People have always helped each other raise children. Monetary cultures that praise independence are a likely source of violence against other people's children. If you know that you are bound in a web of interdependence with people, you don't kill their kids. Their kids are going to grow up and be part of the web, you treat them like your own. Stray cubs are raised, if there is space for them.
Wolves are pack animals, they have very strong instincts to cooperate with each other.
They also commonly limit their reproduction to the top ranking pair, other wolves in the pack are not allowed to reproduce, it would be too big a burden for the pack to care for. If there is no space for a stray, it might also be killed. This behavior of only one pair doing the reproducing works for wolves, since a single model of wolf is the ideal. For people, greater diversity of types, which you get from many pairs of people reproducing just a little, is an advantage for us. We can use many different talents, we don't want one male putting his stamp on all the children, nor one woman.