This was described in the amazing book by Bill Bryson, “A Short History of Nearly Everything” in 2003.
Apparently, an entire civilization in East Africa spent their lives shaping hand axes. They hauled rocks from miles away to their village, and spent their time shaping stone axes, for no any apparent reason. They did this for up to 1 million years before they disappeared.
And the hand axes never improved in quality - they were the same for all that time.
Their brains never evolved past that of a young child.
Very eerie. Can you imagine? One million years of this?
That book by Bill Bryson is one of the best books on history you will ever read. And you should have your children read it as well.
I listened to that book on CD. It has had a powerful effect on me.