liz wrote:... Eben said "The wheel. Or fire." I said "A pointy stick."...
I have a theory.
Some time between Lucy and the stone age, humans started growing bigger brains, which required bigger heads.
Now, we all know that birth is one of the more dangerous times in a creature's life, and that a larger head means more difficult birth.
If you watch pack animals in the wild, you'll notice the other females stand around watching while one of their number give birth. It helps to deter predators, but does nothing for the birth itself.
What the proto-humans did was invent the mid-wife system - they actually helped
with the birth. That made it safer, and allowed bigger brains and intelligence to flourish.
So wheels, fire, even possibly pointy sticks (though bonobos have been seen using those, as have rooks) and iPhones all follow the mid-wife.