www.UsHumans.net: Chapter 6
The emergence of humans
In the previous chapter, we saw that through the last 750 million years a number of animal types evolved in sequence and that humans are included in the category of animals called mammals. Humans have also been placed with monkeys and apes into the primate subcategory of mammals. In the previous chapter we also saw something of the physiological and anatomical differences between worms, fish, amphibians, reptiles, and mammals. These differences help us to see what we share in common with all other mammals and to distinguish ourselves from other animal types. This comparison is continued in this chapter through an examination of the anatomical differences between primates and other mammals. The handful of anatomical differences between humans and the other primates are also described. These differences are part of what it is that makes us human and are the result of the responses to a series of changes (evolution) in climate, food resources, and predators.
At the end of this chapter we'll begin to look at the way in which our culture greatly distinguishes us from the other primates. In the next two chapters we'll look at the similarities in behavior shared by all mammals and then the differences in behavior between primates and the other mammals.
The primary sources for this chapter are The Primates by Sarel Eimerl and Irven DeVore, The Origin of Humankind by Richard Leakey, and Introduction to Archaeology by James J Hester. You might like to read these three books to get a more thorough description of the subject.
The first mammals were small mouse-like animals. Still today, there are numerous, small mammal species who are nocturnal foragers. Through time, mammals diverged and filled many different ecological niches. For example, some mammals eat insects while others eat plants and still others eat animals. Birds, reptiles, and fish have better visual acuity than do most mammals–and more often they have color vision. The typically nocturnal, foraging mammals have less need for vision but an increased need for the senses of smell and hearing. Primates are an exception: their lives in the trees require better vision.
The development of primates begins with the appearance of prosimians about seventy million years ago. Paleontologists have determined the time-evolution of the successive species of mammals from the examination of tens of thousands of fossil skeletons and have determined that prosimians are the ancestors of the primates. One type of prosimian began to dwell in bushes and trees where it ate leaves, berries, and insects. Vision became more important. Its eyes moved forward to enable stereoscopic, three-dimensional vision that could better determine depth and distance and make it easier to move among the branches. After some time, its digging claws were replaced by independently grasping fingers to help it move about the trees more easily. (A squirrel has these digging claws–and also a different history as it is more closely related to mice, rats, and beavers.) The improvement in vision also makes it better at grasping food with its fingers. Since grasping fingers are more individually operated than is a digging-claw, there is an accompanying change in the brain of this animal. This line of prosimians had become primates. For more information about the first primates, visit http://anthro.palomar.edu/earlyprimates/first_primates.htm.
The primate's grasping fingers support more weight; this allows them to become larger animals. Larger animals have slower heartbeat rates and metabolisms; this results in longer lifetimes. Regardless of the species, the lifetime of an animal lasts for about one billion heart beats; those with more slowly beating hearts live for a longer amount of time. Apes typically live fifty years.
Primates diverged into monkeys and apes. Apes first appeared about twenty-five million years ago. Still later, apes diverged into gorillas, chimpanzees, orangutans, and humans. This occurred at the rate of one divergence every five million years or so. Within each of these divergences, further divergences occur about every million years–and yet further divergences within those.
Since monkeys are easily isolated within a section of a forest that has become cutoff from the remainder of that forest, 130 monkey species have evolved; in contrast, there are only a handful of ape species, today. Old world monkeys are divided into two categories. One type is smaller, eats leaves, lives in trees, is agile and timid, and easily escapes from predators. The other type–baboons, for example–eats meat, is larger, lives on the ground, is ungraceful and aggressive and defends against predators. Males do the defending and compete over females, and so have come to be twice the size of the females.
Apes differ from monkeys in that they have developed a rotating shoulder enabling them to raise their arms out sideways when grasping for a tree branch. (You make this motion with your arms as you do "jumping jack" exercises.) A monkey's arms and legs, in contrast to those of an ape, make only a forward and backwards motion; no sideways movement can be made. They cannot dangle and swing from tree branches, instead they run through the trees more in the manner that a dog runs, except that they have fingers rather than paws. The ape's rotating shoulder was followed by the development of elbows and wrists.
It is important to understand that humans did not evolve from today's monkeys and chimpanzees but that humans and these other current primates share a common ancestor. We are not the offspring of today's monkeys but are their "cousins" in the sequence of the Earth's animals. More distantly, we are also the cousins of whales and birds and the offspring of reptiles, amphibians, fish, worms, and bacteria. Every species that has ever existed, is a direct descendent of the first living, bacterial cell.
The transition to the human variety of ape
Next we will list the changes that led to the human variety of ape. Paleontologists have about one thousand skeletal examples of the transition from ape to human and these have been arranged into just a handful of species. The ages of these fossils have been determined by radioactive dating methods (see Chapter 2) and by determining the ages of the geologic ground-layers in which the fossils were found. For images of numerous human ancestors and ancient relatives, see www.mnh.si.edu/anthro/humanorigins/sitemap.htm. Visit www.mnh.si.edu/anthro/humanorigins/ha/qt/qtvr.html for panoramic movies showing rotatable skulls of a few species. You might like to watch the video Tiny Humans: The "Hobbits" of Flores, see www.nationalgeographic.com/channel/highspeed/2005/03/20050314news.html.
