OT: I was reading this article about a potential "real" sixth sense that humans may easily develop: echolocation
https://getpocket.com/explore/item/humans-could-develop-a-sixth-sense-scientists-say

The thought occurred: maybe we already had it when we were hiding in caves under a low/flickering light and then "lost" it.
Some deep caves in South Africa were continuously occupied by H. sapiens for as long at 100000 years or even longer.
It would make sense to develop such 'sense' back then.