Surveying Archaeologists Across the Globe Reveals Deeper and More Widespread Roots of the Human Age, the Anthropocene
Examples of how human societies are changing the planet abound — from building roads and houses, clearing forests for agriculture and digging train tunnels, to shrinking the ozone layer, driving species extinct, changing the climate and acidifying the oceans. Human impacts are everywhere. Our societies have changed Earth so much that it's impossible to reverse many of these effects.
Some researchers believe these changes are so big that they mark the beginning of a new "human age" of Earth history, the Anthropocene epoch. A committee of geologists has now proposed to mark the start of the Anthropocene in the mid-20th century, based on a striking indicator: the widely scattered radioactive dust from nuclear bomb tests in the early 1950s.
Nuclear bomb testing left its mark in the geologic record.
National Nuclear Security Administration / Wikimedia Commons, CC BY
But this is not the final word.
Not everyone is sure that today's industrialized, globalized societies will be around long enough to define a new geological epoch. Perhaps we are just a flash in the pan — an event — rather than a long, enduring epoch.
Others debate the utility of picking a single thin line in Earth's geological record to mark the start of human impacts in the geological record. Maybe the Anthropocene began at different times in different parts of the world. For example, the first instances of agriculture emerged at different places at different times, and resulted in huge impacts on the environment, through land clearing, habitat losses, extinctions, erosion and carbon emissions, forever changing the global climate.
Human practices like burning the landscape – as in this night bush fire outside Kabwe, Zambia – have been affecting the earth since long before the nuclear era.
Andrea Kay, CC BY-SA
If there are multiple beginnings, scientists need to answer more complicated questions — like when did agriculture begin to transform landscapes in different parts of the world? This is a tough question because archaeologists tend to focus their research on a limited number of sites and regions and to prioritize locations where agriculture is believed to have appeared earliest. To date, it has proved nearly impossible for archaeologists to put together a global picture of land use changes throughout time.
Global Answers From Local Experts
To tackle these questions, we pulled together a research collaboration among archaeologists, anthropologists and geographers to survey archaeological knowledge on land use across the planet.
We asked over 1,300 archaeologists from around the world to contribute their knowledge on how ancient people used the land in 146 regions spanning all continents except Antarctica from 10,000 years ago right up to 1850. More than 250 responded, representing the largest expert archaeology crowdsourcing project ever undertaken, though some prior projects have worked with amateur contributions.
Our work has now mapped the current state of archaeological knowledge on land use across the planet, including parts of the world that have rarely been considered in previous studies.
We used a crowdsourcing approach because scholarly publications don't always include the original data needed to allow global comparisons. Even when these data are shared by archaeologists, they use many different formats from one project to another, making it difficult to combine for large-scale analysis. Our goal from the beginning was to make it easy for anyone to check our work and reuse our data — we've put all our research materials online where they can be freely accessed by anyone.
Earlier and More Widespread Human Impacts
Though our study acquired expert archaeological information from across the planet, data were more available in some regions — including Southwest Asia, Europe, northern China, Australia and North America — than in others. This is probably because more archaeologists have worked in these regions than elsewhere, such as parts of Africa, Southeast Asia and South America.
Animation showing the spread of intensive agriculture across the globe over the past 10,000 years, based on ArchaeoGLOBE Project results.
Nicolas Gauthier, 2019, CC-BY-SA
Our archaeologists reported that nearly half (42%) of our regions had some form of agriculture by 6,000 years ago, highlighting the prevalence of agricultural economies across the globe. Moreover, these results indicate that the onset of agriculture was earlier and more widespread than suggested in the most common global reconstruction of land-use history, the History Database of the Global Environment. This is important because climate scientists often use this database of past conditions to estimate future climate change; according to our research it may be underestimating land-use-associated climate effects.
Our survey also revealed that hunting and foraging was generally replaced by pastoralism (raising animals such as cows and sheep for food and other resources) and agriculture in most places, though there were exceptions. In a few areas, reversals occurred and agriculture did not simply replace foraging but merged with it and coexisted side by side for some time.
View of the Kopaic Plain in Boeotia, Greece. People first partially drained the area 3,300 years ago to claim land for agriculture and it's still farmed today.
Lucas Stephens, CC BY-SA
The Deep Roots of the Anthropocene
Global archaeological data show that human transformation of environments began at different times in different regions and accelerated with the emergence of agriculture. Nevertheless, by 3,000 years ago, most of the planet was already transformed by hunter-gatherers, farmers and pastoralists.
To guide this planet toward a better future, we need to understand how we got here. The message from archaeology is clear. It took thousands of years for the pristine planet of long ago to become the human planet of today.
And there is no way to fully understand this human planet without building on the expertise of archaeologists, anthropologists, sociologists and other human scientists. To build a more robust Earth science in the Anthropocene, the human sciences must play as central a role as the natural sciences do today.
