The Next Species: The Future of Evolution in the Aftermath of Man (36 page)

If we look at the growth of
Homo sapiens,
there are similarities between the ongoing human population experiment and that of the microorganisms that Gause described in the 1930s. If geneticists are correct,
Homo sapiens
exited Africa with no more than a few hundred people and migrated over the world, enjoying a series of Edens. Yet, at our greatest expansion, we barely numbered five million. But then about ten thousand years ago we invented agriculture, and the human population began to rise steeply.

In the nineteenth and twentieth centuries we discovered ways to thicken grain stalks, along with methods of producing fertilizers and better systems of irrigation, and in just two hundred years our population went from one billion to seven billion, with two or
three billion more on the way. The bulk of this growth has been in the last fifty or sixty years, a single lifetime. We are definitely like a virus—or at least a single-celled organism. Part of the reason for the frenzied rise in Gause’s experiment was the lack of competing species in the test tube. Competing species would have slowed things down, formed buffers, created competition. But we’re eliminating that possibility . . . aren’t we?

In 2000, Dutch chemist Paul J. Crutzen
gave a name to our time: the “Anthropocene,” the age of man. He regards the influence of human behavior on the earth’s atmosphere as so significant as to constitute a new geological epoch.

But is there a limit to this influence? What if, like Gause’s microorganisms, our numbers rise to an apex but then plummet back down? What if overpopulation, starvation, disease, and the obliteration of native species aren’t healthy and we end up with perhaps 20 percent of the numbers of our current species—back to maybe a population of one or two billion, where we were just two hundred years ago—although isolated perhaps by the aftermath of the devastation?

Ian Tattersall, curator emeritus at the American Museum of Natural History in New York and author of
Masters of the Planet: The Search for Our Human Origins
, doesn’t believe in the emergence of another species under present conditions. “Man has spread all over the world, and mass transportation has made it too easy for us to intermingle,” says Tattersall. But when we propose the idea of a crash similar to what Georgii Gause witnessed in the petri dishes, Tattersall says,
“Then all bets are off.”

If man’s future development mirrors Gause’s experiment, then it might be possible for a member of
Homo sapiens
to develop into another species in a world with far fewer of us present.

The next species could arise out of isolation created by mass extinction as well. It could also be isolated within the present modern cultural context, because of cultural stigma and prejudice. Or genetic
engineering could create a “superspecies” that finds it repugnant to mate with “less-than-super” beings.

Coexistence with the next species must begin by recognition: knowing who they are and what they look like. And how would we do that? The difference could start with something as simple as a few genes that could help the next species consume some more efficient food, as the Indo-Europeans did, or make men more resistant to the future plague of diseases, as were the conquistadors. However, neither the Indo-Europeans nor the conquistadors were different species, so we’d need more.

Science warns against the utopian view that selection will continue to upgrade nature much like a new cell phone. Selection promises only that a new species will be able to outcompete its ancestors in a given region at a given time. Evolution might create a wiser individual with a better, more long-term perspective of the world, but it would happen only as a side benefit; the primary benefit would address maximum fitness right now.

Still, suppose this could happen. Is this around the corner, far off in the distance, or has it already happened and we just don’t know it? If you were to
take a Neanderthal, clean him up, give him a haircut, put him in some new clothes, and shove him out onto the street, few would recognize him as out of place. Douglas Palmer, in
Origins: Human Evolution Revealed
, claims that Neanderthals were a little broader than modern man, the brow a little more pronounced, the arms a little stronger, but he could be a track star, a football player, or a character actor for all we know.

The next species might be a little leaner, continuing the trend from past hominid development, with a larger head for a larger brain, and with a diminished nose, brow ridge, and other facial features. Still, could you pick the next species out of a crowd any better than a Neanderthal? And—get this—even if
you
are the next species and you’re reading this, trying to get a better understanding of those you are about to replace: you’re doomed, too. As Smithsonian’s Hans-Dieter Sues says, 99.99 percent of all the species on earth have gone extinct. There
is no reason to think that man—or his immediate descendants—will, in the long run, outlive them all.

