By Eric Vandenbroeck and co-workers

Out of Africa

Once upon a time there was a village in a place Africa. It was a village on the edge of the forest where the sun shone on the tall grass and the undulating hills. Life was hard, but there were enough roots to dig, nuts to gather, and gazelles or hares to hunt. For shelter, language and fashioned new and interesting tools. Thousands of years and thousands of generations passed. Nobody remembered the village of their origins or how their ancestors had lived. But every knew more about the many villages and towns that now dotted ancient Africa. There were caves or overhanging rocks. But the countryside began to change. The sun got hotter and the air drier. There was less and less food as animals perished from drought or left the area in search of water. Villagers, too, chose to follow the herds to stay near food. As they trudged along, they broke into groups. Some headed north following the animals, others moved toward the ocean.

 A new archaeological find in Botswana by an archaeologist from the University from Oslo shows that our ancestors in Africa engaged in ritual practice 70,000 years ago.

The exodus increasingly separated the groups moving farther and farther away from one another. It was an endless walk. Thousands of years passed.  In their endless, slow wandering through icebound plains, windswept steppes, and snow-capped mountains, the villagers lost their sunburned look. Gradually their hair and eyes changed colors, and even their faces and body shapes were transformed. In their dispersed habitats, the people spread over the vast land, separated by mountains, deserts, and the rising ocean that submerged an earlier land bridge. They spoke a variety of tongues, wore diverse clothes, and ate different foods. Then one day a trader walked over the hill and discovered another human settlement, other people who spoke a different language and fashioned new and interesting tools.

Modern humans develop in East Africa (80,000- 60,000 years ago) followed by a first exodus Arabia, India, Australia (60-40 KYA). Humans remain in West Asia (Middle East) get U6 and M1 mtDNA mutations and migrate from there to East Africa and Europe 50-45 KYA. Migration modern humans from East Africa to other parts of Africa (45-35 KYA):

One estimate puts the number of migrants out of Africa at no more than 150 people, the typical size of a hunter-gatherer population. 1 These early adventurers may have had wanderlust, but they ventured out of their known habitat mainly for survival. Those who stayed on survived by moving to more hospitable parts of Africa. The five billion inhabitants of today's non-African are descendants of those villagers who walked out of Mrica. They are increasingly interconnected and, for better or for worse, interdependent. Homo sapiens-the anatomically modern humans who emerged in Mrica-is the first mammalian species that has voluntarily spread itself out to every corner of the globe and begun what we have come to call globalization. In the sixty thousand years since that early journey out of Africa, humanity has diverged. The physical differences among humans that form the basis of what we call "race" were forged in this period of great divergence by geography, climate, and natural selection. fu we shall see, the multihued great human diasporas from Africa, which sprang up in different latitudes and longitudes of the globe, organized themselves in distinct communities and began reconnecting with long-separated cousins across oceans and mountains.

Unlike our ancestors of sixty thousand years ago, today's Africans are not walking along the Yemeni coast or trudging north through the Nile and Jordan valleys to the erstwhile unknown world of the Mediterranean and beyond. From the Atlantic coast of Senegal and Mauritania, they are boarding fishing boats, cramming into hulls in the hope of a better life across nine hundred miles of water. Their immediate destination: the Canary Islands, stepping-stone to the European Union. It is not just that Africans are again leaving the continent in search of a better life. The sight that often greets the fully clothed African immigrants wading ashore beaches of the Canary Islands compounds the irony: the "naturist" European bathers soaking in the sun are in the same state of undress as when our ancestors left Africa.

Other desperate people from Ethiopia-humanity's cradle land-and Somalia are taking to the ocean in the hope of reaching Yemen and beyond. Globalization continues. In this chapter we will see how the urge to find a safer, better life turned some of our human ancestors into adventurers and set them on a journey that marked the first step in the globalization of our species. It would take more than forty thousand years for human settlements to emerge and the process of connecting with one another to take off. But the same motivations that drive greater and greater integration today have been with us from the day humans formed sedentary communities.1

How do we know that we all are originally from Africa? Twenty years ago the proposition was mostly guesswork. In his work on human evolution The Descent of Man, and Selection in Relation to Sex (1871), Charles Darwin suggested that because Africa was inhabited by humans' nearest allies, gorillas and chimpanzees, "it is somewhat more probable that our early progenitors lived on the African continent than elsewhere."2

Although voluminous biological and paleoanthropological evidence gathered since this statement has fortified the evolutionary history of life on earth, it has been a long wait to validate Darwin's insight about Africa. Opportunity emerged with our new ability to look deep into our cells and decode the history written there. The first step was taken in 1953 when British scientist Francis S. Crick and his American colleague James D. Watson discovered the structure of DNA. "We've discovered the secret of life”, Crick announced with justifiable pride.3 With the discovery of the double helix structure of DNA-the complex molecules that transmit genetic information from generation to generation-we received the most powerful tool to dig into our ancestral history. As Watson wrote, "We find written in every individual's DNA sequences of a record of our ancestors' respective journeys."4 Since these early days, sequencing DNA has gotten much easier, faster, and cheaper. With help from archaeologists, climatologists, and linguists, geneticists and paleo-anthropologists have been able to reconstruct the histories of human populations-a reconstruction that was unimaginable only two decades ago.

The discovery of fossils of Homo erectus in Indonesia and China-the so called Java and Peking men-showed that the ancestors of Homo sapiens, or anatomically modern humans, had begun to travel and colonize Asia and the Old World about two million years ago. The dedicated work of paleoanthropologists like Louis and Mary Leakey in the 1950’s and a slew of researchers in the following thirty years established that ancestors of modern humans lived in East Africa's Rift Valley’s The remains of a hundred-thousand-year-old Homo sapiens were found in Israel, but that species met a biological dead-end, blocked perhaps by the more robust Neanderthals who then inhabited the area. Amazingly, so far the only other remains of modern man dating back to forty-six thousand years have been found in Australia. Did these anatomically modern humans-Homo sapiens-have multiple origins, or did they evolve as a single species in Africa? The first intriguing evidence that those fossil finds in Mrica were, not just the earliest humans, but our direct ancestors, came to light, not in some ancient fossils, but in the history contained in cells of modern women. This startling discovery was built on the earlier discovery of the structure of DNA. By analyzing the DNA of living humans from different parts of the world, geneticists can reconstruct the movement of their ancestors and track the prehistoric human colonization of the world. We now know that around sixty thousand years ago, a small group of people-as few as perhaps one hundred fifty to two thousand people from present-day East Africa -walked out.6 Over the next fifty thousand or so years they moved, slowly occupying the Fertile Crescent, Asia, Australia, and Europe and finally moving across the Beringia land bridge to the American continent. The rising waters at the end of the Ice Age separated the Americas from the Asian continent. It was not until Christopher Columbus's encounter with the Arawak on the shores of San Salvador in 1492 that the long-separated human cousins from Africa would meet each other.7 More about that later. First, we will see how our ancestors succeeded in making humans the first truly globalized species.

The discovery that all humanity stems from the same common parents came in 1987. The New Zealand biochemist Allan Wilson and his American colleague Rebecca Cann reached this conclusion at the University of California, Berkeley, by looking into a so-far ignored part of human DNA. Wilson and Cann's team collected 147 samples of mitochondrial DNA from baby placentas donated by hospitals around the world. Unlike the DNA that is recombined as it is passed from one generation to the next, mitochondrial DNA (abbreviated mtDNA) has tiny parts that remain largely intact through the generations, altered only occasionally by mutations that become "genetic markers." MtDNA is maternally inherited, transmitted only from a mother to her offspring, and only daughters can pass it on to the next generation. The mtDNAleaves intact all the mutations that a daughter inherits from her maternal ancestors, thus allowing one to find the traces of the earliest mutation. Since the rate of mutation is roughly constant, the level of variation in mutations allows us to calculate the age of the family tree created by the mtDNA string passed down through the generations. The result of Wilson and Cann's research was a bombshell. Going down the human family tree of five geographic populations, they found that all five stemmed from "one woman who is postulated to have lived about 200,000 years ago, probably in Africa."8 The press inevitably; if misleadingly, called her the "African Eve." She indeed was, as James Watson put it, "the great-great-great ... grandmother of us all," who lived in Africa some two hundred thousantl years ago.9 Obviously, she was not the only woman alive at that time: she was just the luckiest because her progenies survived to populate the world, while the lines of descendants of other women became extinct.lO Or, in genealogical terms, their lines suffered a "pedigree collapse." 11 Children of the three surviving lines of daughters-identified by mtDNA markers LI, b, and L3-now populate the world. While the first two lines mostly account for the Mrican female population, the non-African women of the world all carry in their cells the inheritance of the two daughters of L3 line- M and N. A scientist has given these lines the nicknames Manju and Nasrin based on the assumption of where the two mutations are likely to have occurred: India and the Middle East.

