Neandertals were the first hominids to turn forest into grassland 125,000 years ago

Neandertals took Stone Age landscaping to a previously unrecognized level.

Around 125,000 years ago, these close human relatives transformed a largely forested area bordering two central European lakes into a relatively open landscape, say archaeologist Wil Roebroeks of Leiden University in the Netherlands, and his colleagues. Analyses of pollen, charcoal, animal fossils and other material previously unearthed at two ancient lake basins in Germany provide the oldest known evidence of hominids reshaping their environments, the scientists report December 15 in Science Advances.

The excavated areas are located within a site called Neumark-Nord. Neandertals’ daily activities there, apparently ongoing throughout the year, had a big environmental impact, the researchers suspect. Those pursuits, which occurred over a span of about 2,000 years, included setting campfires, butchering game, collecting wood, making tools and constructing shelters, they say.

“We might be dealing with larger and less mobile groups of [Neandertals] than commonly acknowledged,” Roebroeks says, thanks in part to warming temperatures after around 150,000 years ago that cleared ice sheets from resource-rich locations such as Neumark-Nord.
His team can’t say whether Neandertals set fires to clear large tracts of land at Neumark-Nord, a practice that has been observed among some modern hunter-gatherers. The geological remnants of many small campfires may look much like those of a small number of large fires, Roebroeks says.

Finds at Neumark-Nord play into an ongoing debate about when humans began to have a dominating influence on the natural world. Some scientists regard this period as a new geological epoch, the Anthropocene (SN: 4/1/13). It’s unclear when the Anthropocene began and whether its roots extend back to the Stone Age.

Regular fire use by members of the Homo genus began around 400,000 years ago (SN: 4/2/12). Evidence of human occupations associated with increased fire setting and shifts to open habitats date to around 40,000 years ago in Australia; 45,000 years ago in highland New Guinea; and 50,000 years ago in Borneo.

Analyses of lake cores and stone-tool sites in southern-central Africa indicate that fires set by increasing numbers of humans kept the landscape open even as rainy conditions conducive to forest growth developed around 85,000 years ago. Open environments still predominate in this part of Africa, Yale University paleoanthropologist Jessica Thompson and her colleagues reported May 5 in Science Advances. “Humans and close human relatives like Neandertals have likely been [modifying] their ecosystems for a very long time,” Thompson says.

A large coal mining operation revealed ancient Neumark-Nord sediments in 1985. German scientists then excavated a large lakeside site, wrapping up that project in the mid-1990s. The same team excavated a smaller site at a lake basin located about 100 meters from the first site between 2004 and 2008.

Pollen from these sites indicates that grasses and herbs, hallmarks of an open landscape, appeared in a brief window of time around 125,000 years ago, Roebroeks and his colleagues say. Large numbers of stone artifacts — some showing signs of having been heated, possibly to make finished edges sharper — and animal bones displaying butchery marks date to the same time at Neumark-Nord, when Neandertals but not Homo sapiens inhabited Europe.
Stone tools and bone fragments displaying signs of heating, burned wood, charred seeds and dense patches of charcoal particles suggested that Neandertals had frequently set fires near the Neumark-Nord lakes.

Pollen from two other sites in the same mountainous part of Germany, where researchers previously found small numbers of stone tools suggesting a limited Neandertal presence, show that forests dominated there when Neandertals inhabited Neumark-Nord’s grasslands. That strengthens the view that Neandertals altered the Neumark-Nord landscape rather than settling there after forests had shrunk, Roebroeks says.

Archaeologist Manuel Will of Eberhard Karls University of Tübingen in Germany agrees. “Neandertal evidence from Neumark-Nord should be a wake-up call for the international scientific community to include archaeologists [studying] the Paleolithic record as part of any team trying to define and identify the beginning of the Anthropocene,” says Will, who did not participate in the new study.

A Jupiter-like planet orbiting a white dwarf hints at our solar system’s future

A glimpse of our solar system’s future has appeared thousands of light-years away in the constellation Sagittarius. There a giant planet like Jupiter orbits a white dwarf, a dim, dense star that once resembled the sun.

In 2010, that star passed in front of a much more distant star. Like a magnifying glass, the white dwarf’s gravity bent the more distant star’s light rays so that they converged on Earth and made the distant star look hundreds of times brighter. A giant planet orbiting the white dwarf star also “microlensed” the distant star’s light, revealing the planet’s presence.

In 2015, 2016 and again in 2018 astrophysicist Joshua Blackman of the University of Tasmania in Hobart, Australia and colleagues pointed the Keck II telescope in Hawaii at the far-off system, which lies some 5,000 to 8,000 light-years from Earth. The team was in search of the giant planet’s star, but saw, well, nothing.

