I believe that humans are a mix of mammal and bird, possibly from horizontal gene transfer. Like birds, we’re bipedal, we build complex nests, we enjoy and produce music, and we enjoy and produce speech. The rest of our talents and tendencies are shared with other mammals.

Male humans have a conflict between the bird habit of mating for life and the mammal habit of humping everything in sight. Some of us are totally comfortable with mating for life. Some are totally humpy. Most are in between and conflicted.