The Next Species: The Future of Evolution in the Aftermath of Man (34 page)

By some estimates, between a tenth and a third of the world’s
untapped oil reserves lie beneath the shallow continental shelves in the Arctic. Large volumes of gas and coal lie beneath the North Slope. Development of these petrochemical bonanzas may be an economic force for open oceans, just as petrochemical exhausts may bring them on quicker.
Summer Arctic sea ice, which hit a record low in 2007, will probably dissolve completely by 2030.

But the downside is a rising ocean. Sea level has been rising steadily over the last century. Part of this is due to the thermal expansion of the ocean waters spurred on by increasing warmth, but another part is due to melting glaciers and ice caps. Mountain glaciers are melting rapidly, as are the boundaries of Greenland and Antarctica. Greenland is up to 10,500 feet (3,200 meters) above sea level, which means its high altitude supports its ice. But as the rim and base of the ice begins to melt, the peaks could lower into warmer air. It is one of the feedback effects scientists are investigating that may accelerate future changes.

The loss of Greenland’s ice could raise the sea level worldwide by about twenty feet (six meters). Right now Greenland’s interior ice is growing, while the margins are melting. Likewise, East Antarctica is growing while the West Antarctic peninsula is shrinking. The shrinking comes from warming seas, the growth from moisture blown over the land, which turns to ice. Increased warmth will stop the growth and increase the melting.

How could this affect modern man? It seems a lot of our megacities could become casualties of sea-level rise. London is perched on a lowlying river just upstream from a strong tidal estuary. If, as some predict, storms and floods accompany sea-level rise, then the Thames Barrier, the world’s second-largest movable flood barrier, erected downstream of Central London, could suffer the same tragedy as barriers set up to protect New Orleans before Hurricane Katrina, perhaps within this century.

Amsterdam may go even before London, since it’s lower. Venice and New Orleans might also have to relocate to higher ground. Large portions of Bangladesh, southern Florida, and the coastal plain of Southeast Asia, where lots of people have settled, will also be under
water. Jan Zalasiewicz, a geologist at the University of Leicester, UK, and author of
The Earth After Us: What Legacy Will Humans Leave in the Rocks?
says all this is possible with a sea-level rise of twenty meters, which he claims is the “small change of geological history.”

But Curt Stager argues that we don’t need twenty meters to cause real damage. After only a three-foot (one-meter) rise, the Florida Keys, the Everglades, and the Mississippi Delta, along with New Orleans, will go under. So, too, will much of the San Francisco Bay Area, much of eastern China, and the southern tip of Vietnam. Also, the Dutch interior, the southwestern rim of Denmark, and the broad deltas of the Nile, Niger, Orinoco, and Amazon Rivers.

Climate change will increase rainfall in the Adirondacks in upstate New York, and this will increase downstream river discharge as well. New York Harbor will rise with the rest of the ocean around the rim of Manhattan Island, while destructive flooding coming from upstream may push the Hudson’s water up and over its banks. That naturally clean New York drinking water may become a thing of the past.

Most scientists believe we are headed for a climate that is going to warm to temperatures not seen in the last ten million years in just the next few centuries. Once there, those temperatures could last over a thousand years. Back in the days of the Kyoto Protocol (an international agreement to reduce greenhouse gas emissions from industrialized nations by 5.2 percent that was adopted in Kyoto, Japan, in December 1997), there was hope we might actually tackle this, but the outlook today looks dim.

But there is another force looming as well. Have we forgotten the ice ages? The dominant weather influence of the last half million years is actually 100,000-year cycles of ice followed by 10,000-year periods of warmth. At various times in Earth’s history, the planet has frozen from pole to pole with ice. Even the oceans have turned to ice. This happened once at 2.5 billion years and again between 700 million and
800 million years. Severe ice ages have occurred 400 million, 300 million, and 200 million years ago. It could happen again—though, ironically, Gifford H. Miller of the Institute of Arctic and Alpine Research at the University of Colorado, Boulder, suggests that
global warming may actually put off the next ice age by thousands of years.

