Enlarge / Hummingbirds—like this golden-tailed sapphire from South America—draw the eye with their bright colors and busy, hovering flight. Biologists are drawn to understand the suite of adaptations they have evolved to survive extreme lifestyles. (credit: webguzs via Getty)

Everyone loves to watch hummingbirds—tiny, brightly colored blurs that dart about, hovering at flowers and pugnaciously defending their ownership of a feeder.

But to the scientists who study them, hummingbirds offer much more than an entertaining spectacle. Their small size and blazing metabolism mean they live life on a knife-edge, sometimes needing to shut down their bodies almost completely just to conserve enough energy to survive the night—or to migrate thousands of miles, at times across open ocean.

Their nectar-rich diet leads to blood-sugar levels that would put a person in a coma. And their zipping, zooming flight sometimes generates g-forces high enough to make a fighter pilot black out. The more researchers look, the more surprises lurk within those tiny bodies, the smallest in the avian world.

Enlarge / A digital advertisement board displaying a Barbie movie poster is seen in New York on July 24, 2023. (credit: Getty | Selcuk Acar)

This post contains spoilers—for the movie and women's health care.

There's nothing like stirrups and a speculum to welcome one to womanhood, but for some, the recent Barbie movie apparently offered its own kind of eye-opening introduction.

The smash-hit film ends with the titular character making the brave decision to exit Barbieland and enter the real world as a bona fide woman. The film's final scene follows her as she fully unfurls her new reality, attending her first woman's health appointment. "I’m here to see my gynecologist," she enthusiastically states to a medical receptionist. For many, the line prompted a wry chuckle, given her unsuspecting eagerness and enigmatic anatomy. But for others, it apparently raised some fundamental questions.

Enlarge / The intrepid three-legged lion Jacob and his brother Tibu prepare for a hunt. (credit: Alexander Braczkowski)

On February 4, scientists monitoring lion populations in Uganda captured nighttime thermal drone footage of two lions—brothers dubbed Jacob and Tibu by the Uganda Wildlife Authority—swimming across the predator-infested Kazinga Channel connecting two lakes, most likely to find mates. While there have been prior reports of lions swimming short distances, Jacob and Tibu covered about 1.5 kilometers (nearly one mile)—the longest swim yet recorded, according to a new paper published in the journal Ecology and Evolution.

"The fact that [Jacob] and his brother Tibu have managed to survive as long as they have in a national park that has experienced significant human pressures and high poaching rates is a feat in itself—our science has shown this population has nearly halved in just five years," said co-author Alexander Braczkowski of Griffith University, who has been working with the government of Uganda since 2017 to monitor the lion population in the area. "His swim, across a channel filled with high densities of hippos and crocodiles, is a record-breaker and is a truly amazing show of resilience in the face of such risk.”

Jacob and Tibu's impressive feat is likely the result of increased pressure from human encroachment, according to Braczkowski. He co-authored a 2020 paper proposing a novel census technique that could be used more broadly as an early warning of lion declines. Their method revealed a worrying movement parameter for both male and female lions in Uganda's Queen Elizabeth National Park, where the home range increased to 3.27 km (a 400 percent increase) for males and 2.22 km (a 100 percent increase) for females—likely a response to systematic prey depletion due to poaching, for example. And the sex ratio was dangerously skewed: one male to 0.75 females, a highly unusual occurrence.

Enlarge (credit: C. Marsicano)

Gaiasia jennyae, a newly discovered freshwater apex predator with a body length reaching 4.5 meters, lurked in the swamps and lakes around 280 million years ago. Its wide, flattened head had powerful jaws full of huge fangs, ready to capture any prey unlucky enough to swim past.

The problem is, to the best of our knowledge, it shouldn’t have been that large, should have been extinct tens of millions of years before the time it apparently lived, and shouldn’t have been found in northern Namibia. “Gaiasia is the first really good look we have at an entirely different ecosystem we didn’t expect to find,” says Jason Pardo, a postdoctoral fellow at Field Museum of Natural History in Chicago. Pardo is co-author of a study on the Gaiasia jennyae discovery recently published in Nature.

Common ancestry

“Tetrapods were the animals that crawled out of the water around 380 million years ago, maybe a little earlier,” Pardo explains. These ancient creatures, also known as stem tetrapods, were the common ancestors of modern reptiles, amphibians, mammals, and birds. “Those animals lived up to what we call the end of Carboniferous, about 370–300 million years ago. Few made it through, and they lasted longer, but they mostly went extinct around 370 million ago,” he adds.

Enlarge / New research lends further credence to the "population crash" theory about Easter Island being just a myth. (credit: Arian Zwegers/CC BY 2.0)

For centuries, Western scholars have touted the fate of the native population on Easter Island (Rapa Nui) as a case study in the devastating cost of environmentally unsustainable living. The story goes that the people on the remote island chopped down all the trees to build massive stone statues, triggering a population collapse. Their numbers were further depleted when Europeans discovered the island and brought foreign diseases, among other factors. But an alternative narrative began to emerge in the 21st century that the earliest inhabitants actually lived quite sustainably until that point. A new paper published in the journal Science Advances offers another key piece of evidence in support of that alternative hypothesis.

As previously reported, Easter Island is famous for its giant monumental statues, called moai, built some 800 years ago and typically mounted on platforms called ahu. Scholars have puzzled over the moai on Easter Island for decades, pondering their cultural significance, as well as how a Stone Age culture managed to carve and transport statues weighing as much as 92 tons. The first Europeans arrived in the 17th century and found only a few thousand inhabitants on a tiny island (just 14 by 7 miles across) thousands of miles away from any other land. Since then, in order to explain the presence of so many moai, the assumption has been that the island was once home to tens of thousands of people.

But perhaps they didn't need tens of thousands of people to accomplish that feat. Back in 2012, Carl Lipo of Binghamton University and Terry Hunt of the University of Arizona showed that you could transport a 10-foot, 5-ton moai a few hundred yards with just 18 people and three strong ropes by employing a rocking motion. [UPDATE: An eagle-eyed reader alerted us to the 1980s work of Czech experimental archaeologist Pavel Pavel, who conducted similar practical experiments on Easter Island after being inspired by Thor Heyerdahl's Kon Tiki. Pavel concluded that just 16 men and one leader were sufficient to transport the statues.]