For centuries, 98.6 degrees Fahrenheit was said to be the average, normal body temperature. It’s not.More recently, researchers have known normal body temperature is actually lower than 98.6 and can vary by gender, size, age, time of day and other factors. But now there’s also new evidence that shows we’ve been cooling off since the 19th century when 98.6 was established as “normal.”Research published last week in eLife, shows body temperature has not only dropped since German physician Carl Reinhold August Wunderlich’s study in 1851 established the average body temperature as 98.6 degrees, but it has also dropped since the 1970s.