Worldwide, too little iodine in the diet is the most common cause of hypothyroidism. In countries with enough iodine in the diet, the most common cause of hypothyroidism is the autoimmune condition Hashimoto's thyroiditis.
The pronghorn is the second fastest land mammal in the world, after the cheetah. It can attain speeds of over 53 miles (86 kilometers) per hour. Size relative to a 6-ft (2-m) man: Fleet-footed pronghorns are among the speediest animals in North America. They can run at more than 53 miles (86 kilometers) an hour, leaving pursuing coyotes and bobcats in the dust.
Story highlights. 1  Elon Musk's proposed Hyperloop system would be twice as fast as world's speediest train. 2  China's Shanghai Maglev train has topped out at 311 mph. 3  To travel from L.A. to San Francisco in 35 minutes, Hyperloop would have to go almost 700 mph. 1  Just how fast would the Hyperloop transportation system envisioned by entrepreneur Elon Musk have to be? Try more than twice as fast as the fastest commercial train in the world.