brain size: 580 - 752 cubic centimeters
intelligence: made stone tools, had some form of language
largest group size: 90 (estimate)
other: Homo habilis is the first in the genus homo. Its most prominent characteristic is a brain size almost twice as large as its ancestor Australopithecus.
Timeline
Ardipithecus | Australopithecus | Homo habilis | Homo erectus | Neandertals | Modern Humans