How To Grow An Alien Brain (Part 1)

Cocktail Party Science

        How To Grow An Alien Brain (Part 1)

(Lessons From Apes, Bears, Elephants, and Cockroaches)

 

What is cocktail party science?  It combines fact and speculation in ways that no real scientist would ever try to get past peer review.  It is not careful to document and footnote every fact and to label every speculation as such.  Is it really science?  At its best it can be.   In these columns I will do my best to combine fact and speculation in a way that will hopefully let you walk away with new knowledge, hopefully not painfully obtained.  Do keep in mind that I’m a computer programmer, not a real scientist and these articles spring from wide eclectic reading and thought rather than any real training in the subjects involved.  This is the first in a series of articles intended mainly as background information for writers, especially science fiction writers.
    The only real data we have on how brains and intelligence develop come from the only animals whose brains and intelligence we can actually sort of measure—the ones here on Earth.  Do those brains give us any useful principles we can apply to creating science fiction aliens?  I think so.
    We humans, or at least some of us, value our brains.  Brains are what differentiate us from the animals and allows us to dominate the planet.  So if brains are so important, why are we the only species around with human-level brains?  After all, presumably every other species has had just as much time to develop big brains.  Why didn’t they?  What makes one animal grow a larger brain than another?  I’ll give you some general thoughts on the whys of growing large or small brains, then I’ll share some insights and data from a spreadsheet I put together of over 200 mammal brain and body sizes.
    First, brains are expensive for an animal.  Supporting a brain takes a little over twenty times the calories that it takes to support an equivalent weight of muscle.  There is a huge incentive for an animal to get by with as small of a brain as possible.  If an animal’s niche doesn’t require a large brain it won’t have one.  If an animal’s food supply is limited or of poor quality, there will be enormous pressure for brain sizes to stay small or even shrink over the generations.  That usually doesn’t happen because there are equally enormous pressures for brain size to grow, and generally mammal brains have grown over the generations.
        Mammal brain sizes have grown on average a little over four-fold since the end of the time of the dinosaurs, though not in the rodent-like and small insectivore niches that mammals inhabited during the time of the dinosaurs.  Apes and fruit-eating monkeys on average have brains a little over twice the size of carnivores or hoofed animals in their size range.  Humans outclass apes by a factor of three to four times in the brain-size department.  In the few cases where dolphins are in the same size range as monkeys and apes, dolphins tend to have around 1.5 times the brain size as the apes, and roughly half the size you would expect for a human that size.  Some dolphins do have larger brains than humans, but in a considerably larger body.
    So, how is that extra brain-size paying for itself in mammals in general and especially in monkeys, apes and humans?  Presumably through increased intelligence, but what is that?  Intelligence in animals isn’t a single set of abilities.  It isn’t necessarily tool use or ability to communicate.  I see intelligence as the ability to use memory and brain processing power to alter behavior in a way that makes the animal more effective in its environment.
     Brain size by itself doesn’t automatically do much for an animal.  It takes the increased brain size, plus the mechanisms to use that additional brain size in some way.  Think of it in computer terms.  When you add memory to a computer, the computer may run a little faster or a little more reliably, but the real payoff is that now you can do things that really weren’t practical before like video editing or 3D animation. In animal terms, the larger brain allows more flexible behavior.  At a certain point it allows learned behaviors to be passed on from generation to generation.  The next step is allowing learned behaviors to be passed from generation to generation without having to be demonstrated to the next generation.  That’s where we are to a certain extent.
      As the high cost of brains implies, intelligence isn’t necessarily the most adaptive way to go.  I use cockroaches and elephants to illustrate the tradeoff involved.   Elephants are very long-lived, and very intelligent in their own way.  Cockroaches are short-lived and rely mostly on instinctive behavior to survive.  If something new comes into an elephant’s environment, it has to be able to adapt to that something new.  If something new comes into a cockroach’s environment, the individual cockroaches have far less ability to adapt to it, but that doesn’t matter because they can quickly breed new cockroaches that are adapted to it.  Elephants simply can’t do that because it takes too long to make a new elephant.
    In computer terms, the individual cockroach has a highly polished set of routines in read-only-memory to call on.  If those routines don’t work in a new environment, then new cockroaches come along with slightly altered routines that do work in the new environment.  In computer terms elephants have a lot of memory and very elaborate and flexible routines to make use of that memory in order to modify behavior.  They have to be able to adapt to changes in their environment over their seventy-year life-spans, and they are.
    Most animals are somewhere between cockroaches and elephants in this tradeoff.  For instance, a gerbil has some elements of flexibility and some elements that are inflexible.  I had gerbils and way too much free time on my hands in high school, so I can tell you more than you probably want to know about their behavior.  One rather odd thing about gerbils is that they have no natural fear of predators.  A gerbil that has never encountered a cat before will attack it.  As near as I can figure out, gerbils figure out what is dangerous in their environment either by personal encounters or by having older gerbils in the colony drum their feet when something dangerous approaches.  That’s flexible, maybe even too flexible for the gerbil’s own good.
