Authors: George M. Church
A common objection to the idea of resurrecting extinct species is that since many of them disappeared due to the loss of their native habitat, it is pointless to bring them back into a world in which those habitats have long since vanished. But it is possible to bring back the habitat along with the animal itself. In the case of the wooly mammoth, there has already been an attempt at this.
In 1989 Sergey Zimov, director of the Northeast Science Station in Cherskii, Russia, together with a number of partners, established a nature preserve covering a sixty-square-mile area (about three times the size of Manhattan) that they called Pleistocene Park. Although it was in Siberia,
within one hundred miles of the Arctic Circle, Zimov did not claim that the park, as it stood, reproduced the mammoth habitat of the Pleistocene epoch. The group's goal, however, was to turn it into one. “In some places we must not only preserve nature, we have to reconstruct it,” said Zimov.
Zimov's hypothesis is that it was human hunting, and not climate change, that destroyed the mammoth. In his paper in
Science
, “Pleistocene Park: Return of the Mammoth's Ecosystem” (2005), Zimov argued that it was the animals themselves, more than temperature alone, that maintained the ecosystem in which mammoths thrived.
“It might not have been the climate changes that killed off these great animals and their ecosystem,” he wrote. “More consequential, perhaps, were shifts in ecological dynamics wrought by people who relied on increasingly efficient hunting practices, which decimated the very population of grazing animals that maintained the tundra steppe.”
Tundra steppe, the mammoth's primary habitat, was mainly grassland, the kind of open prairie that is common in the Midwest. But about 10,000 years ago, at the beginning of the Holocene, the mammoth tundra steppes of northern Siberia disappeared completely, replaced by an ecosystem rich with mosses and forests instead of grasses. According to Zimov, the loss of the tundra steppes was due to the loss of the mammoth, whose grazing habits had formerly kept the grasslands alive and fertile.
To return the area into a mammoth ecosystem, Zimov suggested introducing large herbivores selectively. To that end, in the spring of 1998 Zimov brought to the park thirty-two Yakutian horses, the breed that was closest to those that lived in the region during the Pleistocene. Over the following three years the horses converted a confined area of the park from mosses and shrubs to grassland. Later, Zimov imported some two dozen wood bison from Canada. Gradually, a large, fenced area of Pleistocene Park came to resemble the mammoth ecosystem that was in place when the last mammoths roamed the earth.
If and when woolly mammoths are ever cloned into existence, bringing them to Pleistocene Park would be a case of returning them to their natural habitat. It would be the closest thing to time travel: a return to the flora and fauna of the Pleistocene epoch, a sort of latter-day Siberian Eden.
It would also turn the area into an adventure tourist destination, for the park would in effect be a mammoth zoo.
It might be a while before that happens. The first animal to be resurrected from extinction, the clone of Celia, the bucardo, lived for about seven minutes before dying of a lung condition common to cloned mammals.
*
Seven minutes might not seem like much, but then the first flight of the Wright brothers in December 1903 lasted for all of twelve seconds. Sixty-six years later, in 1969, we were on the moon.
_____________________
*
In 2009, the
Telegraph
(UK) ran an article titled “Extinct Ibex Is Resurrected by Cloning.” The many subsequent news stories that reported these experiments erroneously gave 2009 as the year in which they took place. In fact there was a six-year delay between the successful experiment and the first scientific report in the journal
Theriogenology
, in 2009.
*
In 2000, the Nobel Prize-winning atmospheric chemist Paul Crutzen coined the term “Anthropocene” to refer to the geologic era in which human activity has had a significant impact on the face of nature.
*
In August 2011 a mammoth thigh bone containing bone marrow was discovered in permafrost soil in Siberia. Kinki University scientists plan to use this material for cloning.
*
Denisovans are another recently discovered species of “archaic humans.” (They were named after the Denisova Cave in Russia, where bone fragments were found in 2008.) There is evidence that both Neanderthals and Denisovans interbred with modern humans.
*
Robert Lanza, of Advanced Cell Technology, an adviser to the bucardo project, speculated that if a pulmonary surfactant, which aids breathing, had been promptly and properly administered, the animal might have lived.
Industrial Revolutions.
The Agricultural Revolution and Synthetic Genomics.
The BioFab Manifesto
Industrial Revolutions
The Neolithic era began roughly 10,000 years ago in the Middle East, at the tail end of the Stone Age. By this time in history the genus
Homo
had winnowed itself down to only one remaining human species,
Homo sapiens
â
usâwhich had by then vanquished, assimilated, or otherwise out-survived Neanderthal man, the Denisovans, and all earlier examples of archaic humankind. The period was put on the map and immortalized by the development and use of polished stone implementsâand nice-looking ones at thatâas opposed to the chipped or found stone tools utilized in the earlier Paleolithic.
But the Neolithic is noted for something far more important than stone toolsâthe invention of agriculture. Other than the massive set of effects wrought by the industrial revolution, the single greatest transformation
in human history occurred during the Neolithic, as people turned from hunting and gathering to farming and animal husbandry.
The agricultural and other industrial revolutions are major turning points in human history because they allowed us to make immense leaps in our understanding of and control over nature. They were revolutions in knowledge and in toolmaking, and they have clear analogs in synthetic biology, which is likewise a product of specialized knowledge and a unique set of tools.
