Here is a link to a TED talk from a historian who has a compelling story about why we humans came to dominate the planet. I'll give away the punch line. The answer is in our cooperation among many members of the species, flexibly and over long distances.
No other species does this. Cooperative behaviors of ants in their colonies are hard-wired (thus not flexible). Cooperation among chimpanzees depends on interpersonal relationships (thus limiting the number of chimpanzees who participate in the cooperation).
It's a great talk. Spend a few minutes on it.