Is Intelligent Life Inevitable?

One of the things that gets a lot of coverage in the news these days is the search for exo-planets circling around other stars in our galaxy and in the universe at large. Recent advances in technology have allowed astronomers to perform ever more sophisticated surveys and analyses on behalf of that search. And indeed, recent results suggest that a sizable number of stars appear to have planets rotating around them. Beyond that, our search is preoccupied with how many of those planets might be located in the “Goldilocks zone,” the zone in which liquid water is possible and other conditions are at least not prohibitive to the evolution of life in whatever form.

In our exploration of our own moon and now of Mars, we are looking for any kind of microscopic evidence that might indicate either a form of life itself, albeit adapted to very punishing environmental conditions, or the existence of some form of life in the past when, particularly in relation to Mars, conditions might have been considerably more life-friendly.

Finding any signs of life or perhaps precursor organic compounds, even on an asteroid, would be a huge event, suggesting that life itself is not a uniquely earth-centric phenomenon. (“Eureka, we are not alone!”)

Beyond that highly preliminary but significant discovery, the question then becomes, on a practical level, what would the discovery of primitive organisms on other planets or in other solar systems mean to us?

The presence of ancient organic molecules on Mars, for example, would probably have far less effect on the development of the planet for human habitation than the presence of millions of natives in the Americas, with all their tribes and civilizations, did to the European explorers in their march to conquer new lands.

It would, of course, be extremely fascinating to discover other advanced life forms – native flora and fauna – in some quite different ecosystem on a planet surrounding a distant star. But on a rather pragmatic level, most alternate varieties of plants and animals, potentially based on a quite different kind of chemical structure, would not pose any kind of a threat to us.

Our real preoccupation, the question that animates public interest in science fiction, is the idea that we might discover other intelligent beings or species – that is beings we might communicate with and who might, in the long run, be, either friends or foes.

There is an underlying assumption, I believe, that if there is a planet elsewhere that lies in the Goldilocks zone and life arises there, that in time a dominant intelligent species will arise, just as hominids, and ultimately modern man, did here on earth. It seems a relatively reasonable and logical extrapolation, since the story seems so clear in our own case.

If we look at the evidence of our own planet, however, which is for the most part extremely hospitable to life, the argument becomes somewhat less compelling. Earth today has six hospitable continents. For the most part, these continents have been separated by large bodies of water, or by natural barriers such as enormous mountain ranges or arid deserts. If we look at the history of the Americas for example, even though there is a land bridge connecting them they remain largely separate in terms of ecosystems.

Australia is a particularly good example of an isolated environment. It is the only continent where we find marsupials, and prior to the arrival of man – particularly in the form of European colonists – the entire spectrum of wildlife there was dramatically different from what we find in Asia or in Europe, or for that matter in the Americas.

Each of these unique environments and ecosystems has a history dating back hundreds of millions of years, and we have seen huge shifts and changes, such as the era of the dinosaurs which lasted well over 150 million years (and produced no dinosaur equivalents of humans).

Against this staggering timeline, the first step in human evolution – the emergence of bipedalism – began only about 4 million years ago, with the most primitive hominid ancestors dating back perhaps 7 million years. (And even bipedalism was a fluke brought about by climate change in Africa, when conditions forced us to adapt to life on the savanna.)

If we had been explorers from another solar system surveying these primitive hominids, would they have been any more interesting than lions, tigers, giraffes, hyenas, and so on? Today's chimpanzees and bonobos, our closest cousins, while intelligent in their own way, would hardly qualify in sci-fi terms as an “intelligent species.” (Sorry, Planet of the Apes fans.)

Modern humans first appeared around 300,000 years ago, the blink of an eye in Earth's history. Even then, humans remained in Africa until a mere 70,000 years ago or so, at which point, they began a pattern of rapid migration that led them to colonize every continent and to become the dominant species virtually everywhere.

Where does this leave us? Man is so dominant today that he looks like an inevitability. And yet, although there were a variety of hominid species along the way, man arose only in Africa. (South America, with its own species of monkeys to provide evolutionary fodder, shows no hint of intelligent apes.) Even with a full range of climates in many places around the world, and even with an incredible variety of very different species arising across all these geographies, without Africa, it seems likely that our most intelligent species in Europe, for example, might be wolves or bears, with a similar absence of next-level-intelligence species on any of the other continents. It didn't happen, and gave no signs of happening. Modern humans encountered the Neanderthals in Europe, and the Denisovans in Asia, but these were our cousins, who shared our own African roots.

So, what is the lesson of Planet Earth? Is it that, given a Goldilocks environment, life is likely to arise and to diversify and flourish, and that human space explorers will one day get to visit the kind of colorful multi-species bar depicted in Star Wars? Or is it that our kind of intelligence is essentially a fluke, that arose only on one continent and for much of its existence its survival was tenuous at best?

Many animal species (and perhaps even some kinds of plant species) exhibit some kind of intelligence. Some species of animals, including some bird species and species like porpoises and dolphins, can exhibit very substantial intelligence. But we are the only species that has been able to leverage our intelligence on a level that has transformed our planet (not necessarily for the good). We are the only species that has developed technology, and the only species that has developed techniques of communication that allow us to record the past and speculate about the future. While some other species have managed to hitch a ride on accidental rafts and arrive at isolated islands, we are the only species that has the potential to initiate our own exploration of planets and solar systems beyond our own.

So, are we a one-off, or part of a huge Galactic and intergalactic family that we have yet to meet?

[03/03/21]