Time is part of the problem. Man has difficulty contemplating the enormous range of times that have passed in the history of our planet and how our own history compares with that. “Deep time” is what the scientists call it, and man is, apparently, not a “deep” thinker. Paleontologist Stephen Jay Gould impressed this on his Harvard students by giving them this simple analogy:
if our planet’s beginning is the end of your nose and its present your outstretched fingertip, then a single swipe of a file on the finger’s nail wipes out all human history. This doesn’t refer to the brief period of human civilization but the entire existence of
Homo sapiens
and all his hominid ancestors.

Scientists also like the clock metaphor, which gives human time another perspective. If we look at the
4.5-billion-year history of our planet in terms of a twenty-four-hour day, then the Cambrian explosion doesn’t occur until about 10 p.m. Dinosaurs don’t appear until after 11 p.m. and the big asteroid marks their end at twenty minutes before midnight. Man doesn’t appear until the last few seconds.

Man just might be the ultimate live-fast-die-young animal. Consider that the average longevity for a mammalian species is only one to two million years. We’ve been around only one-tenth of that, about two hundred thousand years, and our existence is gravely threatened. Sam Bowring at MIT thinks the paleontological record for man will expose but a thin layer of metals that
Homo sapiens
dug out of the ground.

Jan Zalasiewicz, lecturer at the University of Leicester, UK, and author of
The Earth After Us
, admits that it is hard to compare human and geological timescales. He suggests we make a trip to the Grand Canyon near Flagstaff, Arizona, and look down into the mile-deep chasm, whose strata span 1.5 billion years. “Measured on this scale, our own species would fit into a layer about three inches thick, while our industrial record would be confined to about one-hundredth of an inch,” he says. Such an interval would seem almost instantaneous to a geologist—not much more than a meteor strike.

But the human population boom, though bad for nature, will be great for future interplanetary geologists.
The more specimens, the more chance for fossils, and man has come up with an explosion of specimens in just the last hundred years. Perhaps our best choice is to aim for fossil importance.

But if you really want your bones to end up in a museum diorama somewhere else in the galaxy, then, as they say in real estate, it’s all about location, location, location. You need to take your final bow down by the seashore or at a river mouth where sediments, soil, and rocks are actively being deposited upon one another, earth upon earth, in layers. For if you sing your final swan song on top of a cliff or a mountain, no matter its dramatic appeal, that’s not good for fossil preservation: there’s too much active erosion. Gradual accumulation or “deposition” of soils, as paleontologists refer to it, layer upon layer on top of your bones, is far better for the preservation of future new fossils than erosion.

So how might
Homo sapiens
finish their act, and nature move to center stage? Look at the way Neanderthals did it. It was in the caves at the base of the Rock of Gibraltar, at the tip of the Iberian Peninsula, that the last evidence of the Neanderthals was found. Global temperatures were cooler and a lot of water was locked up in ice, lowering sea levels 80 to 120 meters. This opened up a huge portion of the coastal shelf that today is under the Mediterranean Sea.

There was plentiful meat and game but not enough water. The end could have come during a summer drought when life was stretched to its limit. In that environment, at that time, rains did not come in summer, and in some years they did not come at all.

Extinction comes when a species reaches a point when births do not keep up with deaths, and numbers gradually diminish. Such a condition for man may come by the end of the century, when many demographers predict population growth may start to diminish. This could be a great thing: man finally reeling in population growth. But
is it cause for celebration, or the beginning of the end? If future populations don’t rein in resource use, then diminishing population growth may be an empty promise.

In recent years, there have been a number of convocations at major universities and governmental offices on threats to man’s existence. Asteroids and comets always come up, since an asteroid had lots to do with the end of the dinosaurs. An asteroid or comet could do us in, as we learned when scientists turned their telescopes to watch the impact of the comet Shoemaker-Levy 9 on Jupiter in July 1994. The warning for such events may be only a year, and the consequences—had that comet hit Earth—could certainly have taken out our species; but it’s more likely to take only a portion of us, with the rest recovering, as in the years following World War II, in a relatively short time.

