Author's note: This chapter, like the last, needs some revision. I will be updating it, adding an opening section on cultural change, and possibly a expanded section on history.
THE SETTING: FROM THE FIRST FISH TO THE ICE AGES
The story of humanity is the story of change at many levels-biological, mental, and cultural. There isn't a single story of human evolution, because there were several human evolutions. But it starts with biology, and even with physical changes in the Earth's climate. So, to begin our story, we will take a series of drastic leaps from our narrative of life on Earth, zooming forward in time and inward in the tree of animal life. Figure 10.1 shows this in an extremely schematic way. Humans are vertebrates, a large division of the phylum Chordata, one of 15 or so phyla of animals. The first vertebrates-jawless fish like lampreys and hagfish-appeared around the time of the Cambrian explosion 580 million years ago. As the eras passed, new branches appeared. First were various kinds of fish. Amphibians-ancestors of today's frogs and salamanders-were the first with four legs. Next came the reptiles, whose waterproof eggs and skin allowed them to live entirely on dry land. Reptiles gave rise to birds (the descendants of the dinosaurs) and mammals, the group of furry, warm-blooded creatures to which we belong. Dinosaurs and other huge reptiles were the Earth's most visible creatures for hundreds of millions of years, until an asteroid crashed near the Yucatan peninsula about 65 million years ago. This killed most of the large reptiles, and opened niches that birds and mammals expanded into.
Figure 10.1 Timescales: From Life on Earth to the First Humans (Very Schematic and Simplified)
(Click to Enlarge)
There are about twenty orders of mammal, most of which arose after the demise of the dinosaurs. We belong to the Primate order, which dates from around that time. Primates are mostly tree dwelling, equatorial creatures. They live on fruit, leaves, and insects, which is why most of them have grasping hands and forward-facing eyes which give them good depth perception and color vision. Modern humans are the only surviving member of the hominids, a branch of the pongids, which also includes orangutans, gorillas, and chimpanzees.
About 30 million years ago, the earth's climate began to get cooler. Icecaps began to form in Antarctica, covering it by 15 million years ago. About three million years ago, South America slowly collided with North America at the Isthmus of Panama. One of many repercussions was a change in the world's ocean currents, which caused the Earth to get even cooler. Icecaps formed in the Arctic about 2.4 million years ago, sending the world into a series of ice ages. Glaciers began to expand southward, deep into North America and Eurasia. These expansions last for about 100,000 years, with gaps of about 10,000 years, in a rhythm based on the wobble that the Earth acquired giving birth to the moon. I have switched to the present tense, because the ice ages aren't over. We are living in one of the gaps.
THE FIRST HOMINIDS
Sometime between 5 and 10 million years ago, some of the forests in Africa gave way to grasslands, causing some animals to adapt to savanna life. Among them were the first hominids; called Australopithicines. One might think that what first separated the hominids from the apes was that they had larger brains. They didn't. What made the Australopithicines unique was their stance-they walked upright. These were furry creatures with low foreheads, looking something like an upright chimpanzee. Like chimpanzees, they occasionally used rocks and sticks as tools. But because they walked upright, their hands were free, and they got more skillful with their tools. By 2.5 million years ago they were improving them by breaking them and using the sharp edges. Nevertheless, the australopithicines died off about a million years ago. In the meantime, the first members of our genus had branched off from the Australopithicines. These were calledHomo Habilis, which means "handy man" (they were avid tool users). Their tools were starting to become more sophisticated, which indicates that they were beginning to have a more sophisticated culture. Habilis was much more like us than the australopithecines. In addition to using tools, and having a rudimentary culture, they had larger brains. From the habilines onward, human brains would grow larger, until they reached their current size a couple hundred thousand years ago..
FORAGING BANDS: THE OLDEST WAY OF LIFE
The habilines, like their predecessors, lived in bands of a few people, making a living by hunting and gathering, or foraging. This is the oldest form of human social organization, and it lasted until the 20th century in hunting and gathering groups like the Australian Aborigines and the San of southern Africa's Kalahari desert. These groups may give us an idea what life was like for millions of years. Foraging bands are fluid, egalitarian systems. Hunter-gatherers tend to be extremely concerned with modestly blending in. Egotistical behavior is considered very bad form, to the extent that good hunters often hold back, letting others bring in food, so that they don't seem too proud. There is practically no social stratification in such bands, and different people take the lead depending on the situation. This may be admirable, but I don't want to romanticize hunter-gatherers. Their lives can be hard, and they are egalitarian because it makes sense to be. They are too mobile to accumulate many possessions, and resources have to be shared because they are scarce. Hunter-gatherers fight and murder each other as often as people in developed nations do. They are not saints, they are people.
