Evolution: the end, or a new beginning?
| April 27, 2011 | Posted by Elliot Davies under international, science |
Is human evolution stagnating? It certainly is, states Professor Steve Jones, celebrated author and geneticist and one of the foremost authorities on evolution, who argues that the driving forces behind our evolution are one by one coming to a standstill.
One such driving force is Darwin’s natural selection, the well-known process by which the best adapted creatures survive while those who do not fit their environment perish. But the trappings of modern society could be rendering all that irrelevant; whereas in the not-so-distant past half of all human children would have died by age 20, these days around 98 per cent of children are reaching at least age 21. According to Professor Jones, advancements in medicines and diets mean our life expectancy is now so high that eliminating infectious diseases and accidents would only raise it by another two years at most. These days everyone has the possibility to pass on their genes to the next generation, not just those best adapted to their environment.
The other problem with natural selection is that it only works when the environment is unchanging for many generations. For example, if the planet entered a cold period then over time the population would evolve – humans with better resistance to the cold would survive more often than those who were better adapted to hotter climates, and so the entire population would gradually gain better resistance to the cold. But this couldn’t happen if the temperature kept shifting every hundred years, say, because natural selection wouldn’t know which way to go.
Professor Steve Jones argues that human evolution is coming to a standstill.
In our case, it is not just the temperature that is changing but the entire environment, and we’re the ones altering it. 10,000 years ago we switched from nomadic hunter-gatherer groups to living in static settlements and farming, and natural selection started favouring those with better agrarian skills, or those who were suited to working outdoors. Then we industrialised, and so natural selection changed to favour those with the ability to work indoors in factories. Since then we have altered our society yet again so that those with intellectual ability are now more likely to succeed, but who knows what our world will look like in another 100 years? Between our unstable environment and everyone having the chance to reproduce, we don’t give natural selection a chance.
Another cause of evolutionary change is mutation – not just from chemicals and radioactivity, but from natural errors in the reproductive process. In fact, one of the most important sources of mutation and variation comes from sperm; for a 29-year-old father, which is the average reproductive age in the West, there are about 300 changes between the DNA sequences of the sperm that created him and the one he passes on. For a 50-year-old father, however, there are well over 1000 changes. But the age of reproduction is falling – most men will not conceive after they turn 35 – leading to fewer older fathers and, correspondingly, a drop in the number of genetic mutations.
The final ingredient in evolution is randomness, but even this is decreasing with the advent of globalisation. That’s right – the same process studied in Geography lessons that big businesses so embrace could be leading to the end of human evolution. The development of agriculture, says Jones, means humans are now 10,000 times more common than we should be by the standards of the rest of the animal kingdom, and those isolated populations which might evolve differently are being lost as the entire world enters one big genetic ‘mixing pot’.
Of course, even proponents of the theory note that it can only really apply to the Western world. In places like Africa, where medicines and higher standards of living are not so readily available, the fittest and most adaptable populations will still outlast the weaker ones. A good example is AIDS – if a gene developed which gave immunity, it would quickly spread throughout the continent (and indeed the world) as the virus would kill those who were not immune, which shows evolution is still active.
There are scientists who disagree with Jones’ theory, such as Professor Chris Stringer at the Natural History Museum in London, who argues that it is near-impossible to guess at future patterns. For example, Stone Age people in Europe 50,000 years ago were trending towards becoming larger and stronger until they were suddenly replaced by lighter, more intelligent humans migrating from Africa, and Stringer argues that evolutionary events like this cannot be predicted.
But if our evolution really is stagnating, could anything kick-start it again? One theory suggests that a sudden and considerable change in the global environment, such as a massive natural disaster, would allow natural selection to act again as those people best suited to the new conditions find themselves better able to survive. But there is no telling what effects such an event might have on the so-called gene-environment feedback loop; if the survivors are unable to form social groups our entire society could simply evolve towards brutishness. Alternatively, something like the weakened ozone layer could even now be filtering out those people with less natural protection from the sun.
Radical Evolution, by Joel Garreau.
The other option, which is both darker and more intriguing in equal measure, is that with advancements in technology we may be able to engineer our own evolution. Joel Garreau, one such scientist in this area of “radical evolution”, sets out his idea of the GRIN technologies (Genetics, Robotics, Information and Nanotechnology) which would make this possible. But if we learn to freely alter our DNA, what characteristics should we change? Do we remove those mutations with a tendency towards cancer, or should we make ourselves immune to disease? The possibility for eugenics is high; where we do we draw the line? After all, why spend money to eliminate back or joint problems if these only develop after child-bearing age? It’s not as if we need to be in top physical condition any longer to survive, either.