Sudden climate change could do it, but we’ve already survived the Younger Dryas event, as well as the last two glacial epochs, and we’re still kicking. Climate change is more apt to wreak havoc on nature, and nature to wreak havoc on us secondhand. Biological warfare? Runaway nanotechnology? We made it through the Black Plague. Even Native Americans survived conquest by the Europeans.

Robots armed with some sort of super–artificial intelligence, and smarter than their makers—able to access the world’s knowledge from the cloud—might be amazingly helpful or harmful, depending upon their designers, but are not likely to turn on all of us at once.

Thermonuclear power has lots of potential. In 2012 the
Bulletin of the Atomic Scientists
announced that it had
moved its Doomsday Clock forward to five minutes to midnight. In 2010 the clock had been pushed back to six minutes to midnight, but it was moved closer again based upon the fact that arms reductions worldwide have stalled, as have efforts to curb climate change. The
Bulletin
mentioned that we still have over nineteen thousand nuclear weapons, “enough to destroy the world’s inhabitants several times over,” and that many countries
are in the process of upgrading their current arsenals. The complexity and resources involved in making these weapons has slowed their spread, but what happens if someone should discover a way to make them from sand—or something similar?

According to the United Nations Population Division, the median population scenario, often seen as most likely, predicts that by 2050 the world will have 9.2 billion people. That’s up from earlier estimates due to increased fertility in Europe and the United States. In 1800, only two hundred years ago, there were only one billion of us.

Man is immensely resourceful at extracting our natural resources from the earth. As Charles Mann, author of
1491,
says, “It is our greatest natural blessing. Or
was
our greatest natural blessing.” We are getting close to the end in some vital areas. In the next hundred years, despite improving extraction technologies, we could run out of oil, phosphorus, and perhaps even fertile land. The World Bank predicted in the late twentieth century that most twenty-first-century wars would be fought over water supplies.

According to UC Santa Cruz professor Jim Estes, “We will either evolve into something new, or we will become a dead end. This
Homo sapiens
lineage will cease to exist. The key thing is the next fifty to one hundred years; that’s the big question. And what’s the quality of life going to be like for those that live through that period? Beyond that, our ability to forecast is very poor. There could still be humans, as we know them today, fifty thousand years into the future. But certainly a million years into the future . . . we will be gone.”

But what might hold us back from that inflection point that Georgii Gause described in
The Struggle for Existence
, where the line plummeted down the other side of the steep rise? The answer is: Don’t go there. Hold back. Stop! But in making that request, we are asking humans to do something that no other species has ever done: constrain its numbers voluntarily. It’s a gargantuan order. Zebra mussels in the Great Lakes, brown tree snakes in Guam, water hyacinth in African rivers,
Burmese pythons in Florida—
all continue to try to overrun their environments.

But Charles Mann expresses hope. In a recent article for
Orion
magazine, he described the conditions of slavery in the eighteenth and nineteenth centuries and how society evolved away from the practice. This was also about the time that
Robinson Crusoe
, Daniel Defoe’s famous novel, came out depicting Crusoe and his men shipwrecked on an uninhabited island off Venezuela where they learned to live off the land. Defoe made Crusoe an officer on a slave ship, then an honorable occupation. When the book came out in 1719, no one complained. Slavery was accepted then.

But in a few decades in the nineteenth century, slavery almost vanished. The road to this change in terms of human consciousness is enormous. In 1860, slaves, all told, were the single most valuable assets in the United States, worth about $10 trillion in today’s money. But the tide turned on slavery, though at great cost to individual lives and national finances. The American Civil War killed more than six hundred thousand combatants and wrecked the US economy, but slavery died. And it didn’t just die in the US: in the nineteenth and early twentieth centuries it died in Great Britain, the Netherlands, France, Spain, Portugal, Korea, Russia, China, and quite rapidly in most of the rest of the world. There are still some vestiges of slavery in the world—forced labor, sexual slavery, and indentured servitude—but there are few open markets for slavery, and for the most part, nations don’t thrive on their slaves.