protruded out. The "keel" effect is very distinguishable on this species, as it is with many of the older hominid species a slight peak on the top of the cranium. Ridges over the eyes were also prominent on this hominid.The next species believed to be in our line of descent is Homo habilis. This is the first being with the distinction of having Homo as its genus. This species, which is dated back to between 1.5 and 2.4 million years ago, had a face, which protruded less than Africanus and Afarensis. Its teeth, though still larger than modern humans, were smaller than those of its ancestors. Finally, its fossil fragments displayed "an average increase in cranial size of 21 percent and 43 percent, respectively, over [Africanus and Afarensis],"(Turnbaugh, 288) with an average cranial capacity of 650 cm3. Skulls found of this hominid also feature a bulge of "Broca's area," an area essential for human speech. It was also taller than the previous hominids, averaging around 5 feet high.At about the same time as Homo habilis and some of the other Homo species, other hominid species belonging to the Australopithecus genus, are believed to have co-existed. Though similar to the Homo line in structure, their bones were thicker and more robust. These other hominids are believed to have developed on a different lineage than the Homo line, and all of these streams died out at around the time of Homo erectus, the next key hominid on the human lineage. Because they are believed to have evolved apart from Homo hominids, it is not important to cover these species in detail. Homo erectus lived between 300,000 and 1,800,000 years ago, and still had protruding jaws and a "keel" effect on the top of the cranium. It, like its predecessors, had no definable chin, and thick brow ridges. However, skull capacity in these hominids jumped from an average of 650 cm3 in H. habilis to an average of 900 cm3 in early specimens and 1100 cm3 in later specimens. The skelet...
