There was once a tribe of humans that was referred to as “the Wild Ones.” They were humans who were linked to the wild natural world, having animal characteristics.
This man looks like no one to be trifled with, and that assessment is correct.
Real World: some Indians in the Amazon treat their eyes with a traditional potion applied with palm leaves. Brutally painful, the drug alters vision, giving the jungle's dense green walls greater texture and dimension. You could adapt this to desert or swamps, or other hard to navigate regions.