A common theme of apocalyptic movies is a small set of survivors trying to build thriving communities after a worldwide disaster. But how small could that number of survivors really be in order to repopulate the earth? Scientists, as well as scriptwriters, have been studying the issue.
The short answer is, it depends. Different catastrophes would create different doomsday conditions for surviving human populations to endure. For example, a nuclear war could trigger a nuclear winter, with survivors facing freezing summer temperatures and global famine, not to mention radiation exposure. However, putting some of these conditions aside and focusing on population size, the minimum number is likely very small compared with the approximately 7.8 billion people alive today.
"With populations in the low hundreds, you can probably survive for many centuries. And many small populations of that kind have survived for centuries and perhaps millennia," Cameron Smith, an adjunct assistant professor in the Department of Anthropology at Portland State University in Oregon, told Live Science.
An article at LiveScience looks at the numbers, by looking to the past and how small populations worked in prehistory, and by looking to the future when people may travel to other planets. -via Damn Interesting