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.
Known as prairie ghosts because they are so elusive, the Sonoran pronghorn is the fastest land mammal in North America. Smaller and lighter in color than other pronghorn subspecies, the genetically and geographically unique Sonoran pronghorn is specially adapted for survival in harsh arid conditions. Sonoran pronghorn are reddish brown on their backs and sides, and have lighter colored undersides. They have bright white markings on their heads and necks; males have black faces and black patches on the sides of their necks. Male Sonoran pronghorns sport large black pronged horns, while females have short black horns.