On well worn paths on moderate to even heavy inclines, a cart is still highly effective at reducing manpower necessary to move heavy objects (like the giant sto

On well worn paths on moderate to even heavy inclines, a cart is still highly effective at reducing manpower necessary to move heavy objects (like the giant stones the Incans moved). The Incans didn't not have the wheel because they wouldn't have found it useful. The Incans didn't have the wheel and axle because it wasn't an obvious invention. All evidence points to the wheel in the "old world" (ugh, I hate that term) being invented in one place at one time. It wasn't obvious. It wasn't simultaneously invented by hundreds of people across Europe, Asia and Africa. It was simply copied everywhere and Europe, Asia and Africa were fortunate enough to be connected.