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Congratulations to these Affiliates on their recent accomplishments! Do you have a kudos to share? Please send potential kudos to Aaron Glavas, GlavasC@si.edu. Funding Conner Prairie (Fishers, Indiana) announced a partnership with Ritz Charles to invest approximately $3 million to renovate and expand Eli Lilly’s historic Chinese House. Support for the project includes a $500,000 pledge […]
Throughout the 20th century, the widely accepted story of humanity’s migration from Africa began with a human ancestor called Homo erectus, a relatively big-brained, tall species of hominin that began to venture all across Asia more than a million years ago. But in recent decades, new evidence has begun to punch holes in that timeline. Now, reports Carl Zimmer at The New York Times, new stone tools unearthed in China indicate someone made it 8,000 miles from Africa to east Asia as far back as 2.12 million years ago, and that someone probably wasn’t Homo erectus.
Zimmer reports that back in 1964, researchers found the skull of a Homo erectus in the Lantian area of the Shaanxi province, which at the time they placed at around 1.15 million years. When researchers revisited the Lantian site in the early 2000s, however, they determined that the layer the skull came from was older—about 1.63 million years old. They also noticed what appeared to be stone tools embedded 200 feet up in a cliff face.
That observation led to 13 years of painstaking excavations. During that time, the team found that various human ancestors occupied the site in Shangchen’s southern Chinese Loess Plateau between 1.26 and 2.12 million years ago. According to their study, published in the journal Nature, the researchers uncovered 80 stone artifacts found in 11 layers of soil deposited when the climate was warm and wet. They also uncovered 16 artifacts in six layers that date to a time when the climate conditions were colder and drier.
Most importantly, they were able to date the layers of soil using a technique called paleomagnetism by looking at certain minerals which align with the Earth’s magnetic field, which occasionally flip flops. The oldest artifacts were found in a layer sandwiched between rock formed 2.14 million years ago and 1.85 million years ago. Based on their position, the researchers estimate six of the tools are 2.12 million years old, making them the oldest stone tools found outside Africa.
The finding doesn’t necessarily indicate that it was Homo erectus which made it to China faster than previously thought. It’s believed Homo erectus hadn’t even evolved by this point, so the artifacts could suggest that a whole other species of hominins expanded east to Asia.
“The implications of all this are large,” Michael Petraglia, a paleoanthropologist at the Max Planck Institute not involved in the study, tells Zimmer. “We must re-evaluate our understanding of human prehistory in Eurasia.”
So if it wasn’t Homo erectus, who was living in China so long ago? A trove of fossils unearthed in Dmanisi, Georgia, which was the previous oldest hominin site outside of Africa, may shed some light. It included stone tools and, more importantly, part of a skull from a relatively small-brained, short hominin. It’s possible that this species or one like it expanded across Eurasia first.
Then again, perhaps we don't have the dates for Homo erectus nailed yet. “It is entirely possible that Homo erectus occupied China at this time, but given the age of the site, and the possibility that artifacts may be found at even earlier ages, another member of the genus Homo may be occupying Asia, such as a Homo habilis-like ancestor,” Petraglia tells Michael Greshko at National Geographic.
Rick Potts, the head of the Smithsonian Institution’s Human Origins Program, agrees, telling Zimmer that he believes that some Homo erectus-like fossils older than 2.1 million years old may still be found in Africa, making it plausible that a larger human-like hominin made the artifacts found in Lantian.
Just because this species made it out of Africa, however, doesn’t mean that they are somehow the ancestor of modern humans. There were likely many species or populations of hominins that left Africa, only to die out somewhere in their journey across the globe. “Some populations got all the way over to eastern Asia, but we have to imagine that these were small, sort of hunting-and-gathering populations,” Petraglia tells Robinson Meyer at the Atlantic. “And while they may have mated across East Asia, it doesn’t mean they survived for a long period of time. Some populations might have become isolated, and some might have become extinct.”
Some might have even gone on to develop into other species, like the Indonesian Homo floresiensis (dubbed the “hobbits” by the media) who may have evolved much earlier than first thought, according to recent research.
