Why it took so long to invent the wheel (2012)
scientificamerican.com
scientificamerican.com
I think this is true for a lot of other inventions too. What we usually point to as the invention is really just the surface of a whole system that had to come together. The iPod, for example, wasn’t just a music player. It only worked because mini hard drives, batteries, mp3 compression, etc. The thing we remember as the invention is really the moment when all the pieces finally clicked.
As all of these technologies come into existence, some "inventions" become inevitable.
Sure, maybe a wheeled cart was constructed in one place first by 20 or 50 years, but we are talking about a time where knowledge did not travel far or fast. We had independent discoveries of the same thing in 19th century that were spread out by 20 years, I'd think it was even more 3500 BC.