Devolution, by my rough definition, is the process whereby a complex organism becomes less complicated. Could this happen to humans? and what would we lose? Perhaps we're already losing our sense of smell? What if our flight or fight instincts were deadened/eliminated? How would that alter society? Would we lose our fear of the future and the insurance industry collapse?
Maybe the loss of species on Earth will decrease the complexity of those that remain? With less competition but increased environmental extremes, will the survivors simplify, shedding inessentials?
I stupidly failed to bookmark an article I read on feral dogpacks in Sofia, Bulgaria. The author commented that from his observations the dogs quickly (through generations) lost breed extremes and zeroed in on a street dog look resembling (and my memory could be at fault) the Australian dingo. They simplified and dominated their ecological niche.