How To Grow An Alien Brain (part 2)

    In the last article I talked about the patterns of brain size in animals here on Earth.  What does all of this tell us about growing alien brains?

      To get really big brains, you need a highly nutritious source of energy that is available in complex and patchy patterns, and that is accessible to a lot of competitors.  You need long-lived animals with a lot of investment in a few off-spring.  You need a certain minimum level of stability in the environment lest the balance shift toward the cockroach strategy.    
    Do you need hands or something similar to manipulate the environment?   That might help, but initially the boost in brain-size may be from an unintuitive source.  It’s easier for an animal to have a large brain if it has a short neck.  Think about a human-sized head on an ostrich-type neck.  Wouldn’t work so well, would it?  If you make an ostrich-length neck thick enough to support a human-sized head, you’ve added a lot of weight to the animal.  In a close chase, that extra weight could be fatal.  So why can’t the neck be shorter?  The animal has to eat and drink.  That means that either the neck is long enough to reach the ground, or the animal has to find some other way of bringing food and water to the mouth.  That means that an animal with some kind of grasping organ like hands, a trunk, or a prehensile tail pays a smaller price for a large brain the one that doesn’t have one.  The grasping organ then allows the animal to develop more flexible behavior.
     If an animal spends most of its time upright, the large brain costs even less in terms of neck mass, because the neck muscles don’t have to work as hard to hold it up.  Purely water-living animals get some of the same benefit because the water supports their heads.  A water dwelling or upright animal won’t automatically have a large brain.  It just costs them somewhat less than normal to have one.  Ironically, Hollywood’s preference for upright aliens has at least a little justification.
    Large brains probably cost flying animals more than they do non-flying ones because of the selective pressure to keep weight down, though fruit-eating bats and birds tend to have proportionately large brains.  There are upper limits for the size of a flying animal though, and that in turn limits brain-size.  A human-sized brain in a body small enough to fly would be quite a trick. 
    Those of us that came through school a few years ago are often conditioned to think of animal development as a progression.  It goes something like: fish, amphibians, reptiles, early mammals, progressive mammals, monkeys, apes, and then us.  That’s not the way life really works.  The reality is that animals of all kinds compete for a variety of niches in a variety of ways.  Fruit-eating birds are very formidable competition for apes and monkeys.  So are fruit-eating insects.  The niche determines many of the characteristics of the animal, though the ancestry determines how an animal exploits that niche.
    There is no guarantee that monkey and ape type niches will always be occupied by monkeys or apes.  For example, in South America most of the niches that leaf-eating monkeys occupy in Asia and Africa are occupied by tree sloths.  Tree sloths aren’t our type of animal, but they are formidable competitors in their niche.
    In an alien environment, don’t expect one progression leading to one type of intelligent life, and especially don’t expect the progression or progressions to follow the same patterns they did on earth.  It’s probably better to scrap the analogy of a tree of life and visualize a field of life, where in certain areas a combination of fertile niches and the right ancestry lead to more intelligent animals, and where other areas are less fertile or the ancestry of the current niche occupants keeps them from growing too intelligent.     Is that helpful?  Ready to build a brainy alien?  I hope so.