The survival of the stupidest? 6

Has evolution ended with Homo sapiens?

On this question, Tom Chivers at the Telegraph reports a fascinating disagreement between Sir David Attenborough and Dr. Adam Rutherford.

We have chosen some excerpts. Read it all here.

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 … “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.” …

And what will happen next fascinates us even more. …

Attenborough … 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 …  “He is absolutely right that the selection pressures on humans have radically changed, … 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. …

“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.

And if we contemplate the intellectual quality of those who have risen in recent years to the commanding heights of political power and academic authority in the West as a whole, we might suppose that the decline of brain-power in the human species has already begun.

Posted under Commentary, Science by Jillian Becker on Saturday, September 28, 2013

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This post has 6 comments.

  • Ian Kummer

    This is borderline hysteria. The United States is a nation of immigrants. We bring in fresh blood – the best and the brightest from around the world every year. We are doing fine. Evolution continues as normal.

  • liz

    The example of the cave fish losing its eyesight is interesting.
    In the development of human intelligence, the Dark Ages, brought on by the Christian religion, caused mental blindness and stunted progress in rational thinking for centuries. Western Europeans finally managed to escape the mental cave religion had trapped them in and regain their mental “eyesight” during the Renaissance and Enlightenment.
    The vast majority of Muslims today are still trapped in the Dark Ages brought on by Islam. In the midst of the Space Age, they live in the darkness of the mental cave their culture was confined to centuries ago by Mohammed, the primitive prototype of Stalin and Hitler.
    So of course, on top of being extra stupid, violent, and barbaric, they are programmed to think they are superior beings(!) who must rule the world.
    Not only has evolution created for us a blind fish, it is a blind “living fossil” piranha the size of a whale, devouring everything in sight.
    Isn’t that so special? Maybe being wiped out by killer viruses isn’t such a bad prospect, after all.

  • consvltvs

    Whether or not selection pressure has diminished for individual humans, it remains robust among human societies. Wilson’s recent work on group selection revives the concept, previously not in vogue. The societies best able to remain internally cohesive and externally competitive will prevail over those that do not.

    • Jillian Becker

      Hi there, consvltvs!

      Wilson? Can you give us a title, a reference, a link?

      • consvltvs

        Hi, Jillian. It’s Edward O. Wilson, The Social Conquest of Earth.

  • WmarkW

    I agree that evolution has been stopped, but it’s possibly only within the last 50-100 years that there’s effectively no correlation between genetic fitness and fecundity. Within Western society, there’s a clear negative correlation between women’s educational attainment (a good proxy for intelligence across a broad population in a society with equal opportunities) and their children ever born. Reproductivity is partly driven by being to dumb to either use birth control effectively, or to have a better economic choice about how to spend their lives.