Our most recent common mother may have been African, but what about the father? Significant recent progress in elucidating the paternal Y-chromosome has filled in the gap. In a groundbreaking research paper in 2000, Italian geneticist Luigi Luca Cavalli-Sforza and his colleague Peter Underhill established that the Y chromosome that determines male sex also has an African ancestry. 12 Just as mtDNA is transmitted only from a mother to her children, the Y chromosome that is passed on from a father to his son also does not undergo the shuffling-or recombination-that the rest of the chromosomes do. But there are mutations just like mtDNA. The result is that the history of our fathers is carried in perpetuity by sons. Human ancestors who left Africa all carried in their cells either the African Adam's Y chromosome, which has been given the prosaic label "M168," or the mtDNA of one of the African Eve's daughters. Based on extensive study of the world's population, geneticists now say that the most recent common ancestor of us all left Africa just fifty thousand years ago. 13

Wilson and Canus thesis of the human out-of-Africa origin was, of course, not unchallenged by some anthropologists and geneticists. The school that believed in multiregional evolution of the modern human refused to accept a recent or unique origin of Homo sapiens. Its proponents argued that the abundant Homo erectus fossils found in China and other regions in East Asia (such as Peking Man and Java Man) demonstrate a continuity, and to these researchers it was evident that Homo sapiens emerged out of frequent gene exchanges between continental populations, since the earlier species Homo erectus came out of Africa about a million years ago. Besides, they argued, the archaeological evidence does not mesh with the out-of-Mrica hypothesis, thus making this conclusion at best premature. 14 At least in the case of Chinese critics, one also suspects that the disclaimer about Mrican origins may be linked to national pride about the antiquity of the Chinese civilization. However, as research in the migration of the human genome has continued to produce more and more evidence of African origins, the scientific opinion has increasingly tilted toward the out-of-Mrica school. Some Chinese objections have been countered with a large new body of research based on a massive DNA database collected by both Chinese and international geneticists. In 1998 a consortium of seven major research groups from China and the United States, funded by the National Natural Science Foundation of China, conducted a DNA analysis of twenty-eight of China's official population groups and concluded that "modern humans originating in Africa constitute the majority of the current gene pool in East Asia."15 Several other researchers, including Chinese, have since sampled a large number of Chinese from allover China and reached the same conclusion.16 Interestingly, research on both mtDNA and the Y chromosome has shown evidence even in Africa of the early colonization by the original group within Africa. The remaining cousins left in East Mrica also spread out to the interior of the continent in search of survival. A strong school of thought in South Africa actually suggests the possibility that the ancestors of the Bushmen also are our ancestors and that the spread of those humans who all became our ancestors was from south to north. Whichever way they moved, their imprint is left in the DNA of the Bushmen or Khoisan of the Kalahari Desert and in certain pygmy tribes in the central Mrican rain forest. 17

The genome revolution and the discovery of the African Eve have sparked a new interest in finding one's roots. The dark-haired New York Times columnist Nicholas Kristof thought he knew who he was. His father came to the United States from Europe, so Kristof assumed himself to be of a typical American European heritage. But he wanted to find out who he really was under the skin and learn more about his origins, and so he sent his DNA sample for analysis. He was in for a surprise. A mere two thousand generations ago his great-greatgreat-grandmother was an Mrican, possibly from Ethiopia or Kenya. Under his white skin and Caucasian features, exclaimed Kristof, "I am African-American!" After the publication of his column he received a flood of e-mails. One particularly droll one read, "Welcome to the club. But look out while driving in New Jersey." However, the African continent alone cannot lay sole claim to Nicholas Kristof. The genetic markers found in his DNA showed he was also related to people who now inhabit Finland, Poland, Armenia, the Netherlands, Scotland, Israel, Germany, and Norway. "The [DNA] testing just underscored the degree to which we're all mongrels."18

One trait of the human community makes it possible to track the genomic journey. Humans prefer to settle down in one place if conditions permit, but they are equally ready to migrate in search of a better life. The result has been that people who settled along the path of the human journey are marked by a lineage associated with geographic regions. The fact that humans have mostly practiced patrilocality-in which women come to their husband's homes after marriage-enables one to associate the Y chromosome with a particular location. Looking at my DNA, geneticists could tell I was from the Indian subcontinent. My M 52 Y-chromosome, shared by a large number of Indians, was a giveaway. This ability has allowed geneticists and anthropologists to sketch out a better picture of when and how the progenies of the African Eve left the old continent and found themselves in their current habitat. DNA shows that this migration, spanning forty to fifty thousand years, came in successive waves, mostly in gentle ripples and sometimes in large swells. The Wilson team found that all the world populations they examined, except the African population, have multiple origins, implying that each region was colonized repeatedly. The lack of archaeological evidence does not allow us to answer with certainty why our ancestors left Africa. Probably a dry spell of the late Ice Age shrank the forests and dried the savannas that provided game for the hunter-gatherer population. When a small group took the momentous step of crossing the Red Sea into the southern Arabian coast, the whole world was open. Following game herds up into the Middle East or following the shellfish beds around the Arabian Peninsula and on into India, the humans were launched on a journey that would result in populating the entire planet.

One of the most striking of those journeys was the arrival of the ancestral population from Africa to Australia in just seven hundred generations. Some have called this journey an "express train" to Australia. Of course, the ancestors did not know they were headed to Australia: they were just following food. But the eastward movement of generations of people along the Indian and Southeast Asian coasts brought them to a continent twelve thousand miles from their East African origins.

In a series of articles in Science in May 2006, a team of international geneticists and anthropologists showed that the dates of this human journey, as gleaned from the paternally inherited Y chromosome, are in broad agreement with the dates derived from the earlier Wilson study of mtDNA. The articles combined the genetic study with anthropological evidence to show that the oldest human remains found outside Africa and the Middle East, at Lake Mungo in southeast Australia dating from forty-six thousand years ago and in a Borneo cave of a thousand years earlier, could have reached their destinations by following a coastal route along the Indian Ocean. In the Andaman Islands, where the indigenous people have long been isolated, the researchers found mtDNA types that matched those of the known founder African group dating back sixty-five thousand years. Amazingly, the aboriginal population of the Andamans had unique markers not shared by the population of South or Southeast Asia, suggesting that they had lived in isolation since the initial penetration of the northern coastal areas of the Indian Ocean by anatomically modern humans migrating out of Mrica fifty to seventy thousand years ago. 19 The investigation of an aboriginal Malaysian group, Orang Asli, or original people, who had also lived in isolation for a long period, showed similar DNA traces going back to Mrica.

Although the coastal route taken by the descendants of the marker MI30 had now been established, how quickly humans from Mrica reached Australia remained an enigma. However, by analyzing the molecular dates of sampled mtDNA across the vast swath of territory from India to Australia, geneticist Vincent Macaulay and his colleagues were able to gauge the speed of population dispersal. An estimated distance of seventy-five hundred miles between India and southern Australia following the coastal routes was covered in some 150 generations. Life along the beaches perhaps was comfortable enough to lead to a fast rise in population and the need for part of the community to move on in search of food-at the remarkable rate of two miles a year. Compared to the Australia-bound express, Macaulay notes that the dispersal rate during the recolonization of Europe after the Ice Age was barely four-tenths of a mile a year.20

Because the rising sea levels after the Ice Age engulfed all archaeological evidence of this migration, paleontologists long despaired of finding evidence of the coastal journey. Then came a lucky break. In 1999 an international team of marine biologists, paleontologists, archaeologists, and geologists led by Robert C. Walter unearthed startling evidence of human habitation near the village of Abdur on Eritrea's Red Sea coast. Fortunately for science, a seismic event had pushed up the limestone reef that preserved the ancient treasure, dating back more than 125,000 years. The rock exposed by the seismic event contained the first concrete information about how the ancestors survived in the new environment of the sea. Scientists speculate that the extremely arid conditionsand shortage of food sources wrought by the glacial age-forced humans to move to the coastal areas to survive. In their beachcomber existence they not only survived, as can be determined from the fossilized midden from their meals, but ate well. They feasted not just on fruits of the sea-oysters, mussels, and crabs-but on meat as well. Scraped bones of large animals like elephants and rhinoceros were found in the same area, suggesting a rather exotic "surf and turf" diet.

