Sometime around six million years ago a new breed of apes began to walk upright on the African savanna. No one is sure exactly why. Most likely the changing climate, which was transforming forests into plains, meant the earliest hominids found themselves in a new environment—one where standing upright brought with it important advantages: the ability to see predators and prey at greater distance, and thus survive. The four limbed locomotion which had served these apes for millennia in the trees was quickly becoming unsuited for travel in the emerging grasslands. This highly complex animal was the result of billions of years of evolution—from the earliest forms of bacteria and prokaryotic organisms to the eukaryotes which ultimately evolved into eels, bony fish, amphibians, reptiles, and, eventually, birds and mammals.
Evolution on this third planet, located in one tiny solar system revolving amid the celestial soup of an unremarkable elliptical galaxy, was a slow process. It was a process which could have just as easily never begun at all. But it did begin, thanks in part to this planet's fortuitous combination of characteristics: a prime location relative to the star it orbited; a liquid core; a tilted axis; a small, orbiting body of its own to create tidal pulls once water gathered on its surface.
Though it took billions of years for the first chloroplasts to come into being, and hundreds of millions more for those chloroplasts to pump out enough oxygen to create an atmosphere and an ozone layer (which ultimately allowed arthropods to follow plant life from water to land sometime around 500 million years ago), the stage was eventually set for life to flourish. And flourish it has. Through numerous ice ages and five mass extinctions, planet Earth has proven again and again to be fertile ground for life of all kinds, sizes, and capacities.
Over the next five million years the descendants and genetic cousins of the those first Australopithecines experienced a slow and sneaky process of genetic mutations and lucky breaks. Until, about 200,000 years ago (there is some debate about this date), the first
Homo sapiens took this bipedal ape family to a whole different domain. With their massive brains—larger, by far, than any other primate before or since—their capacity for adaptation, their propensity for culture and language, and their unique openness to new ways of thinking (what anthropologists call "plasticity"),
Homo sapiens was a formidable species indeed.
Yet they were young, and those of us who have descended from these prehistoric humans, are young too. Amazingly so.
The history of planet Earth is so lengthy that its nearly five billion years are often expressed as 24 hours. It's a trick only the brain of
Homo sapiens could come up with, and it's a good way to understand the relative lengths of each geological and evolutionary stage. Using this analogy gives us perspective. We see that—if Earth's creation took place at midnight last night, and we chart the subsequent 4.567 billion years until midnight tonight (with each second accounting for 53,000 years)—modern humans have been around for only the last four seconds.
Our species is a very recent addition to the biomass of our planet. Many of our most important milestones barely measure on the planetary timeline. We began using fire on a regular basis, and for specialized functions, about 2 seconds ago (
Homo erectus is usually given credit for first controlling fire over 1 million years, or about 19 seconds, ago). We first began experimenting with magic and religious practices .6 seconds ago. We reached the last uninhabited region of the world, the tip of South America, .2 seconds ago. Shortly thereafter—about 1.8 seconds ago—we abandoned our foraging subsistence and adopted agriculture. The two thousand years since the birth of Christ comprise a paltry .04 seconds on our planetary clock.
The timeline for advancements made since the industrial revolution, just 200 years ago, is hard to visualize given this perspective. The age of colonization and slavery, colonial independence from England, universal suffrage, two world wars, the nuclear age, civil rights, the space age, and the environmental movement, all are almost incomprehensibly small ticks on our 24-hour timeline. And the computer age is almost invisible.
Yet the impact of the crafty ape named
Homo sapiens is anything but invisible. In most cases, we have had a dramatic and often devastating impact on Earth. In the last .0038 seconds we have directly or indirectly altered every ecosystem on the planet, destroyed countless species forever (one species each year at our current rate), and thrown the very health of the planet into a chaotic downward spiral. Our rate of population growth in just the last 100 years (.0019 seconds) exceeds every other vertebrate ever to have lived on planet Earth—and threatens to overwhelm it. A looming second nuclear age, global warming, the blight of mega-cities, our haphazard instigation of a sixth mass extinction, and quickly dwindling resources each pose significant threats to the continued existence of
Homo sapiens.
What are we to conclude about such a remarkable evolutionary journey when it has brought us to this point? How should we, both as a species and as stewards of the planet, continue the legacy of not only our resourceful hominid ancestors but of life itself? What can we do, you and I, to ensure that the most noteworthy species ever to exist on this planet (and perhaps any other) does not participate in its own undoing? Finally, how do things change when we expand our perspective to include all life on Earth, even that which might one day develop on our planet—do we have a responsibility to those life forms?
This book will attempt to answer these questions by framing modern humans in a new light. When we become familiar with our own evolution—indeed, with the evolution of all life on Earth—we will better understand both our capacities and our limitations. But biology is only the starting point. As
Homo sapiens have proven since their inception, the capacity for advancement is dictated not by genetics but by our capacity to imagine, to create, to communicate, and to share. Shaping the very thoughts we think is quintessentially human, and it is as capable of leading us astray as it is of creating a new and better way of life. It is this kind of thought revolution which offers us the chance to instigate a new kind of evolution. We have the chance to achieve, in a cosmic instant, the kind of cultural evolution which will—like the biological one we have already undergone—put every other species to shame, and propel humanity toward a bright future.
