The Origin and Evolution of Human Language
Prof. Suzanne Kemmer
This page is still under construction although the structure and many details are place, particularly about H. erectus. I have not yet integrated the more specific information I have been collecting about toolkits in various timespans Also there is a bit more to come on the more recent finds in the same timespan which are now classified as different species from habilis and erectus.--S.K.
The two early hominid ancestors that have been most focused on in the 20th/21st centuries as 'breakthrough' species in the hominid line are Homo habilis and Homo erectus.
Fossilized bone remains of Homo habilis were discovered in the 1960s by Richard Leakey at the famous Olduvai Gorge site. Leakey made the claim that H. habilis was a tool-making creature. More recent claims attribute the tools found at the site to another species. (We need to integrate information from Johanson and Edgar 2006 and the other most up to date sources to see if there is an emerging consensus on this.)
Here is a site from the Smithsonian with some fossil skull pictures: Habilis skull remains
An associate of Leakey's who was a co-discover of the habilis finds is Philip Tobias, based at the University of Witwatersrand, South Africa. Tobias advanced the view that H. habilis had extreme brain lateralization. He argued that such extreme lateralization supports the capacity for toolmaking and ALSO some level of linguistic development. Tobias pointed to impressions on the inside of H. habilis skulls (he has endocasts made from such skulls) which seem to show outlines of Broca's area (or the large veins found around that area). These claims have been controversial; many see no regular impressions that could be ascribed to brain structure.
Moreover, recent research has also shown that a structurally and functionally distinguishable analogue to Broca's area is evolutionarily much older than the hominid line; some aspects can even be seen in language-less species such as other pongids and even monkeys, suggesting that even if H. habilis had a distinguishable Broca's-like area, the species still might not have had language or proto-language.
However, if Tobias is correct and Habilis had a more developed analogue to Broca's area than earlier hominids, this would allow the possibility that at least some of the neurological hardwiring that controls the vocal tract musculature was developed already 1-2 million years ago in Homo habilis. Broca's area is exactly where such cortical structures are found in humans. The fine-tuned sequencing of full-blown spoken language has been claimed by Philip Lieberman to be a late, H. sapiens sapiens devolopment. Lieberman argues on the basis of fossil skull evidence that Neantherthals lacked this musculature and hence its neurological correlate, the capacity for the articulatory sequencing in sound production that modern humans demonstrably have.
In my view, some linguistic vocal development at the stage of Homo habilis is also possible without the full-blown articulatory capability of modern humans. Possible does not mean inevitable however.
In Richard Leakey's account of hominid evolution, Homo habilis was an ancestor of modern humans. Habilis clearly had a much larger brain than the australopithecines, but the rest of its body is more like them: it was a fairly small creature, maybe 4 foot 6 or so, with long arms, more ape-like than other hominids. Recent claims make Habilis another 'aunt/uncle' species to humans, not in the direct human line.
Various claims about the capabilities and behavior of H. habilis are controversial. Tobias and others say tools and some kind of language were already there; others say, no, the only breakthrough we really KNOW about in Habilis is the larger brain size, and the move to the much dryer savannah from the forests inhabited by the australopithecines. But this habitat was characteristic of all of genus Homo from the earlier hominid fossils of 2.5 million years ago.
The focus of attention, among those who look at the fossils from between 1 and 2 million years ago, for 'precursor' attainments and behavior, i.e. aspects of a species that can show developments underlying more recent hominid attainments, has shifted to Homo erectus.
"Erectus" is now somewhat of a misnomer, because the name highlights bipedalism. The idea of Erectus as the first walking hominid harks back to the days before the discovery of other contemporaneous creatures and earlier creatures that were also bipedal, like the Australopithecines, who were walking on two legs a couple of million years earlier than erectus.
Recent findings lead researchers such as Johanson to posit a smarter 'sister species' to Erectus called Homo ergaster. It is still unclear what the relation of Ergaster and Erectus is, and the same bones get classified as one or the other depending on who is looking. There are fewer candidate bones, so fewer claims have been made about this species or subspecies. There are still a good number of finds classified by general agreement as Homo erectus, however.
What do we KNOW, not just infer, about Homo erectus?
What can we SAFELY INFER from these Erectus remains?
The control and use of fire is highly significant. Things it could allow H. erectus to do that non-fire-wielding hominids could not:
Did Homo erectus have containers, carrying slings, bags? If there were any, none have survived. The earliest surviving containers and carrying devices are H. sapiens. We don't know if they had nothing along these lines, or if nothing survived. How about things to carry weapons and tools? (The more settled they were, the less need for things to carry, one could say.)
The following are my own speculations.
The question then arises, do any or all of such attainments, if we can hypothesize that H. erectus had them, suggest the attainment of some kind of language (symbolic communication)?
There is always danger in interpreting these early creatures as like early sapiens or even like modern, neolithic sapiens (some of whom don't make fire, but have full-blown human language and human culture.) Still, the environments of Home erectus were in some cases like those of many early sapiens cultures (and even modern sapiens hunter gatherers in some parts of the world). They had to solve many of the same survival problems and we know they had tools and fire. That is why we are sometimes tempted to compare the more advanced Homo species to Erectus. Homo erectus seems very like modern humans in some respects, especially compared to the earlier hominid species.
Can we allow the possibility of a pre-language, e.g. with simple symbols and no grammar? Would having such a system of communication have helped along developments in tools, artifacts, culture, that would aid survival in the new harsher environments? Many people think Homo erectus had some kind of language, even if not full-blown.
With H. erectus there is no sign of clothing, textiles, or pottery, and there is some disagreement about whether there are wood or antler artifacts that can be posited as belonging to erectus. (I am investigating this.) Is the lack of clear evidence of non-stone artifacts a result of the fact that such artifacts cannot not survive for such a long period, or because Erectus had none of these things? There is also no sign of manufactured shelters in most reports. These, it seems, come only with H. sapiens.
It seems that every hominoid/hominid species that has caused great excitement as 'our earliest human/pre-human ancestor' has ultimately been re-cast as an "aunt/uncle" species not in our direct line. This is true of: Australopithecus africanus; Homo habilis; Homo erectus; and even for the earliest discovered hominid, Homo sapiens neanderthalensis.
In the last case, the fossils were first found in the 19th century, understood to be of ancient origin only in the early twentieth century, and realized to be not the direct ancestor of H. Sapiens sapiens only a generation or two ago, when it was finally understood that Sapiens sapiens emerged from Africa at a much later date and merely overlapped temporally with neanderthalensis.
The traditional simple story of a single line of ancestry linking Habilis--->Erectus-->H. Sapiens is still found in many books and websites, including on some of the general education sites on the web.
The Washington State University site on hominids is a good illustrated site, and its timeline does not actually claim a linear evolutionary development of the three species, but the timeline is nevertheless simplified compared to others. See the links on Habilis and Erectus on this WSU site.
A more authoritative site, which explicitly does not consider Erectus to be a direct human ancestor, is part of the Smithsonian site mentioned above: Early Human Phylogeny.
Another timeline, this one made by the American artist Bruce MacEvoy, who dabbles in paleoanthropology (among many other things) is this: MacEvoy's Handprint site "Chart of Human Evolution". The timeline looks to be based on Johanson et al. (2006), a good source.