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.

some bottleneck ..! the apearance of homo genocidus

for the increased number of children surviving today in spite of
being somewhat less than the pure 100% hunter gatherer
as soon as the survival pressure ease a bit , variations occurs
leading to sub species , then full species .
the astounding population explosion and improved survival rate to
adultood lead to more variant kids , most mutation are bad but
some scientists are not exactly centerfold material , as a rule
mere survival is not suficient ,
the next step is succesful breeding
most negative variants get eliminated ther

"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".

Rubbish, name ONE virus that antibiotics can effect.

Antibiotics do not work on viruses because viruses are not alive. A bacterium is a living, reproducing lifeform. A virus is just a piece of DNA (or RNA). A virus injects its DNA into a living cell and has that cell reproduce more of the viral DNA. With a virus there is nothing to "kill," so antibiotics don't work on it.

So given that you do not understand this basic, I suggest the rest of your post is codswollop.

Confusion about viruses and bacteria aside, I reckon the underlying fallacy in Wayne’s argument is that our understanding of evolution and genetics ought to provide some kind of moral compass or strategic guideline about how we should behave. They don’t: at best they can provide some understanding of where we’ve come from and can give us some insight into some of the more bewildering aspects of human nature and some technologies to reduce human suffering. There is no “very good reason” why nature is so cruel. This is a teleological view of evolution, a remnant of the human tendency to regard the universe as revolving around it. Evolution is purposeless mechanics. It's not all about us.

There’s no doubt in my mind that six billion individuals represents an unsustainable ecological footprint, particularly if we hope for reasonable living standards at some stage for all. Overbreeding is far more of a threat to us (and everything else on the planet) than underbreeding.

Nature is, as Tennyson said, red in tooth and claw. All of us alive today are the genetic survivors of billions of years of ruthless, pitiless selection, and, most likely, tens of thousands of years of intermittent human generated genocides, which continue unabated to the present day. Our challenge is not to see this as an inevitability, but to build a future different to our past

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

I certainly don't believe in establishing a "death squad" that has the right to decide who lives or dies. It would be reminiscent of Hitlers master race stratagem. What we deem important to future generations may not be what mother nature would select.

Personally I think we should do the opposite. Find exceptionally fit and exceptional individuals and pay them to provide their seed to sperm banks. Dilute the genetic defects in the pool by flooding it with robust and healthy DNA. Ofcourse overpopulation becomes a factor then.

"That sounds very much like the perversion of Darwin's "Survival of the Fittest" that was so popular amongst the Nazis."

I fully expected somebody would raise that ugly episode of human history. I didn't give any solutions in my original post. Only details of the problem as my laymans mind comprehends it.

"But what about "Technology to the rescue!"? Why such inconsistency?"

You are pre-supposing that I don't see technology as a possible solution. Untrue. I see technology as the only solution.

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

Interesting observation. We are surrounded by beaches. That might have something to do with it. Also, tribes rarely try to outswim their prey.

"So given that you do not understand this basic, I suggest the rest of your post is codswollop."

That is a rather lame argument. To suggest that any error makes an entire argument wrong is a very ancient political trick. I'll treat it with the contempt it deserves.

"Nature is, as Tennyson said, red in tooth and claw. All of us alive today are the genetic survivors of billions of years of ruthless, pitiless selection...."

Our evolution took a long time as you say. No doubt we could continue to slowly devolve over a long period of time and still be masters of our environment. Perhaps evolution doesn't always go forward but frequently backtracks. I thought this an interesting topic to raise.

Wayne

If you are going to espouse a hypothesis on anything it is diminished when you make a statement that is patently wrong.

Treat it with contempt if you wish.

Thanks for your permission. I will. My confusion between bacteria and viruses was in response to a reply. It was not in my initial posting. I don't mind being corrected when I make an error. To call everything I write "codswallop" because of a minor mistake is insulting. I'm not a doctor but I'm not an idiot either. Nitpicking is actually beneath contempt in my book.