Evolution is like buying a suit
If you wanted to get a new suit, you might order a custom suit tailored to your specific body size, dimensions, etc. However, this is costly, and another possibility would be to simply go out and chose an existing models among a few. Adaptationism argues that individuals evolve to get an optimal fit on their environment, just like the custom suit approach. However, selectionism argues that individuals evolve by making “smart” choices, essentially choosing what works for them more losely, or “satisficing”.