How many ancestors do we have?

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Brian Tristam Williams

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How many ancestors do we have?
« on: 11/02/2011 21:30:03 »
Brian Tristam Williams asked the Naked Scientists:
   How many ancestors do we have?

Recently, my first child was delivered to me, and I knew that this was exceedingly likely to happen, as every single one of my ancestors had offspring. Sexual selection has been in our genes at least since the Cambrian evolution 500 million years ago. So, if a generation is 25 years, we all have a history of 20 million father's-father's-father's-father's...!

However, the length of a generation depends on the species, and ours is only around a million years old, so, is there any estimate on how many generations there have been before us, at least since the beginning of sexual selection?
What do you think?
« Last Edit: 11/02/2011 21:30:03 by _system »


Offline Guthers

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How many ancestors do we have?
« Reply #1 on: 15/02/2011 01:35:52 »
In Richard Dawkins wonderful book The Ancestor's Tale he attempts to estimate the date of each branching point in evolutionary history, and number of generations since.  Although he is getting very cautious about the numbers by this stage he estimates that since branching from our most recent common ancestor with lampreys and hagfish, about 530 million years ago, there have been about 240 million generations leading to us.

That book is absolutely fascinating and well worth a read.