June 6, 2023: Astonishing evidence of culture in a fossil human relative, the sound of black holes colliding and seaweed "blob" brings trouble. Read more below! —Andrea Gawrylewski, Chief Newsletter Editor | | | In the Rising Star cave system near Johannesburg, South Africa, paleoanthropologists have found evidence that the fossil human species Homo naledi, which had a brain a third as large as ours, engaged in several sophisticated behaviors including using fire as a light source, burying its dead and engraving symbolic designs on the rock walls of the cave system.
Why this matters: Scientists have long assumed that increasing brain size drove technological and cognitive advances (like taming fire and thinking symbolically) in human ancestors. If these new discoveries hold up to further testing, researchers may need to rethink the connection between brain size and behavior.
What the experts say: "It's challenging our perceptions of what it means to be human, what it means to be intelligent enough to make art, what it means to communicate graphically," says Genevieve von Petzinger, an authority on rock art. | | | The Sound of Silent Black Holes | Black holes colliding in the vacuum of space make no sound at all. But here on Earth, we have a way to hear the crash. A global network of observatories has so far detected the resulting gravitational waves from about 100 cosmic collisions. When recorded, analyzed and converted to sound, each one's jostling of spacetime becomes its own distinctive, data-rich "chirp."
How it works: Gravitational wave observatories beam lasers down long, L-shaped tunnels. Bounced between mirrors at the ends of each arm of the "L," the lasers act like violin strings. When gravitational waves pass through space, they stretch or contract these "strings," producing slightly different frequencies.
Why this matters: Over the next 18 months, the world's gravitational-wave observatories are turning back on after a long hiatus for equipment upgrades. Soon the somewhat rare "chirps" may become much more commonplace. Listen to a chirp here (Sound, as in a vacuum, isn't carried in an email.) | | | • The Hunga Tonga–Hunga Ha'apai volcanic eruption in 2022 in the area of the Tonga Islands in the South Pacific Ocean triggered the formation of a giant atmospheric plasma bubble, according to a new analysis. | 3 min read | | | • Colombia's invasive hippo population (first introduced by drug cartel leader Pablo Escobar) is even larger than researchers had thought, according to the most thorough census of the animals conducted to date. | 5 min read | | | Wild descendants of the hippo population introduced in Colombia by Pablo Escobar. Credit: Raul Arboleds/AFP via Getty Images | | | • Hvaldimir, a juvenile male beluga whale suspected of being part of the Russian military and known as the "spy whale," has been spotted in Swedish waters showing signs of malnourishment and dehydration. He was likely removed from his own social group at a young age and enculturated by norms specific to human interaction, writes Diana Reiss, a professor at Hunter College. It is now our responsibility to protect him, she says. | 5 min read | | | The number of deaths among Black people that exceed those among white people in the U.S. is rising again after falling and stabilizing in the last two decades. In 2020, COVID hit the U.S., obliterating any progress on reducing health disparities over the past two decades. The disease was a leading cause of death among Black people, while cases of heart disease and physical assault also rose. Click here to see more graphics and analysis on this. | | | In addition to the small-brained Homo naledi study, some fascinating discoveries in the last decade have shed light on the complicated hominin family tree--turns out it's more of a tangled bush than a neat and tidy tree. Check out this article by senior editor Kate Wong who tells the story of how WE came to be. | This newsletter is for you! Tell me how we can improve it by emailing me directly at newsletters@sciam.com. | —Andrea Gawrylewski, Chief Newsletter Editor | | Subscribe to this and all of our newsletters . | | | | Scientific American
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