In a paper in Nature, Walter and others excitedly concluded: "Together with similar, tentatively dated discoveries from South Mrica, this is the earliest welldated evidence for human adaptation to a coastal marine environment, heralding an expansion in the range and complexity of human behavior from one end of Mrica to the other."21 The date of the find suggests that the stone tools at the site overlap in time with the apparent transition from archaic to anatomically modern Homo sapiens in Africa. More important, the artifacts from the Abdur Reef limestone suggest that a coastal existence was becoming common before a group launched their "beachcomber's express" to end up in Australia.22

Low sea levels during the last Ice Age permitted small groups of our ancestors to walk across a newly emerged land bridge on the Red Sea to the Arabian Sea coast in Yemen.23 Some forty-eight thousand years later an Egyptian naval expedition would return, perhaps to the same area on the Red Sea, in the Egyptians' first encounter with Punt, as that part of Mrica was then called. Expanding ice sheets over the northern hemisphere fifty thousand years ago would have lowered the sea level by around three hundred feet, with exposed seabed shortening the distance that now exists between Mrica, India, and Southeast Asia. The geneticist Spencer Wells estimates that it would have exposed as much as 125 miles of land off the west coast ofIndia and would have connected it to Sri Lanka with a land bridge.24 One can speculate that the speed of the ancestors' journey along the coast may have accelerated with the development of stone tools and the availability of new plants and trees when they reached the tropical coastline ofIndia. The abundance of the coconut tree in particular may have been a great boon. The flesh of the coconut provides nourishment, and its juice is a safe drink. Its leaves can be used to build a shelter against sun and rain, its copra to roll into rope, and its trunk to make rafts or dugouts. Tying logs together to make a raft has long been in practice in southern India. The Tamil name for such a boat, kattumaran, later morphed into catamaran. In any case, a low sea level would certainly have made the journey through the shallow Java Sea to Indonesia easy. Those arriving in Southeast Asia could have paddled across the shallow waters of the Timor Sea to arrive in Australia. 25

The fact that the first humans to arrive in Australia introduced the prehistoric dog the dingo to the continent suggests that they arrived by boat.26

All this news about an "express train" of migrants leaving Mrica and reaching Australia in just about five thousand years intrigued me. Were my ancestors on that early train? And did they somehow get offin India? Fortunately, I was able to discover the answer through the Genographic Project launched in 2005 by National Geographic in collaboration with IBM. The ambitious project, directed by Texas-born Wells, seeks to map humanity's genetic journey through the ages: where we came from and how we got to where we live today. As part of the research, the project directors encourage people to participate by sending their DNA samples and providing information about their ancestors. Some ancestors have not been on that "express train" to Australia, where all the travelers carried Mr30-the so-called Australia marker-the characteristic marker for the founder group that had branched off from Mr68.28

Other genetic studies show that a small group of the Levant marker descendants moved north from the Middle East to Anatolia and the Balkans, trading familiar grasslands for forests and high country. While my ancestors crossed the Red Sea-perhaps at the narrowest point at Bab-al-Mandab, or the Gate of Grief-over to the Arabian Peninsula and eventually ended up in India, many people of M89 lineage remained in the Middle East. Others continued their movement and followed the grasslands through Iran to the vast steppes of Central Asia. Herds of buffalo, antelope, woolly mammoths, and other game probably enticed them to explore new grasslands. With much of the earth's water frozen in massive ice sheets, the era's vast steppes stretched from eastern France to Korea. The grassland hunters of the M89lineage traveled both east and west along this steppe "superhighway" and eventually peopled much of Eurasia.

It seems that some ancestors moved west to Anatolia and Central Europe, since the M20r lineage is found among people in that area.29 But judging by the southern direction taken by my ancestors, they may have been among the founders of India's earliest Harappan civilization, which emerged five thousand years ago in the Indus River Valley. One can speculate whether the trade that developed in the third millennium BeE between the Sumerian civilization in the Fertile Crescent and the Indus Valley was or was not a continuation of a much earlier link. As we will see, the Indus and Euphrates-Tigris Valley trade was the beginning of a phenomenon that would eventually connect the whole world. The final marker in my Y chromosome-M52-was acquired when my ancestors reached western India. It seems that my ancestors liked what they found in India because, except for a small number of this marker showing up among coastal Southeast Asian populations, there is not much evidence of further movement by the progenies of the M 52 marker. In the past twenty to thirty thousand years, M 52 spread allover India, making it almost a national marker.

But how did one group of migrants end up in Central Asia instead of sticking with the group that headed east? As geneticist Spencer Wells explains, the early human migration was not a conscious effort to move from one place to another. As they walked on the continuous belt of the Eurasian Steppe, they might simply have been following game further and further afield. Some forty thousand years ago, a new marker, M9, appeared on the Levant lineage-perhaps on the plains of Iran or South-Central Asia. The progenies of this marker, whom Wells calls the Eurasian clan, would expand their range to the ends of the earth in the next thirty thousand years. They soon encountered the biggest mountain ranges anyone had ever seen. As the bitter cold of the last Ice Age gripped the world, the Hindu Kush, Himalaya, and Tien Shan ranges would have proved a formidable barrier to the M9 clan. At this point somewhere in today's Tajikistan the migrants split, with one group heading south and the other north. The southern group, carrying a different marker, M20, ended up in India, forming a uniquely Indian genetic substratum. Their northern cousins, carrying the M45 marker, survived their journey through the Siberian freezer by hunting woolly mammoths and overwhelmingly populated Central Asia. "The Eurasian interior," Wells writes, "was a fairly brutal school for our ancestors .... During their sojourn on the steppes, modern humans developed highly specialized toolkits, including bone needles that allowed them to sew together animal skins into clothing that provided warmth at temperatures not unlike those on the moon, but still allowed the mobility necessary to hunt game such as reindeer and mammoth successfully."31

It would be the members of the M45 clan, hardened by their wintry ordeal, who would reach Siberia and be ready to walk across the Beringia snow to Alaska. But before reaching Siberia, some of the Eurasian-Central Asian members produced another line, MI75, which headed into western China from southern Siberia. Around thirty-five thousand years ago the descendants of MI75 and subsidiary markers largely populated Korea and northern With the exception of such minorities as Uighur, Kazak, Kirghiz, and Hui Salar, who originated from Arab, Iranian, and Central Asian stock, a vast proportion of minorities in China carry the M175 or a derivative marker.32 They now account for 60 to 90· percent of East Asian chromosomes. But before the Eurasian group showed up in China, the descendants of the original Australian express who got off the train, so to speak, in island Southeast Asia were making their moves.

For the story about how the Southeast Asian and other genetic groups came to coalesce in China, we turn to geneticist Li Jin and his students. They wanted to resolve once and for all the controversy about the origin of the Chinese population. Did they really evolve locally from the prehistoric Peking man? Chinese believe they are the descendants of the legendary Yellow Emperor, who unified the tribes of China in the third millennium. Jin and his students fanned out and collected DNA samples from ten thousand males. In all those Y chromosomes, not a single unusual one was found. "We looked," Jin later said. "It's just not there. Modern humans originated in Mrica."33 It seems that had the Yellow Emperor existed, he, too, had an African mother eons ago. Jin's data from the 163 populations across Southeast Asia, Oceania, East Asia, Siberia, and Central Asia also established the same case. Every individual carried the original Grandpa marker, M168, and the Australian express M130 marker. 34

In 2000 Jin also offered conclusive evidence of the Southeast Asian provenance of the Chinese population. He surmised that the first entry of modern humans into the southern part of East Asia occurred about eighteen thousand to sixty thousand years ago. Both Y chromosome and mtDNA analysis of Southeast Asian samples revealed that the same seven main genetic groupings called haplotypes-present in Southeast Asian descendants of the M130 lineage are also found in China. Peering at the genetic markers of today's Chinese population, geneticists can see that "the ancient evidence of a two-pronged settlement is still visible in the blood of today's Chinese."35 Because the southern population had been there longer, the level of genetic variation is greater than among the people in the north. Anthropologists suspect that the genetic mixing that followed might account for the physical differences between northerners and southerners today. The northern Chinese tend to be paler and taller with smaller eyes and a more pronounced epicanthic fold. The southern Chinese are darker and broader, resembling more the peoples of Southeast Asia.36

Besides moving north to China and Siberia, Jin and colleagues found, the population moved in two other directions. One group seems to have island hopped and reached the Pacific Islands, including Polynesia and Micronesia, and the other moved toward Taiwan. 37 These descendants of the same Grandpa chromosome would live in the splendid isolation of Australia and the Pacific for thousands of years before the arrival of Captain James Cook's tall sailing ship. The sketches of the aborigines made by the visitors make them look as if they are from another world.