Whether we have halted natural evolution as a species remains unclear, but with technology marching relentlessly ahead we do need to make sure that we’re prepared to handle the consequences of our naturally selected intelligence.
I don’t like any idea which suggests we go back to social Darwinism – I prefer ‘survival of all’ to ‘survival of the fittest’. To me, science is sometimes good, when its production is beneficial to the human race, but I can’t see any moral argument that could possibly allow the suggestion that we go as far as to let people die just so that evolution can continue.
As for manual alteration of human characteristics, I once again don’t like it unless it would be possible to offer as a free global service. Nobody is at all better than anybody else, and the creation of a separate race due to differences in money etc. can only serve to a) cause discrimination based on that and b) widen the wealth gap.
A very enjoyable read Elliot. I have a few thoughts:
In society, those with higher intellectual abilities are not more likely to succeed per se. Very few people actually die and are unable to reproduce because they are unintelligent. The shift towards higher intelligence in the population is more likely due to the Flynn effect than genetic selection. In monogamous societies where the genetically fit mate with the genetically fit (or at least ‘fit’ in the sense that they have access to resources that attract the genetically fit) and the unfit attract and mate with the unfit, poorer people produce offspring at a younger age and they produce more children than the moderately well-off. Only in very drastic scenarios will the poor completely die off because they are too unfit to get food. They survive and they out-produce the well-off without fail even if they do not live well. From an evolutionary perspective, natural selection cannot happen as long as the unfit out-reproduce the fit and the offspring survive. It would not occur, regardless of whether or not modern selection pressures like intelligence or working indoors changed.
In Palaeolithic days, a cold period would cause the population to gain better resistance to the cold. Where there is money though, natural selection is unlikely to occur. The wealthy man who is very vulnerable to the cold but can afford fur coats and a stash of food for a thousand women will probably produce more offspring that survive than the slightly genetically adapted man who has only a small wealth. When disaster comes to Earth, I’d say that the wealthy will survive and not the genetically fit. Unless it’s to do with disease, genetic variation is too insignificant to affect survival chance much – no one is immune to the cold.
To Joe:
There is no such thing as survival of all. The brutal reality is that we developed societies rely on millions of people dying from disease so we can put food on our plates and have nice things. If science indiscriminately made it so that no one died of disease as morals would have it so, the population would explode. It would soon reach its climax capacity and survival of the fittest would be back in town. Those who weren’t physically fit (or wealthy) WOULD die because there would be such a strain on the world’s resources. We might think that we could ration and feed everyone but society is only a few meals away from barbarism. We’re only civilised because we can get food from Tesco. Clear all the shelves for two weeks and we’d probably kill each other over a rabbit to feed our family and then, natural selection would once again favour the finest physical specimens or whoever is wealthy enough to buy a lot of firearms. Remember, a good deal of our food comes from developing countries that currently have the highest mortality rates.
Then again, if we were in that futuristic egalitarian society, science would probably make magic food for us to all survive on and we’d be on hopping over to other planets whenever things got a little crowded.
Joe – Unfortunately I must agree with what Enigma said; though we may in the future try to save everyone, we simply can’t support even many more people than we have now, and I don’t see any way around that. It would probably be ethically easier not to try in the first place.
I would however agree with you on altering characteristics – unless it’s for medical purposes and it’s available to everyone, I’m against it. But I fear that in such a future we may be seen as utopians. After all, it’s not as if humans are striving to make current medical treatments available to the entire world, and even in most MEDCs healthcare is very expensive.
Enigma – Well, very true. I didn’t go into it in my article, because it would be a discussion unto itself, but many people have suggested that in the future the human race will essentially become less and less intelligent – after all, if you think about it, the members of society today who have the most children are usually those who are on benefits or similar. The more intelligent among the population tend to have fewer children, since they are, for example, pursuing careers. It’s a shame that evolution doesn’t always mean improvement.
I also agree with your conclusions about any future disaster, that those who can afford the best protection will survive. With that said, we must consider that post-disaster the measure of wealth may not be the same as we know it today, and society may function differently, so today’s wealthiest may not be the ‘wealthy’ after disaster strikes.
Hello, I just wanted to mention that some scientists back in the early 20th century thought that a kind of evolution happened backwards, in other words, that all creatures come from man. I wonder what you think of this? I mean it’s obviously completely scientifically wrong, but I just thought I’d mention “anti-evolution” to you, to see what you thought about how people’s views on evolution have changed.
I had honestly never heard about this before! I’ll look into it and let you know