Human history includes at least six different “industrial revolutions.” Arguably we are now in the midst of the sixth industrial revolution, and the tools and knowledge it encompasses have given us the power to remake ourselves. Revolutions are sometimes scary, but they do not have to be. Each revolution begins with a period of tinkering by trial and error. A prehistoric “scientist” stumbles across a fire and tries adding dry leaves that start to burn, hot as the sun. Then he tries adding sand but discovers that this puts the fire out. Revolutions spread outward from the center with vague ways of communicating intentions and degrees of progress, as when our fire man tries to tell his friends that fire is hot, and that friend tells others. Eventually we develop measurements, in this case scalar indications of temperature, and models that enable prediction and design.
Revolutions can have unanticipated positive and negative consequencesâas when a fire rages out of control and perhaps incinerates its maker. Bearing this in mind, we will chart the course of the revolutions that have led to the power to control our future biological developmentâto understand and then manipulate the evolving genome of life itself.
The first industrial revolution was centered on the notion of time. It began 15,000 years ago, when we had no idea of what 15,000 years meant or what a revolution was. Those of us who looked human (including Neanderthals and Denisovans) had spread far beyond Africa and were discovering a need to understand time, so that we could predict the seasons. We could get by in the transition from the season of gathering foods to the season of planting them just by waiting for the warmth of spring. Why, then, bother measuring time?
Because it was reassuring during the winter to visualize the time remaining until spring to pace the use of stored food. Floods and droughts recurred, somewhat predictably, each year. Some life-altering events took place on longer time frames like the five-year cycle of El Niño. Some catastrophes occurred less frequently and lacked a periodic component but required a collective memory to maintain preparedness. Fortunately, the crucial measurements tended to be easy and digital and could be checked against other measures. Thirty sunrises corresponded to one lunar cycle. Twelve lunar cycles made up a year. The day wasn't digital but rather smoothly analog, and dividing it into hours with a sundial and precise seconds with a mechanical clock probably wasn't crucial until we started serious navigation.
What was the killer app, or tool, for measuring time? In terms of tempo, biological systems exhibit natural cycles that are synchronized with some astrophysical cycles. Biological cycles such as times of hibernating, mating, and flowering match up with the earth's tilted revolution around the sun. Bears wake up slowly at the end of winter, and then their prey animals get a fast and rude awakening as the season's first bear claws penetrate into their resting places. Matching the lunar cycles most evidently are the tidal behaviors. Less obviously, some animals (e.g., primates) menstruate monthly, while other mammals generally have nonmonthly estrous cycles. Matching the rotation of our home planet, almost all life has circadian, diurnal cycles of metabolism. Probably all animals with brains have tendencies toward sleep patterns synchronized to the sun. Cave-dwelling animals lost this synchronization over the course of many millennia.
At the scale of seconds, we notice heartbeats and wing beats. In the millisecond range, whales and bats produce ultrasound vibrations of 100,000 per second and up to 180 decibels to navigate and communicate. Some biological systems purposefully avoid simple patterns in order to thwart predation; for example, seventeen-year cicadas and eighty-year cycles for the blooming of bamboo. The point is that the first clocks were hardwired into living things of all stripes, and then human beings started reinventing them and soft-wired them into our culture. Initially this was in service to
the gods of agriculture but the study and engineering of time spread aggressively into many of our technologies today. Our close relatives the great apes tend to think on very short timeframesâinstant gratification. The ability to tell long narratives in the form of epic poems and songs, and to draw cave paintings (as far back as 32,000
BCE
), went hand in hand with a growing awareness of causality and the advantages that such awareness brings. This contributed to developing strategies for hunts and for warfare that required more coordination and timing than even the remarkable skills of wolf packs.
Keep in mind that it doesn't take much of an advantage for a revolutionary advance to sweep through a population. A 5 percent advantage compounded annually for twenty years is a 260 percent advantage, and over two hundred years is a 17,000-fold advantage.
As with most technologies, the taming of time bore unwelcome and unanticipated consequences. Today, as we face impending deadlines, a hectic pace of life, and existential risks of all kinds, it's tempting to think that stress was less severe in prehistoric times. But we have had many generations to adapt evolutionarily, while the revolutionary concepts of time and causality may have had a comparatively rapid onset. The unwelcome consequences of warfare and stealth and deception reverberate in our culture and inherited psyche today.
The moral of the story is that progress comes with hidden costs, risks, and unpleasant surprises. As I chart the course of genomic technologies, I will do my best to point them out.
Agriculture, the domestication of animals and crops, and the trade it resulted in encouraged the concentration of people and led to cities. Probably the first domesticated crop was emmer wheat (
Triticum dicoccoides
), found growing wild in the ancient Near East. Two wild grasses,
Triticumurartu
and
Aegilops speltoides
, had intergenus sex. They were diploid (2X), meaning that they had one copy of each chromosome from their
mother and father, but their intergenetic children were tetraploid (4X), meaning that they kept two copies eachâa full set from all four grandparents. This is rare in any given generation but common over evolutionary time, and ranges from triploid (3X) watermelons and water bears to dodecaploid (12X) plumed cockscomb
(Celosia argentea)
and clawed frogs
(Xenopus ruwenzoriensis).The
tetraploid wheat hybrids were adopted by humans possibly as early as 17,000
BCE
(based on carbon-14 isotopic dating), in what is now southern Turkey (based on DNA studies), and then spread as far as Egypt to feed the pharaonic dynasties. Along the Yangtze River we see another dramatic domestication process dating from 12,000
BCE
: changes in the morphology of rice phytoliths. And yet another in the Balsas River valley in southeastern Mexico around 6700
BCE
, when an annual grass,
Zea mays
, began its long transformation into modern corn. Domestication of thousands of additional species of plants and animals followed.