To point out a few more derpy bits:
In English, you normally use the word "graceful" rather than "gracile", and even then the whole quoted sentence is just awkward and ungainly when you read it.
No, "gracile" is correct. Although it can mean "graceful," it more commonly means "fine-boned and slender," which is what it means in the context here -- the sentence is saying that these guys are slim and delicate compared to more robust normal humans. Although it's a very rare word in everyday speech, it's something you hear a lot in osteoarchaeology.
I'm not saying it's a good word choice, but it's not a synonym for "graceful" -- it has a specific meaning related to body shape.