Prehistoric humans avoided inbreeding as they knew of its dangers at least 34,000 years ago, a study has found.
They developed surprisingly sophisticated social and mating networks, and deliberately sought partners beyond their family, research suggests.
The findings could explain why modern humans proved more successful than other species, such as Neanderthals, that did not avoid inbreeding.
We’ve always got this problem here.
OK, we can agree that they’ve found outbreeding. We can also agree that out rather than in breeding increases reproductive success over the long term. Super. But this doesn’t mean that they knew. It just means we’re descended from those who did this. That is, outbreeding increases reproductive success over the long term.
We’ve also got other intriguing little bits of evidence. Children raised together seem not to – on average of course – go on to have children or even really to date (the communal dormitories of the kibbutz are one piece of evidence for this). Genetic siblings not raised together don’t seem to have the same internal barrier. The occasional stories (occasional because the basic set up itself is rare) we hear of siblings pairing up into a family producing more children tend to be of those not raised together.
Our end result being that we tend to pair up with people who are genetically close to us but not that close. Part of that may well be just geography – until very recently most of those around you would have been second, third, fourth cousins. But the against sibling mating seems to be something innate – although it comes from being reared as if in the same household, nurture rather than actually genetic.
This doesn’t require anyone to know. Sure, maybe they did but the proof of the outbreeding isn’t proof of the knowledge, we can derive it just from other things we know about human behaviour.