Strange But True: Man's best friend can claim two continents


Q: How did dogs become "man's best friend" twice over?

A: "It now looks as if dogs emerged from not one, but two wolf families at opposite ends of Eurasia," says Alice Klein in New Scientist magazine.

Comparing the genomes of a 400-year-old dog skull from Ireland and of DNA samples from 59 ancient dogs, with genomes of more than 600 modern pooches from across Eurasia, Laurent Frantz at the University of Oxford found that "dogs originated from two separate wolf populations in the eastern and western halves of Eurasia. Then, between 14,000 and 6,400 years ago, people brought Asian dogs westward, where they partially replaced their European counterparts." Few modern dogs, though, have pure European or Asian roots: for example, the Tibetan mastiff has largely Asian lineage; German shepherds are more closely aligned to ancient European dogs (Science magazine).

This theory is consistent with archaeological evidence, which places ancient dog remains from more than 12,000 years ago toward the eastern and western ends of Eurasia, but not in the middle.

As for dog domestication, the mechanism is still unclear. Most likely, Frantz suggests, it started "as a natural-selection process, whereby wolves that were less wary of humans were more likely to come closer to camps and become domesticated."

Q: The people of the world are eating more even as they are eating less. How so?

A: The "less" refers to the shrinking variety of foods eaten regularly as people move toward a "one-world menu," says Mark Fischetti in Scientific American magazine. "Diets around the globe are more similar than they used to be," a narrowing of about 68 percent. The "more" is staples like wheat and oil crops, such as soybean, palm and sunflower, becoming widespread. And with those come consumption of more processed foods made from a small number of ingredients and more frying with oils rather than steaming.

Though some regions have benefited from these additional calories, scientists are concerned with the rise in obesity, diabetes and heart disease globally. Also, "if one crop falters, because of disease or drought, food prices could soar and supplies across continents could crumble."

Q: How are some birds like swifts, sandpipers and seabirds able to fly nonstop for days, weeks or months without seeming to sleep? Or do they sleep on wing?

A: For the first time, researchers have discovered that birds do, indeed, sleep in flight, "with either one cerebral hemisphere at a time or both simultaneously," reports the Max Planck Institute for Ornithology.

An international team led by the Institute's Niels Rattenborg used a small flight data recorder to monitor changes in birds' brain activity from wakefulness to either slow wave sleep (SWS) or rapid eye movement (REM) sleep, attaching the device onto female frigatebirds during their non-stop foraging flights lasting 10 days and about 1860 miles.

After sunset, "the awake EEG pattern switched to a SWS pattern for several minutes while the birds were soaring." REM episodes lasted a mere several seconds with only a slight reduction in muscle tone. Most surprisingly, flying frigatebirds slept an average of only 42 minutes per day, though on land they slept over 12 hours with longer episodes, suggesting they're sleep-deprived in flight.

As Rattenborg notes, "Why we, and many other animals, suffer dramatically from sleep loss whereas some birds are able to perform adaptively on far less sleep remains a mystery."

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