Many leading taxonomists have grouped chimpanzees and humans into the same family, hominidae, because

The classification of humans, gibbons and orangs, chimps and gorillas in the same family of hominidae is based on the morphological similarities between the three types of organisms. Moreover, taxonomists also incorporate the genetics of these organisms, and the current molecular-based cladistic classification groups all of these organisms in to the same monophyletic group.

Atissue is a group of connected cells that have a similar function within an organism.