About fifteen million years ago, a continental rift developed and a few-million-year process of lifting mountains began that would alter the rainfall patterns, climate, and species of Northern Africa. Mountains cause rain to occur through the following process. Air temperature, and that of the water vapor within it, decreases as it moves up a mountain side to a higher elevation. The cooling air's water vapor condenses and then falls as rain. Most of the resulting rain falls on the western, windward side of this African mountain, leaving a rain-shadow region on the eastern, downwind side (just like the deserts that lie downwind from the Sierra Nevada mountains). The forests of the eastern side of the mountains dried up, resulting in the East-African savanna. We humans developed from ancestors who were forced to change with this drying climate and dwindling food supply. This climate change played a large role in our past in that it promoted shifts in our anatomy and behavior.
Ramapitheces was a tree-swinging–that is, brachiating–ape that lived about seven million years ago. It had a V-shaped jaw compared to the U-shaped jaws of modern apes. Its teeth were more flat than are those of its western contemporaries. The wear patterns found on fossil teeth show that these were plant-eating apes. Dwindling rain and fewer fruit trees meant that the eastern apes had to begin eating tougher nuts and seeds. Food now had to be ground with the teeth so that canines were in the way and began to diminish in size. Ramapithecus canines were smaller and more blunt than were those of their contemporary ape cousins of Western Africa. (Mountain gorillas have retained their canines because they still use them to ward off male competitors.)
The Australopithecus afarensis species of ape developed about four million years ago. One fairly complete skeleton, named Lucy by her discoverers, is that of a three million-year-old female. (You might like to view the PBS video clip at http://www.pbs.org/wgbh/evolution/library/07/1/l_071_01.html.) The shape of her pelvis, the angle between her thigh bone and knee, her slightly curved feet, her two enlarged vertical inner ear tubes (measured with a CAT scan), and her knee shape indicates that she could move through the trees but also walk upright while on the ground. She was a bipedal individual. Compared with the other apes, we humans have enlarged, more vertically oriented inner-ear tubes for balance while walking upright and we have flat feet for ground-walking instead of curved feet for tree-walking. Page 82 of Lucy to Language shows the reconstructed face of an afarensis individual. This bipedal ape still behaved much like the other ape species. For an image, see www.mnh.si.edu/anthro/humanorigins/ha/afar.html.
Upright walking is likely to have developed simply to make easier travel between the shrinking forests. Scientists have determined that for brachiators, four-legged walking requires more effort than does upright, two-legged (bipedal) walking. The bonobo chimpanzees of central Africa are often seen to walk upright while carrying food. Scientists have also found that upright walking preceded the appearance of stone tools by five million years. This means that upright walking did not develop to free our hands for the use of tools. We have all felt the interior heating that results as we are walking. Since walking warms us, we have less need for the hair that retains heat. Hence, upright walking has also led to our loss of hair. The afarensis split into some branches having increasing brain sizes and some branches that did not; the branch having increasing brain size led to us while the other branch became extinct.
Portions of thirteen afarensis individuals were found at a single excavation in Hadar, Ethiopia. This group likely formed a family that was killed by some event that buried them together. Their bones were not damaged by scavengers and are about three million years old. This group is especially important because it included individuals of various ages, showing how the body of an afarensis changed with age.
Measurements of apes and humans today show that brain size is related to weaning age. Compared to other ape species, human children have a later, more pronounced adolescent growth spurt and reach sexual maturation at a later age. The measurements of the afarensis family showed that they were more apelike than human like in this respect. In The Origin of Humankind by Richard Leakey, Barry Bogin is quoted to suggest that the growth spurt and sexual maturity are postponed in large-brained humans until after children have been taught the group's cultural ways because children are more subordinate while they are smaller than their teachers.
During the period from one to three million years ago there were two African apes, named Australopithecus africanus and Australopithecus robustus. See www.mnh.si.edu/anthro/humanorigins/ha/afri.html for images. Both have large, flat grinding teeth rather than the fruit-eating teeth of other apes. The drying, East-African climate caused their diet to consist of tougher vegetable foods and nuts. Robustus apes chewed so much that their chewing muscles grew upwards along the sides of their skulls, resulting in a so-called sagittal crest. Their brain size was about five hundred cubic centimeters (thirty cubic inches), compared to twelve hundred cubic centimeters (seventy cubic inches) for modern humans. Compared with earlier afarensis, their larger brain may have been due to an increased language and cooperation and to the development of a more complex social system. They had a slightly prolonged childhood, indicating increased culture to learn. Their feet, hips, and back bones had been rearranged for bipedal movement and they could run upright for short distances between the thinning forests. Little evidence of stone alterations has been left by Australopithecus but there is some evidence that they used stones as missiles. Today's chimpanzees are seen to throw stones at snakes and such. (In Kanzi, Sue Savage-Rumbaugh describes how she had to throw rocks to ward off a pack of approaching dogs while she was attending a conference about ape abilities.)
The Australopithecus were the first of our ancestors to have an opposable thumb, which makes your hands far more useful. In contrast, a chimpanzee's thumb cannot touch the other four fingers of the same hand, making it is less able to grip small objects. Instead of holding a toothpick-shaped object in a single hand, a chimpanzee tries to hold it between the two pointer-fingers of both hands. (I once saw a "deformed" cat that had an opposable thumb, and it too learned to use it for gripping.)
