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This chapter examines human cultural evolution. Although biological and social evolution have been a strong influence on human responses to evolution, biology and being social is basic to all humans. However, biology and society are not the only influence on people: there is also the influence of culture, the rules of a certain group of people and how they are to respond to biological and social stimuli.
Human Cultural Evolution
Self-preservation, reproduction and greed are biological imperatives. They arose from millions and billions of years of biological evolution. They are as much a part of human life as any other life on earth.
However, humans are not just biological creatures. We are also social creatures, the most social on earth. The ways we deal with each other, from personal to international relationships, can have as much an influence on our behavior as our instinctive reactions. But our societies and cultures did not spring like Athena, full-grown, from the forehead of Zeus. They grew and developed during millions of years of cultural evolution. And the closer our primate ancestors approached being human, the less biological evolution influenced our behavior, and the more cultural evolution took over.
This does not mean that biological evolution ended. On the contrary, it remained as important as ever. It simply altered direction. The emerging human body evolved to fit its ecological niche, to survive as a living creature. The emerging human mind now evolved to fit its cultural niche, to survive as a social creature. (Leakey, 1978)
We can never know for certain about our primate predecessors' cultural evolution. Unlike bone and stone, culture doesn't fossilize. Nevertheless, it is possible to make educated guesses.
We can start with some assumptions:
1) Humans are biological creatures. We have all the characteristics of biological creatures, such as genes, chromosomes, DNA and RNA, cellular structure, etc..
2) We are as sensitive to our environment as any other organism. When presented with environmental problems such as lack of air, food or water, we die, just like other organisms.
3) We evolve as an adaptation to the environment, just like any other living organism. The archeological record shows alterations in human structure and behavior (although often the last is an educated guess) as the environment, according to geological evidence, changed.
4) Our primate ancestors behaved similarly to today's primates. Genes guide how a body develops; bodies develop to cope with the conditions in its environmental niche; we are 99.6% genetically like chimpanzees. (Sagan, 1992) It is reasonable to assume we, at one time, lived lives similar to chimpanzees'. As Carl Sagan and Ann Druyan say in Shadows of Forgotten Ancestors, "If we want to understand ourselves by examining other beings, chimps are a good place to start."
The first three assumptions require little discussion, since they are self-evident. It is the last that is important to an examination of human cultural evolution, how humans became human, how we evolved from an early ape into ourselves.
Chimpanzees live a comparatively relaxed life: they sleep, play, form social bonds, forage for plant foods augmented by the occasionally hunted meat. It is the latter, the difference in how chimps and protohumans gathered food, that caused a great break between them. (Leakey, 1978)
Chimps (and other apes) eat plant foods when and where they find them. They don't gather them or share them -- each ape feeds rherself.
However, when meat is available, it becomes the center of attention. The other chimps gather around, "asking" for a share. Whichever chimp brings it in shares it however rhe wishes. It is probable that protohumans did the same thing with meat.
It is how protohumans handled plant foods that differs from other apes. Instead of an individual foraging for rherself and eating what rhe finds on the spot, protohumans began
gathering the food and bringing it back to a central area. Here they shared it among the other members of the band.
Why would protohumans change the way they handled food from what is obviously a perfectly acceptable method for chimpanzees? The answer probably lies in the environment in which the protohumans found themselves. Chimpanzees inhabit tropical-zone forests where plant food is near at hand. It's so near they need merely stretch out and grab it. The search or food is more for favorites than for needs. Chimps live in an environment where resources are relatively abundant.
Protohumans changed their way of dealing with food. Since they did so, it must have been in adaptation to their environment to improve their ability to survive. The most logical reason for a change in the pattern of "eat what comes to hand" would be a lack of food that came to hand. That is, the protohuman must have evolved in a marginal environment, one in which food was scarce or difficult to gather. This led to a basic change in the relationships between the members and the social life of the band. (Leakey, 1978)
For the first time (as far as we know) apes began working together to gather food. This was probably an adjustment to the band living in these marginal conditions. Where resources are abundant, there is no need for cooperation. An individual can get what rhe needs on rher own. In marginal conditions, a cooperative group can do a better job than individuals in exploiting what resources there are.
