In nature, of which we are a part, although we sometimes like to pretend otherwise, life is cheap. On average 9 out of 10 juveniles do not reach adulthood. This is for a very good reason. Whether through physical inability to compete with well with siblings, susceptibility to disease, being unable to outrun competitors, making a stupid error of judgement or any number of possible other failures they are cast out of the gene pool. This is how evolution works.

All of us are born with countless genetic differentiations. Quite random and usually detrimental to our survival ability were we to be living in a dangerous environment like other life forms. However, humans have no natural predators, are mollycoddled until their teens and even the weakest most degenerate members are protected. All male and female humans breed regardless of mental or physical health.

As a result of this abnormal situation humanity has been physically devolving for many decades now and perhaps even centuries. Weight for weight a Chimpanzee is 6 times stronger than a man. Our intelligence is the only advantage we have over other animals and even in that area we see a remarkable percentage of people with mental illnesses.

Like sightless fish in the ocean depths, in nature you either use it or lose it. Humans need nothing to survive and live a full life, and therefore we are losing everything.

Population controls would worsen the situation by diminishing the gene pool even further each generation.

The reason the greatest sportsmen come from Africa and other countries with a recent tribal past is that civilisation has had less time to weaken these people. With a drop in mortality comes an increase in genetic devolution. Humanity reached its pinnacle long ago and now we are on the downward slide. Those who talk up population controls are willing an acceleration of this descent into darkness.

Science is based on truth and not evangelical wishful thinking.

“However, humans have no natural predators”

Really? How about the fact that our bodies are in constant war with bacteria and viruses? Aside from microorganisms our biggest natural predator is our own kind.

“As a result of this abnormal situation…’

How can it be abnormal? You said we are part of nature, so everything that has happened to us and is happening must be natural. Even to discuss population control is part of our nature. If we become extinct, despite our best efforts, why worry about it? That’s nature.

"How about the fact that our bodies are in constant war with bacteria and viruses?"

Even the immune system is getting a helping hand from anti-biotics. Doctors now realise that they've been over-prescribing this cure all and viruses have been building up an immunity as a result. We've been relying on medicine to fight viruses while our immune systems haven't kept pace with the new strains. Expect some really bad plagues in the next few decades if medicine doesn't again come to the rescue.

"...our biggest natural predator is our own kind."

Any idiot can fire a gun. Modern warfare involves munitions capable of taking out thousands of people at the touch of a button. Luck seems to be the greatest survival factor and that's a random quantity. The only competition which seems to have any bearing on success in breeding is monetary. Rich people are more favoured by females. Ofcourse they are also too busy to have much time for raising kids and prefer a small family while unemployed couples living in a trailer park might have a dozen children to reap in the extra social security payments.

"How can it be abnormal? You said we are part of nature, so everything that has happened to us and is happening must be natural."

It seemed an adequate word to describe a situation peculiar to very few species on Earth but you are right. Human evolution and our apex predator status is a result of millions of years of natural progression. However, using that argument it can be aid that nothing is abnormal.

"Even to discuss population control is part of our nature."

As is discussing the price of such a move.

"If we become extinct, despite our best efforts, why worry about it? That’s nature."

If we become extinct we will be incapable of worrying about it. I daresay it's more likely a catastrophe will wipe out much of the population and force it back to a stone age culture. The imminent erruption of Yellowstone Parks volcano which is about due to turn supervolcano for instance.

I agree with Wayne.Our human species is devolving because we are saving babies that would normally die.Imperfect genes are being given to the next generation.

We have but these choices,either we stop saving defective humans or we let science intervene and start genetically engineering the human race.In the past natural selection eliminated the negative genes that gave us deformities.Nature produces an enormous variety of genetic outcomes to cope with possible environmental changes,however there are many failures.We cannot afford to eventually to have half our population surviving on an intravenus drip while the rest of the population slaves away paying taxes to support them.8% of our working population are now on disability pensions.How will we cope if this number trebles?

If the body be the vehicle for the soul,shouldn't we be improving the vehicle?If there is re-incarnation,would you like to come back with genetic deformities?

"The reason the greatest sportsmen come from Africa and other countries with a recent tribal past is that civilisation has had less time to weaken these people. With a drop in mortality comes an increase in genetic devolution."

That sounds very much like the perversion of Darwin's "Survival of the Fittest" that was so popular amongst the Nazis. Lennie Riefenstahl certainly shared your appreciation of the physical quality of Arfican tribesmen. Nazis also adopted the idea of eugenics, where defective members of the community could be sterilised, though they decided to expand this idea by using this "life not deserving of life" for medical experiments.

But what about "Technology to the rescue!"? I am often perplexed at how population growth proponents will readily spout about how technology will solve any problem created by population growth. Yet mention a problem associated with a stabilising or falling population, including your hypothesis, and suddenly the prospect of any technological rescue evaporates. Why such inconsistency?

There is remarkably little genetic variety in the human species compared with other mammals. (Consider dogs, for example.) Evidence suggests that humans passed through a "genetic bottleneck" around 70,000 years ago, during which the human race was reduced to a few thousand individuals, wiping out much of whatever genetic variety pre-existed.

Now that there are well over 6 billion humans, even aggressive birth control (such as the former Chinese one child policy) is unlikely to wipe out what variety exists, anytime soon. Even a few thousand survivors could be sufficient for our species to survive and increase in numbers again.

"The reason the greatest sportsmen come from Africa and other countries with a recent tribal past is that civilisation has had less time to weaken these people."

Presumably this is why some of the greatest swimmers come from Australia?

Genetic variants more common in Eastern Africa (e.g. Kenya) than elsewhere in the world account for East Africans' frequent success in middle and long distance running.

Different genetic variants more common in West Africa (which is where most black American and British athletes' ancestry stems from) provide particular advantage in sprinting and jumping. This is nothing to do with weakening by civilisation or the absence thereof.

Conversely, East Africans tend not to be brilliant at sprinting, nor West Africans at distance running.

If nine out of ten humans were wiped out tomorrow, the remaining number would still be larger than the world's human population was in the year 1700. Some, concerned with the condition of the planet, say that even this number would be too many.