Ben Marwich is an associate professor of archaeology at the University of Washington.
Erie C. Ellis is a professor of geography and environmental systems at the University of Maryland, Baltimore County.
Lucas Stephens is a research affiliate in archaeology at the Max Planck Institute for the Science of Human History.
Nicole Boivin is the director of the department of archaeology at the Max Planck Institute for the Science of Human History.
Ben Marwick receives funding from the Australian Research Council, the Wenner-Gren Foundation and the National Geographic Society.
Erle C. Ellis received funding from the National Science Foundation for this project under grant CNS 1125210. He is a fellow of the Global Land Program, a member of the Anthropocene Working Group of the International Commission on Stratigraphy, and a senior fellow of the Breakthrough Institute. He is a member of the American Association of Geographers.
Lucas Stephens receives funding from the American Council of Learned Societies. He is a Mellon/ACLS Public Fellow and Senior Research Analyst at the Environmental Law and Policy Center and a Research Affiliate at the Max Planck Institute for the Science of Human History.
Nicole Boivin receives funding from the Max Planck Society. She is Director at the Max Planck Institute for the Science of Human History, an Honorary Professor at the University of Queensland, and a Research Affiliate at the Smithsonian Institution and University of Calgary.
Reposted with permission from our media associate The Conversation.
The ghoulishly named ogre-faced spider can "hear" with its legs and use that ability to catch insects flying behind it, the study published in Current Biology Thursday concluded.
"Spiders are sensitive to airborne sound," Cornell professor emeritus Dr. Charles Walcott, who was not involved with the study, told the Cornell Chronicle. "That's the big message really."
The net-casting, ogre-faced spider (Deinopis spinosa) has a unique hunting strategy, as study coauthor Cornell University postdoctoral researcher Jay Stafstrom explained in a video.
They hunt only at night using a special kind of web: an A-shaped frame made from non-sticky silk that supports a fuzzy rectangle that they hold with their front forelegs and use to trap prey.
They do this in two ways. In a maneuver called a "forward strike," they pounce down on prey moving beneath them on the ground. This is enabled by their large eyes — the biggest of any spider. These eyes give them 2,000 times the night vision that we have, Science explained.
But the spiders can also perform a move called the "backward strike," Stafstrom explained, in which they reach their legs behind them and catch insects flying through the air.
"So here comes a flying bug and somehow the spider gets information on the sound direction and its distance. The spiders time the 200-millisecond leap if the fly is within its capture zone – much like an over-the-shoulder catch. The spider gets its prey. They're accurate," coauthor Ronald Hoy, the D & D Joslovitz Merksamer Professor in the Department of Neurobiology and Behavior in the College of Arts and Sciences, told the Cornell Chronicle.
What the researchers wanted to understand was how the spiders could tell what was moving behind them when they have no ears.
It isn't a question of peripheral vision. In a 2016 study, the same team blindfolded the spiders and sent them out to hunt, Science explained. This prevented the spiders from making their forward strikes, but they were still able to catch prey using the backwards strike. The researchers thought the spiders were "hearing" their prey with the sensors on the tips of their legs. All spiders have these sensors, but scientists had previously thought they were only able to detect vibrations through surfaces, not sounds in the air.
To test how well the ogre-faced spiders could actually hear, the researchers conducted a two-part experiment.
First, they inserted electrodes into removed spider legs and into the brains of intact spiders. They put the spiders and the legs into a vibration-proof booth and played sounds from two meters (approximately 6.5 feet) away. The spiders and the legs responded to sounds from 100 hertz to 10,000 hertz.
Next, they played the five sounds that had triggered the biggest response to 25 spiders in the wild and 51 spiders in the lab. More than half the spiders did the "backward strike" move when they heard sounds that have a lower frequency similar to insect wing beats. When the higher frequency sounds were played, the spiders did not move. This suggests the higher frequencies may mimic the sounds of predators like birds.
University of Cincinnati spider behavioral ecologist George Uetz told Science that the results were a "surprise" that indicated science has much to learn about spiders as a whole. Because all spiders have these receptors on their legs, it is possible that all spiders can hear. This theory was first put forward by Walcott 60 years ago, but was dismissed at the time, according to the Cornell Chronicle. But studies of other spiders have turned up further evidence since. A 2016 study found that a kind of jumping spider can pick up sonic vibrations in the air.
"We don't know diddly about spiders," Uetz told Science. "They are much more complex than people ever thought they were."
Learning more provides scientists with an opportunity to study their sensory abilities in order to improve technology like bio-sensors, directional microphones and visual processing algorithms, Stafstrom told CNN.
"The point is any understudied, underappreciated group has fascinating lives, even a yucky spider, and we can learn something from it," he told CNN.
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