One type of footwork you probably haven’t seen during the Rio Olympics dressage events is an “amble,” a sometimes comical four-beat gait for a horse that’s faster than a walk, slower than a gallop and well-suited for smooth, long rides. In a study in Current Biology, scientists suggested that ambling horses arose in medieval England and then the Vikings took them to Iceland and spread them across Eurasia. From the DNA in remains of 90 ancient horses, researchers found the genetic mutation tied to ambling in samples from England dating to the ninth century. They also found the mutation in Icelandic horses from the ninth to 11th centuries. Author Leif Andersson also noted that some Chinese horse sculptures from nearly 2,000 years ago seemed to depict ambling.

Saturn’s largest moon is flooded with hydrocarbons

Deep, narrow canyons on Titan, Saturn’s largest moon, are flooded with liquid hydrocarbons, radar data from NASA’s Cassini spacecraft has found. On Earth, the dynamics of climate arise from the transformations of water among liquid, ice and vapor phases. On Titan, the minus 300 degrees Fahrenheit are close to where methane can similarly coexist as liquid, ice and vapor, and that generates similar climate and geological phenomena. When Cassini passed over what appeared to be rivers flowing into a northern sea, it recorded three reflections from its radar signal The timing of the reflections provided a measure of the depth — 790 to 1,870 feet, with slopes greater than 40 degrees.