Collections Diversity: Think All Squirrels Look Alike? Think Again People often ask, “So, you pick up dead squirrels on the road . . . when will you have enough?” The answer is never. You might think that every squirrel looks alike, but would you say the same about humans? Probably not. The same variation we find in people occurs in most mammals on the planet. Our collections represent a wide variety of mammals, as well as a diverse selection within species and subspecies. This diversity allows scientists to examine variation, including: sexual variation and variation among a particular species across age, location, and time.