    On the other hand, in some ways gerbil behavior is very inflexible.  Gerbils love to explore, so I tried a couple of experiments when I was back in high school (remember, way, way too much free time).  I put a gerbil in a container shallow enough that it could jump out, but deep enough that the jump was difficult.  I set the container next to the arm of the couch.  Then I waited.  The gerbil would inevitably jump up onto the couch arm and pause there to look around.  I would then pick it up at set it gently back down in the container.  This would go on for 10 to 15 cycles with absolutely no variation.  Then, usually after the 12th time, the gerbil would stop, wash its face and look over the situation.  It would then repeat the jump and pause one more time.  After I put it back it would jump again, but this time it would dodge as soon as it landed.  I was ready for that, grabbed the gerbil and put it back.  The gerbil would repeat the new set of actions 10 to 15 times, then repeat the face-washing and looking things over.  It would then repeat the set of actions one more time, then add a new variation—usually jump, dodge, then run.
    The new tactic was always added onto the existing sequence, and it was always a logical answer to the challenge.  This would go on until I either found something better to do, or the tactics got effective enough that I was afraid the gerbil would get away.  As I recall it, gerbils would retain their new set of tactics for a couple of weeks or maybe a month.  A more ‘intelligent’ animal would probably develop the more effective tactics much more quickly, and that undoubtedly does have survival benefits.   
    Is an elephant better or worse adapted overall than a cockroach?  It depends on how stable the environment is.  Elephant-style adaptation tends to work well in relatively stable environments and cockroach-type animals tend to be marginalized.  In extremely unstable environments the cockroach approach seems to work better.  Want to bet on which type is most likely to recover from a catastrophic asteroid strike?  Elephant-style adaptability is also expensive.  As I mentioned earlier, big brains take an enormous amount of energy to support, so animals don’t grow them without having a very good reason to.  The brain has to allow the animal to access enough additional energy sources to offset the energy drain, or selective pressures will lead to smaller brains.    
    So what kind of animal grows large brains here on earth?  As I mentioned earlier, fruit-eating and omnivorous monkeys and apes generally outclass most carnivores and herbivores at a given size.  Monkeys with a diet mainly of leaves tend to be intermediate between fruit-eating monkeys and carnivores, probably because their relatively poor quality diet makes really large brains too expensive.  Dolphins have noticeably larger brains than apes.  Seals overlap the bottom of the monkey/ape range.  So do bears, though in the case of the bears, the overlap is entirely due to the Malaysian Sun Bear (Helarctos malayanus), which is almost exactly in the middle of the ape/monkey range.
    Among marsupials, opossums and the Australian marsupial carnivores do very poorly in the brain department, with brain sizes for opossums averaging around 14 percent of the brain you would find in a comparably-sized monkey and the Australian marsupial carnivores (Dasyures) in the 14 to 21 percent range.  That puts them at about half the brain size of a typical carnivore at best, though some of the weasels and some of the members of the mongoose family come close to overlapping the marsupial carnivores.  The extinct Tasmanian wolf does quite a bit better, at around 30 percent of what you would expect from a monkey it’s size.  A comparably-sized placental wolf would be at around 65%, but the Tasmanian Wolf does beat out quite a few placental carnivores.    
    Kangaroos and wombats do quite a bit better than the marsupial carnivores.  They actually overlap the carnivores fairly substantially.  The extinct marsupial lion, which was actually related to kangaroos rather than other Australian marsupial carnivores like the Tasmanian devil, apparently had a brain-size almost indistinguishable from normal carnivores in the same size range.    
    So what does all of this mean?  In terms of land mammals on Earth, the key to a large brain seems to be an omnivorous diet, with fruit as the major component.  That holds true mainly in the tropics because of the huge number of species of fruiting trees that a fruit-eating animal has to keep track of, and the high level of competition for the fruit.  Get to a big fruiting tree the day after a big troupe of monkeys found it, and you get famine instead of feast.  The Malaysian Sun Bear is somewhat convergent on monkeys and apes in that it is small, exclusively tropical, a good tree-climber, and a major fruit-eater.  It seems to also be convergent in terms of brain-size.    
    Marsupials have a somewhat different pattern than ‘normal’ (placental) mammals in that the largest brain-sizes are seen in big herbivores, possibly because they developed the same kind of thick interconnection between the two hemispheres of the brain that ‘normal’ mammals did.  Opossums and the Australian marsupial carnivores never developed an equivalent interconnection and they may not be able to develop specializations between the hemispheres as easy as other mammals. 
     There are no marsupial equivalents to the omnivorous/fruit eating monkeys or apes, though sugar gliders and their relatives are in some ways vaguely monkey-like.  Sugar gliders are also somehow very alien in a lot of their behavior patterns, based on the one I had as a pet—somehow a different way of being flexible and somewhat intelligent.  (to be continued)

Note: This kind of thing may be a little too academic for this group.  If so, let me know and I won't post the rest of it here.  I have created a group called SciTech for Writers, which is intended specifically for writers to share this sort of info.  If you prefer I can restrict this kind of posting to that group.  Just let me know in the comments.  The SciTech For Writers Group is at:

http://scitechforwriter.gather.com/ 

Thanks

Dale C.