Homo habilis gave way to homo erectus, who had even bigger brains, and developed more sophisticated tools. While the habilines lived by gathering plants and nuts, possibly hunting small animals, and probably scavenging, erectus was getting better at hunting. They began to kill larger animals, and hunt in bigger, cooperative groups. Bands began to take on the division of labor they have today, where women gather plants and nuts (supplying most of the food), and men hunt, bringing in the occasional big animal. Erectus expanded out of Africa, reaching as far as China and Java. The last population of erectus-type hominids, called Homo floresiensis, was discovered very recently. They lived on islands in Southeast Asia, and, as some island species do, became very small-a little over a meter tall. These little people lived until about 18,000 years ago, far longer any other known population of erectus type hominids.
NEW HOMES, NEW CULTURES
The pace really began to pick up when Homo sapiens, the species you and I belong to, evolved in Africa about 150,000 years ago. Modern humans, as we can call them now, developed more sophisticated cultures, and were even better hunters than erectus. They spread out of Africa about 100,000 years ago, had spread throughout Europe, Asia, and Australia by 40,000 years ago, and reached the Americas by 12,000 years ago. About 30,000 years ago, cultural change seemed to hit a critical mass. Before that, cultures (or at least the artifacts they left behind) had changed very slowly. The first major culture of modern humans, which archaeologists call the Mousterian, lasted for over 50,000 years. After that, things accelerated. The archaeological record shows cultural artifacts showing up and replacing each other after just a few thousand years. Art began to appear in caves. Different groups begin to have very different cultures. Around this time, the only other kind of human, the Neanderthals, disappeared.
TALKING THE TALK
Some people have speculated that this cultural explosion happened because of the emergence of language. Nobody knows for sure, although there is some evidence that language appeared much earlier, judging from the shape of skulls. Whenever it came along, either suddenly or gradually, there is no doubt that language was another major leap in the way our minds and cultures work. Before language, people could have only gestured, pantomimed, or perhaps drawn pictures in the dirt to get ideas across. But with language, incredibly complicated ideas can be transmitted from mind to mind in no time. Imagine communicating the following instructions without language: "There is a herd of antelope around the second mountain to the north, where my uncle was eaten by a lion two years ago. Take four hunters with you, and see if you can kill some of them, and the rest of us will meet you by the big waterfall in two days." This kind of planning simply couldn't have happened until language came along. When it did, it put things in yet another higher gear.
THE AGRICULTURAL REVOLUTION
Remember that the world is in a period of glacial cycles. Before the last one ended about 10,000 years ago, most of North America and Eurasia was covered with ice or sparse tundra. The people in those places were making a living by hunting big animals like mammoths, since vegetables were scarce. All this changed when the ice began to recede. People in the Middle East soon started domesticating animals and raising crops. Agriculture had begun, and the world changed again. Agriculture would be invented independently several times, in India, China, New Guinea, and the Americas. Whenever it came along, it transformed the social structure. Agriculture has two big effects: it allows more people to live on less land, and it allows a part of the population to supply enough food for everyone. Populations get more dense, and people settle down, becoming less mobile. Since not everyone has to help with the food gathering, people start to take on different roles. In short, societies became more complicated.
At first, the changes were not that drastic. The first kind of farming was usually simple slash and burn cultivation-really just gardening. People had learned to keep animals for food, but not as beasts of burden. Many of these first agricultural societies were organized as tribes, which are a bit larger and more complex than bands. A tribe may have a couple hundred members. Their leaders are usually "big men"; charismatic leaders who can exert a lot of influence. Tribes are less egalitarian than bands. Some people have higher status than others, and there are differences in wealth. Many tribal, horticultural cultures still exist today in the Amazon, Africa, and on islands like New Guinea.