“We expected that we’d see a star similar to the sun,” Blackman says. “And so we spent quite a few years trying to figure out why on Earth we didn’t see the star which we expected to see.”
After failing to detect any light from the spot where the planet’s star should be, Blackman’s team concluded that the object can’t be a typical star like the sun — also known as a main sequence star, which generates energy by converting hydrogen into helium at its center. Instead, the star must be something much fainter. The microlensing data indicate that the star is roughly half as massive as the sun, so the object isn’t massive enough to be a neutron star or black hole. But a white dwarf star fits the bill perfectly, the researchers report online October 13 in Nature.

“They’ve carefully ruled out the other possible lens stars — neutron stars and black holes and main sequence stars and whatnot,” says Ben Zuckerman, an astronomer at UCLA, who was not involved with the work. He notes that only a handful of planets have ever been found orbiting white dwarfs.

The new planet is the first ever discovered that is orbiting a white dwarf and resembles Jupiter in both its mass and its distance from its star. Blackman’s team estimates that the planet is one to two times as massive as Jupiter and probably lies 2.5 to six times farther from the white dwarf star than Earth does from the sun. For comparison, Jupiter is 5.2 times farther out from the sun than Earth is. The white dwarf is somewhat larger than Earth, which means the planet is much bigger than its host star.

The white dwarf formed after a sunlike star expanded and became a red giant star. Then the red giant ejected its outer layers, exposing its hot core. That former core is the white dwarf star.

Our sun will turn into a white dwarf about 7.8 billion years from now, so the new discovery is “a snapshot into the future of our solar system,” Blackman says. As the sun becomes a red giant, it will engulf and destroy its innermost planet, Mercury, and perhaps Venus too. But Mars, Jupiter and more distant planets should survive.

And Earth? No one yet knows what will happen to it.

‘Life as We Made It’ charts the past and future of genetic tinkering

With genetic engineering, humans have recently unleashed a surreal fantasia: pigs that excrete less environment-polluting phosphorus, ducklings hatched from chicken eggs, beagles that glow ruby red under ultraviolet light. Biotechnology poses unprecedented power and potential — but also follows a course thousands of years in the making.

In Life as We Made It, evolutionary biologist Beth Shapiro pieces together a palimpsest of human tinkering. From domesticating dogs to hybridizing endangered Florida panthers, people have been bending evolutionary trajectories for millennia. Modern-day technologies capable of swapping, altering and switching genes on and off inspire understandable unease, Shapiro writes. But they also offer opportunities to accelerate adaptation for the better — creating plague-resistant ferrets, for instance, or rendering disease-carrying mosquitoes sterile to reduce their numbers (SN: 5/14/21).

For anyone curious about the past, present and future of human interference in nature, Life as We Made It offers a compelling survey of the possibilities and pitfalls. Shapiro is an engaging, clear-eyed guide, leading readers through the technical tangles and ethical thickets of this not-so-new frontier. Along the way, the book glitters with lively, humorous vignettes from Shapiro’s career in ancient DNA research. Her tales are often rife with awe (and ripe with the stench of thawing mammoths and other Ice Age matter).
The book’s first half punctures the misconception that we “have only just begun to meddle with nature.” Humans have meddled for 50,000 years: hunting, domesticating and conserving. The second half chronicles the advent of recent biotechnologies and their often bumpy rollouts, leading to squeamishness about genetically modified food and a blunder that resulted in accidentally transgenic cattle.

As we teeter on a technological precipice, Shapiro contends we have a choice to make. We can learn to meddle with greater precision, wielding the sharpest tools at our disposal. Or, she writes, “we can reject our new biotechnologies” and continue directing evolutionary fates anyway, “just more slowly and with less success.” Shapiro speculates about what the future may hold if we embrace our role as tinkerers: plastic-gobbling microbes, saber-toothed house cats, agricultural crops optimized for sequestering carbon. Whether these visions will come true is anyone’s guess. But one thing is clear. No matter which route we choose, humans will continue to stir the evolutionary soup. There’s no backing out now.

Speaking out for women in science

Jessica Cantlon
Cognitive neuroscientist
Carnegie Mellon University

Jessica Cantlon, featured in 2016, studies the evolution and development of complex mathematical thinking, including the traits that set humans apart from other primates. In 2017, she was recognized as a Time Person of the Year, as a “silence breaker” speaking out against sexual harassment during the height of the #MeToo movement.

What has been the most notable progress in your research since 2016?
We’ve expanded our repertoire to compare people across different cultures, who have different educational practices. We’ve been going to Bolivia to work with this group of people called the Tsimane, who live in rural parts of the Amazon forest. They don’t have the rigid, formal schooling where kids go through these particular curricula to achieve mathematical cognition. Instead, education there is more organic and more deeply connected to their way of life. That allows us to try to understand what effect does a particular type of education have on numerical thinking.

There was one study that we did, comparing species — nonhuman primates and humans — to understand the evolution of these concepts. Across all species and stages of development and cultural groups, there’s this bias that when you’re looking at a set of objects, and you’re trying to quantify it, you think about that set numerically. And you don’t have to; you can think about that set of objects spatially, as an amount of stuff, you can think about how much surface area is there, or the perimeter around it. But primates, including humans, [tend to] think about that set as a set of discrete objects, and count them up.

