Having studied and written about the parade of life that had evolved and become extinct, I began to consider the extinction of our own species. My investigations eventually led to The Decline and Fall of the Human Empire, in which I chart the unlikely rise and probably catastrophic fall of our species.
Falling population
The explosive population growth of humans, rising exponentially since the invention of agriculture 10,000 years ago, has slowed, and will begin to fall – dramatically.
So many epochal events happened in the 1960s, but the most momentous was the moment when the rate of population increase peaked at just over 2% a year. While the population itself is still rising, the rate of its increase is slowing. Right now, it’s less than 1% and falling fast.
By the 2060s, the population will top out at between 10–11bn and start to fall. By 2100, it could be the same as it is now (just over 8bn), and all projections suggest that the fall will continue. By 2300, there could be as few as a billion people – the same as in Napoleon’s time.
The reason why the population is starting to slow is a perfect storm of many different things that have accreted over the past few centuries, an eye-blink in the seven-million-year history of the human lineage.
Over-exploitation of resources
Humans – one species among millions – sequesters as much as 40% of all the food that plants create by photosynthesis. Humans and their domestic animals account for 96% of all mammals by mass.
Everything else, from anteaters to zebras, has to squeeze into the remaining 4%. Six out of every ten birds in the world are domestic poultry. By many measures, humans have overstretched the Earth’s capacity to sustain it.
Climate change – economic and social effects
In the next century or so, climate change will render many countries uninhabitable – most in the least developed and poorest parts of the world. These factors have had a knock-on effect on the global economy which has been stagnant for the past quarter-century.
There have been ups and downs, such as the financial crisis of 2008, but the outlook is essentially flat. Humans feel this instinctively, whether this is mediated by property prices, job security or disposable income. Over the past generation or so, people all over the world have chosen to have fewer children, or to delay starting families.
Fertility rates in all countries, apart from a few in sub-Saharan Africa and some other exceptions, have plummeted, and these countries, too, will follow. To keep a population stable, each woman should have an average of 2.1 children in her lifetime. (It’s 2.1, not 2.0, to correct for factors such as the slight excess in male births as opposed to females.) But the Total Fertility Rate (TFR) is well below 2 almost everywhere. By 2100, all countries will be at or below replacement rates.
Is there a solution?
Without mitigation, the populations of some countries will halve by 2100. Pro-natalist policies – encouraging people to have more babies – don’t work. Even if they did, it would take 20 years to create a new tax-paying member of society. The quick fix is immigration. Wise governments will be doing all they can to encourage immigration now, from those countries that still have TFRs above 2.1, because eventually, even these places will have no more people to spare.
Is humanity heading into an ‘existential crisis’?
Even people who want to have families are having a tough time. Male fertility is in crisis. The health of human sperm all over the world has declined to such an extent that scientists, not normally given to hyperbole, have called it an existential crisis.
Nobody knows the reasons for sperm decline. Pollutants, diet and stress have all been suggested. One cause could be that nearly half of all humans now live in cities, and this proportion is increasing. Crowding is quite alien to the way that humans have lived for most of their evolutionary history – living instead in small family groups spread thinly over the landscape.
On many occasions, humans have almost become extinct. The result of this – near extinction followed by expansion from an impoverished pool of ancestors – means that humans are amazingly samey in terms of genetics.
There is less variation in the whole of humanity than in a single troupe of wild chimpanzees in West Africa. This samey-ness makes us remarkably prone to diseases and pandemics. Even without killer robots, nuclear war or asteroid impacts, humans have finally drawn the shortest straws.
Are there any positives?
One cause of human population decline is undeniably a good thing. Despite the fact that the human population has more than doubled in the past fifty years people are, in very broad terms, healthier, better educated and better fed.
This is a consequence of agricultural technology, medicine, sanitation, and especially female emancipation. In just the past century or so, women have achieved governance over their own bodies. This has an effect on reproductive choices of course, but the effects have been all to the good for everyone.
It’s salutary that female emancipation has happened so recently in terms of the span of human history. So recently, that it could easily be removed as has happened in countries such as Afghanistan, and also in the United States with the revocation of Roe v. Wade.
But it’s not all doom and gloom. The book has a celebrity fan in the form of Monty Python’s Eric Idle, who notoriously always looks on the bright side of life.
The Decline and Fall of the Human Empire will be published by Picador in the UK on 13 March, and St Martin’s Press in the US and Canada on 18 March. The launch will be at Aylsham Town Hall at 18:30–19:00 on Friday 14 March. Tickets £5, redeemable against book purchase.
