My boss's son is one of the smartest 18 month old kids I have ever met. He communication levels are through the roof, and for words he might not be able to say, or things he might not be able to express, he knows rudimentary sign language to communicate, e.g., he has a hand signal for "I'm tired" or "I'm hungry" -- he almost never has to cry to show he needs something.
Do you have children? I know ostensibly that is irrelevant but what you're describing is good and impressive but it's probably not as uncommon as you think. Baby sign language is pretty popular in the parenting world. Actually, many babies can do that at much earlier ages. Not to detract anything, just saying ... :)
my 15-month daughter runs to her high chair when she's hungry. sometimes she skips the chair and runs directly to the fridge. i don't think it's unusual, i hear the same things from my friends.
one related anectode: my boss' 3-yo son said to him, 'dad, i'm not stupid, i'm just small' :)
It's really quite impressive.