I remember reading a short story with the following synopsis:
An Earth exploratory expedition arrives at a planet thinly populated by friendly humanoid folk at a very primitive technological level - no wheel, no sails, etc. Perhaps they lack some key concept, I don't recall the exact reason for the technological block. However they turn out to be all of them extremely highly intelligent. From clues innocently and accidentally dropped by members of the expedition, and by observing their technological artifacts, in mere days they invent the wheel complete with ball bearings (made with round hard nuts), and other things which make expedition members afraid. The commander considers exterminating the village they made contact with, but it turns out that messengers have already gone to other villages and one guy has invented the sail and went overseas to transmit the new knowledge. The expedition decides to leave before any more knowledge leaks out, and takes with them a girl child who desires to see more marvels. The story ends with the commander musing that the girl won't ever come back to tell her people about what she has seen: Earthmen will have to "dissolve", by assimilation and intermarriage, the people of this planet, who are yet very few, within the huge mass of humanity, to prevent them from dominating the galaxy.