A division of labor also arose in that gathering of food. The males gathered the meat supply. At first they were probably scavengers, finding animals that had died or predators had killed, since they were too small, weak and harmless(2) to have much success as hunters. However, as cultural evolution continued, cooperation overcame those limitations, leading to a greater hunting ability, much as chimpanzees do today.(3)
While the males went in search of meat, the females foraged for the plant foods. This division of labor made sense because of the biological need to reproduce and the obligations imposed by that need. The females, being the ones with the biologically dictated responsibility of bearing and rearing the young, were probably often burdened with them. Thus, females would find hunting difficult, since it undoubtedly involved traveling long distances and maintaining silence on a stalk, both hard to achieve with an infant along.
In addition, there are dangers on a hunt, particularly for a small primate that can change from predator to prey in an instant. The female is biologically more valuable than the male: she bears and rears the young, and has a much greater stake in reproduction than the male (see Chapter Three). Biologically, the male's only purpose is to aid the female in reproducing. (Gould, 1983) He can't do that without her (although she can -- some species can reproduce parthenogenically (i.e., without the need for a male to fertilize the eggs)). Thus, the death of a female is a greater blow to a species' survival than the death of even many males. It makes little genetic sense to place so valuable a member of a species in harm's way.
However, there is little of hunting's dangers in foraging for plants -- it's hard to imagine being pummeled to death by a rampaging cucumber. Thus, it is sensible for the females in the band to do this job, while the males do the hunting.
The division of labor allowed the group to better exploit its niche (see Chapter Three for a discussion of the niche). When each animal is foraging only for itself, it must personally find all its needs. In an environment where this isn't possible, some animals will find enough and others will fail (read, die). However, dividing the labor in such marginal conditions allows each animal to gather what it can, rather than what it needs. If it falls short of what it personally needs, it gets the rest from the surplus others have found. Thus, males that fail in their hunt can still eat what the females have gathered. When the males succeed, all gain from the concentrated nourishment that meat provides,(4) and can save the plant food for more lean times.
The division of labor led to two things. The first was the camp. Most apes are constantly on the move, following the food supply, foraging as they go. Wherever evening overtakes them, they stop for the night. With abundant resources, there is no need to scavenge everything in an area to survive: the band need merely follow the line of least resistance or most resources.
However, sharing food requires a central place to which the animals can return to do the sharing. Such a place, a camp, serves two purposes. First, it is a convenient place where all the members of the band know the others will eventually be, particularly the males who may be gone for hours or even days on their hunts. This also makes it easier to share the food found.
Second, it allows the band to better exploit its range. The members of the band can radiate out from the camp in different directions every day, eventually covering the entire area. When, after a few days, the band has exhausted the area, they can move on and find a new camp.
The third effect of the division of labor was each gender depending on the other for survival. Although the females could have lived exclusively on vegetation (as vegetarians do today), the greater concentration of nutrition in meat would benefit both the females and their young.
The males, of course, probably couldn't survive on an exclusively meat diet. Many primates are omnivorous, and depend on plant foods for vitamins and minerals that meat alone doesn't provide. Although the males could have gathered plant foods to fill their nutritional needs, this would have lessened the effectiveness of the group in exploiting their niche. In addition, hunting and scavenging are not always successful. Thus, the males depended on what the females gathered, while the females and their young benefitted from what the males gathered, leading to a much closer relationship between all members of the group.
The two effects of dividing food-gathering labor, the camp and the dependence of the sexes on each other beyond reproduction, were the first great steps toward modern human culture.
