Asimov admitted that even by the standards of scientific knowledge in 1939, the possibility that Mars might have a native intelligent race was unlikely, and the possibility that Martians and humans would be interfertile was even more so . " I can only shake my head wearily, " he writes . " I knew better in 1939; I really did.
12.
In a direct parallel to the chimp human case, the Przewalski's Horse ( " Equus przewalskii " ) with 33 chromosome pairs, and the domestic horse ( " E . caballus " ) with 32 pairs, have been found to be interfertile, and produce semi-fertile offspring : male hybrids can breed with female domestic horses.
