Why it took approximately 6 billion people to create you

I found this video when I googled ‘How many generations back do you have to go to have a million ancestors?”

Key points from this video:

With more diversity

• People can have over a million unique ancestors going back just 20 generations.

With less diversity

• In small populations, nearly every possible mate is closer than a 4th cousin.
• In small populations, individuals could have from only a few hundred unique ancestors (counting back 20 generations) to as little as 6 unique ancestors.

Over centuries

• You have 6 billion ancestors (plus or minus a few billion) from over the last 12,000 years
• One hundred fifty generations ago (more or less) every human alive today had the same set of ancestors.

We normally think of our family tree with ever increasing branches, however, as this diagram explains, historic population limits does not allow that to be true. The real shape is more like a spinning top. Not a tree of ever expanding branches.