alt Hacker NewsThey did have immense networks and were constantly communicating with one another. In On the Origin of Species, I was amazed how Darwin basically knew all the top breeders and naturists form South America, Arab Gulf, Oceania, which he mentions by name. He mentions his peers from the first page in the introduction and the correspondence and responses he got from them.
There's not many geniuses without an ecosystem around them that produced them. And even if there are, how would we know about them if they weren't well connected enough to start mattering?
Famously Leibniz was a genious comparable to Newton, but we have only recently started to learn the scope of his thinking and research, since most of it was left unpublished.