There are many intelligent extraterrestrial races as well. Curiously, a large number of them are humanoid, even human-like, in form (such as Kryptonians, who outwardly appear identical to Earth-born humans); some can even interbreed with Terrans. Some of these races have natural superpowers, but they are usually the same for all individuals of the same race, unlike Earth's metahumans. This was explained by the fact that in Earth's distant past Martians experimented on humanity, severely culling the metahuman potential; this means that a species that was meant to have a wide range of powers, like Tamaranians or Kryptonians, ended up "just...human". However, there are also plenty of nonhumanoid races.