China and Southeast Asia turned out to be the holding area and later launching pad for migration to Japan. Sometime between twenty thousand and twelve thousand years ago, when a low sea level linked Japan to the Asian mainland, hunter-gatherers from Central Asia moved into northern Japan. An estimated three thousand people from the area between Tibet and the Altai Mountains in northwestern China walked to Japan and developed what came to be known as the Jomon culture. Rising sea levels cut Japan off from the Asian mainland for nearly ten thousand years, during which people in Southeast Asia and South China's river valleys developed agriculture. Rice farming spread to the Korean peninsula and the cold-resistant rice strain was developed. Some twenty-three hundred years ago people carrying the same genetic markers as Southeast Asians and Koreans sailed to the southern Japanese islands.38 The farmer immigrants introduced wet rice culture, which spread throughout Japan and emerged as a marker of Japanese identity. In the twentieth century Japan would resist opening its rice market, claiming that Japanese-grown rice was unique.

After East Africa and the Levant, the Central Asian mountains and steppes were a major churning point for the human genome. Some thirty thousand years ago the Central Asian marker M45 led to the rise of another lineage, MI73, who changed the northeastern direction of the journey so far and began moving westward across the steppes toward Europe. These migrants would form the bulk of present-day Europeans. Based on fossil evidence as well as on cave paintings in France, we know that reindeer of the cold tundra were then common in the steppes that extended to Germany and perhaps even France. The Eurasians who had by then been schooled in the coldest of Central Asian winters moved into Europe and in the course of a few thousand years populated a vast area. The Neanderthals-the archaic human form that shared mitochondrial genomes of modern humans and inhabited Europe and western Asia-ceded ground to modern humans.

Until very recently there has been no evidence of a Neanderthal genocide.39 It was believed that in the process of natural selection, modern humans with the advantages of language, toolkits, intelligence, and social hunting skills won.40 There are also indications that over many areas of Europe the demise of the Neanderthal populations may have coincided with the sudden onset of much colder and drier climatic conditions. If, as current evidence suggests, the new anatomically modern human populations were better equipped technologically and culturally to deal with these severe glacial conditions, then, notes researcher Paul Mellars, this could have delivered the coup de grace to the Neanderthals.41 By about twenty-five thousand years ago the Neanderthals had vanished, leaving our ancestors alone to roam the world. And as M 52 did for Indians, M45 for Central Asians, and MI75 for East Asians, so did the M173 lineage emerge as the terminal marker defining Europeans.

The journey of people carrying the Central Asian marker was not finished. Their progenies who had reached Siberia in pursuit of reindeer and woolly mammoths would quietly slip into the last continent completely devoid of people, even of hominids. Although it is generally agreed that the first settlers to North America came from Siberia, when they first arrived remains hotly debated. Ever since an eleven-thousand-year-old fluted stone blade lodged in a mammoth bone was discovered in Clovis, New Mexico, in 1932, anthropologists have argued whether the Clovis people were the first to arrive from Asia. That claim was shattered when even more ancient relics of human habitation were found in the Meadow croft Rock shelter in Pennsylvania and at Monteverde in Chile. Exhaustive analysis of native American DNA reveals that over 90 percent of Indians carry the Y chromosome of a man who has been dubbed the Native American Adam.42 He lived roughly 22,500 years ago and sprang from the lineage that had lived in Siberia and Central Asia's Altai Mountain range area. Only after the Ice Age began to recede some fifteen thousand years ago was it possible for even the hardened veterans of Siberia to enter the North American plains. Paleoclimatologists believe that an ice-free corridor opened up east of the Rocky Mountains where the Canadian plains abut the foothills.43

From mtDNA analysis it seems that the number of maternal lineages was small among the big-game hunters and settlers who trudged their way through the Alaskan snow to the corrjdor. The women were all closely related.44 But once the group reached the Great Plains, the land and all the animals were theirs for the taking. Not only did the population explode, but successive waves of settlers made it to the American continent and soon spread out in all directions. About fourteen thousand years ago, the human journey begun so long ago in Ethiopia completed the conquest of the earth when Native Americans reached the southern tip of Chile. Like Pacific islanders, Native Americans would live in total isolation until Europeans sailed to their shores. Their long isolation from the gene flow in the Old World, as we will see, deprived them of immunity to many common diseases and brought calamity after their first encounter with the Europeans. Yet curiously, some typical genetic markers termed haplogroup X-had reached America long before Columbus. Geneticists have been surprised to discover that Italian and Finnish populations share genetic links with some Native Americans. There is enough mutation on the marker to make it at least ten thousand years old and therefore not brought by Europeans who arrived after Columbus. How did this European marker reach the Americas? Given the walls of glaciers and ice sheets that covered the northern Atlantic, it would have been impossible for people to reach America by a northern route. That mystery remains to be solved by future geneticists.45

The ancient connections like the land bridge between Siberia and Alaska, between Japan and China, between continental Europe and Britain, and between Indonesian archipelago and mainland Southeast Asia all began drowning with the end of the Ice Age and rising oceans. Since the end of the Ice Age, the sea has generally risen about four hundred feet; and land so long covered under ice sheets has risen up to one hundred feet. The diversification of humanity that began as a centrifugal movement out of Africa fifty thousand years earlier peaked with the physical separation of much of the landmass they had covered. As historian David Christian put it, "With humans now settled throughout the world, this severing of ancient links threatened to divide humans into separate populations with separate histories. "46 What emerged instead were four world zones: Afro-Eurasian, Australia-New Guinea, American, and Pacific world zones. The interconnection among humans living in each zone-in their known universes-would grow and intensify, creating mini-globalizations until the age of Columbus would break the ocean barrier. The American continent, which had disappeared from the sight of the Old World, would reappear in 1492 with the exultant cry of "Tierra, tierra!" when in the pale moonlight the night watch on Columbus's Santa Maria spotted the contours of San Salvador.

One of the amazing things about this global journey is that it was undertaken almost entirely on foot, with occasional use of rafts or dugouts over waters. The horse was not domesticated until six thousand years ago and the camel only three thousand years ago, long after the exodus from Africa or the ancestors' arrival on South America's southern tip.47 A tiny population of men and women walked to find a better life. Their children, grandchildren, and two thousand subsequent generations kept moving until they found a place to settle. While some continued a nomadic life-as do some thirty to forty million pastoralists all over the world even today-others settled down to a sedentary life of agriculture, fishing, and hunting. The forty or fifty thousand years that out human ancestors spent walking the length of the earth, experiencing the unimaginably harsh weather of the late Ice Age, have carved our bodies, altered our faces, and changed our pigmentation. The effect of the first globalization the dispersal of humans around the globe-has been the emergence of a superficially diverse human species.

Two thousand generations after leaving the African savanna, the descendants who came to occupy different parts of the earth looked remarkably different from one another and spoke mutually incomprehensible languages. But nothing perhaps divides us humans more than the most superficial of changes that occurred in our body during those fifty millennia of journey-in morphological traits like skin color. It has become an important element in creating the category called "race." Although genetically all humans are 99.9 percent alike, that minute difference in our DNA that accounts for the visible difference of skin color throws a spoke in the wheel of the globalization wrought by the human species. However insignificant those differences may be in a string of three billion nucleotides, they nevertheless often correspond to a geographic area. Francis Collins, co-discoverer of DNA, says that genetic variations can be used to make a reasonably accurate prediction of geographic origins of an individual, at least if the individuals all came from the same part of the world.48

As the geneticist Luca Cavalli-Sforza put it, the diaspora of Africans to the rest of the world exposed them to a great variety of environments: from hot and humid or hot and dry surroundings, to which they were already accustomed, to temperate and chilly ones, including the coldest ones of the world, as in Siberia. "One can say that each ethnic group has been genetically engineered under the influence of the environments where it settled," Cavalli-Sforza wrote.49

