Red AlertA brilliant red dye derived from tiny insects once treasured by the Spanish conquistadores gives some modern foods and cosmetics an alluring blush. In a small number of people, though, it can cause swelling, rashes, or respiratory problems. The U.S. has now mandated that the coloring be identified as “cochineal extract” or “carmine” on product labels. Previously, vague phrases such as “color added” were acceptable.

Native to the New World, cactus-eating cochineal bugs are dried and crushed to produce a powdered dye. Beginning in the 16th century, Europeans of wealth and status wore clothing reddened with rare cochineal. The deep, durable color was even used to produce the British Army’s famous red coats for more than 200 years. Cochineal harvesting declined after the invention of cheap synthetic dyes in the 1800s, but it has rebounded—mostly in Peru and the Canary Islands—with the dye’s use as a natural alternative to artificial colorings. —A. R. Williams

Red dye made from cochineal insects (enlarged above) colors a range of products.

Food and Drink

Candies, cookies, yogurts, gelatins, and juices may contain cochineal, but enhanced reds in the U.S. usually come from artificial red No. 40.

Return of the King

How heavy is the head that wore the crown? About five pounds. It also bears distinctive knife cuts, a pierced ear, and a lesion near the nose. Those forensic clues, along with preserved tissues and organs, helped a multidisciplinary team confirm that an embalmed skull (right) belonged to Henry IV, the beloved French king who was assassinated in 1610.

After the ruler’s remains were desecrated during the French Revolution, his head vanished for more than a hundred years. A pate said to be Henry’s was sold at a Paris auction in the early 20th century, then moved quietly among private collections. From 1955 until last year it was in a tax collector’s attic.

Now, after nine months of scientific and historical scrutiny, it’s in the hands of a royal descendant. With its reinterment at the Basilica of St.-Denis near Paris, this weary head may finally be able to rest in peace. —Jeremy Berlin

The head of France’s King Henry IV lies with a Legion of Honor medal that bears his portrait.

PHOTOS: STÉPHANE GABET AND PIERRE BELET, GALAXIE PRESSE; NATIONAL MUSEUM OF THE LEGION OF HONOR, PARIS (LEFT)

29 Names, Same Plant

In 1753 Swedish naturalist Carl Linnaeus published Species Plantarum, a book describing some 6,000 plant species that became the foundation of modern plant nomenclature. The list of names has since ballooned to 1.05 million, but of those, only around 300,000 are now confirmed to be unique species. Nearly half a million others, it turns out, are redundant.

The scientific moniker for English oak has 314 synonyms, the common daisy (left) 29, and the giant sequoia 18. Those are just a few identified so far in the Plant List, a working database created in 2010 by the Missouri Botanical Garden and London’s Kew Gardens after years of vetting. “It’s like people. We have different eye colors, shapes, and sizes, but we’re all people,” says botanist Bob Magill. “There’s huge variation within a species.” —Luna Shyr

ART: OLIVER MUNDAY

Hybrid Bears on the Move

In the past five years two odd-looking bears, with white fur and brown patches, have been killed by hunters in the Canadian Arctic. DNA tests confirmed it: Polar and grizzly bears, after starting to diverge 200,000 years ago, are interbreeding in the wild. Climate change seems to be driving their reunion. But to what end?

Evolutionary biologist Brendan Kelly says that as natural barriers like sea ice vanish, 22 Arctic species are at risk of rapid hybridization. That could be bad news for polar bears, which rely on specialized adaptations to survive. Kelly says if “pizzlies” in the wild lack some of those vital Arctic traits—as zoo-born hybrids* (left) seem to—interbreeding could further imperil an already threatened species. —Jeremy Berlin

*A mix of polar and brown bears, of which grizzlies are a subspecies

PHOTO: ZOO OSNABRÜCK

A Second Career

As the foragers of their colony’s caste system (left), media leaf cutter ants start out with mandibles as sharp as surgical scalpels. But over the course of their lives, the repetitive slicing of leaves into small disks dulls their V-shaped blades. Rather than retire, the ants shift their role to just carrying sheared-off vegetation to the nest, where food production begins.

Observing Panama’s Atta cephalotes, University of Oregon’s Robert Schofield and his team found that ants with dulled blades used about twice as much energy and time to carve a leaf as their still sharp colleagues, triggering the job switch. “It’s an advantage of social living that we’re familiar with,” says Schofield. “Humans who can no longer do certain tasks can still make worthwhile contributions to society.” —Erin Friar McDermott

PHOTO: KONRAD WOTHE, MINDEN PICTURES.

Ten elements in the PERIODIC TABLE, including carbon, nitrogen, and oxygen, are getting revised atomic weights. • A study finds that several CORAL SPECIES around Japan have shifted north some 700 miles, possibly due to warmer oceans. • KOREACERATOPS: the name given to a dinosaur, based on a rare fossil find on the Korean Peninsula. • California’s COASTAL FOG occurs some 33 percent less frequently than in the early 20th century, say University of California, Berkeley scientists.

At a rate of 30 miles a day, it would take around 15 months to walk through the Americas from Alaska to Argentina.

GRAPHIC: ÁLVARO VALIÑO

Hop to It

Back in 1973 Professor Terence Dawson had some unusual guests working the treadmills at Harvard University. “One young lady hopped for half an hour,” recalls the animal physiologist, who, like his subjects, was visiting from Australia at the time. “She’d come out of the pen and stand on the treadmill, waiting for us to turn it on.” Dawson spent the next four decades back in Oz studying what is mostly a curiosity to others: how a kangaroo moves.

Observing red kangaroos, he and colleagues found that longer strides, not more frequent ones, increase speed. Hopping strides range from 2.5 to 17 feet. Walking changes to hopping at around four miles an hour. And top speeds reach about 35 miles an hour.

Specialized body features (next page) give kangaroos superb power and mechanical efficiency, says Dawson. Hopping marsupials may have evolved from tree ancestors some 40 million years ago—plenty of time to patent a signature gait. “It’s an incredibly graceful way of moving,” he notes. “They appear to be just gliding along.” —Luna Shyr

Walk This Way

At slow speeds these graceful jumpers use their forelegs and tail to hold themselves up while swinging their hind legs forward.

ART: BRUCE MORSER. SOURCE: TERENCE DAWSON

A—A kangaroo’s heart is a powerful pump—1.5 times larger than a similarly sized mammal’s.

B—Eighty percent of total muscle mass is packed around the pelvis. These muscles are loaded with capillaries and energy-producing mitochondria.

C—Large tendons and calf muscles compress and release like a spring.

Built to Bound

ART: BRUCE MORSER. SOURCE: TERENCE DAWSON