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Evolution – it’s not over yet
By Tom Chivers Science
Last updated: September 10th, 2013
From Wednesday's Daily Telegraph: Sir David Attenborough has claimed that the process of natural selection has stopped. Tom Chivers suggests otherwise
Like every other species on Earth, Homo sapiens is the product of more than three billion years of evolution: random, blind changes put through the filter of natural selection, leading from one simple original form to all the startling variety of life we see around us. Humanity’s lineage split with that of our closest relatives, the chimpanzees, six million years ago, and our ancestors have been evolving separately ever since. In that time we have gone from short, robust, hairy apes – perhaps partly tree-dwelling and knuckle-walking, like chimps – to tall, gracile, naked humans. It has been quite a journey.
But is that journey over? It might be, according to Sir David Attenborough, who said in an interview with the Radio Times: “I think that we’ve stopped evolving. Because if natural selection, as proposed by Darwin, is the main mechanism of evolution – there may be other things, but it does look as though that’s the case – then we’ve stopped natural selection.”
To support his case, he points out that, unlike any other species, we can use technology to keep ourselves alive until breeding age, when otherwise we would have died. Specifically, he points towards the vast improvement in infant mortality rates: “We stopped natural selection as soon as we started being able to rear 95-99 per cent of our babies that are born. We are the only species to have put a halt to natural selection, of its own free will, as it were.”
Human evolution has fascinated us since Darwin pointed out that we evolved: Darwin himself spent a long time with an orang-utan in London Zoo, examining its facial expressions, and wrote The Descent of Man, applying evolutionary theory to human history and discussing how humans are related to the rest of the apes. It’s a subject of extraordinary controversy – and not just with stubborn creationists.
Suggestions that differences in human behaviour might be evolved – for instance, that women and men have innately different approaches to sex or child-rearing – led to uproar. One evolutionary biologist, E.O. Wilson, had a cup of water hurled on him during a lecture, to chants of “racist Wilson you can’t hide, we charge you with genocide”, for suggesting that human social behaviour and morality are the products of natural selection, of our genes.
And what will happen next fascinates us even more. The “next stage” of human evolution has been a staple of science fiction since the genre’s earliest days – think of H.G. Wells’s Morlocks and Eloi. Arthur C Clarke, in Childhood’s End, pictured us leaving behind our physical beings and becoming creatures of pure energy. Modern superhero movies imagine “mutants” with psychic powers or wings.
Attenborough, though, is suggesting something at once prosaic and startling: that human evolution ends here, that we are the final stop on the journey. You can understand his reasoning. After all, if we (at least in the affluent, technologically advanced West) can take even the most vulnerable babies, babies who would have died within hours of birth a hundred years ago, and keep them alive – essentially repair them so that they can live into adulthood and breed – have we not ended the cruel process of natural selection?
It’s not that simple, says Dr Adam Rutherford, a geneticist, author of Creation and a BBC colleague of Sir David. “He is absolutely right that the selection pressures on humans have radically changed,” says Dr Rutherford. “And he’s right that one of the most profound changes to those pressures is infant mortality rates. But that’s not really, in a pure scientific sense, how evolution works.”
The fact that certain evolutionary pressures have been reduced – for example, the requirement for a baby’s lungs to be fully developed and functional by birth, now that we can keep that baby alive on a respirator until its lungs are grown – does not mean that all of them have gone. “The robust answer to the question 'are humans evolving?’ is: we don’t know, because the timespans are too short to make a judgment,” says Dr Rutherford.
While we can watch evolution happen in viruses and bacteria – or fruit flies, or mice – human generations are just too slow; even the longest-lived of us can only reasonably hope to see great-grandchildren. Our split with the chimps takes us back to our great times-250,000 grandparents.
We can look at our own recent history, though, and at our genes. Several studies have suggested that human evolution has actually speeded up, not slowed down, since the advent of agriculture in the last 10,000 years – an eyeblink in evolutionary terms. In the past few thousand years some humans have evolved the ability to digest milk, unlike any other adult mammals.
“Another example is the Arya Vaishya caste, in India,” says Dr Rutherford. “It was noticed in the Nineties that this caste, a merchant class, responded differently to a particular anaesthetic. Everyone else was unconscious for about 10 minutes, but members of this caste stayed unconscious for five hours. A genetic analysis was carried out, and it was found that it came from a single mutation in an individual several thousand years ago, and has spread to every Vaishya.”
