Interesting. I wonder if this fellow might reasonably be considered a new species.
"A species" is typically defined as something like "a group of individuals that can breed with each other".
A healthy mule can't mate with another healthy mule and have baby mules.
People who happen to be sterile or decided not to have kids can remain a part of the human species...
http://www.npr.org/blogs/krulwich/2011/05/10/136029423/the-l...