Sharing of resources and its concomitant division of labor led to a divergence in both the biological and cultural evolution of the sexes. Evidence shows that women are more group-oriented in their activities than men, while men are more individualistic; that women's senses are generally sharper than men's; that women are more language oriented than men, while men are more spatially oriented; that women are better able to "read" faces for emotion than men. (Moir, 1989; Tannen, 1991) Each of these differences arises from how the brain works, both in perception and response to that perception. Several aspects of protohuman social life based on cooperative food gathering could well have contributed to these biological differences between how each gender's brain functions.
Biological pressures would alter the females' lifestyles under the new system of food sharing. These changes would include becoming more sedentary, developing a group mentality, improving their senses, and making them the major influence on socializing the young. The last is a primary difference between humans and most other creatures on earth.
First, the females bearing and rearing the young would have bound them to a fairly sedentary lifestyle and made gathering plant foods their contribution. There is no need to pursue a running rice stalk or dodging carrot -- plants tend to stand still. And carrying a child would make any such pursuit difficult if not impossible, anyway. Their obligation to rear and care for the relatively immobile young would also contribute to staying sedentary.
Second, the females would likely have stayed together in a group for several reasons. Plant foods are often small: they would have to gather many individual nuts or roots or cereal grains to provide nourishment, unlike meat that comes in comparatively large and easily transported packages. As the adage says, "Many hands make light work."
Also, a group is more efficient than an individual in searching an area; many eyes can see more signs of edible vegetation than a single pair. A group mentality would be an advantage in exploiting a marginal environment.
In addition, there is safety in numbers. Predators are less likely to go undetected when there are many eyes, ears and noses at work. And even if a predator attacks, the confusion several running, screeching animals can cause could lessen its chances of success.(5)
Finally, a group of females is more efficient in rearing young. They can help each other, act as babysitters for each other, share in the training. As mentioned above, the latter becomes more and more important as an animal increases in intelligence and social life.
The greater an animal's intelligence and the more complex its social life, the more likely much of its behavior is learned rather than instinctive. This in turn requires a period of training in the use of that intelligence and how to function in that society. Such training would take place during an animal's childhood.
A human needs more training than any other creature. That this is true is clear from the differing lengths of childhood of various animals.(6) Most fish and reptiles are born ready to survive on their own. They need little if any training from their elders. Mice are ready in days, cats and dogs in weeks, lions and wolves in months. However, chimps, with a complex lifestyle and social life, require two to three years. Humans need 12 to 14 years for their basic training, and an additional seven or more for advanced training, the longest childhood on Earth. Protohumans probably fell somewhere between chimps and humans. And since the females bore and raised the young, at least the basic training fell to them.(7)
These factors may have contributed to the differing evolution of the male and female brain. As stated above, women's senses are sharper than men's. Women can distinguish colors better, have sharper hearing, have a better sense of smell. In fact, they can see, hear and smell things that men are incapable of detecting at all. (Moir, 1989)
The evolution of such abilities makes sense when placed in the context of the female protohuman's gathering of resources. The sharper sight would make finding food easier. Gathering plant foods requires seeing a tiny leaf or shoot and identifying it as edible by its shape and color. The better the sense of sight, the faster and more efficient the gatherer can be. The sharpening of the sense of smell would help her in locating plants. It would also help her discriminate between those that might look very similar but have different properties, like poisonous or medicinal effects. Better senses of hearing and smell would aid in evading predators.
In addition, women's greater facility with language and ability to read facial expressions could have come from the combination of working in close-knit groups and rearing children. As protohuman society gained complexity working toward true humanity, the learned behaviors became more and more complex and hard to teach just through example and gestures.
Many animals use vocal noises that carry meaning, such as warnings or courtship rituals. Some even make sounds that carry more specific meanings. For example, the colobus monkey makes a hawk warning versus a snake warning, separate sounds that cause different reactions from the troop. The former makes them dive down through the trees and into deeper foliage, the latter sends them scampering into the high branches. (Attenborough, 1991)
It isn't much of a stretch to extend the making of warning sounds to the making of sounds that carry other, more complex meanings. Of course, this requires three adaptations to occur: a vocal apparatus capable of making complex sounds; a brain capable of controlling the muscles of such an apparatus; and brains capable of abstraction to give random noises meaning to the members of the group.