So we will still have our dance with global warming, but after a few thousand years of that, then comes ice. Another ice age would radically reduce the volume of plants and animals. We will have to do more with much less. Overpopulation would become lethal. What’s left of us will have to rely on agricultural land that won’t be as rich as it once was. But, as before, we’ll be plagued by that hunter-gatherer mentality that has proven so lethal to this world: Move into a new area, use what there is, and move on. Don’t worry about the future.

The future will take care of itself. Though, perhaps, not in a way we would approve of.

I met biologist Rob Jackson at his new Stanford University office one day and we discussed Anthony Barnosky’s earlier prediction that we could be entering a mass extinction event in the next three centuries. Jackson revealed that he disagreed with Barnosky’s assessment, and just as I was about to breathe easier, he hit me with this: Jackson thinks the intersection of climate change, invasive species, and ocean acidification is a recipe for serious disaster that is more urgent than Barnosky’s predictions. “All these things could come together in a fifty-to one-hundred-year timescale to completely transform the surface of the earth,” he said. “And once we realize it’s happening, the results may come so fast that we can’t stop them.”

An ominous portent, I thought. But could another species make it
better?

T
HE FOUNDING DIRECTOR
of the Harvard Business School’s Life Sciences Project, Juan Enriquez, posed a question at a TEDxSummit in Doha, Qatar, in April 2012. TEDx is the international component of TED, a nonprofit organization based in New York devoted to spreading game-changing ideas through short, powerful talks, often delivered at conferences. Enriquez’s question was one that he had been enthralling audiences with a lot. He spoke about the history of life, tracing it from the Big Bang, to the birth of the stars, to the perimeter of the galaxy, to parts played by the sun, earth, and man, a history that spanned 14 billion years, involved trillions of stars, and then he asked the audience one question: What was the purpose of all this? He moved on to the next PowerPoint slide to provide the answer: A photo of Pamela Anderson and then Michael Jackson—the point being that man is the almighty purpose, the be all and end all of life, after which, he claimed, evolution flatlines to the end.

His next questions was “Wouldn’t that be slightly arrogant? There has been
something like twenty-five human species; why couldn’t there be another?”

Indeed, why couldn’t there, particularly if we were entering a mass extinction? Many scientists believe that natural selection operates mainly on the frontiers of change.

Seventy-seven thousand years ago, a human sat in a limestone cave in Africa on a cliff overlooking the Indian Ocean, cooled by a sea breeze and warmed by a small fire. He picked up a sharp rock and made a crosshatch design on a piece of reddish brown stone that scientists claim is the oldest known example of an intricate design made by a human being. It demonstrates the ability of man to communicate symbolically, which scientists believe sets
Homo sapiens
apart from other hominids on earth at that time.

This symbolic communicator with his stone tools and weapons had a competitive advantage as he moved out of Africa on the “Great Migration” into territory occupied by other species of the
Homo
genus.
Homo sapiens
first traveled to Asia eighty thousand to sixty thousand years ago. By forty-five thousand years ago this new hominid had settled Australia, Papua New Guinea, and Indonesia.

Keep in mind that by this point
there may have been four different species on the planet:
Homo sapiens, Homo floresiensis,
Neanderthals
,
and Denisovans, the last a potential new human species described from a finger bone fragment found in Denisova Cave in the Altai Mountains of Siberia. But
Homo sapiens
eventually won out—the actual last man standing.

Harpending and Cochran think there has been significant evolution in the past fifty thousand years between human populations separated by great distance and geographical barriers. “No Finn could be mistaken for a Zulu, no Zulu for a Finn. There have been substantial changes in the genetic makeup of humans since man spread out of Africa, and those changes have taken on significant characteristics in different populations,” they wrote in
The 10,000 Year Explosion
.