The species named Homo habilis appears about 2.5 million years ago. Homo habilis had smaller teeth and an 800 cubic centimeter (fifty cubic inch) brain size. Its skeletal structure allowed it to be better at running than were the Australopithicenes, who became extinct by one million years ago. For images, see www.mnh.si.edu/anthro/humanorigins/ha/hab.html. In The Origin of Humankind (see page 74), Richard Leakey describes a typical day in the life of a Homo habilis group. We humans are later members of the Homo species. Many fossil hominids have been found in Tanzania’s Olduvai Gorge, which can be seen in the photos at www.sfu.ca/archaeology/museum/olduvai/index2.html.
As mentioned above, brain size is related to several other characteristics: weaning age, a delayed and pronounced growth spurt, age at sexual maturity, and the duration of a pregnancy. These attributes have been measured in each of fossil Australopithecus, Homo habilis, and modern humans and apes. A comparison of these measurements shows that Australopithecus had more apelike attributes while Homo habilis had more human-like attributes. Homo habilis brain sizes and growth spurts indicate more extensive culture because intensive training is needed to learn culture. Also, molar eruptions are later in humans than in apes (the number of microscopic lines on a tooth indicates the owner's age). Here too, Australopithecus are more apelike while Homo habilis are more human-like.
Today’s mountain gorillas live in small groups. Visit www.vagabonding.com/travelogue/000099.html for a video clip of gorillas. Females have their first child around age thirteen and then another child every three or four years after that. When males reach the age of sexually maturity they will leave their original group and move off to join another. Within each group, sexually-mature males compete for female mates and so are twice the size of females. Similarly, Australopithecus males were twice the size of females, but Homo habilis males were only 20 percent larger than females, as is the case for modern humans. This suggests that Homo habilis males were not physically competing for female mates.
Homo habilis may have been our first ancestor to have developed monogamous parenting relations. This may also be the time at which women's breasts became permanently enlarged. In other mammals, female breasts are enlarged only while breast feeding newly born infants. Did our menstruation cycle become hidden–that is, lacking the four-inch (ten centimeter) swelling that occurs in chimpanzees–at this time or was it simply never as pronounced as it is in other animals? When did we begin copulating in private? No other animals do this. Are any of these things related?
Homo habilis were the first of our ancestors to begin using base camps. We know that the large brains of our babies today result in infants who are born early and are especially helpless for many months. (For many other mammal species, infants are ready to run with the herd within a few minutes.) Given the increased helplessness of its infants, it is easy to believe that base camps served as a place for mother and child to stay and for the child to grow. Base camps soon led to other social changes, such as increased labor differences among group members.
Homo habilis was the first of our ancestors whose diet consisted of an appreciable amount of meat, as indicated by the shape of their teeth, and was the first of our ancestors to use stone tools. Stone tools will find more extensive use by meat-eaters than by plant-eaters because animal material requires more processing. This shift in diet was necessary because of the change in available food resources in the drying climate of the East-African savanna. An animal species that eats both plants and animals is more likely to continue to exist through a climate change than is an animal species whose diet is restricted to just plants or to just meat. The previous existence of our opposable thumb, social groupings, increased brain size, and the climate-caused shift to a meat-eating diet each played a large part in our development of stone tools.
Food getting had been easy in trees–each individual simply reached out and grabbed a meal. In the savanna, our small, hominid ancestors could not catch many of the animals. A single hominid could not physically compete with the existing carnivores whose evolution had honed them for this type of food getting, but groups of hominids could cooperate to trap prey in muddy spots and such. By chance these hominids had previously developed enough brain capacity to be able to adapt their food-getting strategy in this way. Without their previously existing social ways they may have become extinct when the African rift and mountain growth resulted in a drying climate and changing food sources.
Scientists debate the food-catching tactics of our first meat-eating ancestors. There are excavated examples of kill sites that occurred in places where the more agile prey could not easily move, including river beds and muddy areas. Alternatively, it may have been the case that our ancestors had simply thrown rocks to drive away a larger but lone carnivore from the prey it had just killed. A lone hominid could get killed while attempting this but a cooperating group would be in less danger. After learning to drive a carnivore away from its kill, the hominid group could next learn to cooperate in killing that carnivore. Through time and trial-and-error, they could learn to kill other types of even larger animals. Recent gatherer-hunters use their brains to notice exploitable behaviors in the animals also occupying the neighborhood. The tactics of the Amahuaca show that animals are more harvested than hunted (see Chapter 8) and indicate the difference in natural abilities between a human and a predator such as a lion.
The first stone tools were made by hitting two stones together to produce a sharper cutting edge. If you try this at home then you will find that it is not as simple as it sounds. You must know which type of rock to use and exactly how to hold and strike them. In the recent past, scientists had wondered if there was any way that nature could have produced the objects that were being interpreted to be human-made, stone tools. Since the stone tools were found with bones scratched by those tools, scientists were convinced that the rocks were in fact stone tools.
We have seen how a changing climate can play a large role in driving the evolution of species. The appearance of the African rift caused changes in climate and hence in the food sources of a particular species of ape and lead to much of the human animal. These hominids were developing tools, language, more complex social systems, larger brains, monogamous parenting-relations, and increased culture and cooperation. Each of these items causes changes in each of the other items and are some of the largest elements in what it is that makes us human. For the last few million years we have been living in little groups of twenty to one hundred persons. Still today, we can know only that number of persons well enough to predict their behavior; this is the “built-in” capacity of our brain. Our biological heritage has been based on a design parameter of groups of twenty to one hundred persons.