The last is not so hard to imagine. Research has shown that chimpanzees can think in abstractions. For example, Lucy, a chimp at the University of Oklahoma Institute of Primate Studies who has learned sign language, calls a watermelon drink fruit, ducks water birds, and invented the name rock berry for the Brazil nut. (Leakey, 1978)
It is the first two, the complex vocal apparatus and a brain capable of controlling it, that appear the special province of humans. In fact, a way in which anthropologists classify fossil skulls as human or primate is the shape of the skull base to leave room for such an apparatus. As protohumans evolved into humans, their larynxes and skulls altered to allow them to increase the variety and intricacy of the sounds they could produce. (Willumsen, 1992) There would be little reason for such a change to evolve unless it provided an advantage in surviving. In fact, the advantage had to be considerable, since the change brought with it an increased chance for its possessor to die. The altered larynx meant rhe could no longer swallow and breathe simultaneously, possible before the change. Rhe could easily choke.(8)
The only purpose for such a change is to facilitate an intricate modulation of sound -- in other words, to speak. The purpose of speaking is to permit communication of concrete and abstract ideas. For communication to be more valuable than the ability to avoid choking to death, then the message communicated must provide a greater survival value. Obviously, the training in the intricacies of human survival, which require so much time, is best provided by speech. And since physical survival, the training in finding food and water and avoiding predators, is better taught by instinct, example and practice, it must be the intricacies of survival in human society that speech teaches and carries out.
Getting back to why women are better with language with men. It's clear that, with female protohumans providing the children with their basic training, it would be the female that would first evolve the ability to speak, and need to. The complex social life would evolve along with it because of the females' group mentality, which carried so many survival advantages for them and their offspring. Thus, the complex social life led to complex thought, which led to complex communication, which complicated the social life, requiring more complex thought, which need complex communication skills.
Her ability to recognize subtle emotional shifts in others' faces would also arise from her bearing and rearing the young. She would be with her infant from birth and always pay close attention to it, often just looking at its face as it rested in her arms. Since it would be unable to speak, she would have to deduce its feelings and thoughts from its expressions. The finer her ability to discriminate one expression from another, the better she would be at determining its needs and caring for it.
What about the males? It appears that the females evolved speech, society, cooperation, bigger and more efficient brains, and just about everything else that makes humans human, and that the males just tagged along. Well, in a way that's true. Nature alters animals through evolution to suit them better to their environments. Most of the changes discussed above were to improve the female's and her young's suitability, since they and not the male were most important to the continuation of the species. Of course, the male had to evolve, too. If he didn't, the species would have died out.
However, his evolution did not parallel hers since his role in the evolving human culture was different. He had to evolve the ability to speak and comprehend speech, or he couldn't have understood his training to fit his role in the society. However, he didn't need speech in his role as a hunter. Signs are as efficient as speech in organizing the hunt, and less likely to ruin a stalk by alerting the prey.
Unlike the female, the protohuman male was probably much like the present-day chimpanzee about fatherhood. That is, not much of a consideration. At least, not at first. He might take an avuncular interest, or provide protection. However, unequipped to feed it, his interaction with an infant wouldn't have the strong biological attachment that its mother would have.
Later, as the child grew, he would take a greater interest if it was male. It would his job to train the child in his function in the society -- to be a hunter. However, this would again probably not be a fatherly interest, but a mentor's.
The male would have had an active, rather than sedentary lifestyle. His duty to the group is hunter dictates this. Hunting, in a gatherer-hunter society, consists of tramping over large areas looking for signs of game. Once he finds game, he must stalk and kill it. The latter can often mean a lot of running. Males would be active, the more active the more efficient as hunters.
