I'm less worried about E.Ts now, they exist but only their technology is better then us in most cases, Humans won the genetic lottery! Coming from Apes a strong fast species that can go for long walks, Their is a reason most alien encounters are accounts of little green men, once humans know how to make Alien technology anything we build can be built stronger and faster then what ever they build, because we are stronger and faster, amplifying our abilities. Of course their will be aliens with DNA lotteries with similar success to us , But genetically we are at the top end of physical speed and strength, Shame some of us are wasting it staying on sofas eating Twinkies and making ourselves fat!