This ancestor could no longer live without its culture, its complex social arrangement, and its stone tools. We were no longer just a molecule-machine but now began to create our own culture. The evolution of molecule-machines naturally leads to brain cells that remember, learn, and predict and that also develop culture. What is learned and the culture that will develop is not so highly determined by physics, chemistry, and biology. We were now able to begin to choose the details of our own way of life.
Two million years ago, Homo erectus emerged and lived alongside Homo habilis for a while. For images, see www.mnh.si.edu/anthro/humanorigins/ha/hab.html. For a panoramic view of Homo egaster and a comparison with older species visit www.mnh.si.edu/anthro/humanorigins/ha/qt/wt15kmov.html. Their brain size ranges from 775 to 1225 cubic centimeters (50 to 75 cubic inches), the upper limit of which reaches that of modern humans. Homo erectus was as tall as six feet (200 cm) and looked much like modern humans. It is often said that you could shave a Homo erectus man, dress him up in a nice suit, put him on the subway, and he would be unnoticed and fit right in with the crowd.
The culture of Homo erectus enabled them to spread from Africa northwards into the climates of Southern Europe and eastwards into India and China. Excavations find that the diet of this hominid included elephants, hippos, horse, cattle, baboons, pigs, rhinos, rodents, birds, and reptiles. Being able to kill the larger of these animals indicates that they were resourceful hunters. They used stone tools, wooden spears, and cooperative tactics. There is evidence that multiple bands met at some kill sites.
There is evidence of the use of fire at the 700,000 year-old Choukoutien site in China. Cooking kills germs and makes food easier to chew. Cooking caused big changes in our daily way of life. Do you suppose its early use met the same sort of resistence as occurs for new techniques today, such as the computer? How do you suppose we stumbled across the technique of cooking our food? Did one funny Homo erectus individual discovered cooking while trying to burn the hair off a dinner-animal so that it wouldn’t have to be scraped and peeled away, or maybe during one winter day someone was thawing the remains of yesterday's dinner and fell asleep? We will see that our ways of cooking remained unchanged until the iron stove came into use around the year 1850; the microwave oven .
Oldowan stone technology is associated with Homo habilis and was used from 2.5 to 1.4 million years ago. For some photo examples of oldowan tools, visit http://flinthro.co.il/telesite_33ol/bin/0-26-234/1-0.jpg and www.ucm.es/info/preh/actividades/peninj/IMAGENES/F9.JPG . These stone tools were simply broken to give a sharp edge; no additional modification was done to change the shape of the rock. About one million years elapsed before it occurred to an individual to make additional, smaller breaks to refine that first edge. The shape of the rock was further worked to produce either a sharper surface or a pointed end. This so-called Acheulean stone technology, see http://people.uncw.edu/albertm/ant210summer03/05tools.gif , was used from 1.4 million to 50,000 years ago and was made by the hominid Homo erectus. Acheulean tools were more varied, harder to make, and more useful than were the previous, Oldowan tools. Some tools were used to scrape the insides of animal skins, to drill holes into hides, or to break open a bone to obtain the marrow. For the first time, our ancestors could cut through tough hide. Many uses were found for strips and sheets of hide, from string to clothing, so that our way of life was much altered. Cooking and clothing both caused big changes in our daily way of life and made us unlike any other animal on the planet.
After weeks of trial-and-error attempts, scientists found how to properly strike rock to produce Acheulean tools. As they strike a "core rock" they knock loose some waste fragments; however, the fragments and core are different for right-handed and left-handed people. Some excavated Acheulean core and waste fragments have been reassembled to find that the flakes were broken off by right-handed hominids. Other animals do not favor a hand: they are neither right-handed nor left-handed. The right- and left-handedness of humans is due to the right and left division of our brains and is associated with our production of language. The right-hand-made fragments suggests that Homo erectus had an increased language ability. For a morphing of erectus, see www.mc.maricopa.edu/~reffland/anthropology/anthro2003/origins/homind_journey/javanstory.html.
Homo neanderthals existed from 135,000 to 35,000 years ago. They had a more robust shape than we do because Neanderthals were shaped for cold while we are shaped for a warmer climate. They had a very round head, big eyes, no chin, a big brow, and a bigger brain than modern humans. Since Homo sapiens and Homo neanderthals were temporarily contemporaries, there has been a lot of scientific debate about their possible relations. Genetic studies show the two to be distinct species, sharing a common ancestor some 600,000 years ago, but not all scientists think that the findings are conclusive. Some believe that the were nothing more than a local variation of Homo sapiens, while others believe the Neanderthal interbred with the Homo sapiens as they arrived in Europe. Visit http://sapphire.indstate.edu/~ramanank/morphology.html for a comparison of them.
The Homo neanderthal species became extinct, perhaps due to an over-reliance on prey that disappeared with a warming climate or to competition with Homo sapiens. Remember that when two species seek the same food within the same environment, that species having a mere 1% advantage will soon out-populate the other. They may have been 1% less successful than Homo sapiens due to their social system or less capable language.