It’s unlikely this will be the only discovery about early humans to come out of China. While most paleoanthropologists have spent most of their time and resources searching for hominins in Africa, an increase in fieldwork in China and the rest of Asia is sure to dig up a few more surprises about our increasingly complex human family tree.
Coral reefs are facing many threats, including agricultural runoff, coastal development, overfishing and rising sea temperatures. But one threat has more or less flown under the radar: Some reefs lack enough bird poop. Ed Yong at The Atlantic reports that a new study in the journal Nature shows that reefs around islands where seabird populations are thriving—and defecating—clearly fare much better than those where bird populations have been wiped out.
The study was made possible by an accidental experiment. The Chagos Archipelago is an isolated group of 60 or so largely uninhabitated islands in the middle of the Indian Ocean. During the eighteenth and nineteenth centuries, sailors stopping in the area brought with them black rats, which colonized about two thirds of the islands, decimating seabird populations. The other islands are rat free and contain huge colonies of seabirds. In the 1960s, the few Chaggosians in the archipelago were relocated to make way for an American military base on Diego Garcia, the largest of the atolls. So for over 40 years, the rats have been allowed to roam free without human interference and the islands with birds have also been left to nature.
That’s why the Chagos are a perfect place to study the impact of rats—which have infested 90 percent of the globe’s island groups—on bird populations. The team examined six rat-infested islands and six rat-free islands, finding the ecological harm of the rodents extends into the soil and hundreds of feet out to sea, even impacting coral reefs.
The biggest difference, of course, is that the rat-free islands are full of birds—bird density was 760 times higher. “Islands with no rats are noisy, their skies are full of birds, and they absolutely stink of guano,” lead author Nick Graham from Lancaster University tells Yong. “But if you step foot on an island with rats, the skies are empty, it’s quiet, and it doesn’t smell. The difference is unbelievable.”
All those birds, incuding boobies, frigatebirds, noddies, shearwaters and terns, poop. Their guano adds the nutrient nitrogen to the islands, leading to big changes in the ecosystem. According to a press release, not only does that nitrogen make its way into the soil, plants and shrubs on the island, the team found it also leaches into the sea where it spurs the growth of algae and sponges. In fact, there were 50 percent more fish in the reefs around the birdy islands versus the ratty islands. Those fish contained more nitrogen and grew larger. And algae grazing, in which species like parrot fish nibble away algae and dead coral from the reefs stimulating new coral growth, happened 3.2 times as often around the birdy banks. “It was mind-boggling to see just how strong the differences are, across the board, for everything we looked at,” Graham tells Yong.
While the fact that rats have decimated entire ecosystems is sobering, it’s also good news in a way. While stopping pollution and climate change are monumental tasks, eradicating rats is low-hanging fruit—humans are pretty good at pest control and Yong reports rats have been eliminated from 580 islands globally so far, with projects getting even more ambitious. In fact, just last May, South Georgia Island near Antarctica, which has been plagued by rats for centuries, finished a $13 million, decade-long rat eradication, the largest ever conducted. It was officially declared rodent-free and its endangered native birds and other wildlife now have a fighting chance. New Zealand, home to tons of rare endemic species being gobbled up by rats, cats, weasels and other invasive species, is undertaking a monumental campaign to eradicate non-native mammals by 2050. Even the Chagos Islands themselves have seen some success. Last year, the Chagos Conservation Trust announced that rats had been exterminated from Ile Vache Marine, an important bird habitat.
The study shows that rat eradication projects are even more important than previously thought. “These results show how conservation can sometimes be a bloody business, where doing right by the ecosystem means there is a time to kill,” co-author Aaron MacNeil of Dalhousie University says in the press release. “For these invasive rats, that time is now."
Graham tells Victoria Gill at the BBC that rat eradication could also help mitigate the impacts of climate change, since healthier reefs are more resilient and can probably recover faster from warm-water bleaching events. And the Chagos need all the help they can get. A bleaching event in 2015 and 2016 damaged or killed 85 percent of the corals in the archipelago, which may never fully recover.