eli5: More diversity within groups than between groups

Question

Not sure if it’s in the right subcategory but in my intro to anthropology course we went over gene pools and comparing inhabitants of different continents one point that was made about biodiversity was the statement: there is more diversity within groups than between groups
But if they are different groups wouldn’t the two groups have more differences than the people w/in the groups have with each other?
Unless I’m remembering it wrong

In: Biology

Answer 1

Take two groups of dice-rolls. The tribe of 2d6’s vs the tribe of 2d8s. The 2d6’s will range from 2-12 and will average at 7. The 2d8’s will range from 2-16 and will average at… 8?

2-12 is a range of 10. There’s a lot of diversity. The average of 7 vs the average of 8 is only 1, Not so diverse. When talking about the group of 2d6’s, you’re talking about their average.

There’s lies, damned lies, and statistics.