Rock carvings show humans, ancient dogs

Our bond with dogs is etched in stone.

In a study published this month, archaeologists exploring rock engravings in the Saudi desert have found what they say may be the earliest depictions of human-canine companionship.

The ancient carvings date back about 8,000 to 9,000 years and depict hunters using dogs to overwhelm prey such as gazelles and ibex before they fired killing blows with bows and arrows.

“You can almost hear the dogs barking and the humans yelling,” said Melinda Zeder, a curator of Old World archaeology at the Smithsonian Institution’s National Museum of Natural History, who was not involved in the study. “You can almost smell the fear in the animals.”

With their pricked ears, angled chests and curly tails, each dog in the rock art resembles the modern breed of Canaan dogs. In one scene there are two lines connecting the necks of two dogs to the hips of the humans.

“This is the first imagery of a dog with a leash,” said Michael Petraglia, an archaeologist from the Max Planck Institute for the Science of Human History, in Germany, and an author of the study that appeared in the Journal of Anthropological Archaeology. He said that because of where the lines were on the dog and human’s anatomy, they most likely represented actual leashes and were not mere symbolic lines.

The team also found that the dog images were carved beneath images of cattle, which they said indicated that the dog images came earlier.

Do lefties have a sports advantage? It depends

Violins, cameras, school desks, computer mouses, can openers — these are just a few items that demonstrate how routinely disadvantaged left-handers are in this world.

One notable exception may be sports. Whether it is Lou Gehrig in baseball, Wayne Gretzky in ice hockey, Martina Navratilova in tennis or Oscar De La Hoya in boxing, some of the best athletes in history have been portsiders.

But even in this realm, the southpaw advantage may vary, being more pronounced in sports where a player has less time to react to an opponent, like table tennis, according to Florian Loffing, a sports scientist at the University of Oldenburg in Germany and author of a study published this month in Biology Letters. In such games, he found a higher proportion of lefties than in those with longer intervals between players’ actions.

Including an analysis of the pressures of time shows “that there is an additional effect” in left-sider sports dynamics, said Kirsten Legerlotz, a professor of sport sciences at the Humboldt University of Berlin who was not involved in the research. Loffing’s “conclusion appears convincing,” she added, although it would need to be examined in other sports and verified with lab experiments.

Loffing chose to analyze baseball, cricket, table tennis, badminton, tennis and squash, because they lent themselves to a standardized measure of time pressure, he said.

Comparing all six sports against one another, he found the proportion of southpaws increased as the time available for players to act decreased. Nine percent of the top players were left-dominant in the slowest contest, squash, while 30 percent of the best pitchers were lefties in the fastest, baseball. Overall, left-handedness was 2.6 times more likely in the sports with higher time constraints (baseball, cricket and table tennis) than in ones with lower time pressure (badminton, tennis and squash).

The scuba diving flies of California’s Mono Lake

Most people visit Mono Lake in California for the Dr. Seuss-esque towers called tufas. But to experience the truly bizarre, look for the scuba-diving alkali flies.

In water, most insects inevitably become fish bait or can’t escape or emerge too wet to function. But in Mono Lake’s salty waters, the fly species Ephydra hians is an exception.

Dickinson teamed up with Floris van Breugel, who now studies fly and mosquito behavior at the University of Washington, Seattle. They published their discoveries in the Proceedings of the National Academy of Sciences this month.

The fly’s secret to staying dry is an air bubble — a tight, flexible, silvery sheath that the fly dons like “a superhero costume,” Dickinson said.

Its body — hairier and waxier than that of other flies and insects — repels water, forming a bubble around itself as it dives. In a way, the fly carries the dry sky down with it.

The bubble does not cover its red eyes, allowing the fly an undistorted view through the water. It walks along the tufa without becoming too buoyant by clinging on with elongated claws.

These adaptations are particularly impressive in Mono Lake.

The hypersaline conditions make it inhospitable to fish, but very hospitable to brine shrimp, algae and bacteria. Underwater, the alkali flies feast on algae and lay eggs free from competition and predators.

Even whales have to exfoliate

In August 2014, Sarah Fortune was trying to tag bowhead whales with transmitters so she could study their feeding habits in Canada’s Cumberland Sound, where many of the large sea mammals spend their summers.

But the whales kept swimming into a small, shallow bay with large boulders, where at least one removed a transmitter by rubbing against the rocks. “The whales were just rolling onto their sides, lifting their flippers out of the water, doing headstands, lifting their tails out of the water,” she said.

The mystery of the rock-rubbing whales dates back at least 170 years. Around 1845, whalers started calling bowheads “rock-nosed whales” after seeing them rub their heads on boulders. Several subsequent papers have also noted the behavior, usually concluding the whales were using the rocks to rest.

But Fortune noticed that large pieces of skin were peeling off some of the whales. Perhaps, she thought, they were “using these rocks like humans using pumice stones, to get rid of calluses or dead skin.”

Fortune and a team of researchers published a paper in the journal PLOS One this month that seems to confirm her suspicions. Overhead footage of the whales taken by drones in 2016 — part of another study tracking the whales’ summer feeding habits — reveals that the animals are using the large rocks to rub dead skin off their bodies.

The findings confirm long-held suspicions about how bowhead whales molt.

Like humans, most whales, dolphins and porpoises are thought to shed skin and hair continuously, a little at a time, throughout the year. But certain cold-water whale species — belugas and narwhals — are believed to shed their skins during the summer, when they relocate to warmer places.

Knowing why whales prefer a particular habitat will aid researchers as they seek to understand how global warming will affect marine creatures, Fortune said.

‘Jigsaw puzzles’ improve our views of coral reefs

A century ago, if you wanted to document ocean life, you’d throw on a 60-pound glass helmet, dive in and sketch whatever passed by with a lead pencil on a zinc tablet.

Now a scientist can carry along a camera in a waterproof box, take thousands of photographs an hour and upload those images to computers too fast to exist a decade ago. Powerful software then stitches together the photos and identifies unique features, creating billions of reference points that help to calculate the location of corals in 3-D space.

“It’s like doing one of the most crazy jigsaw puzzles you can ever imagine,” said Stuart Sandin, a coral reef ecologist at Scripps Institution of Oceanography at the University of California, San Diego. He and his colleagues have analyzed some of the first of these 3D photomosaics in a study published last month in the journal Coral Reefs.

With the help of computer scientists and engineers at their university, Sandin and his team created their digital maps using more than 39,000 photos of about 44,000 coral colonies living on reefs at Palmyra Atoll near Hawaii. In analyzing digital reconstructions of about 1,000 square feet each, they discovered for the first time that rather than distributing themselves randomly wherever larvae happened to fall, corals of every species and type cluster together across the reef.

Scientists think breaking and clustering is how forms of coral hold onto space and survive on a highly competitive reef. They believe it’s a sign of health in this protected atoll, where bleaching, overfishing and disease are not really threats.

To confirm this hypothesis, the research team will compare their reconstructions of the Palmyra Atoll to 99 other reefs in varying states of health across the globe. The 100 Island Challenge aims to create baseline maps and track how reefs are changing over time.

“The 800-pound gorilla is that the climate is changing,” and the prevailing story is that it affects corals disproportionately, Sandin said.

— The New York Times

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