Robert Fogel, a University of Chicago economist, while studying the effects of American slavery, discovered that over the past few
centuries—particularly in the last fifty years—
Americans in general have been growing taller, living longer, and getting thicker. In 1850, the average American male was five feet seven inches tall and weighed about 146 pounds. By 1980 he stood five feet ten inches and weighed 174 pounds. A team of economists extended the statistical search worldwide and found the trend was global.

It turns out that advances in medicine, better nutrition, better working conditions, cleaner water, and a general reduction in pollution have netted humans a biological advantage. It’s most dramatic when you consider age. When
Homo sapiens
first emerged in Africa about two hundred thousand years ago, the average life expectancy was twenty years. By the year 1900 it had become forty-four years. Today it is closer to eighty years, almost doubling in only a hundred years. And these are heritable trends passed on from parents to children, generated by improvements in health and medicine.

So is there another species in the wings?

As we’ve shown, nature does better when there are multiple species of any animal. Our single species is a bit unnatural. Multiple species of man have historically been the norm, rather than the single species we have today. Nature prefers biodiversity. A single species is not a strong holding position to maintain for any animal. But how could another species evolve?

There are two dominant types of speciation:
allopatric speciation and sympatric speciation, with two other variants, peripatric speciation and parapatric speciation, in between. Allopatric speciation occurs in geographic isolation; sympatric speciation, however, occurs in the presence of other species, such as a lake where fish might segregate in the water column—some to the top, some to the bottom—and over time become separate species. Species could also form by specializing on different types of food, as the finches of Peter Grant’s study on the Galápagos. Though Grant has yet to record a verifiable speciation, he has keyed into the possibility of that happening
by studying how different sizes of seeds select for different beak sizes among the finches and how that selection pressure might produce another species.

Robert C. Stebbins
studied populations of a small salamander at UC Berkeley in the 1940s. He proposed that
Ensatina
originated in the state of Oregon and spread south among the mountains on both sides of California’s Central Valley, the valley floor being too dry and hot for salamanders. As the pioneering populations moved southward, they evolved into several subspecies. Each subspecies had new color patterns as well as adaptations for living in different environments. But by the time they met again at the southern end of the Central Valley, they had evolved so much that they no longer interbred—even though they blended into one another and had interbred in the mountains around the valley rim. This minimum of isolation was all it took to differentiate a species.

Are we overstating geological separation as a starting point for the next species?

Could we do it with sympatric speciation—splitting into two in the presence of others? What evolutionary pressures in the human population might produce another species of modern man? Cochran and Harpending have looked at how cultural isolation altered the genetic code of some of our ancestors. The two scientists speculate that European Jews were genetically isolated during the Middle Ages, not by oceans or mountain ranges, but by Jewish rules against intermarriage reinforced by external prejudices against Judaism. For most of the Middle Ages,
intermarriage with non-Jews, as well as conversions to Judaism, were quite rare.

The dominant trait that puts them at a culture difference—as being large does the Samoans, as being tall does the Tutsis, and as being milk tolerant does the Scandinavians—is intelligence. Several different sphingolipid mutations—a special type of genetic anomaly that creates a buildup of lipid or fat molecules that enhance signal transitions in neural tissues—could cause this. This increases connections in the neurons, the basis of the central nervous system.

Ashkenazi or Eastern European Jews in the Middle Ages specialized as financiers, estate managers, and merchants, jobs that required analytical thinking along with cultural understanding, since they often served as intermediaries between Christians and Muslims. These effects were highly heritable, each generation becoming slightly more adapted and slightly more analytical than the first.

As a result, European Jews have one of the highest IQs of any ethnic groups known, claim Harpending and Cochran. Their IQs average around 112 to 115, whereas other Europeans average about 100. But because of a lack of diversity in their genes, they also have a set of genetic diseases a hundred times more often than other Europeans. These include Tay-Sachs disease, Gaucher disease, familial dysautonomia, and a couple of forms of hereditary breast cancer.