A clever and painstaking new analysis has revealed that the famous Homo erectus fossil known as Peking Man is 200,000 years older than previously thought. The fossil, discovered almost a century ago during excavations of the Zhoukoudian caves near Beijing, is now thought to be about 750,000 years old. The revised date could change the timeline and number of migrations of the Homo erectus species out of Africa and into Asia [LiveScience].
Homo erectus were the first hominids to leave the evolutionary cradle of Africa. The species had a distinctive barrel-shaped torso and stood [57 to 70 inches] tall, walking upright in a similar way to modern humans [Nature News]. Researchers had previously suggested that one wave of Homo erectus wayfarers migrated out of Africa between 2 million and 1.6 million years ago, settling Indonesia and southern Asia first before moving northward. But new fossil discoveries, coupled with the new dating of Peking Man, are forcing paleoanthropologists to rethink this scenario.
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The spit in each person’s mouth contains a diverse and unique universe of bacteria, according to a study in the journal Genome Research, and there’s no geographical pattern to the differences between one mouth and the next. A new worldwide survey of the human saliva microbiome – the bugs in our spit – finds that a man from La Paz, Bolivia, shares no more microbes in common with his neighbours than with a woman from Shanghai [New Scientist].
Molecular anthropologist Mark Stoneking made the discovery while searching for a better way to trace prehistoric human migrations. He had been impressed by how anthropologists were able to trace human migrations through the differences in the strains of the stomach bug Helicobacter pylori in various groups of people…. “With that species, you see very strong geographic patterning,” says Stoneking. But getting a sample of H. pylori is relatively difficult, as it requires a stomach biopsy. He wondered whether any of the bacteria in spit would work instead [ScienceNOW Daily News].
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The tools found in Colorado resident Patrick Mahaffy’s backyard weren’t the typical collection of weed whackers and shovels. Instead Mahaffy’s yard hosted a collection of chipped stone knives and axes that date from the time of the Clovis people, who are believed to have been among the first inhabitants of America around 13,000 years ago. “The idea that these Clovis-age tools essentially fell out of someone’s yard in Boulder is astonishing,” [anthropologist Douglas Bamforth] said. “But the evidence I’ve seen gives me no reason to believe the cache has been disturbed since the items were placed there for storage about 13,000 years ago” [LiveScience].
The prehistoric tool cache was turned up when landscapers were digging a hole for a fishpond in Mahaffy’s backyard, and struck stone. The collection contains 83 knives, axes, and smaller pieces of flint, and a chemical analysis of blood residue left on the blades revealed that the tools had been used to butcher extinct types of North American camels and horses, and well as bears and sheep.
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Two groups of researchers seem to have solved the mystery of how and when the first human settlers spread out through the Pacific Islands. One group studied the evolution of a stomach bacteria while the other examined the evolution of language, but both came up with remarkably congruous results. The evolutionary trajectory implied by words and bugs begins with an initial migration from Taiwan 5,000 years ago, with a first wave of people spreading to the Philippines and a second to western Polynesia [Wired News].
In the bacterial study, researchers took stomach samples from people native to Taiwan, Australia, Melanesia, Polynesia and New Guinea. They measured genetic variation in Helicobacter pylori, a common gut microbe that traveled with humans when they first left Africa more than 60,000 years ago…. They found that the [bacteria] from people’s guts in Polynesia and Melanesia–islands stretching from New Caledonia all the way to Samoa–were genetically similar to the samples from aboriginal people in Taiwan. What’s more, the Taiwanese bacteria had more genetic diversity than other populations [The Scientist]. Because genetic mutations accumulate over time, these results indicate that the early Taiwanese people were the ancestors of the other groups that split off over the centuries.
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When the first bands of early humans made their intrepid journey into the Americas, they found plenty of room to spread out, according to a new study. Researchers who conducted a genetic analysis of Native Americans say that they can trace their ancestry back to two groups of migrants who arrived in America around the same time, between 15,000 and 17,000 years ago, but took distinctly different routes. The researchers argue that one group moved down the Pacific coastline all the way to the tip of South America, and the other group crossed into North America through an open land corridor between ice sheets and settled near the Great Lakes.
Along the Pacific coastal route, travelers in skin boats are presumed to have hunted marine mammals and found shelter in shoreline refuges beyond the reach of the retreating glaciers…. Movements along the inland route – where big-game hunters originally from Siberia are believed to have migrated through a gap in the glaciers in present-day Northwest Territories and Alberta – led to the earliest mid-continental settlements in the New World, scientists believe [Canwest News Service].
Paleoanthropologists generally accept that the original colonizers of North and South America came from eastern Asia and migrated to the Americas after spending some time–perhaps several thousand years–in a region called Beringia, which included parts of Siberia and Alaska and the land bridge that once connected them [ScienceNOW Daily News]. But the question of where they went next has been a subject of considerable controversy, with some researchers arguing that harsh climate conditions didn’t allow humans to settle in North America until long after the crossing of the land bridge. While the new study isn’t likely to settle the argument, it supports the theory that humans quickly spread out over both continents.
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The small band of Homo sapiens that left Africa around 60,000 years ago, taking the first steps on a journey that would eventually disperse humans all around the world, may have been composed mostly of men. A new analysis of DNA variations in contemporary humans indicates that non-Africans descend from a population that contained far more males than females [New Scientist].
In the study, published in Nature Genetics [subscription required], researchers compared genetic samples from present-day African, European, and Asian populations. They were looking at the chromosomes that determine sex (two X chromosomes in women, one X and one Y chromosome in men), as well as the other 22 chromosome pairs, which are the same in both sexes. They examined the rate at which mutations randomly spread through the X chromosome over dozens or hundreds of generations as compared to the mutation rate in other, non-sex, chromosomes [AFP].
