What's The Fewest People That Could Repopulate Earth?

[00:02] alien lasers killed off almost all of the humans on Earth. Obviously, there post-apocalyptic problems that we would have to deal with depending on the disaster at hand. Our food supply might be irradiated, our atmosphere

[00:16] unbreathable, heck, all the planet's water could have boiled away. And if any doomed no matter what. But, all those problems aside, how many people [music] would it take to actually rebuild a genetically sustainable human population

[00:29] >> [music] >> We have some actual science to go on considered by two groups of researchers, those who study [music] space colonization. And the big issue here is

[00:42] bad genes. Hi, I'm Cameron and this is Minute Apocalypse. >> Any given human probably carries recessive genes for at least one deadly disease or another. And while a single copy of one of these genes is no big

[00:56] deal, having multiple copies could end up giving you that disease, genetically survivors there are, the smaller the pool of genes will be that future generations will draw from, increasing a person's chances of getting two copies

[01:10] of the same bad gene. Likewise, the more survivors there are, the more different chances would be that one would get multiple copies of the same disease-giving gene. So, there must be a critical minimum number of survivors.

[01:25] And the space colony scientists have estimated that an off-world founding population would [music] likely need roughly the population of 11th century London, at least 14,000 people, in order to maintain a healthy gene pool and to

[01:38] preserve the technological and cultural aspects of society. But, we want redeveloping society and technology later. If we're only concerned with our species' survival, [music] space colony math suggests that we could get by with

[01:52] roughly 5,000 people. But, about 800,000 years ago, our primate ancestors an even smaller number, a breeding pool of around 1,300 people. [music] Those people might have gotten away with this, at least in part, because the group was

[02:06] genetically diverse. They likely didn't share the same bad genes. And if we were to get really lucky as far as genes goes, the math suggests we could get by with as few as 150 to 500 survivors, which is about the number of people on a

[02:21] single commercial airline flight. But that's close to an absolute minimum. However, if we could see the apocalypse coming, [music] some scientists argue that we could get by with a carefully selected, genetically diverse group of

[02:33] as few as 98 people. And in this scenario, all the survivors would have to be at reproductive age, and they'd need to be managed by a strict set of only mate with the most distantly related member of the population. This

[02:47] basically is how zoos run breeding programs for endangered species, one of which rehabilitated the black-footed ferret population from just 24 surviving animals. This scenario raises a mind-boggling number of ethical

[02:59] questions, but theoretically it could work. And if you want to get really technical, we could restart society with one survivor. We would just really have to plan ahead. Like, [music] if before the apocalypse even happens, we create a

[03:14] bank of frozen fertilized embryos that the lone survivor could give birth to, we'd have plenty of genetic diversity to stave off the bad gene problem. This fraught, but theoretically [music] it's possible. And it would take only around

[03:27] 420 years to get back to our current population size. [music] So, yes, with a lot of planning, we could restart humanity with just one person. But let's not build nuclear bombs this time. All right?