I also can't show conclusive evidence that there wasn't a continent of Atlantis in the middle of the Atlantic 10k years ago that mysteriously disappeared without a trace. Yet if someone enters a conversation about geography with me and inquiries about Atlantis I'm probably going to tell them that it never existed without bothering to wrap that statement in multiple layers of clarification about the evidence and probability estimates and highly unlikely contingencies.

We can't prove that there wasn't some isolated genius who engaged in animal husbandry in Africa before everyone else but was ignored by the rest of his tribe or whatever. But we have managed to place some fairly low upper bound on how much of that could have been happening. At some point it is reasonable to conclude that your typical society in that time and place didn't have access to it.