First discovered by Johnathan Leakey (as part of a team led by Lewis and Mary Leakey) in 1960 and described in 1964, Homo habilis was not a widely accepted classification early on. They lived very early in our lineage, with pretty considerable overlap with Australopithecus. Not everyone was convinced they weren’t part of the latter genus.
With a brain size of about 600-650 cubic centimeters, they were on the small size for Homo, but on the large size for Australopithecus. And 600cc is the average…they get smaller still. The limited postcranial material found means that a lot is kind of up for interpretation.
They had a long run. 2.4 million years ago is well within the time frame of Australopithecus, but they lived until about 1.4 million years ago. Meaning they also coexisted with several other members of the genus Homo, including H. erectus, H. ergaster, and H. rudolfensis, as well as the robust australopithecine Paranthropus robustus.
Some of these interpretations have habilis with a less modern gait than would/should be expected of Homo. These arguments tend to classify them in the genus Australopithecus. Fairly small bodied with slightly elongated proportions of their arms, they apparently have precision grip adaptations as well as climbing adaptations. Their feet seem overall less adapted for life in the trees than do Australopithecus and so it seems that while they’re very much on the cusp of things, the classification is safe and sound.
Regardless, habilis is on the cusp. And they arguably gave rise to the rest of our genus, with H. rudolfensis right along side them. As with most predictions about what should have looked like when and where, habilis exhibits a mosaic of features that make classification a delightful headache for all those involved. They made tools (hence “habilis”), which was at the time considered a hallmark of our genus. But it’s since been discovered that habilis wasn’t the only handyman on the savanna: Australopithecus was making Oldowan tools around 3 million years ago.
Really these things are always pretty messy. We are dealing with fragmented remains of something dead for 2 million years. And it’s found (despite painstaking excavation and back/knee breaking labor) almost by accident.
Habilis is a species near and dear to me because I have personal experience with it. After hiking literally hundreds of miles in literally 120 degree heat, carrying our own water and hoping to not get injured because it’s either an air lift or several days drive through the bush to the nearest hospital, it took crawling on our hands and knees, arms width apart, moving individual bits of sand with a tiny stick to find…two teeth. I found one, and Dave Patterson found the other. And this was at a known site at which habilis materials had been found before.
The odds are highly stacked against you finding anything. Careers, lives, endless amounts of time and money are spent dedicated to finding fleeting bits that are then measured and compared to other fleeting bits for generations to come. Such scant evidence obtained through unimaginable planning and work has brought us so much closer to understanding the foundations of who we are, biologically.
It is almost unfathomable how much we can glean from so little. It’s shaped all of the work I have done since, whether or not it has been related to biological anthropology. And it has made pretty much all of my subsequent research seem almost simple by comparison.
The story of us has so many more chapters left to read. The one tooth that I have personally contributed to the human fossil record is going to help contribute to the story long after I am gone from it.