The ancestors who walked out of Africa presumably were mostly dark believed to have been the result of our ancestors' Central Asian and Siberian passage. Cavalli-Sforza points out that the Mongoloid body, and particularly the head, tends to be round, increasing body volume. The reduced evaporative surface area of the skin in relation to body volume means that less heat is lost. The small nose has less likelihood of freezing, with narrow nostrils warming the air before it reaches the lungs. Fatty folds of skin protect the eyes from the cold Siberian air while acting as a visor against glare from snow. As we have seen, the group with MI75 marker who survived the journey through the Central Asian freezer began moving to China and Korea some thirty-five thousand years ago. Of course, as Darwin speculated, other factors, such as particular tastes ofindividuals in "sex selection," could have been at play. Cavalli-Sforza suggests that it is very likely that some characteristics, such as eye color and shape, undergo sexual selection. The prevalence of the almond eye shape in East Asia may also be due to Darwinian selection. Some group is likely to have come to view this shape as attractive, leading to its proliferation. 54 Eyes with an epicanthic fold, notes Cavalli-Sforza, are also characteristic of the Bushmen of southern Africa and other African population groups. Similarly, the shape of the eye was probably diffused by sexual selection from northeastern Asia to warm and moist Southeast Asia. While wondering about the physical differences that arose among humans, it is useful to remember Cavalli-Sforza's words of caution: "We must also bear in mind that the genes that react to climate are those that influence external features. Adaptation of the body for the most part requires changes, because this is our interface with the outside world. It is because they are external that these racial differences strike us so forcibly, and we automatically assume that differences of similar magnitude exist below the surface, in the rest of our genetic makeup. This is simply not so: the remainder of our genetic makeup hardly differs at all."55

Although the global journey has produced morphological changes among humans, the descendants from Africa have carried hidden in their cells mutations that would cause disease hundreds, even thousands of years later. Paul Plotz, a researcher who studies rare muscle diseases at the National Institutes of Health in Bethesda, Maryland, was intrigued to find a rare form of disease among unrelated African-Americans whose genome nonetheless showed a similar mutation. He teamed up with a historian to pursue the source of the mutation and concluded that it occurred some one thousand years ago among the Hausa tribe in Nigeria. Through a trading connection with the Ashanti people in present-day Ghana-which obviously involved genetic exchange-the mutation was passed to the Ashanti. All the American patients with the mutation had Ashanti ancestors who had been brought to the United States as slaves. Reports of the same disease mutation found in a Pakistani man also brought tantalizing evidence of Mrica's slave-trade connection with South Asia. 56

By ten thousand years ago the human race had reached virtually every continent except Antarctica and was poised for the beginning of a new era heralding a process that would eventually set human communities on the path of reconnection. Soon after 20,000 BCE global warming began, and after many ups and downs and a brief return to extreme cold and drought, the end of the Ice Age truly began by 10,000 BCE. As if on cue, everywhere on the planet the melting of the ice sheets was followed by the rise of agriculture and the emergence of settled communities of farmers that supported specialist craftworkers, priests, and chiefs. Those who remained hunter-gatherers mostly took to the pastoral life, emerging as the ambulatory connector between settled communities. With surplus agriculture arose towns, new crafts, and the production of commodities. Informal exchanges of earlier times developed into trade networks. The warfare that had been a constant feature of the hunter-gatherer life became more organized with the rise of states. Empire building soon followed.

Essentially, the basic motivations that propelled humans to connect with others the urge to profit by trading, the drive to spread religious belief, the desire to explore new lands, and the ambition to dominate others by armed might-all had been assembled by 6000 BCE to start the process we now call globalization.
Climate change wrought a greening of the landscape, with trees sprouting on the Sahara and forest advancing on the cold steppes. Growing moisture and the creation of lakes and rivers allowed for the rise oflarger population settlements along the banks and in turn the need to grow more food from the same area. 57 In a critical switch in the human mind, as Harvard archaeologist Ofer BarYosef said, "people decided to intervene in nature and supply their own food rather than relying on what was provided by the gods."58 From the banks of the Euphrates to the Yangtze Valley, agrarian communities sprouted. One reason that the hunters' nomadic life became less viable was that humans no longer had the options that beachcombers once had during their millennial journey east.

They had moved on to the next beach when the food supply in an area dwindled. But twelve thousand years later, simply moving on may not have been an option, for it would have brought migrants into conflict with other people living in the area. Learning how to adapt seeds of wild grass to grow as crops and domesticating animals and fishing may have seemed an easier option. Although there is some evidence of the transfer of seeds of domesticated plants across distances, agriculture arose simultaneously in several parts of the world. It was in the Fertile Crescent region on the eastern shores of the Mediterranean that the earliest human settlers learned to exploit wild plants and animals. Wheat, barley, rye, chickpeas, lentils, sheep, goats, and pigs were all first grown or domesticated in this area before being diffused through the connected parts of the Old World. Wheat, first domesticated in what is now Turkey, spread to the Indus Valley and into China between six thousand and four thousand years ago. 59 China's Yangtze River basin saw the domestication of rice some 11,500 years ago, from where it spread southward. 60 Waves of agricultural migrants creating rice fields would ripple down Southeast Asia's river valleys all the way to Indonesia. The genetic trace of that ancient journey can still be found among to day's population.

The rise of agrarian communities provided a rooted identity for the first time to groups of humans who floated across the land in search of edible roots, fruits, and nuts and game to hunt. Recent archaeological evidence shows that humans began putting down their roots literally by planting a garden-of fig trees. The discovery that the fig was the earliest plant to be domesticated by humans offers a tantalizing clue to the beginning of what can be called territorial loyalty and identity linked to the land. Excavating an ancient site in the Lower Jordan Valley north of Jericho, archaeologists came across burned figs: Analysis revealed that these nearly twelve-thousand-year-old figs were the earliest examples of a domesticated food-bearing plant.

A genetic mutation seems to have created a variety of fig that produced infertile fruit but could be easily domesticated because the cuttings developed roots more easily than those of any other fruit tree. Researchers reported that the figs were found stored with other vegetal staples such as wild barley, wild oat, and acorns, which indicates that the subsistence strategy of these early Neolithic farmers was a mixed exploitation of wild plants and initial fig domestication.61 Since fig trees and later plants like olives and dates could take years before producing fruit, planting orchards could be seen as the first flag posts of identity for a people who had chosen a sedentary life.62 Wheat and barley fields would follow. Until other discoveries push back the date of the domestication of crops, the planting of these domesticated figs can be considered the beginning of the agrarian phase of human evolution. Agriculture required humans to put down roots and finally halted the ceaseless dispersion across the globe. The olive, a plant that has become the icon for rootedness and identity in the Middle East, was not domesticated until five thousand years later. 63

Initially, people tended and adopted species like the fig that grew where they had settled. Over time a range of other plants, and then animals, were integrated into their life. By 10,000 BCE sedentary cultures centered on crop growing and animal husbandry had taken shape across the broad arc of the Fertile Crescent. As in the Near East, Indus Valley, or Yangtze basin, the rise of human settlements identified with a specific geographic location was the first step in the rise of civilization, states, and empires. The earliest known people to practice sedentary agriculture in the Jordan Valley have been called the Natufians. In the millennia that followed, others emerged to occupy different parts of the Fertile Crescent: Sumerians, Akkadians, Assyrians, Hittites, Scythians, Canaanites, Philistines, Phoenicians, Hebrews, and many others.64 Occupation of a particular territory came to be associated with a people for the occupation of which incessant wars were fought. How strongly possession of and association with land became part of one's identity and honor was summed up in the ultimatum that marked the beginning of catastrophic war in the Indian epic the Mahabharata of about 500 BCE: "We'll not cede land worth the point of a needle without war." Communities rose and transformed into principalities and kingdoms; they connected with other communities for the exchange of goods or by launching military attacks and occupying others' land. That process continued until the emergence of modern political structures.

Agriculture brought in its train four prime movers of growing interconnection: migration, trade, religion, and the conquering power of state. With an assured food supply from planted crops, populations grew, setting the stage for migration of people to other areas along with their tools and seeds. The urge to migrate in the postagrarian period was different from the earliest out-of-Africa exodus. It was not a journey in search of means of survival as it had been in the initial period. As one anthropologist explains, later migration was "a behavior [that was] typically performed by defined subgroups (often kin-recruited) with specific goals, targeted on known destinations and likely to use familiar routes."65 It was a purposeful journey to find new land where a people could settle down with their old tools and planting skills. These early migrants looking for cultivable land also encountered other clusters of settled communities.

