Jill Paton Walsh
Toolmaker
1973
from the dustjacket:

In Ra's tribe each man makes his own tools and hunts for himself. It is a disturbing new idea for all of them when Yul asks the boy to make him a spearhead, in return for food. Gradually Ra becomes toolmaker to the whole tribe — but when the bad weather comes and they find that he has forgotten his skill at hunting, he is left to die.

But Ra survives and finds a new tribe. These people, who can tame oxen, grow crops and bake bread, seem to him to have magical powers. Even so, Ra has his own skill to offer them, and he is in a position to bargain when he confronts his own people once again.

What it must have felt like for a Stone Age boy to stumble on a culture so much more advanced than his own is brilliantly put over in this absorbing story.

Four full-colour pictures and sixteen line drawings by Jeroo Roy.