Read each of these scenarios describing the evolution of decreased body hair in humans. Scenario X: As hominins migrated to more open environments and became mid-day hunters/scavengers, they were exposed to higher levels of heat. In order to effectively cool the body, hominins needed to have less hair, so a mutation for decreased body hair occurred. Eventually, evolution favored those with less body hair such that all hominins had less body hair. Scenario Y: As hominins migrated to more open environments and became mid-day hunters/scavengers, they were exposed to higher levels of heat. Hominins with less dense hair, a trait that had heritable variation within the population, maintained a cooler body temperature and were more successful in obtaining food. Over time, hominin populations evolved to have less body hair. Scenario describes evolution by natural selection. I know this because. Group of answer choices X; mutation occurs that increases survival of the species X; it describes evolution of individuals who became adapted to the environment. Y; it involves heritable variation and fitness Y; hominins acquired a needed characteristic so that they were more successful hunters.