Apart from the economic "push" of negative stresses at home and the "pull" of the attraction of the new destination, a cultural-ideological factor may have prompted migration. The anthropologist David Anthony notes, "Among societies in which male statuses and roles were largely determined by success in war, and in which young males therefore actively sought opportunities for conflict, the cumulative effects of sustained glory-seeking raiding might lead to significant outward migration. "66 Whether through peaceful assimilation or violent occupation, the known world, expanded as did people's connections. Migrations moved like a stream finding its way and avoiding obstacles to reach the destination. The trail that was blazed eventually became a well-trodden path for more migration and trade. As we will see, these adventuring pioneers and migrants-grouped as adventurers in this book-emerged as a key actor of globalization. Short-distance migration that might have begun as a recurring response to localized resource shortages was soon to become a phenomenon spanning vast distances.

Although the cause of many waves of migrations remains in dispute, their impact has clearly been to create a web of relationships. For example, many linguists believe that the spread of the agricultural way of life from Anatolia played a key role in the diffusion of what is called Proto- Indo-European language over vast areas of Europe and Central and South Asia. According to one of the more widely accepted hypotheses, supported since by genetic and linguistic forensic analysis, early farmers searching for more land migrated from Turkey and Asia Minor to southeastern Europe in about 7000 BeE and spread the proto-IndoEuropean language that gave birth to eighty-seven languages-including Sanskrit, Greek, Latin, and Persian and eventually to such modern languages as English, French, Russian, and German.67 Beside this "plow school" of explanation for the spread of Indo-European languages, another school offers the power of the sword as the explanation. This theory argues that Indo-European languages were spread by the ax-wielding horsemen invaders from the so-called Kurgan culture of present-day Ukraine.68 According to this theory, a semi-nomadic group from the lower Volga region who had domesticated the horse migrated across the vast stretch of steppes from Europe to Central Asia and southward into present-day Turkey and Greece at a time when the warming climate favored their pastoralist economy. In the process, they or associated groups gained political control and ended up spreading their Indo-European languages and culture.69 The debate over what caused the spread of language continues, but there is in the lower Volga-Dnieper region was a seminal development in connecting dispersed communities. Yet it was not until two millennia later that the horse made an appearance as a draft animal attached to wheeled carts. Late in history the horse would be the engine of Mongol imperial expansion and indeed the means of transportation well into the modern period. Horse-drawn streetcars served New York City until the late nineteenth century. David Anthony and colleagues' sleuthing of the bit mark on horse teeth fossils provided the evidence of the horse's early domestication. But as the researchers note in Scientific American, its immediate impact was remarkable:

The acquisition of horses wrought a revolution in virtually every aspect of life of the Plains tribes. Riders could move two to three times farther and faster during a day than people on foot. Resources, enemies, allies and markets that had previously been beyond effective reach suddenly became attainable. Subsistence and economic survival in the dry grasslands, an uncertain and risky proposition for pedestrian hunters, became predictable and productive. Sedentary horticultural villagers whose river valley settlements had been the centers of population and economic productivity became vulnerable to lightning raids by mounted enemies who could not be pursued or punished.70

The horse helped migrant traders and soldiers establish connections with distant agrarian settlements that had been inconceivable earlier. As we will see, thanks to the horse, the vast steppes that spanned Eurasia were turned into an immense conveyer belt for the transmission of people, goods, and ideas"
Agrarian communities also gave birth to the second actor of globalization: the trader. Foraging communities had already accomplished exchanges of produce, ritual exchanges over marriage, and other gift-giving traditions. The spread of agriculture gave the practice of exchange an important momentum because now people in one location regularly grew food crops or plants that they could sell or exchange with people who did not have them. How agriculture stimulated early trading can be seen in the archaeological finds in one of the world's earliest urban settlements, Catal Hoylik (7400-6000 BeE), in present-day Turkey. Located near two active volcanoes, Catal Hoylik operated a virtual monopoly on the trade in obsidian in the eastern Mediterranean and Levant.71

Obsidian, a sharp-edged volcanic rock that could be used as a scythe, was an essential tool for harvesting crops. Many generations earlier, the beachcomber settlements on the Red Sea had used obsidian to pry open oysters. Food surpluses in other parts of Europe later led to the rise of specialized crafts like the mining of flint and turning it into ax-heads and other tools.72 In exchange, settlements received many shells from the Red Sea and the Mediterranean, along with stones or materials of all kinds that craftsmen turned into tools and ceremonial objects or wove into fabrics.73 The trading of agricultural goods among peoples on the heavily traveled routes linking Africa to the Mediterranean may have led to the rise of ancient towns like Jericho. River craft made of reed and animal hide sailed on the Euphrates and the Nile, and the cloth sail made its appearance by the fourth millennium BCE. In the fourth and third millennia, the Mesopotamian civilization emerged in the lower Tigris and Euphrates River Valley based on trade with neighboring areas of Syria and Anatolia that procured such items as metals, good timber, stone, and other exotic items. With time, the trade network expanded to the Persian Gulf and western India.74

Mesopotamian barley fed the Gulf Arab population, who supplied copper fOf making weapons and tools. Exchanges of luxuries and gifts also became an important way of connecting with other communities and developing alliances among chiefs.75 In search of frankincense, myrrh, ebony, and other exotic products, Egyptian pharaohs began to send trading expeditions to Punt, probably to day's Eritrea (from where their ancestors had once walked out of Africa). To barter with the chiefs they took strings of beads, axes, daggers, bracelets, and wine and beer. The expeditions also brought back skins of giraffe and leopard and perhaps the first African slaves, pygmies who were made to dance for royalty. That first recorded encounter in the mid-third millennium between humans who had left Africa and those who stayed behind seems to have set the tone for what would happen to Africa in the millennia of broadening contacts that would follow. Ironically, many centuries later Arabs and Europeans brought almost identical products to buy slaves from Africa.76

The expeditions to Punt, conducted aboard large ships with sails and by donkey caravans, were already a huge advance in trading. As economies developed, the role of merchants and long-distance trade widened. Like drops of ink on wet paper, the trade-linked areas from Mesopotamia and Egypt kept spreading. The trade network by donkey caravans that debuted in Catal Hoyuk and reached out from Mesopotamia to the Indus Valley and sub-Saharan Africa kept expanding. By the first century CE new blots of ink flowing from China and India and Southeast Asia had begun to overlap and merge with others, in the process diffusing ideas and culture. Trade would transform societies when a trading class would rise to challenge state power. With the expansion of long-distance exchanges, trading diasporas would emerge to connect communities even more closely.77 Driven by traders-people who earned a living by exchange of goods and services or, in the modern parlance, businesspeople-the commercial network would continually expand, thicken, and accelerate to eventually encompass the globe in an ever-tightening web.

The rise of agrarian society also led to the emergence of states, some of whose imperial ambitions proved to be the third key driver in connecting states within the Afro-Eurasian world zone and eventually with the other three zones. What began as isolated agrarian communities around towns like Catal Hoyiik expanded over larger areas in the Fertile Crescent and Egypt as well as to the new grasslands of Sudan. In India's Indus Valley and Ganges plains and in China's Yellow River basin, agrarian communities grew and started coalescing. Whether forced by a strong leader or out of the necessity of managing an increasingly complex society, rudimentary state power came into existence.78 About five thousand years ago, small city-states appeared in the Euphrates Valley and later in the Nile Valley. Nourished by agriculture in the Indus plains, urban civilization took shape in Mohenjo-Daro and Harappa. The territory of Mesopotamia between the Euphrates and Tigris rivers witnessed the rise of the first state when a desert tribe from today's Syria led by Sargon established the empire of Akkad (2340-230 Be). Sargon's conquests spanned the Mediterranean to the Persian Gulf-covering virtually all of the settled communities in the Levant except Egypt-making Akkad the world's first empire that sought to forge nations different in race, religion, and culture into a political weapon under one man's control. 79 Another key motive for imperial intervention was the control of resources. For instance, Sargon went to war to secure timber, a daily necessity lacking in Mesopotamia and Egypt.80 His was the first state with a standing army, an administrative service, and organized trade. Perhaps in the first example of imperial pride at promoting trade, Sargon boasted that he brought the boats of Dilmun [modern-day Bahrain], Magan [in the Persian Gulf], and Meluhha [Harappa] to dock at the newly founded imperial center at Agade [probably at the confluence of the Tigris and Euphrates rivers]. 81 Sargon defeated rival city-states, and instead of following the common policy of exacting ransom from the defeated population, he incorporated them into his empire.

