re: Everyone alive today has had a living ancestor at every point in history

You divided by zero didn’t ya?

Smh.

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But wait. If you conservatively estimate that there are 5 generations per century

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You're ignoring an uncomfortable fact for a lot of folks - cousin marriage was probably the rule, not the exception, certainly outside of cities, until about 200, 250 years ago. So, most folks family trees will not look like a logarithmically expanding triange which, as you suggest, doesn't make sense in the context of a shrinking population as you go back in time, but rather a weird diamond shape that might be disconcerting when you discover the same couples sprinkled uncomfortably throughout all sides of your family tree at a certain point.

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So the number of living ancestors you had living on Earth at a given time can be expressed as 2 to the power of g where g equals the number of generations back you want to go.

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No.

No it can’t.

You are ignoring several principles, the biggest of which is inbreeding.


An individual can be your great great great great great grandfather on your mother’s side, and one on your father’s side too.

So one person in reality, but 4, 8, 12, 24, etc by your calculations. These greatly funnel what with otherwise he exponential.

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Every person alive has one biological mother and one biological father. Four biological grandparents. Eight biological great-grandparents. Sixteen biological great-great grandparents, and so on all the way back.

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Actually, this is not remotely true. You have double the amount of female ancestors than you do male ancestors. Basically if you go back before the Renaissance, you will find lots and lots of rape. That was the big loot of war in that if you survived, you got a guaranteed lay. But lots of them did not. Plus women are far more picky than men in who they'll willingly have sex with.

That and you often married your cousins. This is still exceptionally common in many parts of the world, particularly Pakistan where over half of marriages are to first cousins.

Calls me a retard after saying:

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you'd have had 1,073,741,824 living ancestors on Earth in 1418. 

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And if you're going to say "I meant only if they could all be alive," then state that in the post. Don't expect everyone else to read something dumb and know you didn't mean it to be dumb.

OP is a dumbass

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He's ignoring that people die.

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Sure, but the principal is, somewhat, sound. Going back in time, you would have roughly double every generation - and even if there were shifts in generations, there would have been some overlapping lifespans, and theoretical doubling every full generation.

You don't dispute that part of his analysis, do you? I'm alive now. Both my parents were alive mid 40s to ~1990. All 4 of my grandparents were alive from ~1910 to ~1970. All 8 of my great grandparents were alive ~1880 - ~1940, etc. At some point, that upside down pyramid flips and becomes a diamond.

don't drink and do math

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You guys are completely missing the entire point. You had sixteen great great grandparents alive roughly around the same time in the same generation. Before that, you had 32 great great great grandparents alive at roughly the same time in the same generation. It doubles each generation all the way back. Get it?

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I get that you're a fricking idiot. You take no other factors into account. This is an argument you'd get from a third grader who just learned multiplication. There's a good chance you've fricked a 5th cousin, particularly if your family hasn't moved in a few generations.