[Old Professer]

Math aside, why then don't we see a piece of the progenitors of either?

[Ichneumon]

Math aside, why then don't we see a piece of the progenitors of either?

We do. Here, for example.

There are a lot more "pieces" of DNA which can be traced than just the mitochondrial or Y-chromosome DNA, and each one gives different views into the big picture.

[CobaltBlue]

why then don't we see a piece of the progenitors of either?

How long have there been human beings, homo sapiens sapiens?

[Stallone]

Simple.

Women were hatched until approximately 60,000 years ago.

At that time, males were created, and contributed the 'brain'.

Unfortunately, the species only passes them only to the male offspring.