On 31-Aug-17 11:14 AM, taf wrote: > On Wednesday, August 30, 2017 at 5:25:16 PM UTC-7, Peter Stewart wrote: > >> If you don't use a paper trail to establish which people "came through >> Mary but did *not* come through Franz" in order to eliminate >> cross-relationships for DNA testing, how else do you do this? By ouija >> board perhaps? > Without a paper trail (and that is after all why we are doing this) you would have to compare all 7 billion genomes on the planet to every other one, a 50 septillion-fold matrix with a million sites in each genome to compare. If you have a supercomputer that can do a million-site comparison in a millionth of a second, it would still take about 37 million years to complete the comparisons. Once you start matching sibling genomes and reconstructing hypothetical parental genomes, each of those would then have to be compared to all 7 billion. It is ludicrous to suggest such an analysis would take place, even were the data all to be collected. (and this doesn't even take the data-loss problem into account) Perfectly satisfactory for me, whether or not such a ludicrous attempt is ever made - if there is a species 37 million years from now that has evolved from homo sapiens, I doubt that they will care a fig about individual human beings from any era. I suppose quantum computers might speed things up in the meantime, an if so they can resent the waste of energy in misapplying all this analytical power. A few years ago cosmologists used to snigger condescendingly at anyone who asked "What came before the Big Bang?", but now they are busily (and many of them shamelessly) asking the same question themselves. I hope geneticists will not be so foolish in failing to recognise the extent of their ignorance. Peter Stewart