So, unlike in humans, every chimp male's sperm has to fight really hard to fertilize a single egg. |
That's because every other chromosome has a pair. |
The genes in the palindrome region are primarily sperm-producing genes, and most other genes unique to the Y aren't located there, |
This led to the 'The Y is Falling' hypothesis. |
We find evidence that natural selection is, in fact, maintaining those 16 genes. In fact, the human Y hasn't lost any genes over the past 6 million years. |