Also, Darwin wrote a lot more about cooperation than competition. Competition is kinda the simplest aspect of evolution, but if you wanna understand (literally) the birds and the bees, you gotta talk about the development of mutually-beneficial systems.
A lot of the big evolutionary milestones are cooperative. An impossibly long time ago, a big cell swallowed a little cell and (for whatever reason) did not digest it. Together they accomplish more than either cell could on their own. That symbiosis is the ancestor to practically every multicellular organism you can find. Being multicellular is itself another huge development in cooperative evolution. Predation and competition may make a hide tougher or a tooth longer, but cooperation is what really pushes the boundaries of what is biologically possible.
We’ve learned pretty recently that almost all nutrition of plants and animals relies on symbiotic relationships with microbes with their own distinct genetic material and reproduction. The microbiome in animal guts or in the soil where plant roots live turned out to be really important for whether the actual cells in the larger multicellular organism are getting what they need to thrive.
