marcelo_gleiser's picture
Appleton Professor of Natural Philosophy, Dartmouth College; Author, The Island of Knowledge
We Are Unique

To improve everybody's cognitive toolkit, the required scientific concept has to be applicable to all humans. It needs to make a difference to us as a species, or, more to the point I am going to make, as a key factor in defining our collective role. This concept must impact the way we perceive who we are and why we are here. Hopefully, it will redefine the way we live our lives and plan for our collective future. This concept must make it clear that we matter.

A concept that might grow into this life-redefining powerhouse is the notion that we, humans in a rare planet, are unique and uniquely important. But what of Copernicanism — the notion that the more we learn about the universe the less important we become? I will argue that modern science, traditionally considered guilty of reducing our existence to a pointless accident in an indifferent universe, is actually saying the opposite. While it does say that we are an accident in an indifferent universe, it also says that we are a rare accident and thus not pointless.

But wait! Isn't it the opposite? Shouldn't we expect life to be common in the cosmos and us to be just one of many creatures out there? After all, as we discover more and more worlds circling other suns, the so-called exoplanets, we find an amazing array of possibilities. Also, given that the laws of physics and chemistry are the same across the universe, we should expect life to be ubiquitous: if it happened here, it must've happened in many other places. So why am I claiming that we are unique?

There is an enormous difference between life and intelligent life. By intelligent life I don't mean clever crows or dolphins, but minds capable of self-awareness and the ability to develop advanced technologies, that is, not just use what is at hand but transform materials into new devices that can perform a multitude of tasks. Keeping this definition in mind, I agree that single-celled life, although dependent on a multitude of physical and biochemical factors, shouldn't be an exclusive property of our planet. First, because life on Earth appeared almost as quickly as it could, no more than a few hundred million years after things quieted down enough; second, due to the existence of extremophiles, life forms capable of surviving in extreme conditions (very hot or cold, very acidic or/and radioactive, no oxygen, etc.), showing that life is very resilient and spreads into every niche that it can.

However, the existence of single-celled organisms doesn't necessarily lead to that of multicellular ones, much less to that of intelligent multicellular ones. Life is in the business of surviving the best way it can in a given environment. If the environment changes, those creatures that can survive under the new conditions will. Nothing in this dynamics supports the notion that once there is life all you have to do is wait long enough and puff, there pops a clever creature. (This smells of biological teleology, the concept that life's purpose is to create intelligent life, a notion that seduces many people for obvious reasons: it makes us the special outcome of some grand plan.) The history of life on Earth doesn't support this evolution toward intelligence: there have been many transitions toward greater complexity, none of them obvious: prokaryotic to eukaryotic unicellular creatures (and nothing more for 3 billion years!), unicellular to multicellular, sexual reproduction, mammals, intelligent mammals, edge.org...Play the movie differently, and we wouldn't be here.

As we look at planet Earth and the factors that came into play for us to be here, we quickly realize that our planet is very special. Here is a short list: the long-term existence of a protective and oxygen-rich atmosphere; Earth's axial tilt, stabilized by a single large moon; the ozone layer and the magnetic field that jointly protect surface creatures from lethal cosmic radiation; plate tectonics that regulate the levels of carbon dioxide and keep the global temperature stable; the fact that our sun is a smallish, fairly stable star not too prone to releasing huge plasma burps. Consequently, it's rather naive to expect life — at the complexity level that exists here — to be ubiquitous across the universe.

A further point: even if there is intelligent life elsewhere and, of course, we can't rule that out (science is much better at finding things that exist than at ruling out things that don't), it will be so remote that for all practical purposes we are alone. Even if SETI finds evidence of other cosmic intelligences, we are not going to initiate a very intense collaboration. And if we are alone, and alone have the awareness of what it means to be alive and of the importance of remaining alive, we gain a new kind of cosmic centrality, very different — and much more meaningful — from the religiously-inspired one of pre-Copernican days, when Earth was the center of Creation: we matter because we are rare and we know it.

The joint realization that we live in a remarkable cosmic cocoon and that we are able to create languages and rocket ships in an otherwise apparently dumb universe ought to be transformative. Until we find other self-aware intelligences, we are how the universe thinks. We might as well start enjoying each other's company.