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Does it follow that same would apply for all humans of Mark Antony's time?

NeoTar 4y ago
Kinda! This is covered in Randall Munroe's (of XKCD fame) latest book - What If 2; chapter 33 "Ancestor Fraction" Obviously a human who did not have any children cannot be the ancestor of anyone - this includes the circa 50% of humans who died during infancy, and the 25% of adult humans who did not have children. Also, for some people who had children the line will die-out; if you have four children all of whom die in infancy, your line dies out. If none of your grand-children have children, your line dies out. Randall quotes a study which estimated that this applies to 40% of all people who ever had children. So, taken together roughly 25% of all humans who were ever born went on to have children and form a part of the modern human 'ancestor web'. In Summary: If you picked a random human of any age from the time of Mark Antony there is a roughly 25% they are an ancestor to all humans. If they are an adult that rises to 50%, and if they already have kids it rises to about 62.5%.
- mannykannot 4y ago
  Does this take into account geographical limitations? I don't know about today, but if you applied the same analysis to the global population of 1600, it seems impossible on geographical grounds for either Mark Anthony or one of his contemporaries in South America to be an ancestor of everyone alive in 1600.
- tomp 4y ago
  You’re assuming much more “cross-polination” than actually happened. Humans didn’t use to mix geographically (hence different races). And there’s isolated subgroups that didn’t mix or mixed much less (e.g. Jews in Europe)
- saalweachter 4y ago
  Is that "are" or "will be" an ancestor to all humans?
User23 4y ago
No. I don’t know the names of any great first century subsaharan African or Native American leaders, but even 80 generations back there are almost certainly none in my family tree. On the other hand I wouldn’t rule out some Asian steppe leader being in there somewhere.

Kinda! This is covered in Randall Munroe's (of XKCD fame) latest book - What If 2; chapter 33 "Ancestor Fraction" Obviously a human who did not have any children cannot be the ancestor of anyone - this includes the circa 50% of humans who died during infancy, and the 25% of adult humans who did not have children. Also, for some people who had children the line will die-out; if you have four children all of whom die in infancy, your line dies out. If none of your grand-children have children, your line dies out. Randall quotes a study which estimated that this applies to 40% of all people who ever had children. So, taken together roughly 25% of all humans who were ever born went on to have children and form a part of the modern human 'ancestor web'. In Summary: If you picked a random human of any age from the time of Mark Antony there is a roughly 25% they are an ancestor to all humans. If they are an adult that rises to 50%, and if they already have kids it rises to about 62.5%.

mannykannot 4y ago
Does this take into account geographical limitations? I don't know about today, but if you applied the same analysis to the global population of 1600, it seems impossible on geographical grounds for either Mark Anthony or one of his contemporaries in South America to be an ancestor of everyone alive in 1600.
tomp 4y ago
You’re assuming much more “cross-polination” than actually happened. Humans didn’t use to mix geographically (hence different races). And there’s isolated subgroups that didn’t mix or mixed much less (e.g. Jews in Europe)
saalweachter 4y ago
Is that "are" or "will be" an ancestor to all humans?

User23 4y ago

No. I don’t know the names of any great first century subsaharan African or Native American leaders, but even 80 generations back there are almost certainly none in my family tree. On the other hand I wouldn’t rule out some Asian steppe leader being in there somewhere.