All four-limbed, land-based vertebrates came from a common ancestor with legs that ended in five toes. Over time, many animals lost some of their digits. But only the group of animals containing modern horses ended up with a single toe per foot. A study in Proceedings of the Royal Society B lends support to hypotheses about the transformation in horses’ hoofs. Namely, as horses evolved and got larger from their ancestral, dog-sized form, it was better to have one very robust toe than several smaller ones to support their increased body mass. And having just one toe reduced the weight horses had to carry at the end of each leg, making it easier for them to run and maneuver.

Hints of trigonometry on Babylonian tablet

Two Australian mathematicians assert that an ancient clay tablet was a tool for working out trigonometry problems, possibly adding to the many techniques that Babylonian mathematicians had mastered. “It’s a trigonometric table, which is 3,000 years ahead of its time,” said Daniel Mansfield of the University of New South Wales. Mansfield and his colleague Norman J. Wildberger reported their findings in the journal Historia Mathematica. The tablet, known as Plimpton 322, was discovered in the early 1900s in southern Iraq and has long been of interest to scholars. It contains 60 numbers organized into 15 rows and four columns inscribed on a piece of clay about 5 inches wide and 3.5 inches tall.

Yellow lab helps search for invasive insects

Scientists assessing long-term efforts to eradicate invasive ants on the Channel Islands off the Southern California coast have enlisted a four-legged expert to make sure a project to kill off the destructive pests has succeeded. A yellow Labrador named Tobias keeps his snout to the ground, rooting through more than 1.6 square miles of underbrush, searching for nests of Argentine ants that threatened the ecosystem after they were introduced decades ago. Tobias has not yet discovered any new ant populations — a sign that a project has probably worked.

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