Your body is constantly generating heat. If that heat has nowhere to go, your temperature goes up and up.
You need to be in an environment that sucks heat away as fast as you create it - and if the external air temp isn't cold enough to do that on its own, then you have to rely on evaporation of sweat to help shed the heat.
It’s the feature that let us become the dominant predator. We could track large game that is wounded until the collapsed from heat exhaustion. Yay sweaty humans!
So are you saying that people who sweat more in hot environments are better suited for long distance hunting? Because I'm a gross, sweaty mofo and I would like to feel better about it
Probably not I'm sorry. Sweating enough so that the sweat evaporates as fast as it excretes from your pores is optimal. Skin being more wet doesn't cool faster (drops of sweat falling off you don't cool you), so excess sweat would just dehydrate you faster. Sorry
It also seems like this is part of why there were so many powerhouses around the mediterranean, the climate there is just right that you can work a lot without melting, and warm enough that it's comfortable to walk basically naked.
And it makes sense when you consider that humans evolved for a comparatively sedate lifestyle (even hunting isn't going to involve sprinting that much) in subsaharan africa.