Neanderthals constructed shelters when in the open ground and they used caves. They buried their dead. They made clothes, did woodworking and bone-working, made many tools to make other tools, and had an increased variety of tools. Microscopic examination of stone cutting surfaces indicates that some tools were used for a single, specialized purpose–for example, to cut only hide, meat, plants, or grass. Non-utilitarian objects have also been found–for example, a mammoth bone polished to an oval shape.
Homo sapiens sapiens, which is the scientific name for our own species, began appearing 200,000 years ago. Human gene studies have found that every human alive today shares a common grandmother who lived in Africa about 150,000 years ago, which is about 7,500 generations ago. This means that our species has spread outward from Africa. Pinker discusses the neuronal changes that are likely to have occurred more recently, and he points out that the Homo sapiens sapiens skeletons dated to 100,000 years ago still had larger brow ridges and were more heavily built than we are today. To see a morphing from archaic to modern Homo sapiens visit www.mc.maricopa.edu/~reffland/anthropology/anthro2003/origins/hominid_journey/archaicmod.mov. Also see www.mc.maricopa.edu/~reffland/anthropology/anthro2003/origins/hominid_journey. For images of sapiens see www.mnh.si.edu/anthro/humanorigins/ha/sap.htm. To view a video clip comparing human and chimpanzee skeletons, visit www.pbs.org/wgbh/evolution/library/07/1/l_071_02.html.
Culture becomes much more complex with the arrival of Homo sapiens. From this time on, humans show innovation and constant change whereas the Oldowan and Acheulean cultures had each been static for a one-million-year time-span. Not only does culture give us a way of changing as rapidly as the environment without having to change physically, it also gives us a way of changing as rapidly as we can migrate to differing climates. The success of culture allowed humans to spread into every region of the Earth even though we were not physically matched to the extremes of climate we encountered. This is in contrast to the Neanderthal who did not spread outside of their single climate of more-glacial Europe. We made our way across sixty miles (one hundred km) of ocean to Australia about 45,000 years ago using some sort of boat–indicating much technological ability even way back then–and entered the previously isolated American continent about 20,000 years ago while there existed a temporary ice-crossing over the Bering straight (see Chapter 4). By 1,000 years ago, we had spread to most every island throughout the ocean.
We show our concern about the death of our loved ones by burying them in the ground along with flowers; this was a worldwide custom. The remains of these flowers have been found on bodies excavated by archaeologists. This indicates that the most amazing things to these ancestors were life and death, just as we still marvel about these events today. It means that you have the same thoughts as they did and that in some basic ways it is possible for you to put yourself in their place. To try and put myself into the mind of the first ancestor of ours to bury the dead, I can imagine that after seeing the remains of a loved one being eaten by animals, from then on I would either bury the deceased underground or use timber to raise them above the ground.
Our amazement of the occurrence of life and the miracle of birth begins to be recorded in the form of artistic carvings, such as the Villanova fertility figure. Birthing mothers–and nearby fathers, too–describe a strong feeling that rushes over them at the moment of delivery, endearing their new children to them for the rest of their lives. This feeling is produced by the hormone oxytocin and can be measured to occur in other animals. We can bet that this feeling has been occurring for countless generations. The same feeling may have inspired a mother to carve a fertility figure 35,000 years ago.
Art objects appear suddenly in the archaeological record. The date of this appearance varies from one geographical region to another, occurring between 35,000 and 150,000 years ago. Within each of those regions before this time there is no evidence of art. But after the first appearance of art, everything is decorated from then on. Art is created on bones, beads, and clothing. Scientists have used the techniques of chemical spectroscopy to determine the geographical origin of the materials used to make pendants, beads, bracelets, and anklets and such and have found that these objects were traded for distances of hundreds of miles. Cave paintings began to appear throughout the world. They depict animals, the hands of the painters, and many other items. Some show three-dimensional movement. You can take virtual tours of the Lascaux Cave in France by visiting www.culture.gouv.fr/culture/arcnat/lascaux/en/index.html and the Cave of Chauvet-Pont-d’Arc at www.culture.gouv.fr/culture/arcnat/chauvet/en/index.html. Flutes and other musical instruments also appear at this time in our past. Some scientists have noted the natural concert-hall-like acoustical properties of caves and wondered if music played a role in gatherings around the paintings.
If nobody in your group had ever seen a drawing, what would be the first things you would depict as drawing was first invented? What things would have been most important to our ancestors? Try to imagine the first time a person was shown a drawing of an animal. The drawing could be seen to actually be this animal. (We can imagine how everyone laughed when the bully of the group ran from the drawing of the big wolf.) If an ancestor painted an item onto their home or utensil, it could be seen to represent the essence of the depicted item–just as you feel today about a religious painting hanging on your wall at home. Do you have a special feeling toward a photograph of your spouse or child? Would you protect that photograph? Would an ancestor have felt the same way 35,000 years ago?
