Living Without Brains

An immature sea squirt is mobile and has a brain of sorts, but when it grows to maturity, it attaches itself to a rock and settles down for the rest of its life. With no further need for a higher nervous system -- the adult stage consists of "not much more than a mouth (branchial siphon), a stomach, and an exit tube (atrial siphon)" and "is a hermaphrodite, with one testis and one ovary" -- it eats, or more accurately absorbs, its "notochord, tail, sense organs and nervous system":

Why the Sea Squirt Eats Its Brains Out

Scientists tell us evolution has no "goal." Evolutionary "success" equals how many copies of itself a gene can generate. In the words of Heinlein's Lazarus Long, a zygote is a gamete's device for making more gametes (an update of the homespun saying, "A hen is an egg's way of making more eggs").

And if evolution had a goal, it wouldn't be brains. Those organs require a lot of energy to produce and maintain. Why bother growing one, especially a large one, if you don't need it?

Because of our relatively huge brains and the things we've used them to create, Homo sapiens tends to regard ourselves as Earth's dominant species. Alien explorers studying our planet, though, might decide it's ruled by bacteria, which vastly outnumber us and have existed a lot longer. In fact, there are slightly more bacterial cells than human cells in our bodies. The alien biologists might think we function mainly as hosts for microbial life.

Limiting observation to multicellular organisms, extraterrestrial observers could make a case for Earth's being ruled by grass. According to an AI answer to my question about grasslands, they occupy "roughly 15.8 to 21.6 million square miles, covering about 31% to 43% of the Earth's land surface." Moreover, grasses obviously keep human beings as slaves. We feed them, encourage them to reproduce, and protect them from predators. Millions of miles of grasses such as wheat exist and thrive thanks to our labors.

Why would a species need a brain when it can entice us big-brained, mobile, technology-using creatures to serve it?

Margaret L. Carter

Please explore love among the monsters at Carter's Crypt.