He wouldn't develop a group mentality. Instead, being independent would be a more valuable characteristic. Hunters are more successful when they work together. They can go after and kill faster, larger animals than an individual hunter can. This would be especially true for the protohumans, who had little in the way of weapons beyond rocks and clubs (once they figured out how to use them). However, such a hunt is a cooperative effort between independently acting agents, each participant acting alone and responding to conditions he personally sees and can control. An analogy would be a football game. The coach sends the play in. Each player has the same end in mind: offense wants to gain yardage, defense wants to prevent that. However, once the play starts, it's every man for himself, moving and reacting in the way he thinks will best carry out his team's objective; no one gives orders. They don't even consider the idea of everyone doing the same thing -- it wouldn't work.(9)
He would also evolve senses that operated differently from women's. He didn't need such acute hearing or smell, fine color discrimination, an ability to detect subtle nuances in expressions, since none of these were necessary for hunting. What he would evolve are a better sense of spatial relationships, geometry, ballistics, and an ability to concentrate his attention on the task at hand to the exclusion of distractions.
The first two, a fine sense of spatial relationships and geometry, are necessary for efficient hunting. A good hunter can make fine discriminations in distance and angle, since his prey and his approach to it constantly change both.
The last three, ballistics, touch and manual dexterity, are a result of the gradual evolution of the protohuman male to the human man. One of the attributes of humanity is the ability to make and use tools. Many animals use tools: the chimp makes a tool to probe termite hills and draw them out, and uses a rock and anvil (another rock or a branch) to crack open nuts; some birds crack open snails and shellfish by either throwing them at rocks, or rocks at them. (Attenborough, 1991)
However, humans are better at making and using tools than any other creature on earth. One reason is people's fine sense of touch and ability to do fine manipulation of things with their hands. As humans evolved, so did their tools. Early tools were probably more accidental than intentional -- a pebble or stick that happened to be there; a rock that broke, making a sharp edge that the user found effective; a bone that, when broken, became pointed. In any case, they probably used and then discarded such tools on the spot. (Leakey, 1978)
Eventually, though, some bright protohuman realized that it was a good idea to hang onto such useful items. Instead of dropping them, rhe took them along. However, everything wears out. Finally, someone saw how accident shaped the stones or bones or antlers, and tried to do it rherself. After a few, or few thousand, attempts rhe succeeded. Refinements followed.
Real refinement in making stone and bone tools requires a delicacy of touch and manipulation. Banging two rocks together will make a serviceable edge. But to make a truly useful tool requires many small blows to create flakes, chip a fine, straight edge, adapt a flint knife to a scraper or awl or spear point. Without fine control over rher hands, a toolmaker is more likely, through clumsiness, to destroy than create such tools.
It is possible that the male manipulative abilities and single-minded concentration arose because his ancestors made fine tools and weapons. Although it's true that female protohumans were as likely to make tools as her male counterparts, the tools she made didn't need the same precision and quality: a pointed stick will dig up a root; a crude stone flake will work as a hide scraper or ax. Thus, she had less pressure on her to develop manual and concentration skills.
However, there is a difference in magnitude between a rock and a sharp-edged, well-balanced spearpoint when hunting. The better a male's skills, the higher the quality of his tools and weapons, and his consequent success as a hunter. The pressure on him to develop manual dexterity was strong. In addition, to insure doing what he wanted in making a tool, he had to concentrate on what he was doing: a moment's distraction might result in an imprecise blow to a flint spearpoint, ruining all the careful previous shaping.
Finally, a good sense of ballistics would evolve in the males as they developed their hunting techniques to include throwing rocks, spears, and eventually using bows and arrows. It was no longer a matter of instantly analyzing angles and distances to cut off a running animal rather than just following in its tracks. It was now necessary to take account of angle, distance, speed, gravity and personal strength to determine where a moving target and a thrown object would intersect. Such an ability would insure hitting the animal more often, improving the success of the hunt, leading to an evolutionary pressure to improve such an ability.
The above are some possible biological effects of the protohumans' change in how they gathered and shared food. However, humans are not only biological, but social creatures. At this point I would like to explore some of the effects on social relationships that arose from the camp and the mutual dependence of the sexes.
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