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| Photo: Inverse |
DNA testing has
made tracing family trees into a common past-time for our globalized
world, but according to one mathematician, we might be overthinking it.
Joseph Chang, a statistician at Yale University, applied statistical modeling
to find the most recent common ancestor of all humans on earth. His
model, using the number of ancestors of each individual as well as
current population size numbers to calculate the point at which all
possible family bloodlines converge. He finds that it was a lot more
recent than we think.
For those of European
ancestry, the most recent common ancestor lived 600 years ago — making
him/her a contemporary of Johannes Gutenberg (1400-1468), the inventor
of the printing press. Expanding from Europe, the most recent common
ancestor of everyone alive today walked the earth in 1400 B.C.,
or 3,400 years ago — and, taking migration patterns into account,
likely lived in Asia.
The number of ancestors that each person has grows exponentially the
further back that we go. Everyone has two parents, four grandparents,
eight great-grandparents, and sixteen great-great-grandparents, and if
you follow that back a thousand years, or approximately forty
generations, everyone has over a trillion direct ancestors.
Except that the total number of humans that have ever lived doesn’t come
close to a trillion people, so this only makes sense when we remember
that our ancestry is shared.