Is there a specific change that occurred in our ancestors that is directly responsible for the sudden cultural flourishing? It may be that this is the time at which language, or its spoken grammar, fully developed. It may be that the physical anatomy for fully developed speech occurred at this time through the descent of our larynx. In Primate behavior: information, social knowledge, and the evolution of culture, by Diane Quiatt and Vernon Reynolds, the authors discuss several interesting aspects of speech in our history. They point out that group members must agree on a syntax in order for a spoken sequence of words to have a single meaning. For example, “I eat apple” is a different message than “Apple eat I.” They explain that a couple hundred words–like big, small, blue, red, close, and far and such–is enough to communicate basic needs but that no real discussion is possible. A couple hundred words may have been enough to allow Homo erectus to spread from Africa to Europe, India, and China. But a variety of words and a syntax is needed for Homo sapiens to discuss institutions, plants, animals, and how to catch food. To view the PBS video clip Birth of a Language about syntax, visit www.pbs.org/wgbh/evolution/library/07/2/l_072_04.html. A diversity of tools, and regional differences in the same tool, argues for complex language in early Homo sapiens. By the way, since some mothers use a shortened language when talking to their infants, Quait wonders if such "motherese" might resemble our early language. Without realizing it, some of us speak motherese to our infants. Another aspect of communication involves our use of hand gestures. Many of us gesture rapidly while talking. Visit www.americanscientist.org/template/AssetDetail/assetid/15639 for a discussion of the gestural precursor to language. Facial expressions are biologically older than words and can still convey more than words. For animated facial expressions, visit the websites www.towiac.net/html/images/face/faceexpressions.mov, www.artfoundry.com/dsm/gallery/3dDigi/3dDigi.html and www.spaceisland.net/images/facialexpressions.qt For happy, surprise, and disgust, see www.cs.ubc.ca/~jhoey/zern/zerns2.html.
The climate was again warming from 11,000 to 7,500 years ago, and this caused many changes. The European region changed from tundra-covered to forested, its residents became forest dwellers, and the large cold-adapted mammals began to disappear. Instead of hunting herds of large animals, humans begin to hunt single deer, pig, and antelope. The bow and arrow is developed for this reason. Fishing, trapping, and trade increase. The first dugout canoes, paddles, skis, and sleds appear. We found ways to obtain more cutting edge per pound of stone, producing three hundred feet (one hundred meters) of cutting edge from two pounds of flint. Visit www.pastperfect.info/sites/lowhauxley/images/knappingclip.html for a virtual reality animation of a flintknapper. Flint arrows were hafted in grooves that are cut into bones, wood, or antler. A row of such arrows produced a saw that was very effective at cutting wood, and this wood-cutting technology produced all sorts of everyday objects. Ancient Egyptian burial tombs have revealed many such items.
The development of the African Rift and its associated mountain range caused a drying of the East African forests and changed the climate and food sources for our ancestral species. This led to the human variety of ape and to the beginnings of our cultural solutions to new problems. Anatomically, the largest differences between humans and the other apes are our opposable thumb, upright stance, hidden oestrus, permanently enlarged breasts, altered larynx, flat feet, and larger brains.
From the time of the first humans until about 10,000 years ago, all of us were living as gatherer-hunters. What was daily life like during this stretch of time? (To get a general idea of life back then, Chapter 9 contains a description of the way of life of some of us humans who live as gatherer-hunters today.) We were usually part of a group of a few extended families who spent a couple hours per day collecting food from streams, lakes, forests, and fruit trees and such. We preferred to live near such a variety of food sources.
We can imagine that each morning, family heads would decide that sort of food to eat that day and then headed off in its direction. We can hear a child ask if we can go see if that clump of her favorite fruit trees in the valley has ripened yet. If the region contained a lot of food and several groups of families, some adventurous children might spend part of the day with one group and then rejoin their own family group as they crossed paths later that day (as we see is done by some chimpanzee groups).
We can also expect that similar conversations about proper behavior, how to do things, and answers to "what and why" occurred between parents and children then as does with your own today. You might like to list the topics of your conversations with your children today and try to decide which of these topics would also have been discussed between parents and children of your gatherer-hunter ancestors. (This exercise helps us think about temporary and more-permanent characteristics of humans.) If your family was living as gatherer-hunters today, what sort of chores do you think you would be assigning each day to each of your children?
Now that we have traced the development of our anatomical structure, from atoms to Homo sapiens, we are ready to discuss the origins of our culture, behavior, social system, ethics, and morals in the following chapters.
Questions
1. Do chimpanzees or gorillas make and enjoy art (see www.koko.org/friends/kokomart_art.koko.html)? At which age did your child begin to make and enjoy art? What sort of things have chimpanzees painted?
2. Is there a biological reason for the teenager's "rebellious" move to become independent of their parents? At what age would this have happened 30,000 years ago? How did the process unfold 200 years ago, when we lived on the family farm?
3. The ancestors of today's humans, gorillas, chimps, and orangutans began to follow separate evolutionary paths between five and fifteen million years ago. In what ways are today's ape species similar to the fossil apes described in this chapter? For example, today we observe chimps throwing rocks to ward off snakes. In what other ways are today's chimpanzees similar to the Australopithecus.
4. Do chimpanzees have culture that is learned from their parents?
5. Instead of the East-African forests becoming dry savanna, how would we humans be different if the forest had instead become wetter swamp lands?
6. Could you catch a Rhino? Could you and twenty other persons catch it?
7. How many years did it take you to learn all the details of your culture? About how many details do you think there are? Is it 1,000 or 10,000 or 100,000 or even more?
