One interesting point here is that Darwin is a relative latecomer to this view. This was the common perception of most natural, social and political scientists for centuries and, I suspect, before he did any of his research, Darwin had, like most people, accepted without thought or question the notion that competition was natural law, was the driving force of life. All he saw was what he looked for, or expected to find. The notion that competition is the driving force of the life process has been put forward for a very, very long time. Competition, we had come to believe, is the way things are.
Competition is natural.
For literally centuries, virtually every stream of human-generated data repeats or symbolizes, or in some way is based on or emphasizes, this view. We have been taught to compete for everything we might have wanted or needed, from physical basics like food to psychological basics like self-esteem, recognition, love. Gender was not, is not, a factor in this teaching. Little girls are taught to compete just as thoroughly as little boys. In the case of human beings, this principle is not only at the core of our own minds, but it permeates our entire social structure from family and community existence through national and international existence.