Indeed, as the historian Jean-Jacques Glassner writes, Akkadian imperialism exhibited new attitudes toward war, where warfare outside the zone of direct political control became an instituted economic activity driven by a search for booty and tribute in the form of corvee labor and military service.82

This approach to expanding a territorial and population base would be pursued by ambitious rulers through history, thus linking ever-wider areas of separate populations. The need to gather intelligence about potential threats and alliance building seen in Sargon's time also called for diplomacy. One of the earliest examples of a long-distance diplomatic mission was in 130 BCE, when an envoy of China's Han emperor traveled to the periphery of Persia in search of allies against nomadic tribes that periodically threatened China.83

By the beginning of second millennium BCE, the first "modern" state with its written legal code emerged in Babylon. The 282 laws of the Hammurabi Code on various personal and public aspects of life, including currency and trade, created a framework that would later inspire Roman law and its extension to diverse other populations of the empire.84 The state's growing involvement in trade that would later become the norm was visible in one law: "If the merchant give, to an agent corn, wool, oil, or any sort of goods with which to trade, the agent shall write down the value and return (the money) to the merchant; the agent shall take a sealed receipt for the money which he shall give to the merchant."85 Organizing and managing trade emerged as key functions of the emergent states in peacetime. The result was the creation of a web of long-distance exchanges encompassing the Eurasian zone with far-reaching impact on societies and cultures.

With the rise of more efficient means of transportation, especially horse and chariot warfare, and growth of a solid economic base, the size of the empires and their armies expanded. Political scientist Rein Taagepera has calculated that the area controlled by empires grew from 0.6 megameter (I megameter = 100,000 km2) under Sargon of Akkad to 3 megameters under the Mauryas in India, 4 megameters under the Roman Empire, 6 megameters under China's Han dynasty, and reached the maximum extent of a land empire under the Mongols with 25 megameters.86 Humanity's growing mastery of the ocean and the age of exploration in the sixteenth century allowed for the first time in history the creation of the empires over which the sun never set. Economic exploitation, political control, and massive migration resulting from European empires created a dynamic of world integration that has rolled on despite periodic interruptions. As we will see, the imperial drive-embodied by the warriors for the purpose of this book-has played a major role in shaping today's interconnected world.

Religion as a set of symbolic forms and acts that give meaning to human existence has been a part of human life since the beginning. In the early millennia of the rise of agriculture, the cult of the Mother Goddess, the source of all fertility, emerged independently in agrarian societies. She was called Inana in Sumer, Ishtar in Babylon, Anat in Canaan, Isis in Egypt, and Aphrodite in Greece. We don't know what she was called in India, but terra-cotta figurines of the Mother Goddess have been found in the Indus Valley. As the agrarian civilization flourished and the power of the state grew, the state was increasingly associated with divinity. The success of the state was attributed to the blessings of the gods. The ruler was part of the divinity, and the god's imagined abode inspired the creation of temple towers such as Babylon's ziggurats. With the growing complexity of life, many more gods were imagined, and mythologies blossomed. Yet in early agrarian societies, religions tended to be local, and gods were invoked to protect local tribes or cities. The emergence of empires and expansion of trading networks brought within their folds different faiths and deities, enabling the concept of universal religion. Indeed, as David Christian notes, most of the universal religions appeared in the hub region between Mesopotamia and northern India. By the first millennium BCE, people's material progress seems also to have generated "an extremely negative evaluation of man and society and the exaltation of another realm of reality as alone true and infinitely valuable."87

For Gautama Buddha, in sixth-century BCE India, life even in the palace meant endless cycles of suffering that could be ended only by the pursuit of a virtuous path. Buddhism, like Christianity and Islam that were to follow in half-millennium intervals, was a missionary faith. After Gautama attained the enlightenment to become the Buddha, he decided not to be content in his own bliss but to go forth and explain his way to the world. For the next forty-five years of his life he traveled allover the land preaching. That mission to spread the faith to the far corners of the world was later taken up by devout kings and monks. The commission that Jesus gave his disciples was not very different: "Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, and teaching them to obey everything that I have commanded you" (Matt. 28:19). The monotheistic Islamic faith that arose in seventh-century Arabia in response to the hedonism and corruption brought by trade was driven by messianic zeal in converting the nonbelievers. fu we will see, in the centuries to come the proselytizing spirit of these universalist religions would emerge as the fourth prime mover in connecting the separate populations across the world, binding them more closely and shaping their lives. The spirit of the universality of the human condition that lies behind missionary activities would later be taken up by secular groups. Environmental and human rights advocates bring to their work convictions about helping humanity as a whole, tying our world even more firmly together.

Over time, ripples have turned into waves. In a new out-of-Africa move, no doubt feeling the desperation of our ancestors from long ago, people board boats to cross the Atlantic and the Mediterranean, and tens of millions of migrants from other continents continue to flow to where they see hope for a better life. Adventurers of the past have been replaced by a new class of tourists. Caravan traders of the past have been succeeded by multinational companies transporting their goods on container ships. Another new actor pushing globalization today is the consumer, whose demand for cheaper and better goods and services is fueling the fire of global commerce. The likes of Amnesty International and Human Rights Watch have enlarged the scope of traditional preachers in reaching out to distant lands with their message of common good. Imperial ambitions of the past have been replaced by political ambition to spread democracy and human rights. Multinational forces are spread through out the world, attempting to subjugate the "enemies of democracy" or maintain peace between warring nations. The result of all this has been to intertwine peoples' lives across the globe ever more intimately. The process of reconnecting the dispersed human community that started more than ten thousand years ago is stronger than ever, and thanks to technology it is continuously accelerating, binding us ever more tightly.

 

1.     Nicholas Wade, Before the Dawn: Recovering the Lost History of Our Ancestors (New York: Penguin Press, 2006), 75, 81.

2.     Charles Darwin, The Descent of Man, reprint ed. (New York: Penguin Classics, 2004), chap. 6.

3.     Matt Ridley, Genome: The Autobiography ofa Species in 23 Chapters (New York: HarperCollins, 2000), 49.

4.     The estimated dates of human colonization are based on mtDNA dara; James D. Watson, DNA: The Secret of Life (New York: Alfred A. Knopf, 2003), 246.

5.     Richard Klein and Blake Edgar, The Dawn of Human Culture (New York: J. Wiley, 2002).

6.     Wade, Before the Dawn, 58.

7.     Steve Olson, Mapping Human History: Genes, Race, and Our Common Human Origins (New York: Houghton Mifflin, 2003), 206.

8.     Rebecca L. Cann, Mark Stoneking, and Allan C. Wilson, "Mitochondrial DNA and Human Evolution," Nature 325 (I January 1987): 31-36.

9.      Watson, DNA, 233-39.

10.    Olson, Mapping Human History, 26.

11.    Rebecca L. Cann, "DNA and Human Origins," Annual Review of Anthropology 17 (1988): 127-43, at 127.

12.    A. Underhill et al., "The Phylogeography ofY Chromosome Binary Haplorypes and the Origins of Modern Human Populations," Annals of Human Genetics 65 (2001): 4362.

13.    Russell Thomson et al., "Recent Common Ancestry of Human Y Chromosomes: Evi. dence from DNA Sequence Data," Proceedings of the NationalAcademy of Sciences of the United States 97 (20 June 2000): 7360-65.

14.    Xinzhi Wu, "On the Origin of Modern Humans in China," Quaternary Internationalr17 (2004): 131-40.

15.    Robert Lee Hotz, "Chinese Roots Lie in Africa, Research Says," Los Angeles Times, 29 September 1998.

16.    Yuehai Ke et al., "African Origin of Modern Humans in East Asia: A Tale of 12,000 Y Chromosomes," Science292 (II May 2001): II51-53; see also LiJin and Bing Su, "Natives or Immigrants: Modern Human Origin in East Asia," Nature Reviews: Genetics I (November 2000): 126-33.

17.    Peter Forster and Shuichi Matsumura, "Did Early Humans Go North ot South?" Science 308 (13 May 2005): 965-66.

18.   Nicholas Kristof, "Is Race Real?" New York Times, 11 July 2003.

19.   KumarasamyThangara et al., "Reconstructing the Origin of Andaman Islanders," Science 308 (13 May 2005): 996.

20.   Vincent Macaulay et aI., "Single, Rapid Coastal Settlement of Asia Revealed by Analysis of Complete Mitochondrial Genomes," Science308 (13 May 2005): 1034-36.

21.   Ibid., 69.

22.   Robert C. Walter et al., "Early Human Occupation of the Red Sea Coast of Eritrea during the Last Interglacial," Nature 405 (4 May 2000): 65-69.

23.   Stephen Oppenheimer, The Real Eve: Modern Man's Journey Out of Africa (New York: Carroll and Graf, 2003), 80; Walter et al., "Early Human Occupation of the Red Sea Coast of Eritrea," 65-69.

