(November 4, 2014 at 6:14 pm)Reader Wrote: Why do we only have two genders, male and female? [excluding asexual animal reproduction] ... just humans and almost all animals? Why only two? Why not ... say ... seven, or seven-thousand? If we have evolved over time from a single celled organism ... why did we only evolve into two genders and not more? Why did it stop at two? Thanks for your time.
You have to think about it as an optimization problem.
Sexual reproduction allows for greater variability -> higher likelihood to produce an advantages trait.
The minimum requirement for sexual reproduction is 2 sources. Once you start require more, you reduce your likelihood of finding 3, 4, 5, ... mates to produce 1 offspring.
