I was wondering if one theoretically wanted to start a new civilization
or colony somewhere, what would be the minimum number of people needed to
insure that there will no inbreeding? This assumes that there are no frozen
eggs or sperm or other such external aids. I know that royalty used to breed
within their lineage to keep the blood pure, but I also read that this lead
to a higher rate of children with health problems. 
600? 6000? 2? 
Thanks.