24.   Spencer Wells, The Journey of Man: A Genetic Odyssey (London: Penguin, 2002), 104.

25.   Wade, Before the Dawn, 81.

26.   Alan J. Redd et al., "Gene Flow from the Indian Subcontinent to Australia: Evidence from the Y Chromosome," Current Biology 12 (16 April 2002): 676.

27.   Paul Plotz, quoted in Elia T. Ben-Ari, "Molecular Biographies: Anthropological Geneticists Are Using the Genome to Decode Human History," BioScience 49, no. 2 (1999): 98-I03.

28.   Spencer Wells, quoted in ibid., I04.

29.   Cengiz Cinnioglu et al., "Excavating Y-Chromosome Haplotype Strata in Anatolia,' Human Geneticsu4 (2004): 134.

30.   Susanta Roychoudhury et al., "Fundamental Genomic Unity of Ethnic India Is Revealec by Analysis of Mitochondrial DNA," Current Science 79 (IO November 2000): U82-9I Toomas Kivisild et aI., "An Indian Ancestry: A Key for Understanding Human Diversil:) in Europe and Beyond," in Colin Renfrew and Katie Boyle, eds., Archaeogenetics: DN.I and the Population Prehistory of Europe (Cambridge: McDonald Institute for Archaeological Research, 2000).

31.   Wells, Journry of Man, 117.

32.   Wei Deng et al., "Evolution and Migration History of the Chinese Population Inferrec from Chinese Y-Chromosome Evidence," Journal of Human Genetics 49 (July 2004) 339-48.

33.   Olson, Mapping Human History, 131; Ke et al., "African Origin of Modern Humans in East Asia."

34.   Ke et al., ''African Origin of Modern Humans in East Asia."

35.   Wells, Journry of Man, I2I.

36.   Olson, Mapping Human History, I3I.

37.   Jin and Su, "Natives or Immigrants."

38.   Michael F. Hammer et al., "Dual Origins of the Japanese: Common Ground for Hunter Gatherer and Farmer Y Chromosomes," Journal of Human Genetics (Tokyo) 51 (2006) 47-58.

39.    In November 2006 scientists were reported to have found new genetic evidence suggesting that modern humans and Neanderthals interbred, at least on rar! occasions. Th legacy of that interbreeding is now found in a gene that is present among 70 percent 0 the world's population. John Noble Wilford, "Neanderthals in Gene Pool, Study Sug gests," New York Times, 9 November 2006.

40.   Watson, DNA, 245; Charles Pasternak, Quest: The Essence of Humanity (Chichester: Wiley, 2003), 97.

41.    Paul Mellars, "A New Radiocarbon Revolution and the Dispersal of Modern Humans in Eurasia," Nature 439 (23 February 2006): 931-35.

42.   Diego Hurtado de Mendoza and Ricardo Braginski, "y Chromosomes Point to Nativ American Adam," Science283 (5 March 1999): 1439-40.

43.   Olson, Mapping Human History, 207.

44.   A. Gibbons, "Geneticists Trace the DNA Trail of the First Americans," Science 259 (I January 1993): 312-13.

45.   Olson, Mapping Human History, 205.

46.   David Christian, Maps of Time: An Introduction to Big History (Berkeley: University c California Press, 2004), 212.

47.   Carles Vila et al., "Widespread Origins of Domestic Horse Lineages," Science 291 (19 January 2O01), 474-77.

48.  Francis S. Collins, "What We Do and Don't Know About 'Race,' 'Ethnicity,' Genetics and Health at the Dawn of the Genome Era," Nature Genetics Supplement36 (November 2004): SI3-S15.

49.  Luigi Luca Cavalli-Sforza, Genes, Peoples, and Languages, trans. Mark Seielstad (Berkeley: University of California Press, 2001), II.

50.  Ian J. Jackson, "Pigmentary Diversity: Identifying the Genes Causing Human Diversity," European Journal of Human Genetics 14 (24 May 2006),978-80.

51.  Wade, Before the Dawn, 16.

52.  Watson, DNA, 254.

53.  Ibid., 255.

54.  Olson, Mapping Human History, 133.

55.  Luigi Luca Cavalli-Sforza and Francesco Cavalli-Sforza, The Great Human Diasporas: A History of Diversity and Evolution, trans. Serah Thorne (Reading, MA: Addison-Wesley, 1995),124, emphasis in original.

56.  Ben-Ari, "Molecular Biographies," 103.

57.  Olson, Mapping Human History, 99.

58.  Ofer Bar-Yosef quoted in John Noble Wilford, "In West Bank, a First Hint of Agriculture: Figs," New York Times, 2 June 2006.

59.  J. M. J. DeWet, "Grasses and the Culture History of Man," Annals of the Missouri Botanical Garden 68 (1981): 87-104.

60.  Dennis Normile, "Archaeology: Yangtze Seen as Earliest Rice Site," Science 275 (17 January 1997): 309-10.

61.  Mordechai E. Kislev, Anat Hartmann, and Ofer Bar-Yosef, "Early Domesticated Fig in the Jordan Valley," Science 312 (2 June 2006): 1372-74.

62.  Not surprisingly, five of the biblical seven species derive from fruit trees: olive oil, wine, dry raisins, dates, and figs.

63.  Daniel Zohary and Pinhas Spiegel-Roy, "Beginnings of Fruit Growing~in the Old World," Sciencn87 (31 January 1975): 318-27.

64.  Romana Unger-Hamilton, "The Epi-Palaeolithic Southern Levant and the Origins of Cultivation," CurrentAnthropologno (February 1989): 88-103.

65. David W. Anthony, "Migration in Archeology: The Baby and the Bathwater," American Anthropologist 92 (1990): 895-914.

66.  Ibid., 898.

67.  Michael Balter, "Search for the Indo-Europeans," Science 303 (27 February 2004): 1323.

68.  For a summary of the debate between two schools, see Guido Barbujani and Andrea Pilastro, "Genetic Evidence on Origin and Dispersal of Human Populations Speaking Languages of the Nostratic Macrofamily," Proceedings of the NationalAcademy of Sciences 90 (May 1993): 467°-73.

69.  David W. Anthony, "The 'Kurgan Culture,' Indo-European Origins, and the Domestication of the Horse: A Reconsideration," Current Anthropology 27 (August-October 1986): 291-313.

70.  David Anthony, Dimitri Y. Telegin, and Dorcas Brown, "The Origin of Horseback Riding," Scientific American (December 1991): 44-48.

71.  Steven Mithen, After the Ice: A Global Human History, 20,000-5000 BC (Cambridge, MA: Harvard University Press, 2004), 67.

72.  Robert P. Clark, The Global Imperative: An Interpretive History of the Spread of Humankind(Boulder, co: Westview, 1997), 46.

73.  Ian Hodder, "This Old House," Natural History, June 2006.

74.   Joan Oates, "Trade and Power in the Fifth and Fourth Millennia Be: New Evidence from Northern Mesopotamia," W'orldArchaeology24, no. 3 (1993): 403-22.

75.  Rita Smith Kipp and Edward M. Schortman, "The Political Impact of Trade in Chiefdoms," American Anthropologist 91 (1989): 370-85.

76.  G. A. Wainwright, "Early Foreign Trade in East Africa," Man 47 (November 1947): 143-48.

77.  Philip D. Curtin, Cross-Cultural Trade in W'orld History (Cambridge: Cambridge University Press, 1984).

78.  Christian, Maps of Time, 248.

79.  Saul N. Vitkus, "Sargon Unseated," BiblicalArchaeologist, September 1976, II4-17.

80.  Fernand Braudel, Memory and the Mediterranean, trans. Sian Reynolds (New York: AlfredA. Knopf, 2001), 60.

81.  Christopher Edens, "Dynamics of Trade in the Ancient Mesopotamian 'World System,''' American Anthropologist 94 (1992): 131.

82.  Cited in ibid., 132.

83.  Charles O. Hucker, China's Imperial Past: An Introduction to Chinese History and Culture (Stanford, CA: Stanford University Press, 1975), 126.

84.  R. H. Pfeiffer, "Hammurabi Code: Critical Notes," American Journal of Semitic Languages and Literatures (1920): 310-15.

85.  "Business in Babylon," Bulletin of the Business Historical Society 12 (1938): 25-27.

86.  Cited by Christian, Maps of Time, 317.

87.  Robert N. Bellah, "Religious Evolution" (lecture, University of Chicago, 16 October 1963).

 

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