Visualizing E.T.

New Scientist has a short piece discussing what interstellar life might look like. For example, they note the obvious truth that intelligent life will almost certainly be an omnivorous or carnivorous species. However they completely miss the reason for this:

"Predators tend to be more intelligent," says evolutionary biologist Lynn Rothschild of NASA's Ames Research Center in Moffett Field, California. "They have to do more moving around to outsmart the other guy. You don't have to be terribly intelligent to grab a leaf of lettuce."

One would think that an evolutionary biologist would be aware of the greatest predator species in the history of the planet, Tyrannosaurus rex, who was at or near the top of the food chain for millions of years, yet had a cerebrum the size of a walnut. Or perhaps an evolutionary biologist would be aware of a group of animals that have dominated the aquatic food chain for hundreds of millions of years, also known as "sharks", who have brains so small that they are hard to find during dissection (for example a 950 lb shart has a 1.2 ounce brain). And one would assume an evolutionary biologist would know of the "gorilla", a super-intelligent (smart enough to learn sign language) herbivorous creature that lives peacefully in jungles throughout Africa.

Being a predator does not, in any way, require a species to be intelligent, or even more intelligent than their prey. It only requires them to be better at killing their prey than their prey is at escaping death.

Rather, the reason extra terrestrials are likely to be omnivorous or carnivorous is simply that "meat goes farther" in the sense of nutritive power. For example, lions eat one meal every several days, whereas ungulates in the same ecology must eat almost constantly to survive. Matt Ridley, in his pivotal "Guns, Germs, and Steel" argues that the human species liberated itself when it became intelligent enough to hunt in excess of its nutritive minimums, i.e. when food was aplenty, we had time to sit on our butts and dream up better ways to hunt. And then we hunted even more efficiently, which freed up even more time, etc etc until you end up with a society where only a small percentage actually are food-gatherers and the rest engage in civil activities like clothes-making, security forces, and food-preparation.
And so that would be why extra terrestrials would have meat in their diet - they had to have protein to get over the hump.

This all assumes, of course, that E.T.'s home planet contains biology that follows the evolutionary rules to which we have grown accustomed here. It could be that on an alien planet, the plants contain huge amounts of protein, and the herbivorous species that grow big enough or grow defense mechanisms adept enough to outpace predators become the dominant species on the planet, in which case E.T. might arrive on Earth in the form of a cud-chewing brachiosaurus.


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