identifying objects embedded in a field
completely non-reactive to loud noises (clap, starter pistol fired directly behind head)
immediately response to very quiet noises of interest, even from a substantial distance (video in the next room, played quietly)
undistracted by socializing, chitchat
quiet -- does not talk much if at all
able to and interested in imposing order on collections (arranging books, video, etc. in a row)
interest in producing music, perfect pitch
If you had to be transported back in time and space to a hunter gatherer society, I cannot imagine a better kid to have around. They'll help you collect food (flora and fauna), they won't respond to Big Scary Animal Noise in a way that gets you into trouble, if you are interesting to them, they'll probably be able to find you from a good distance away and come instantly and quickly to you (or to whatever else might interest them). And they'll be able to keep your gear together, arranged in a way that makes it easy to access and transport.
If you're lucky, they'll be able to amuse you in the quiet, long stretches of the night by singing, or playing a pipe or something similar.
Just because someone isn't going to make a great lawyer, or a talk show host, or whatever, doesn't mean they can't be useful.