That reproductive strategy comes naturally to those of the race that evolved in Tropical Africa. Having small numbers of children by one woman is the reproductive strategy that's natural to those who evolved to survive in Europe during the Ice Age. In the tropics, the best way to spread your genes around into future generations is to have lots of kids by many women with whom you only have a casual relationship, and generally don't spend time with once insemination in accomplished. In the north, where frozen winters come every year, and are quite long (especially during the Ice Age), that strategy would result in none of your genes surviving to the next generation. Instead, you have to commit to one woman, and a smaller number of children (instead of 43, something like six or seven total, spread out over fifteen or twenty years), and devote yourself to providing for them so they don't die over the winter due to lack of support.
