Humans are different from each other in many ways, including in their sizes, shapes, skin color, facial features, and handedness. however, all humans are classified as one species because it is possible for one person from one location on the earth to reproduce with another person from a different location on the earth. what other evidence can be used in support of the idea that humans are a single species and unique from other species? a. all humans have one vertical line of symmetry in their body plans. b. humans from different locations speak different languages. c. humans from different locations can donate blood and organs to one another. d. all humans possess body hair.