Paleoanthropologists have for many years made the equation between and among the ability to make stone tools, lateralization of the brain, and the ability to use language. Homo erectus clearly made and used stone tools, and thus for many years the species has been considered capable of speech, albeit at perhaps some decreased level of function. Anthropologist Grover Krantz, for example, made the intriguing but ultimately untestable suggestion that Homo erectus youths may not have learned to talk until adolescence.9
Our ideas about speech being the quintessential human attribute have also evolved. Anthropologists have for years been influenced by an idea of culture that was all or none. Many of the major cultural anthropologists of the last century, such as Alfred Kroeber and Clyde Kluckhohn, believed that cultural origins occurred at a specific critical point, like the boiling point of water, rather than a more gradual evolution through time. The
"critical point" viewpoint was recently resuscitated by archaeologist Richard Klein who postulated a gene mutation fifty thousand years ago that suddenly made language possible—a linguistic "hopeful monster."10 Tool use, documented by archaeologists, has been a more generally agreed-upon sign that culture has appeared. Homo erectus was for decades the earliest human ancestor found to have abundant stone tools (early australopithecines do not have stone tools), and thus in this view erectus was hailed as the first bearer of human culture. By inference then they were the first hominids capable of speech. Much has been learned to cast doubt on this view.
The language abilities of chimpanzees have been paramount in showing that symbolic communication need not involve speech. Chimps can, for example, use a red triangular plastic chip to mean "water" without ever uttering a word, which of course they cannot do. The gap between ape and human communication has narrowed significantly as more research has been carried out on chimpanzees, both in the laboratory and in the wild. Chimps may well represent a near-mute form of hominid—capable of symbolism but not of speech. Some primatologists even contend that chimps bear "culture," but if so it must be a very primitive form, without language.
The earliest tools have also shown that culture did not evolve all at once. Sileshi Semaw, now of Indiana University together with Jack Harris of Rutgers University and colleagues have discovered the very earliest stone tools at 2.6 million years ago in Ethiopia, and they are little more than smashed pieces of quartz with sharp edges. We only know that they are tools because of where they were found and their association with fossil bones having cut marks made by the tools. Deliberate flaking of stone need not be invoked to explain these tools. Hominids could have easily thrown lumps of quartz forcefully on the ground or against other rocks to make these stone tools. We can imagine chimps engaging in this sort of behavior, and indeed a recent discovery of chimpanzee stone artifacts suggests that the earliest hominid stone tools are little different.11
Homo erectus was a species in which natural selection increasingly emphasized brain growth. We deduce this from the fact that fossil skulls show increasing cranial capacity through time. We infer that an increasing brain size would reflect that more neurons and interconnections within the brain were developing to deal with environmental and interspecies challenges to survival. Language, manual dexterity, and increasingly lateralized functioning of the brain may all have been involved. But at the same time as the ballooning Homo erectus head was evolving to accommodate more brain, natural selection was also conferring on the species defensive head armor as postulated in chapter 3. These two adaptive trends, working in one sense antagonistically, must both have played a part in the composite adaptive evolutionary biology of Homo erectus.
Our significantly better fossil and archaeological records make it clear that toolmaking ability, fire use, and language must be decoupled in terms of their times of appearance and perhaps even their functional relationships to one another. That Homo erectus made stone tools is beyond dispute. Their using fire or making fire before the first hearths—dated in Europe at 230,000 years ago—is still contested by some archaeologists. We, on the other hand, are persuaded by the early evidence for fire and do not think hearths need be present before fire can be accepted as an important part of Homo erectuss adaptation. Stone tools and fire are major cultural advances and we believe that they tie in importantly to increases in brain size and intellectual capacity. On the other hand it is unlikely that Homo erectus produced and used speech in a modern human manner because the anatomical parameters that we have adduced from its skull indicate an overall pattern unlike speech-producing Homo sapiens. Like other higher primates, Homo erectus certainly used a rich repertoire of verbal communication and, if we knew more about it, we might term it "protolanguage." There may have been a mixture of vocalizations and gestural language, a la American Sign Language, and even singing, but at present we do not know. And, unfortunately, we have not yet conceived a convincing way of finding out.
Summarizing what we believe that we know about Homo erectuss behavioral abilities, we can say that the species made stone tools, used fire as an ecological tool if not as a primary domestic focus (as indicated by the lack of hearths), and lacked human language. We next turn to one of the most contentious behaviors hypothesized for Homo erectus—cannibalism.
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