Is human evolution over?
What if this is as good as it gets?
Melvin Udall's wicked one liner in the film "As Good As It Gets" may have been intended to pile on the pathos for a group of depressed psychiatric patients, but the phrase works equally well as a sub-heading for Steve Jones' lecture on human evolution.
The point the celebrated geneticist and author is making is that we've reached Nirvana: If you want to know what utopia looks like, he says, just look around you. The human race has reached the point where it can step off the evolutionary treadmill.
Advances in technology, medicine and culture mean it isn't just the fittest who get to pass their genes on to the next generation. In ancient times half our children would have died before the age of twenty. In western societies today 98% survive to the age of 21, and life expectancy is so good that even eliminating accidents and infectious disease would only raise it by another year or two. These days almost everyone gets to hand their genes on through their children.
Mutation too is slowing down as the average age at which men reproduce has fallen. Unlike women, men never rest...when it comes to making sperm. By the time the average man is 28 he's copied and pasted the original sperm - the one he got from his father - about 300 times. The figure for a fifty year old man is well over a thousand. So the fewer older fathers there are the less chance there is for random mutations to slip into the copying process and be passed on to the next generation.
The increasing ease of global travel also means that modern human populations are continually stirring and homogenising the genetic pot. While small, isolated populations can evolve quite quickly, a global gene pool acts to block evolutionary change - the future is brown.
The result is that we're no longer subject to the driving force of evolution - natural selection. We've reached stagnation.
It's a controversial view, and plenty of geneticists believe it's a mistake to try and predict future patterns in evolutionary development. Chris Stringer at the Natural History Museum points to the fate of early hominids like the neanderthals. Natural selection was driving stone age people to get bigger and stronger, but then quite suddenly, they were replaced by smaller, lighter people migrating out of Africa.
Others argue that humans are becoming less brainy and more neurotic, and still others that we're getting more brainy but less robust.
So what's the prognosis for a species that ceases to evolve? Well, presumably there's a chance that others, perhaps our closest relatives like Chimps and Gorillas might catch us up. Then again maybe the challenge to our supremacy will come from an unexpected quarter...perhaps Dolphins will inherit the earth.
Given the glacial pace of evolutionary change we probably won't have to worry about that for thousands of years. But the steady accumulation of random mutations in the gene pool does pose more of a problem. Without natural selection to winnow out the weak medical science could have its work cut out in years to come.
Then again, perhaps we'll get so smart we'll be able to repair and augment our children's DNA. Then we really will have triumphed over evolution.