That is, he points out, an example of a genetic mutation arising and spreading throughout an entire population of millions of people, thanks to the behaviour of that population. That is a clear example of rapid human evolution – and what’s more, it happened without any noticeable physical change at all. It wasn’t until the invention of a particular class of anaesthetic, thousands of years later, that it had an effect.
“If you look at changes in the frequency of genes in a population, which is the true measure of evolution, then I don’t think there’s any evidence to suggest that we’re not evolving,” says Dr Rutherford. The question, of course, is how we’re evolving. There have been various suggestions, of varying stupidity, up to and including the suggestion that we’ll evolve fatter thumbs to help us text. (“That’s called Lamarckism, and it’s just wrong. The Jewish people have been cutting foreskins off their boys for 5,000 years and one hasn’t been born without a foreskin yet,” snorts Dr Rutherford.) More obviously plausible hypotheses include the idea that our tendency to have children later in life will select against people who are unable to do so.
What won’t necessarily happen is that we’ll become cleverer, or in any arbitrary way “better”, than we are now. Evolution doesn’t work that way. The 2006 film Idiocracy suggested that clever people are having fewer and fewer children, while stupid people are having more, so the future of humanity is one of everyone being thick. That was a joke, but it illustrates quite neatly that evolution is not a stairway to a glorious pinnacle called “humanity”; intelligence is not the culmination of evolution, it’s just one tool that works for one species at the moment, just as sonar works for bats. If powerful brains become less useful in future, then we can expect them to dwindle away, like the eyes of cave fish – they’re expensive, energy-draining things, and natural selection is a brutal accountant.
Pace Sir David, then, because it seems human evolution isn’t over. From the evidence of our genes, it’s ticking along, perhaps faster than before. Whether it will change the way we look, or the way we think – and if so, how – is a harder question, simply because it takes too long for results to appear.
“The only real way we can determine whether we are physically evolving,” Dr Rutherford says, “is to come back in 10,000 years and see if we’re different.” 8)
http://blogs.telegraph.co.uk/news/tomch ... -over-yet/
By Tom Chivers Science
Last updated: September 10th, 2013
From Wednesday's Daily Telegraph: Sir David Attenborough has claimed that the process of natural selection has stopped. Tom Chivers suggests otherwise
Like every other species on Earth, Homo sapiens is the product of more than three billion years of evolution: random, blind changes put through the filter of natural selection, leading from one simple original form to all the startling variety of life we see around us. Humanity’s lineage split with that of our closest relatives, the chimpanzees, six million years ago, and our ancestors have been evolving separately ever since. In that time we have gone from short, robust, hairy apes – perhaps partly tree-dwelling and knuckle-walking, like chimps – to tall, gracile, naked humans. It has been quite a journey.
But is that journey over? It might be, according to Sir David Attenborough, who said in an interview with the Radio Times: “I think that we’ve stopped evolving. Because if natural selection, as proposed by Darwin, is the main mechanism of evolution – there may be other things, but it does look as though that’s the case – then we’ve stopped natural selection.”
To support his case, he points out that, unlike any other species, we can use technology to keep ourselves alive until breeding age, when otherwise we would have died. Specifically, he points towards the vast improvement in infant mortality rates: “We stopped natural selection as soon as we started being able to rear 95-99 per cent of our babies that are born. We are the only species to have put a halt to natural selection, of its own free will, as it were.”
Human evolution has fascinated us since Darwin pointed out that we evolved: Darwin himself spent a long time with an orang-utan in London Zoo, examining its facial expressions, and wrote The Descent of Man, applying evolutionary theory to human history and discussing how humans are related to the rest of the apes. It’s a subject of extraordinary controversy – and not just with stubborn creationists.
Suggestions that differences in human behaviour might be evolved – for instance, that women and men have innately different approaches to sex or child-rearing – led to uproar. One evolutionary biologist, E.O. Wilson, had a cup of water hurled on him during a lecture, to chants of “racist Wilson you can’t hide, we charge you with genocide”, for suggesting that human social behaviour and morality are the products of natural selection, of our genes.
