The Ascent of Man
By Way of Introduction
It was my second semester as a Freshman at U.C. Berkeley. I remember sitting cross-legged on the floor of the Barrington Co-op single, just inches below the smoke line, across from some friends and some strangers. Outside to the East, the sun was casually peeking over the Berkeley Hills.
It was one of the strangers who said it: "Evolution is dead, killed by the bloody hands of culture," or something equally, prosaically Freshmanlike. What she meant, of course, was that the invention of culture had stifled human morphological evolution by deintensifying the pressures of a hostile environment. For example, eyeglasses, by reducing the adaptive advantage of better sighted individuals, create a `cultural buffer zone' between individuals and the environment. This buffer zone deprives morphological metamorphosis of its prime motivator: Natural Selection.
Although I thoroughly disagreed with her at the time, I argued more from intuition than from logic so my arguments were quickly cut to shreds. Of course, I was hardly convinced of anything more than the fact that I should have studied debate in High School. Actually, though I didn't realize it for some time, that morning marked the beginning of a long, and continuing, personal quest for the meaning and processes of evolution; A quest which has led me to Anthropology 7 and its final paper.
"Cultural advance," writes Prof. Miller, "has not occurred independently of morphological change; indeed the two are almost inextricably linked." What better topic with which to redeem myself! Of course, any discussion of this claim must first be preceeded by an outline of the cultural and morphological changes to which she refers.
The Handy Man
"Twiggy" must have had a fairly difficult and dangerous life on the East African savanahs. She and her companions were surrounded by a hostile environment, unprotected by steel-framed buildings, inconvenienced by a lack of supermarkets and inhibited by other hominids competing for the same resources. How was it that she and her genus were able to survive and flourish under such conditions?
The answser lies in Twiggy's genus name Homo habilus, or, handy man. Clearly, H. habilus had an affinity for making and using tools, a trait that clearly set it apart from its predecessor, the Australopithecines. In fact, as Melvin Konnor notes in The Tangled Wing, "the dependance on tools, be they stones, hammers, or languages, is what separates man from his hominid ancestors and makes him unique." [Konner 1982:157]
While H. habilus technology was still very basic, consisting mainly of stone choppers and chopping tools, through such basic tool use, H. habilus could better "face the challenges of the environment" and hence, better utilize the resources of that environmnet to outcompete other hominids.
However, the innovation of tool creation and usage depended on certain morphological transformations. As Asimov points out in Extraterrestrial Civilizations, "though dolphins may have just as much potential for cultural ability as humans, because they lack hands and the ability to make and control fire they are caught in a technological dead end." [Azimov 1979: 16]
The morphological distinction of H. habilus begins with a recognition of cranial morphological change. On average, H. habilus brains were 100 cubic centimeters larger than the Australopithecines. Further, changes in the shape of the skull vault suggest some cerebral reorganization. [Nelson and Jurmain 1991: 439] Together, such changes clearly gave H. habilus an increased ability to design tools. Further, the trend towards more efficient bipedalism was also of great importance. H. habilus could free up his hands to both carry and manipulate his tools. Bipedality allowed him to run down prey while putting his newfound tools to use. [Miller 1993: Lecture] Such skills were far beyond those of the Australopithecines and clearly gave H. habilus the advantage.
Out of Africa
The next step up the ladder of evolution was Homo erectus. "as one might expect," write Nelson and Jurmain, "[H. erectus] were taller, larger brained...and more effective bipeds."[Nelson and Jurmain 1991: 463] Further, the dentition of H. erectus became more adaptive to a softer, omnivorous diet. Hence, though still displaying a "mosaic of primitive traits," like thick bones, prognathism, and skull shape, H. erectus slowly continued and expanded the morphological trends initiated by H. habilus. [Nelson and Jurmain 1991: 490]
More striking than the morphological changes were advancements in culture. H. erectus was also, "more culture-dependent and [a] more skillful toolmaker." [Nelson and Jurmain 1991: 463] At Zhoukoudian, for instance, we find suggestions of the controlled use of fire, development of bifacial Acheulian tools, communal living, sexual division of labor and limited communication. [Nelson and Jurmain 1991, 483] Why would cultural evolution progress so much more rapidly than morphological evolution, and what environmnetal stimuli might provoke such a difference?