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The tumult of the Spanish Inquisition, which began over 500 years ago, has echoed down through the generations of people living on the Iberian peninsula in a remarkable way. A new genetic study has revealed that many current Spaniards have Sephardic Jewish or North African heritage, indicating that their ancestors converted to Christianity during the religious upheaval of the 15th century in order to remain in Spain. The study showed that one in ten Iberians has a North African ancestor, while one in five had Jewish forebears.
This melting pot probably occurred after centuries of coexistence and tolerance among Muslims, Jews and Christians ended in 1492, when Catholic monarchs converted or expelled the Islamic population, called Moriscos. Sephardic Jews, whose Iberian roots extend to the first century AD, received much the same treatment. “They were given a choice: convert, go, or die,” says Mark Jobling, a geneticist at the University of Leicester, UK. Some of those that became Christian would have ended up contributing genes to the Iberian pool [New Scientist].
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The newly elected president of the Maldives, the island chain south of India, says his country must start saving up money to buy a new homeland, in case global warming causes sea levels to rise so much that the waves submerge the archipelago entirely. Says Maldivian President Mohamed Nasheed: “We can do nothing to stop climate change on our own and so we have to buy land elsewhere. It’s an insurance policy for the worst possible outcome…. We do not want to leave the Maldives, but we also do not want to be climate refugees living in tents for decades,” he said [The Guardian].
The Maldives are the lowest-lying nation on the planet: most of the islands are only a few feet above sea level, and the highest point, in the capital city of Malé, is about seven feet above sea level. But the white sandy beaches are a major tourist attraction bringing in billions of dollars every year…. Mr Nasheed’s plan is to create a “sovereign wealth fund” using tourism revenues to buy land so that future generations will have somewhere to rebuild their lives if they have to leave. He wants somewhere within the region, where the culture is similar – possibly India or Sri Lanka [BBC News]. However, Nasheed also mentioned Australia as a possibility, because of the vast swaths of unoccupied land on that continent.
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Researchers have long debated whether human migration out of Africa was spurred by climate changes that forced the early humans to move along or by technological innovation that let them take advantage of new possibilities; now a new analysis of stone tools from southern Africa is lending support to the latter camp. Researchers determined that two types of tools were developed during the crucial age from 60,000 to 80,000 years ago when modern humans began to move towards new regions of the globe.
Researchers examined tools from nine sites in South Africa, Namibia, and Lesotho. The sophisticated Still Bay tools were made from hard, fine-grained rock called silcrete, and were fashioned between 71,000 and 71,900 years ago. The Howieson’s Poort implements were made between 59,500 and 64,800 years ago, and were composed of chipped silcrete rock attached to wood shafts to form weapons. Comparing these dates with palaeoenvironmental records failed to turn up a close correlation between the industries and dramatic climatic changes, [lead researcher Zenobia] Jacobs says. “We see no consistent pattern between the timing of these industries and major climatic changes” [Nature News].
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The first migration of Homo sapiens, when they left the East African landscapes where they evolved and began a long trek across the Sahara, may have followed a different route than previously believed. A new study shows that prehistoric river channels fed by monsoons once traced a path north through the desert and argues that the modern humans may have followed those channels, going from oasis to oasis until they reached the sea.
The Sahara has had several periods of increased rainfall that made it a wetter and greener place, including one interlude between 130,000 to 170,000 years ago when the researchers believe these river channels flowed with water. Now only visible with satellite radar, the channels flowed intermittently from present-day Libya and Chad to the Mediterranean Sea, says [lead researcher] Anne Osborne…. Up to five kilometres wide, the channels would have provided a lush route from East Africa – where modern humans first evolved – to the Middle East, a likely second stop on Homo sapiens‘ world tour [New Scientist].
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When the Vikings set sail for the British Isles they had small, furry stowaways aboard their ships, and researchers say that the descendants of those mice can offer clues about the voyages taken by Viking seafarers. A new study examined the DNA of house mice throughout the British Isles and found that mice from areas where the Vikings are thought to have settled are genetically distinct from mice in other regions.
Says study coauthor Cath Jones: “We have found that most of the mice in the north of Scotland – from Orkney, Shetland and Caithness – are all of one very similar type that we have named the Orkney lineage and they are very similar to Norwegian mice. And the only explanation for that is that when the Vikings came raping and pillaging to Scotland they took their house mice with them” [Scotsman].
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By examining half a million tiny differences in the genomes of Europeans, researchers can determine with surprising accuracy where on the continent each person comes from, easily distinguishing the Irish from the English, for example. Two new studies reveal that our DNA contains a sort of global positioning system, which researchers can use to pinpoint where in the world both we and our relatives came from [ScienceNOW Daily News].
The findings surprised geneticists by showing that despite centuries of immigration and intermarriage throughout Europe, genetic differences between Europeans are almost entirely related to where they were born. This, however, does not mean that the citizens of each European nation represent miniature races. “The genetic diversity in Europe is very low. There isn’t really much,” says Manfred Kayser [New Scientist], author of one of the studies.
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A clump of hair that lay frozen in the Greenland tundra for 4,000 years has yielded DNA from the earliest Arctic residents, and offers clues to their origins.
Researchers have long wondered who those rugged settlers were, and where they came from. Were they part of a massive migration that swept through all of North America, or were they a separate tribe that eventually gave rise to Greenland’s present-day Eskimos?
Until now, no ancient human remains had been found in that harsh climate to allow researchers to study the genetics of those “Paleo-Eskimos.” But the new discovery sheds some light on the people, and suggests that neither of the earlier theories is correct; in fact, they were a distinct tribe that journeyed all the way from Siberia to Greenland, but didn’t stick around to populate the frozen north.
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