Rising complexity is an integral feature of cosmic evolution, an outstanding product of which is humankind itself. By no means an anthropocentric statement, our human complexity is clear and demonstrable. Large amounts of information are needed to describe ordered structures like ourselves in a Universe that is otherwise growing increasingly chaotic—and large amounts of per capita energy are needed to keep us alive. We may not be the most well adapted species on the planet (the microbes probably are), nor those with the greatest potential for long-term survival (the microbes again?), but we and our technical gadgets are currently the most complex clumps of matter known anywhere. There’s no denying it.

While approaching the here and now along the arrow of time, we naturally wonder about the evolutionary route that led from our ancient ancestors to us modern humans. Not that it was a straight and narrow path, rather more likely meandering and convoluted, which is the way evolution works—by fits and starts, with lots of blind avenues and dead ends, among myriad branches that rarely yet wonderfully yield newly adapted species. Questions flood the mind: Where did we come from? How did humankind emerge from all that went before? What were the circumstances that led to our decidedly odd body shape, our strong behavioral attitude, our desire to know who we are? Specifically, what factors caused the development of our fabulous attributes of thinking with our brain, seeing with our eyes, talking with our mouth, walking on our legs, constructing with our hands, and wondering about ourselves?

Having gained an appreciation for the origins of matter and life, we naturally confront other trenchant questions close to home in time and space: What are we? Not what is our Sun, our planet, or life itself. But what and who are these 21st-century human beings inhabiting Earth? Everyone ponders these more personal queries at one time or another. They are among the most profound and interesting issues of all—not least because we are asking them.

The seventh, CULTURAL EPOCH doesn’t concern human names, social security numbers, or political affiliations, though admittedly these and other vital statistics do tell others a little about ourselves. Instead, we seek a more general understanding of the origin and evolution of the human species, which, in a nutshell, seems to be as follows: Each of us is the product of many ancestral life forms—a cluster of genes inherited from all of them, and shaped by environments that are partly ours, partly our parents’, partly our parents’ parents’, and so on far back in time.

Some 1000 years ago, each of us would have had more than a million ancestors, all alive simultaneously. They were likely spread across much of the world, living in a range of environments, most struggling to survive and few better off than any others. Going back another 2000 years, some of our ancestors could well have been leaders of ancient Greece or Rome; yet another 3000 years, of the ruling class of old Egypt or Babylonia. But the bulk of our forebears were probably slaves or peasants, likely able to neither read nor write. They were probably ignorant, superstitious, and cruel—primitive farmers at best. Few of them would have touched metal or spun a wheel. By modern standards, most of our ancestors of several millennia ago were savages. They survived largely by hunting and gathering, living only within their immediate environment. It’s hard to relate to them, but modern science suggests that we must. Evolution stipulates that we carry in our bodies some of their genes, and perhaps in our minds some of their temperament toward the world around them. Part of our anatomy, abilities, attitudes, and desires, as well as our outlook on life and way of thinking, all derive to some extent from the genes of our ancestors, molded partly by the environments in which they lived.

Answers to the fundamental questions about ourselves, then, are still evolutionary ones. These are issues that permit us to relate our individual selves to all of humankind, indeed to all living things. If we can find rational answers, then perhaps we can learn who we really are, as well as how it is that we can think and experiment about ourselves and our Universe.

Long ago, our distant ancestors possessed none of these traits. They were not human. They made no tools, had no intellectual vision, probably displayed little curiosity. They were small-brained beings populating forests, largely intent on surviving and reproducing. Somehow they gave rise to humans. Somewhere in our ancestral past, evolutionary links join creatures that clearly were human with creatures that clearly were not.

The learning goals for this epoch are:

  • to concentrate on the past 20 million years, which while a long time by human standards is <0.5% of the total age of Earth
  • to understand some of the techniques used to sketch the recent paths of human evolution
  • to meet our australopithecine forebears, the classical “ape-man” of a few million years ago
  • to realize how chimpanzee lifestyles can teach us a bit about ourselves
  • to appreciate the many environmental and societal factors that helped make us cultured human beings
  • to recognize the ways and means that some life forms evolved wondrous clumps of matter known as brains
  • to appreciate how the enterprise of science helps us understand our modern selves and the Universe around us.

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