8. How does the intelligence of dolphins and humans compare? In the future, will other species become intelligent?
9. How would our civilization be different if we each lived for just ten years? 1000 years?
10. What interactions would we have with other animals if we were 100 feet (30 meters) tall? One inch (2.5 cm) tall?
11. Describe the ten most important aspects of your biological inheritance found by timing those things that makeup the largest portion of your daily life.
12. If we were still plant-eaters, how would our civilization be different? For example, during the lunch break would we could all climb trees to sit and eat leaves. Would we have made stone tools? If we didn't make stone tools would we have ever made any tools? Do farmers use any stone tools?
13. When did we first begin to use clothing? When did we begin to make fashion rules? Are these rules universal or culturally local? When did we first use fashion to make statements about our lifestyle–for example, rebellious, classy, conservative, or sloppy? List ten clothing styles that portray a lifestyle. Are these genetic and universal or are they culturally chosen? How do we form an agreement about the type of clothes that a rebellious or conservative person wears?
14. What possible changes might occur in the anatomy and physiology of our species? Will our species become extinct?
15. Why do we like music? When did we first make music? In which situations do you most feel like singing? Which animal species sing? Why do they sing? In which situations do they most feel like singing?
16. Why did we start using fire? Why did we start cooking? Did both happen on the same day? When we eat spicy food, we perceive a "hot" sensation because the chemicals of the spicy food evoke the same response from the chemical-detectors of our tongues as does high-temperature food. Why should our million-year-old tongues be sensitive to hot materials? Did this sensitivity develop before after our habit of cooking food appeared?
17. Describe how our ancestors might have accidentally discovered they could make sharp rocks–for example, by throwing rocks. Could it be that one rickety hominid named Clack was walking down a dry river bed one day, tripped on a log and fell and cut his hand on a sharp rock. He was then throwing rocks with the group in the river bed because they liked to see the sparks of light that would occur as the thrown rocks hit the rocks on the ground. They would jump up and down and shriek like graduate students when they threw these sparker-rocks. Then Clack noticed that one thrown rock had broken such that it produced a sharp edged stone just like the one that had cut him earlier. Clack used the rock to cut an animal carcass and from then on the group would spend many hours per week searching for the best way to produce more sharp rocks. The neighboring group saw how their sharp rocks could cut a carcass and began doing this also.
18. How does an infant learn which objects are friendly and which are an enemy?
19. Can you wiggle your ears as some people do? When you begin to fall, or see someone else begin to fall, do you feel yourself attempting to raise your tail to regain your balance?
20. What is the preferred climate for a human and when did this become part of our nature?
21. We sometimes talk about the animal nature of our past. If human biology has not changed in 50,000 years then we still contain the same animal nature as always. In what ways do we act differently today than we did 50,000 years ago? Why? Are there differences in the past and present personal relations between parents and their children, or between extended family members, or within intergroup relations?
22. Make a note of your animal responses for the day, for example, catching your balance, smelling fire, seeing or hearing an object of biological importance, experiencing taste and hunger.
23. Keep track of your conversations for a day. How many sorts of ideas do you communicate? Which words do you use most frequently? If you had just twenty five words today, they would have to communicate the jist of your most important messages. Which things would be both in our own and in our ancestor's twenty-five-word lists and which would not? Some of the words common to both lists are likely to be among the first words of our ancestors. If you were our ancestor and had only one hundred words, which words would they be? You might be able to communicate basic needs while in a foreign country if you learn just one hundred words, including such things as far, close, big, small, one, two, three, and several.
24. One friend's cat has a mutation that has given it an opposable thumb, which it has learned to use in appropriate ways. Our babies flail their arms and legs around as if their brains are trying out available nerves and circuits just to see what happens. If we were born with eight arms, would we learn to use all of them?
25. If improvements in nutrition are making our children reach the height of an adult in fewer years, what effects might occur on an adult's teaching relationship with not-so-small or subordinate children?
26. Why did we begin to bury the bodies of our deceased family members and friends? If you saw the body of a dead loved one being eaten by scavengers you would feel sharp pains (most of us were all living as nomads just 10,000 years ago). One way to avoid such an incident would be to place the body on an erected platform or to bury it below ground. When did we begin to care for our family and friends and when did we begin to bury their dead bodies? Did we first need to posses complex language abilities before we could perform burials? You might like to read how the ancient Hittites constructed homes, lived in villages, and carried the dead bodies of their relatives some distance away from their village to be left until just the bones remained. The bones were then carried back to be placed under their beds so that the deceased relative remained with the family (see Chapter 10).
27. Do you agree that people today and people 30,000 years ago both use tools mostly for the same purposes–to make utensils, food, and clothing? What do factories mostly make today? Why do both groups make art? Are both groups of the same mind? In which ways are they the same and in which ways do they differ? What are the most important things in the life of a person from each of the two groups? Do you believe that if one could take a newborn baby from each time-group and plop it into the other group, both would grow up to fit into the other's group just fine and think that their world was natural and right? In what ways do babies from different groups grow up to be different? Do they have different thoughts, actions, behaviors, concerns, desires, interests, or goals?
