Well, depending on your religious convictions, they did it once …
From Zaria Gorvett at BBC:
The last man on Earth is a common trope in fiction – but what if it actually happened? How many people would it take to save our species?
So how much variety do you need? It’s a debate that goes right back to the 80s, says Stephens, when an Australian scientist proposed a universal rule of thumb. “Basically you need 50 breeding individuals to avoid inbreeding depression and 500 in order to adapt,” he says. It’s a rule still used today – though it’s been upped to 500-5,000 to account for random losses when genes are passed from one generation to the next – to inform the IUCN Red List, which catalogues the world’s most threatened species.
But before you write off our couple, as one scientist pointed out, we’re living proof of the concept’s inherent flaws. According to anatomical and archaeological evidence, our ancestors wouldn’t have made our own population targets, with 1,000 individuals in existence for nearly a million years. Then between 50,000 and 100,000 years ago, we hit another rough patch as our ancestors migrated out of Africa. As you would expect, we’ve been left with astonishingly low genetic diversity. A 2012 study of the genetic differences between neighbouring groups of chimpanzees found more diversity in a single group than among all seven billion humans alive today.
So what of the last man and woman? It’s impossible to say with any certainty, though Stephens is tentatively optimistic. “The evidence for the short-term effects of low genetic diversity is very strong, but all these things are probabilistic. There are stories of incredible journeys back from the brink – anything is possible.” More.
Oh well, in that case … back to Genesis 3.
See also: In a pickle about Adam and Eve
Adam and Eve and Ann Gauger