What is something that excites you right now in your work?
We’ve looked at the similarities and differences between boys and girls as their brains develop. We’ve done some of the first, early studies comparing children’s brains that can truly allow us to collect evidence on the trajectory of similarity between boys and girls…. We’ve shown that very early in development, between around 3 and 8 years of age, there’s evidence during mathematical processing that most of the brain — over 95 percent — shows functional similarity in that processing between boys and girls.

But as we know, much later on in development, we see a severe underrepresentation of girls in mathematics-related fields. What’s happening? There’s evidence in the field … that what happens in late childhood and adolescence is that children’s interests are shaped culturally.

What are some of the greatest challenges you’ve faced since 2016?
In 2016, [some of my colleagues at the University of Rochester and I] filed a sexual harassment complaint against a faculty member in our department who was sexually harassing women — undergraduate and graduate students and faculty. It became this situation that hijacked my career for a number of years.… We went public with our complaint, partly to protect ourselves, but also partly to let people know at other universities that this kind of thing is happening to students, and it’s affecting women’s career paths in ways that are discriminatory and unequal.

Ultimately, it was really important. Our complaint went public in September of 2017. In October 2017, the Harvey Weinstein story came out in the New York Times, and that kicked off a series of reactions that ultimately culminated in millions of people saying #MeToo, which I think was really powerful and important, and was something that we got to be a part of.

I’ve had dozens of women reach out to me for advice, about how to file a complaint at their university, how to take legal action, if that’s what they’re thinking, what the risks and benefits are. And so, part of my career now — and I’m excited by it, and I think it’s really important work — is to be an advocate for women who are experiencing discrimination and harassment at universities.

One response that we thought was really great was that the National Academies of Sciences, Engineering and Medicine did a full study on sexual harassment in the sciences…. It has a lot of ideas about what might effect larger-scale change.

— Interview by Aina Abell

How massive stars in binary systems turn into carbon factories

The next time you thank your lucky stars, you might want to bless the binaries. New calculations indicate that a massive star whose outer layer gets torn off by a companion star ends up shedding a lot more carbon than if the star had been born a loner.

“That star is making about twice as much carbon as a single star would make,” says Rob Farmer, an astrophysicist at the Max Planck Institute for Astrophysics in Garching, Germany.

All life on Earth is based on carbon, the fourth most abundant element in the cosmos, after hydrogen, helium and oxygen. Like nearly every chemical element heavier than helium, carbon is formed in stars (SN: 2/12/21). For many elements, astronomers have been able to pin down the main source. For example, oxygen comes almost entirely from massive stars, most of which explode, while nitrogen is made mostly in lower-mass stars, which don’t explode. In contrast, carbon arises both in massive and lower-mass stars. Astronomers would like to know exactly which types of stars forged the lion’s share of this vital element.

Farmer and his colleagues looked specifically at massive stars, which are at least eight times heavier than the sun, and calculated how they behave with and without partners. Nuclear reactions at the core of a massive star first turn hydrogen into helium. When the core runs out of hydrogen, the star expands, and soon the core starts converting helium into carbon.

But massive stars usually have companion stars, adding a twist to the storyline: When the star expands, the companion’s gravity can tear off the larger star’s outer envelope, exposing the helium core. That allows freshly minted carbon to stream into space via a flow of particles.

“In these very massive stars, these winds are quite strong,” Farmer says. For instance, his team’s calculations indicate that the wind of a star born 40 times as massive as the sun with a close companion ejects 1.1 solar masses of carbon before dying. In comparison, a single star born with the same mass ejects just 0.2 solar masses worth of carbon, the researchers report in a paper submitted to arXiv.org October 8 and in press at the Astrophysical Journal.

If the massive star then explodes, it also can outperform a supernova from a solo massive star. That’s because, when the companion star removes the massive star’s envelope, the helium core shrinks. This contraction leaves some carbon behind, outside the core. As a result, nuclear reactions can’t convert that carbon into heavier elements such as oxygen, leaving more carbon to be cast into space by the explosion. Had the star been single, the core would have destroyed much of that carbon.

By analyzing the output from massive stars of different masses, Farmer’s team concludes that the average massive star in a binary ejects 1.4 to 2.6 times as much carbon through winds and supernova explosions as the average massive star that’s single.

Given how many massive stars are in binaries, astronomer Stan Woosley says emphasizing binary-star evolution, as the researchers have done, is helpful in pinning down the origin of a crucial element. But “I think they are making too strong a claim based on models that may be sensitive to uncertain physics,” says Woosley, of the University of California, Santa Cruz. In particular, he says, mass-loss rates for massive stars are not known well enough to assert a specific difference in carbon production between single and binary stars.

Farmer acknowledges the uncertainty, but “the overall picture is sound,” he says. “The binaries are making more [carbon].”