Habilines
The "habilines" is a generic term used to denote the two well-accepted species of early Homo: Homo habilis and Homo rudolfensis. The habilines developed either out of early Australopiths or late gracile Australopiths. The habilines are, in fact, very much like the australopiths, and lots of researchers think they should all be in the genus Australopithecus.
Similarities between Habilines and Gracile Australopiths:
found in East and South Africa, and not outside of Africa
the post-cranium of both groups is very similar:
long arms for climbing
fully bipedal, with a specialized biped gate
ape-like torso (barrel-chested)
small body size (5 feet, 100lbs)
their diets were probably similar. The habilines, like the gracile australopiths, were scavengers, and there's not a lot of indication that they ate more meat than the australopiths. At the site of Olduvai Gorge in Kenya, anthropologists have found animal bones with both cut marks and marks from carnivore teeth (like leopards, lions, or hyenas). Sometimes, the tooth marks are on top of the cut marks (the carnivores came after the habilines had butchered the animals). Sometimes, it's the other way around.
Differences between Habilines and Gracile Australopiths
encephalization (increase in brain size)
average chimp brain = 350-450cc
average australopith brain = 350-500cc (depends on species and body size)
average habiline brain = 600-800cc
brain isn’t just bigger, also shaped differently
growth of Broca’s Area, a part of the brain associated with language ability
lateralization of brain, marked functional separation of cerebral hemispheres (based on evidence for handedness, see below)
found with shaped stone tools (lithic technology)
What's the Big Deal about Stone Tools?
Probably all of our hominin ancestors used some types of tools. After all, chimps do! But stone tools work better because they last longer and can be shaped to fit the needs of the user. It's not 100% clear that habilines made all of the early stone tools that we've found. Robust australopiths are also found at these same sites. But it is clear that habilines did make tools, so they are usually accepted as the first tool maker.
But stone tools require more skill to make than the unmodified rocks or simple sticks of a chimpanzee. They require hands with shorter, more agile fingers, and an understanding of fracture mechanics (what will happen when you hit a rock with another rock, at a particular angle.) Apes are not capable of making real stone tools. Researchers have tried to teach them, but their hands aren't agile enough, and while they understand that bashing rocks together will break the rocks, they aren't capable of understanding that the specific angle and force of the blow will affect the shape of the broken rock.
Humans, interestingly, have a strong, "natural" ability to make stone tools. Merely based on your experiences with everyday physics and manipulating objects, you could easily make a simple stone tool, if given the right materials. Anthropological research has shown that the average undergraduate can pick up this skill with only a few wacks of a rock.
Chimps do use tools - all apes do - but not as frequently as humans. They are not dependent on technology. Many chimps, especially males, do without tools entirely. But all modern humans are completely dependent on tool use. Just look around you! Anthropologists define tools and technology as anything created by humans to help them interact with each other or the environment. So the computer that you're using to read this is a tool, but so are your glasses or contacts (if you need them), the clothes you are wearing, the chair you are sitting in, and the building surrounding you. Humans interact with tools or technology almost every moment of their lives.
Were habilines as dependent on tools? The answer is probably not, based on the following evidence:
First, many bones from habiline sites show heavy butchery marks. People who know what they're doing don't hit their knives into bone while defleshing an animal. That will dull the blade. So the fact that habilines left numerous, heavy butchering marks suggests they may not have had a lot of practice using tools. They were an "every once in a while" kind of activity.
Secondly, there are very few types of early tools. We call the tools made by the habilines Olduwan Technology. (This is named for Olduvai Gorge, in Kenya, where it was first described. Some students in the past have called it Obi wan technology on the exam. Don't be that student.) Olduwan Technology is very simple, and includes [few different shapes. In other words, most of the tools looked the same. If tools are an important part of your daily life, then usually those tools will be specialized to particular tasks. For example, I do not own a potato masher. I only make mashed potatoes once a year, at Thanksgiving, so I can make do with a fork. I have lots of forks already, and the fork is pretty inefficient as a potato masher, but for one day a year, I don't particularly care. If, however, I started making mashed potatoes once a day, or once a week, I would want to buy a potato masher. That investment in a more specialized technology would be worth it, if I used that technology frequently. The cost of the masher would be made up for by the greater efficiency in mashing potatoes on a regular basis. The fact that Olduwan technology is unspecialized suggests that efficiency wasn't a major concern. Perhaps tools weren't used that often, so their efficiency wasn't as important.
Finally, Olduwan technology changes little through time. Quite literally a million years goes by without much change in function or style of stone tools. This suggests that the habilines were not under a lot of pressure to adapt tools to environment. A lack of pressure suggests that habilines were not particularly dependent on tools, relative to modern humans.
In sum, habilines were moving down the road toward human dependence on tools, but they were not quite there yet.
One last important point about stone tools: they can indicate whether their maker was left- or right-handed. This is an important indication of brain lateralization.
Chimps have dominant hands, but individuals are equally divided, with roughly half favoring their left hand, and half favoring their right. Modern humans are 90% right handed (although that might be an oversimplification, since some people can only use their right hand for most fine tasks, while others are incompletely dominant with their right hands. Most left-handed people are incompletely dominant with their left hands.) The shift toward dominant right-handedness reflects the lateralization of brain, with a marked functional separation of cerebral hemispheres (right brain vs. left brain). This lateralization is occurring as early as 2mya. Olduwan technology from the site of Koobi Fora shows that 90% of the tool makers were right-handed. This could indicate that habilines had more human-like communication and cognitive abilities than the australopiths, although it is unlikely that they had full language abilities.
Species of Habilines
Homo naledi (tentatively placed among the Habilines until we have more information)
Were these species of habilines different? Yes! Do I care how? No!