That would be the case if the breeding strategies of all races were the same. Look at the traditions of many African civilizations. Full of voodoo and human sacrifice. In Fiji the chief would force 2 teams to play against each other in a local sport. Guess what happened to the winning team? Cannibalized. Many parts of Africa I've read about horrendous yearly rituals where they would make babies race each other and whichever baby crossed the finish line first would be cannibalized. Seems backwards to kill off your best doesn't it? Well if you breed this way for thousands of years what will you be left with?