The first scientists to classify organisms were Lewis and Clark in the early 1800s as they described hundreds of plants and animals. Classification systems organize information about organisms into groups with consistent naming which facilitates communication among scientists and helps understand organisms' needs. The lowest classification level is species, with humans belonging to the Kingdom Animalia, Phylum Chordata, Class Mammalia, Order Primates, Family Hominidae, Genus Homo, and Species Homo Sapiens. The kingdom level has six main subgroups and the most important reason for classifying is that it allows for efficient communication in science.