If we ever find extraterrestrial life, what will it look like?
I think the answer is pretty simple: bacteria. After all, bacteria have inhabited our own world for most of its 4.5 billion year history. It’s only in the past 500 million years or so — a mere one-ninth of Earth’s existence — that multicelled creatures have arisen.
Even today bacteria outweigh all the other forms of life on the planet. So don’t be surprised when the first forms of life we find on another planet are microscopic, single-celled bacteria. Or their like.
But what about intelligent life? We can’t expect to find brainy bacteria. Intelligent life requires more size and complexity, doesn’t it?
Probably. We simply don’t know, because the only sample of intelligent life we know of is us, ourselves.
In science-fiction stories and films, intelligent aliens are almost always depicted as two-legged critters very much like ourselves. Maybe they are smart lizards, or cats, or bears — but they almost always have the same basic body plan as we do.
You can’t much blame the filmmakers: they have to work with human actors and makeup people. But is it likely that intelligent aliens will be built much the same as we?
How much of our own physical structure is due to engineering necessity and how much is due to accidents of history?
It makes some engineering sense to place the most important sensory organs as close to the brain as possible. That’s why our eyes, ears, noses and tongues are in the head, near the brain that receives and interprets their signals. This is true far down the history of life on Earth: flatworms have their eyespots next to their rudimentary brains.
Paleontologists have surmised that if the dinosaurs hadn’t been wiped out in the colossal meteor impact of 65 million years ago, they might eventually have produced an intelligent species. Their imaginative drawings of such a hypothetical creature, though, inevitably show a bipedal animal that looks a lot like us, except for a lizard-like head.
However, an intelligent extraterrestrial might not be a land dweller at all. The planet Jupiter is about 11 times bigger than Earth, and covered with swirling colorful clouds. Beneath those clouds, physicists have calculated, there must be a planetwide ocean 10 times bigger than Earth, with no land anywhere in its enormous vastness.
What kind of creatures might live in that ocean? Could they develop intelligence? That’s a problem I’m struggling with in the novel I’m writing at the moment. Its working title is “Leviathans of Jupiter;” it’s about enormous creatures living in that world-spanning ocean, creatures the size of mountains.
Could they be intelligent? And if they are, would we ever be able to make meaningful contact with them? Perhaps we wouldn’t recognize the intelligence of an extraterrestrial species, or even if we did we mightn’t be able to understand each other.
Which brings up another question. We tend to assume that if life begins on a planet, in time an intelligent species will arise there. But is this inevitable?
Remember, it took planet Earth 4.5 billion years to come up with an intelligent race. Countless species of creatures came and went, many of them existing for many millions of years, without developing intelligence.
Is intelligence an inevitable outcome of life? Or is it merely another adaptation that organisms have utilized over the long eons of Earth’s history, like wings or gills or the ability to harness sunlight for energy.
Intelligence seems inevitable to us because we have developed it and used it to our enormous benefit. But all the other forms of life on our world have gotten along perfectly well without it — including the bacteria, the most successful life forms of all.
Life may be abundant throughout the universe, as ordinary as stars and rocks. But intelligence may be rare, perhaps even unique.
We might be alone, after all.
Or, as the British biologist J.B.S. Haldane put it, the universe is not only queerer than we suppose, it is queerer than we can suppose.
Quite a challenge for a science-fiction writer!
Bova, a Naples resident, is the author of more than 120 books, including “Faint Echoes, Distant Stars,” a nonfiction study of the search for life — and intelligence — on other worlds. Bova’s Web site address is www.benbova.com