Where agriculture was a little more productive, societies got a step more complex. These were chiefdoms. Chiefdoms are larger than tribes-they may have several thousand members. While big men rise and fall based on their charisma, chiefdoms have inherited positions of power. People have formal titles and offices. Chiefdoms tend to be more stratified than tribes. Important people often engage in extravagant displays of wealth, such as throwing huge feasts. Chiefs may treated with diffidence. People bow their heads or avert their eyes when the chief comes around. Some chiefdoms were based on pastoralism, where people follow herds of animals in open areas, like many societies in central Asia. Chiefdoms were common in the Pacific islands until fairly recently.
INTENSIVE AGRICULTURE AND THE FIRST STATES
Things got really complicated when agriculture became more productive. At various times and places farmers went beyond simple gardening and began to plant large, irrigated crops along rivers like the Tigris and Euphrates, the Yellow, the Indus, and the Nile. They learned how to harness animals as beasts of burden, making them pull plows and haul loads. This made agriculture far more productive. Divisions in status exploded. Since farmers have many children, women were often pregnant or caring for babies. Men did more of the fieldwork, and male dominance got really intense for the first time. Society became divided between virtual slaves toiling in the fields, and ruler-priests, often claiming to be gods. Religion switched from worship of nature deities to those of crops, sun, and rivers. A hierarchy of priests and advisors emerged, and religion became a means of top-down social control. Human sacrifices were common. These were the first states, large political entities of hundreds of thousands of people.
As more and more people turned to farming, good land became a commodity, and different states began to compete for it. Warfare became common. A warrior class arose between the priests and the peasants, and after a while warrior-kings began to partly displace the priests. These warlike rulers conquered other states, building the first empires. From these less-than-civil beginnings, human civilizations emerged, with all their glories and their agonies. As states and empires, with their cities and vast croplands, began to spread, the landscape was transformed. Forests were leveled and rivers diverted. Humans were no longer just another player in the ecosystem. We began to dominate it, changing the countryside to suit our needs. We had become a major force, changing the world with culture, at a pace equaled only by volcanoes and asteroid impacts.
The rise of states and intensive agriculture set humanity on the path it has taken since. What happened later is what is taught in standard history books, and it is far too vast to go into in this chapter. As we will see in Volume II, it is a story of steady acceleration-of human ingenuity, creativity, power, and shear numbers-punctuated by further world-altering transitions, all coming faster and faster (Figure 10.2). Writing would emerge, as well as wheels, alphabets and gunpowder. Wars would pound a constant backbeat. Great religions and schools of thought would arise. But for now, I want to mention only the latest revolutions. The last few hundred years, about a ten millionth of Earth history, have seen some of its biggest changes.
Figure 10.2 Timescales: Human Evolution to the Last Hundred Years (Click to Enlarge)
EUROPEAN DOMINANCE AND THE INDUSTRIAL REVOLUTION
The first big change would come with the European domination of the globe, aided by the rise of secular thought, science, and the industrial revolution. Europe used its emerging
technologies to find and conquer less sophisticated societies like those of the Americas, whose land and labor enabled them to dominate equally sophisticated societies like India, China, and the Muslim world. We see positive feedbacks, as power begets power, and technology begets technology. With the industrial revolution, Europe learned to harness machines, mass production, market economies, and fossil fuels. The average European was becoming a city dwelling wage-earner instead of a farmer. The industrial revolution spawned astonishing increases in wealth and productivity, and at first, astonishingly dehumanizing conditions for its workers. It also made European dominance nearly unassailable until the twentieth century.
WHAT NEXT?: THE EMERGING WORLD
The 20th century was in many ways the story of the world moving beyond European dominance and industrialism. The great world wars broke the back of European control, in the process highlighting the horrors of industrial, mechanized warfare. Power shifted east and west, to the United States and the Soviet Union, who menaced each other until the Soviet Union finally collapsed. In the meantime the old colonies had begun to rule themselves. The world's polarization switched from Capitalist and Communist to Developed and Developing. Computers, telecommunications, and the internet helped switch developed economies from crude industrialism to high tech, information and service industries, while the old fashioned factories moved to developing countries. East Asian nations grew powerful. The world became united, but only economically. Here at the beginning of a millennium, the world is shrinking day by day, grappling with the problems of balancing local and global, traditional and modern, sacred and profane, human and natural.