Get it right!

Here's another shot in the War On Innumeracy. I was reading an otherwise respectable textbook called Genetics At A Glance by Dorian J. Pritchard and Bruce R. Korf when I came across this doltish statement on page 27:

"Reassortment of paternal and maternal alleles within chromosomes creates an infinite potential for genetic variation between gametes."

This is just hogwash. The potential variation is not even close to being infinite - whatever that might mean...

I sat down with my pen and paper and made some basic simplifying assumptions such as there are about 30,000 genes in the human genome, and that the average gamete (ie: sperm or egg) has about 40 paternal/maternal crossovers, and concluded that the average person could conceivably (ho ho - pun intended) produce about 10 to the power of 160 different gametes. You should have seen how excited my tute group was when I told them!

Is that number really really large? Yes.

Is it infinite? No.

Shame shame shame.