these animals have powerful and complex cognitive capacities.

And indeed, the social brain theory suggests that brain size affects the speed, volume, and sophistication of decisions that can be made amongst interacting individuals.

Written By: George Dvorsky
continue to source article at io9.com

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  1. ” But other animals, like primates, whales, dolphins, and elephants, have social lives that are far more dynamic, often involving intense coordination with multiple group members. And it’s no coincidence, say some scientists, that these animals have powerful and complex cognitive capacities.”

    A couple of these organisms, whales and dolphins, are more coalition centered than familial, though the intense interaction is still there.and the cognitive levels are very high. Still, wolves are highly social and very family oriented without the cognitive accomplishments of the above named organisms.

    • In reply to #1 by Neodarwinian:

      A couple of these organisms, whales and dolphins, are more coalition centered than familial, though the intense interaction is still there

      Orcas (they’re the best ;) live in fully matrilineal societies for the most part, where both daughters and sons remain with their mothers. (Elephants, on the other hand, have sons that disperse). There are a few orca types where some dispersal occurs.

      Bottlenose dolphins often have daughters remaining with mothers. Males form pair bonds, and these are sometimes brothers.

      I wonder why horses don’t reflect this, though.

      • In reply to #5 by Kim Probable:

        In reply to #1 by Neodarwinian:

        A couple of these organisms, whales and dolphins, are more coalition centered than familial, though the intense interaction is still there

        Orcas (they’re the best ;) live in fully matrilineal societies for the most part, where both daughters and sons remain with the…

        Yes, that is the exact definition of coalition.

        ” Orcas (they’re the best ;) live in fully matrilineal societies for the most part, where both daughters and sons remain with their mothers. (Elephants, on the other hand, have sons that disperse). There are a few orca types where some dispersal occurs.

        Bottlenose dolphins often have daughters remaining with mothers. Males form pair bonds, and these are sometimes brothers. “

        All organisms of this social type need to disperse for obvious reasons but actual families, such as wolves usually form, is another matter entirely.

        • In reply to #6 by Neodarwinian:

          All organisms of this social type need to disperse for obvious reasons but actual families, such as wolves usually form, is another matter entirely.

          I don’t understand how this is different from the fish-eating orca societies – there are often several generations remaining together for life.

          • In reply to #7 by Kim Probable:

            In reply to #6 by Neodarwinian:

            All organisms of this social type need to disperse for obvious reasons but actual families, such as wolves usually form, is another matter entirely.

            I don’t understand how this is different from the fish-eating orca societies – there are often several generations re…

            The adult female and her offspring is a coalition. The breeding pair and their offspring is a familial grouping. Both parents contribute to the survival and reproductive success of the progeny.. In orcas, several generations or not, it is a true matriarchy of one coalition.

      • In reply to #5 by Kim Probable:

        Orcas (they’re the best ;) live in fully matrilineal societies for the most part, where both daughters and sons remain with their mothers.

        I wonder why horses don’t reflect this, though.

        Horses are not pack hunting top predators. You don’t need much brain to out-wit grass!

        Elephants follow matriarchs long distances along migration routes to water holes.

        • In reply to #12 by Alan4discussion:

          In reply to #5 by Kim Probable:

          Orcas (they’re the best ;) live in fully matrilineal societies for the most part, where both daughters and sons remain with their mothers.

          I wonder why horses don’t reflect this, though.

          Horses are not pack hunting top predators. You don’t need much brain to out-w…

          Horses are surprisingly brainy, though, for herbivores, and it’s surely no coincidence that they’re also highly social and one of the few animals with the necessary social behaviours suited for domestication.

  2. I really wish the theory of Geoffrey Miller explaining our big brains as a result of sexual selection would get more attention. It’s the only theory in this field that ever gave me an ‘aha-erlebnis’: aha, so that’s how it works! Also want an aha-erlebnis? Read his book ‘the mating mind’.

  3. This is what I primarily visit this forum to find.

    But I also of course very much enjoy everything else it has to offer.

    Long live RDFRS!

    But where’s Lewis Black gone? He’s hot on evolution, and sends up creationists and their dim ilk brilliantly.

  4. Also worth noting that larger groups cover a wider geographic range and therefore have much more widely varying resources to cooperate about.

    Examples that could be sensitive to selection pressure for primitive humans being access to the right kinds of rocks, plus the investment of time in acquiring relevant skills, for things like specialising in hand axe manufacturing. Crucial resources are often not conveniently collocated, like access to the kinds of food sources that can be processed and stored to smooth out seasonal variations in food availability. This kind of random and wide geographical distribution of natural resources opens up trading/cooperation possibilities.

    Other tradeable resources being reproduction – smaller groups can’t be too cohesive because they depend on dispersed genes among the entire species. Large groups with low, but almost sufficient, intra group genetic diversity can be more self-contained.

    It’s no accident that of all animals humans have the most sophisticated language, plus the largest groups, and possibly the least genetic diversity of all primates. Brain size, plus the opportunity cooperate & reciprocate, drives further mental and language complexity.

    Maybe that’s a reason why human like intelligence would be unlikely to emerge in a marine environment, regardless of the extent of social cooperation and group dynamics. Reason is the selection driver based on the value of trade involving tangible resources, most of which need to be carried long distances and probably also depend on the use of fire. Which implies walking with free hands rather than swimming. Plus fire technology isn’t compatible with a marine environment.

  5. I still wonder why this kind of selection would be pushed in the first place. Hundreds of thousands of species get on perfectly well with more straightforwardly Darwinian social arrangements, so under what conditions would a subset of them evolve more complicated ones? The article points out that complex group dynamics, and therefore the requisite processing power, require more energy to maintain than standard-sized groups and standard-sized brains, yet at no point does it describe where the extra calories are coming from nor why complex group living is an effective means of acquiring it.

    To be fair, I’m not disputing the finding that greater social cohesiveness and coordination requires more brain power and could potentially have been the strongest pressure on the evolution of language, but I am asking under what conditions the greater social cohesiveness and coordination would be selected over more straightforward group dynamics.

    Personally, I suspect that this isn’t the complete picture, and that factors involved in the evolution of creatures like elephants and dolphins both:

    A) require pre-existing adaptations to build on, so only species with specific evolutionary histories could evolve more rigorously social brains. For instance, it might be exclusive to species which balance between kin selection and reciprocal altruism in a very precise ratio, or it might depend on the presence of a highly nutritious diet like carnivory or one involving certain kinds of plants, or it might require certain senses to be highly sophisticated (such as vision and hearing over smell and touch), or some combination of like factors,

    and

    B) were rare enough that it would explain why only a small fraction of modern species, and an even smaller fraction of extinct ones, went along the route. For instance, perhaps it’s an ungainly arrangement that only works by co-opting specific mental modules and building on them, or it required a specific body plan like that of the endothermic mammals to fuel the body, a body plan which was itself an adaptation justified only under certain evolutionary circumstances.

  6. It is cortical neurons that count.

    We have 1000 times more neurons than a mouse in toto but 5,000 more cortical neurons, those dedicated to high level inference generation. Fully a fifth to a quarter of our brain is cortex.

    Brains evolved to manage movement and in one sense all brain activities are directed towards actions and potential actions. Octopodes (troo) like all non-mamals have no cortex in the strict sense, but they do have four times as many neurons as a mouse, consistent with a much higher limb coordination task.

    Elephants have half the cortical neurons we do but it accounts for half of their total neuron count.

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