StoneSoup Posted March 14, 2015 Report Share Posted March 14, 2015 Interesting thought experiment. Think of your ancestral "tree". You had two parents, they each two parents, and so on - all the way back. Assume 25 years (on average) between ancestral generations. If the number of ancestors doubles each generation, then basically - to figure out how many ancestors you had at any generational level in the past, you just multiply back by two. Well, if you multiply out 2n where "n" = number of generations, then after 31 generations, each person had 1,073,741,824 ancestors. Multiplying 31 generations x 25 years = 775 years - or the year 1240 A.D., counting back from 2015. According to https://www.census.gov/population/international/data/worldpop/table_history.php , the world population in the year 1250 was unlikely to have exceeded 450,000,000 people - and Earth's population did not hit 1 billion until after 1750. I'm not sure exactly what this means - but it seems very likely that most of us have common ancestors within the past 300 years or so (just 12 generations back). I invite criticism - because this story seems too easy - and also too unlikely. Cheers, SS Link to comment Share on other sites More sharing options...
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