Read more: “Existence special: Cosmic mysteries, human questions“
WRESTLING with mortality is difficult. But it is not just the prospect of personal annihilation that we have the dubious luxury of contemplating. One day, humanity itself will cease to exist. Like all species, we will either become extinct or evolve into something else. From a purely existential perspective the latter sounds infinitely preferable. So what are our chances?
First the good news: time is on our side. The average mammalian species lasts around 1 million years before it evolves into something else or dies out. By that reckoning, Homo sapiens has some 800,000 years to play with.
Advertisement
But that’s assuming we are just another mammal. It is tempting to think that we have changed the game so drastically that the normal rules do not apply. Have we?
Let’s deal with evolution first. There are two key ingredients: variation and selection. The key generator of variation is genetic mutation, and we certainly haven’t broken free of that. “If anything, we are probably increasing the rate of mutational change,” says Christopher Wills at the University of California, San Diego, noting that our world is awash with human-made mutagens.
But it is conceivable that we have changed the rules of natural selection. In general, individuals who are better adapted to their environment are more likely to survive and pass on their genes. Is that still true for humans when modern medicine and technology have increased everybody’s ability to survive?
It seems that it is. Advances in genomic analysis make it clear that natural selection is still alive and kicking. One study found that around 1800 gene variations have become common in the past 50,000 years (). Another study found that selection actually accelerated over this time, perhaps because by colonising the world and creating complex cultures we have subjected ourselves to a wide variety of new selection pressures ().
“There is no reason to think that humans will stop evolving,” says Stephen Stearns at Yale University, whose research reveals continuing evolution in modern populations. “The only question is in what ways will we change as we continue to evolve.”
“The only question is in what ways we will change as we continue to evolve”
Without strong, universal forces shaping our entire species, we could evolve aimlessly, but even then the cumulative effects would be significant. Palaeoanthropologist Chris Stringer from the Natural History Museum in London foresees a distant future hundreds of thousands of years from now when our descendents have accrued so many genetic and physical changes that they could no longer interbreed with today’s humans, and would therefore be a new species.
Presumably it would be recognisable as a hominin, but what exactly it might look like is anybody’s guess.
Dramatic events
Dramatic events would speed things up. “A pandemic could swiftly reduce the human population by 90 per cent or more,” says philosopher Dan Dennett from Tufts University in Medford, Massachusetts. Depending on who was able to survive, the humans that passed through this bottleneck could emerge as a new species.
Extreme climate change could have the same effect. And if some people left Earth and set up home elsewhere, speciation seems inevitable, says Wills.
Advances in reproductive technology might allow us to direct our own evolution by picking the characteristics we most desire for our offspring. We could even choose to become superhuman as advances in computing, robotics, biotechnology and nanotechnology enable us to rebuild and extend our bodies and brains. “Very few people will opt out completely,” predicts futurologist Ray Kurzweil. “Kind of like the Amish today.”
Of course extinction is also a possibility. In the wild, extinctions occur for a variety of reasons, with competition from other species, predation and loss of genetic diversity among the leading causes. Given our huge population and our dominance over other species none of these seem to be a threat.
But we may well do unto ourselves what we have done to so many other species and cause enough environmental destruction to drive ourselves to extinction. We also have no control over phenomena that have wreaked havoc in the past, such as asteroids, supervolcanoes and the like.
Meanwhile, our species’ indomitable curiosity may lead us to create a new form of annihilation – perhaps with atomic particles, “grey goo” or a lethal bioengineered life form.
Although we can’t predict our future, we can say one thing for certain: our existence is just a passing whim.
Read previous article: “Existence: Is there more than one me?“
Read next article: “Existence: What happens when computers overtake us?“
