The nation – or at least the broadcasters – can't get enough of Sir David Attenborough as he approaches his 100th birthday on May 8.

Last month, the BBC launched a new series called Secret Garden presented by a man who began his career in front of the camera in 1954, with Zoo Quest.

And this week, Netflix came out with Gorilla Story, in which Attenborough returned to the scene of his most celebrated encounter with the animal kingdom.

If anyone can be described as a 'national treasure', Sir David – who remains admirably modest in the face of all the adoration – is that person.

Yet there is a side to him which is distinctly chilly, and it concerns his attitude to one particular species: homo sapiens.

He has little good to say about us and has long argued that we are nothing but trouble. In 2009, when becoming a patron of an advocacy group then called the Optimum Population Trust, he declared that: 'I've never seen a problem that wouldn't be easier to solve with fewer people.'

Four years later he told The Daily Telegraph: 'We are a plague on the earth. It's [a matter of] sheer space, places to grow food for this enormous horde.'

He also complained: 'We keep putting on programmes about famine in Ethiopia, that's what's happening. Too many people there.'

This was essentially a repeat of what he said at the time of the Ethiopian famine in 1983. Then he told us that it was 'barmy' to send food aid (as inspired by Sir Bob Geldof) because the hunger was entirely due to the fact that there were 'too many people for too little piece of land'.

This was untrue as well as callous. The famine was the direct result of civil war and the deliberate destruction of crops and livestock by the ruling Marxist junta.

Besides, the population density of Ethiopia is – at about 80 people per square kilometre – sparse compared to, say, Monaco (18,000 per sq km), which does not seem to be on the verge of starvation.

Yes, a wealthy place like that imports its food but here's the other fallacy touted by those who sing dirges from the Attenborough song sheet. They have failed to notice that while the global population has more than doubled since 1960, its food supplies have more than tripled.

That helps explain why, as the science writer Matt Ridley pointed out in his book, The Rational Optimist, there has been a 99 per cent decline in the death rate (per billion of the population) from famines since the 1960s.

And what about Attenborough's concern that human agriculture is taking ever more land from other species? 

In fact, the world has passed 'peak agricultural land'. As a recent report from Our World In Data set out, there has been 'a global decoupling of agricultural land and food production. Global agricultural land has peaked while agricultural production has continued to increase strongly, even after this peak.'

This is the result of constant improvements in technology. Yes, the more humans you have, the more likely there will be some with astonishing new ideas to improve means of production.

Even though Attenborough's Malthusianism – the doctrine promulgated by Robert Malthus in 1798, which held that population growth will inevitably outpace food production – has been proved wildly wrong, he has a sort of follow-up defence. 

Too many humans breathing (rather than expiring through imaginary famines) is a curse on the planet, because we exhale CO2, which adds to 'climate change'.

Sir David is a great admirer of Greta Thunberg, declaring that 'she is very realistic about the issues'. 

In fact, the Swedish campaigner's hysterical claims that billions will perish from some sort of global incineration unless we all, now, give up hydrocarbons completely is not supported by any proper scientific research. Indeed, it is the abandonment of fossil fuel-based fertilisers which would lead to the deaths of billions through famine.

Anyway, in 2021, during a talk with The Sun newspaper, Attenborough warned his interviewer in Thunbergian tones that 'we are damaging the environment just by sitting here, breathing. The carbon dioxide going out of this window as a consequence of meeting here is quite significant'.

I thought that was bonkers scaremongering but Sir David's awestruck interviewer treated this reverentially.

As it happens, Attenborough is about to see all his dreams for the planet come true. We are on the cusp of a population implosion. With the exception of swathes of Africa, global fertility rates are plummeting below replacement level.

As the leading British demographer Paul Morland wrote in his 2024 book No One Left: Why The World Needs More Children: 'Endless expansion in human numbers is undesirable, but as country after country experiences more deaths than births, the prospect haunting the globe is no longer uncontrollable population explosion, but unstoppable population collapse.

'At recent South Korean levels, more than 80 per cent of the population is lost in just two generations.'

Something similar is happening in Japan. During a visit there in 2010, I was stunned to learn from the head of the country's biggest nappy supplier that his business sold more of their product to the incontinent elderly than to families with infants.

It's a different story when it comes to the population of the African mountain gorilla. In recent years, thanks to conservation efforts partly inspired by Sir David's work, it has been steadily increasing. Perhaps Sir David should do a film about human existence in Japan, before that unique and ancient culture disappears from the earth.

In the UK, the fertility rate is barely over 1.4, compared with 2.9 in 1964. We are already in a situation where a decline in the working-age population, combined with a rising number of pensioners, is confronting the leaders of our political parties with an uncomfortable truth – one which they do not dare tell the public.

This is that the much-loved 'triple lock' (the commitment to raise the state pension every year by 2.5 per cent, the inflation rate or average wage growth, whichever of the three is highest) is already unsustainable. 

If current fertility rates are maintained, in 60 years there will be more retirees in the UK than people of working age. Never mind the triple lock, there would be no pension lock of any sort which the state could guarantee.

This would only be exacerbated if more people live to anything like the age now achieved by Sir David Attenborough. As Morland warns: 'If fertility levels in the UK do not change for the remainder of this century, the nation's immigration ratio will need to rise to 37 per cent by 2083 to maintain a sufficient working age population [to fund pensions and social care].'

This would be socially and politically unacceptable. So the only answer is to do what Sir David Attenborough has for so long denounced as disastrous – have bigger families ourselves.

To be fair to Attenborough, he is not a demographer, still less an economist. His deep concern for the diversity of the animal kingdom is something which is shared by countless millions of the faithful audiences for his programmes in this country.

But if we all viewed the world as Sir David does, there would in due course be no one around to watch the repeats after he's gone.