When dogs, cats, and reptiles (among many other animals) soak up rays they obviously have no clue what they are doing as they increase their cancer rate.... or maybe nature knows better than what humans have been pushing for the past 80 yrs.   I'll bet on nature.   When you just think about it rationally, there is basically no way that humans are not benefiting from sun exposure throughout 1M+ years of evolution with constant daily exposure.