Tech billionaire Elon Musk has not been quiet about his belief that low birth rates could be humanity's downfall. Now, however, he has a new concern: what if declining birth rates mean that we won't have enough people to populate Mars?
In a Twitter thread on Tuesday, Musk wrote that he believes that we should be much more worried about population collapse than we are.
"UN projections are utter nonsense," he wrote. "Just multiply last year’s births by life expectancy. Given downward trend in birth rate, that is best case unless reversed."
"If there aren’t enough people for Earth, then there definitely won’t be enough for Mars [Frowning face]."
So far, precisely 0 humans have gone to the Red Planet, but this hasn't stopped Musk from claiming he could put 1 million people up there by 2050 on spaceships capable of carrying 1,000 people at a time. A million may not sound like a lot to ask (in comparison to the billions on Earth today), but Musk is clearly worried that the Martian project will not happen if birthrates here on Earth decline.
In the 1950s, women worldwide on average had 4.7 children over the course of their lifetime. Recent research has shown that the fertility rate was nearly half of that at 2.4 in 2017, and the same team projected that the total fertility rate would be 1.6. Any number lower than around 2.1, and the population begins to decline. The team predicted that the population will peak in 2064 at 9.73 billion before this decline happens.
While a challenge – particularly in regards to how we look after an aging population – others are concerned about how an ever-growing population can be sustained on Earth.
"All of our environmental problems become easier to solve with fewer people," David Attenborough famously (and controversially) said. "And harder – and ultimately impossible – to solve with ever more people.”
Musk, meanwhile, believes that a decline in our numbers is a threat to our existence.
“I think one of the biggest risks to civilization is the low birthrate and the rapidly declining birthrate,” he said in December 2021.
“And yet, so many people, including smart people, think that there are too many people in the world and think that the population is growing out of control. It’s completely the opposite.
“Please look at the numbers – if people don’t have more children, civilization is going to crumble, mark my words.”