The answer lies in the pioneering spirit of H. erectus who was the first to make it out of Africa. H. erectus remains are found in Java and China as well as East, South, and North Africa. H. erectus probably migrated because of climatic and geographic changes which changed food types and availability. [Nelson and Jurmain 1991, 494] Such migration led H. erectus to a vast aray of ecological niches ranging from the savanahs of Africa to the Rain Forests of Java, to the colder climes of Northern China.
Because mutation rate limited rapid morphological evolution however, H. erectus was forced to find other ways of coping with the varied environments. Clearly, cultural advancement was the key. Cultural tools could substitute for the limitations of morphology. Group hunting tactics could make them more efficient hunters, carefully honed stone implements could aid in killing and consuming prey and communal education could sufficiently pass on learned skills.
On to the Present
As Nelson and Jurmain note, "it was H. erectus, commited to bipedalism and a cultural way of life, who transformed hominid evolution to human evolution." [Nelson and Jurmain 1991, 494] Hence, we see a marked increase in cranial capacity from H. erectus to Archaic Homo sapiens. Professor Miller cites an increase of 600 cubic centimeters. [Miller 1993,: Lecture] Clearly, brain size was being expanded to support a greater dependence on culture as the manipulation of culture became the pivotal selective adaptation for natural selection to work with. Those sapiens who could best utilize culture, would be most fit. And though the archaic H. sapiens remained somewhat primitive morphologically with their extremely robust features, such morphology was advantageous in their relatively unconquered world of physical hardship.
Meanwhile cultural advancement continued to develop. Archaic H. sapiens are known for such advancements as ritualistic buriels, cave art, and the levallois technique for tool manufacture. However, geographically dispersed cultural variations began to flourish. For instance, where skull drilling might be employed to affect curing of disease in Kabwe, disease or deformation might go untreated in groups like Shanidar. Either way, we clearly see the proliferation of culture in the Archaic H. sapiens.
However, the story does not end there. We must finally discuss the anatomically modern Homo sapiens. Morphologically the a.m. H. sapiens reflect the heightened dependence on culture. In contrast to the constant growth of cranial capacity however, the a.m. H. sapiens show a decrease in size but a tremendous transformation in brain organization. This shift of focus from the "paleo- mammalian brain" to the "neo-mammalian" brain provided a heightened ability to form complex thoughts and use symbols, both crucial to the manipulation of culture. [Bloom 1988: 167] Further morphological changes include the loss of prognathism, thinning of the bones, and development of the chin.
As would be expected, such morphological change was accompanied by expansions of cultural manipulation. A.m. H. sapiens are noted for mnuch more complex usage of tools including blades, bows, and sewing needles, and, as time passed, cars, airplanes and computer networks.
Hence, we see that though cultural advancements did, as Prof. Miller states, increase our "ability to face the challenges of new environmnets," this advancement was both dependent upon and the precurser of important morphological transformations which worked congruently with their cultural counterparts to increase the fitness of homo sapiens and their close ancestors. And with that we can put to rest the idea that "evolution is dead." Evolution is certainly not dead. If anything, it has grown in complexity as its fractal has incorporated cultural as well as morphological facets. Evolution may have a new identity, but it is certainly alive and well.
BIBLIOGRAPHY 1.Harry Nelson and Robert Jurmain, Introduction to Physical Anthropology Los Angeles: West Coast Publishing, 1991. 2.Konner, Melvin, The Tangled Wing, Biological Constraints on the Human Spirit New York:Henry Holt and Company, 1982. 3.Bloom, Floyd, Brain, Mind, and Behavior, New York: W.H. Freeman and Company, 1988 4.Asimov, Isaac, Extraterrestrial Covilizations, New York: Crown Publishing Inc, 1979
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