Yan Wang
speaker
26 appearances
1 recordings
1 series
first heard Nov 2014
last heard Nov 2014
Yan Wang’s voice in public audio — every appearance, attributed to the second.
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Appearances
Well, it's not that inbreeding creates genetic disorders.
What it is, is that inbreeding exposes genetic disorders that are already present in the population.
And in fact, if you do inbreeding, because it exposes it, that actually reduces the amount overall in the population eventually.
But as for the actual numbers, you might have thought that it was quite large, say in the hundreds, because people who are interested in interstellar, intergalactic travel have done calculations and they come up with hundreds of people and ecologists have this...
rule called the 50-500 rule, which says that for short-term viability of a population, you need about 50 individuals.
In fact, that's the effective population size, so probably more like several hundred.
And for long-term maintenance, you need about 500 individuals.
So the real number of individuals is probably in the thousands.
I think that's slightly misguided, actually, because it's not the long-term population size you need to worry about.
It's just the number of founders of your colony that you take with you on your little escape pod.
There are examples from other animals where really quite small numbers of individuals have founded successful populations.
There are deer in Finland, three females and one male, and there's even a single breeding pair of wild sheep here.
that were introduced from a Paris zoo to Oort Island in the Curligan Archipelago.
In terms of humans, there are two examples that people often come up with, and that's Pitcairn Island, which famously was founded by people from the Mutiny on the Bounty.
The breeding population there now springs from
six Polynesian women and 11 Caucasian men.
Nine of those were from the bounty and two arrived later.
And if you look at the other example, Tristan da Cunha, it seems that you can trace everyone back to seven females and eight males.
These aren't perfect experiments because there probably were the occasional people visiting and immigrating, but under 20 seems like a reasonable conclusion for founding a human population.
The problems, from a genetic point of view, aren't really inbreeding.
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