And what will happen next fascinates us even more. The “next stage” of human evolution has been a staple of science fiction since the genre’s earliest days – think of H.G. Wells’s Morlocks and Eloi. Arthur C Clarke, in Childhood’s End, pictured us leaving behind our physical beings and becoming creatures of pure energy. Modern superhero movies imagine “mutants” with psychic powers or wings.
Attenborough, though, is suggesting something at once prosaic and startling: that human evolution ends here, that we are the final stop on the journey. You can understand his reasoning. After all, if we (at least in the affluent, technologically advanced West) can take even the most vulnerable babies, babies who would have died within hours of birth a hundred years ago, and keep them alive – essentially repair them so that they can live into adulthood and breed – have we not ended the cruel process of natural selection?
It’s not that simple, says Dr Adam Rutherford, a geneticist, author of Creation and a BBC colleague of Sir David. “He is absolutely right that the selection pressures on humans have radically changed,” says Dr Rutherford. “And he’s right that one of the most profound changes to those pressures is infant mortality rates. But that’s not really, in a pure scientific sense, how evolution works.”
The fact that certain evolutionary pressures have been reduced – for example, the requirement for a baby’s lungs to be fully developed and functional by birth, now that we can keep that baby alive on a respirator until its lungs are grown – does not mean that all of them have gone. “The robust answer to the question 'are humans evolving?’ is: we don’t know, because the timespans are too short to make a judgment,” says Dr Rutherford.
While we can watch evolution happen in viruses and bacteria – or fruit flies, or mice – human generations are just too slow; even the longest-lived of us can only reasonably hope to see great-grandchildren. Our split with the chimps takes us back to our great times-250,000 grandparents.
We can look at our own recent history, though, and at our genes. Several studies have suggested that human evolution has actually speeded up, not slowed down, since the advent of agriculture in the last 10,000 years – an eyeblink in evolutionary terms. In the past few thousand years some humans have evolved the ability to digest milk, unlike any other adult mammals.
“Another example is the Arya Vaishya caste, in India,” says Dr Rutherford. “It was noticed in the Nineties that this caste, a merchant class, responded differently to a particular anaesthetic. Everyone else was unconscious for about 10 minutes, but members of this caste stayed unconscious for five hours. A genetic analysis was carried out, and it was found that it came from a single mutation in an individual several thousand years ago, and has spread to every Vaishya.”
That is, he points out, an example of a genetic mutation arising and spreading throughout an entire population of millions of people, thanks to the behaviour of that population. That is a clear example of rapid human evolution – and what’s more, it happened without any noticeable physical change at all. It wasn’t until the invention of a particular class of anaesthetic, thousands of years later, that it had an effect.
“If you look at changes in the frequency of genes in a population, which is the true measure of evolution, then I don’t think there’s any evidence to suggest that we’re not evolving,” says Dr Rutherford. The question, of course, is how we’re evolving. There have been various suggestions, of varying stupidity, up to and including the suggestion that we’ll evolve fatter thumbs to help us text. (“That’s called Lamarckism, and it’s just wrong. The Jewish people have been cutting foreskins off their boys for 5,000 years and one hasn’t been born without a foreskin yet,” snorts Dr Rutherford.) More obviously plausible hypotheses include the idea that our tendency to have children later in life will select against people who are unable to do so.
What won’t necessarily happen is that we’ll become cleverer, or in any arbitrary way “better”, than we are now. Evolution doesn’t work that way. The 2006 film Idiocracy suggested that clever people are having fewer and fewer children, while stupid people are having more, so the future of humanity is one of everyone being thick. That was a joke, but it illustrates quite neatly that evolution is not a stairway to a glorious pinnacle called “humanity”; intelligence is not the culmination of evolution, it’s just one tool that works for one species at the moment, just as sonar works for bats. If powerful brains become less useful in future, then we can expect them to dwindle away, like the eyes of cave fish – they’re expensive, energy-draining things, and natural selection is a brutal accountant.
Pace Sir David, then, because it seems human evolution isn’t over. From the evidence of our genes, it’s ticking along, perhaps faster than before. Whether it will change the way we look, or the way we think – and if so, how – is a harder question, simply because it takes too long for results to appear.
“The only real way we can determine whether we are physically evolving,” Dr Rutherford says, “is to come back in 10,000 years and see if we’re different.” 8)
http://blogs.telegraph.co.uk/news/tomch ... -over-yet/