There are several thousand species of humans, but only 5 surviving species. And when we say 5 surviving species, we really mean 1 that has any significant numbers, 4 down to their last members.
According to wikipedia (http://en.wikipedia.org/wiki/Homo_(genus)) there is only one species of humans remaining, Homo Sapiens. The last species of humans besides homo sapiens died out about 12,000 years ago.
"The value of marriage is not that adults produce children, but that children produce adults." -- Peter De Vries