28. Which of our hominid ancestors were the first to have war? What would be a reason for them to go to war? What would the spoils of war have been? What percentage of our ancestors have been killed in war? We often hear about "cavemen." Did "cavemen" have wars? Do gatherer-hunters go to war with neighboring groups? Why? Did we have war 30,000 years ago? What would they fight about? Was there any booty to attract invaders? Was there poverty or famine 30,000 years ago? What is the percentage of people who died of poverty or famine rather than from natural causes? (You might like to read R. Brian Ferguson’s article The Birth of War in the July/August 2003 edition of the Natural History Magazine, see www.naturalhistorymag.com.)
29. Did we have religion 30,000 years ago? Why?
30. Do you believe that if one could take two newborn babies from opposite ends of the earth today and plop them into each other's group both would grow up to fit into the other's group just fine and think that their world was natural and right?
31. In what ways would two-year-olds behave the same 30,000 years ago as they do today? How and why would they behave differently? In what ways do two-year-olds behave the same, and differently, when growing up on opposite ends of the earth today?
32. When were we able to stop worrying about being eaten by a predator every day? When you see a chicken in the field, do you lick your lips with thoughts of tastes to come? Do you do this when you see a packaged chicken in the grocery store?
33. Why were humans decorating our tools 30,000 years ago? While taking the time to shape rock, wood, and bone tools you might as well decorate them while you're at it. Wouldn't you do that today? Why didn't we decorate our tools 500,000 years ago?
34. Imagine going on a permanent "camping trip" with all the members of five of your neighboring households. Try to decide how you would agree on the details of daily activities like food collection, fire building, and choosing the night's camping spot. What would daily life be like? Which daily chores would you assign to each of your children?
35. Is it in our nature to look around for something to fashion into a tool when unequipped for the task at hand?
36. It is often said that we invent stuff whenever a need arises. What was the initial need that was solved with stone tools? Did we begin to use stone tools to obtain meat simply because our usual sources of plant-food were dwindling? Did this dwindling occur at the same time that the Homo habilis began to modify rocks? What was the initial need that was solved with the use of fire? If we weren't already using base camps would we use fire as a tool? About 2.5 million years ago, our Homo habilis ancestors started modifying rocks to get food but our modern ape relatives still do not do this. Is this because they have not had to? Can they be taught to do so (see Chapter 8)? About 750,000 years ago, our not-yet-fully-human ancestors began using fire but our nearest relatives have not done so still to this day. Why not? How many tools did our ancestors develop during each one-million-year interval of our past? Which tools are common to Australopithecus afarensis, Australopithecus robustus, Homo habilis, Homo erectus, Homo neanderthals, and modern humans? Did each of these ancestral species mostly use tools to make clothing, utensils, and prepare food? Are those the main reasons we still make tools today? For what other reasons do we make tools today? What sorts of things are made in today's factories?
37. Do Australopithecus, habilis, or Neanderthal individuals have an innate talent to become engineers, artists, or doctors? Would Homo sapiens individuals have these innate talents if they were born 100,000 years ago? 50,000 years ago? 10,000 years ago?
38. If you lived in a gatherer-hunter group 25,000 years ago, what sort of things would you paint on a cave wall? What things would your siblings and three best friends paint? Why do we make art today? Why did our ancestors make art?
39. Create a piece of art describing our human ancestors.
40 Whom do you aid first during an argument, your spouse or a member of your extended family? Describe some situations in which one or the other gets your assistance.
41. Do you think that if you took a newborn child from a family of "cavemen" and raised it within your own city today that this child would want to become a rock star? Would it adopt those "funny teenage fashions?" Is there any way that this child would be a different person than your own children?
42. What was the number of words in use one million years ago? 100,000? 10,000? 1,000? 100?
Primary sources for the chapter
The Primates, Sarel Eimerl and Irven DeVore and the editors of Time-Life Books, 1974, New York.
The Origin of Humankind, Richard Leakey, 1994, BasicBooks.
Introduction to Archaeology, James J Hester, 1976, Holt, Rinehart and Winston, New York.
Suggestions for further reading
The Man in the Ice, Konrad Spindler, 1994, Harmony Books, New York. (For a photo sample of the findings, see www.utexas.edu/courses/classicalarch/images1/otzireconstr.gif.)
The Neanderthal Legacy, An Archaeological Perspective from Western Europe, Paul Mellars, 1996, Princeton University Press, New Jersey.
From Lucy to Language, Donald Johanson and Blake Edgar, 1996, Simon and Schuster, New York.
Bonobo, The Forgotten Ape, Frans De Wall and Frans Lanting, 1997, University of California Press Berkeley.
Dawn of Art: The Chauvet Cave, The Oldest Known Paintings in the World, Jean-Marie Chauvet, Eliette Brunel Deschamps, Christian Hillaire, 1996, Harry N. Abrams, Inc Publishers, Thames and Hudson Ltd, London. The oldest paintings in this cave have been found to be 32,000 years old.
Becoming Human, Ian Tattersall, 1998, Harcourt Brace & Company, New York.
Ancestors, In Search of Human Origins, Donald Johanson, Lenora Johanson, and Blake Edgar, 1994, Villard Books, New York.
Children of the Ice Age, How a Global Catastrophe Allowed Humans to Evolve, Steven M. Stanley, 1996, W.H. Freeman and Company, New York.
Walking With Cavemen, John Lynch and Louise Barrett, 2003, Headline Book Publishing, London. This video and book set contains people dressed in costume and makeup to portray our ancestral species, bringing bones to life and transporting one back in time to visit our ancestors.
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