Scientists at Stanford University have completed a study, and the study found that since the 19th century, the average human body temperature had dropped in the U.S. One researcher says that our temperature isn’t what people think it is. Julie Parsonnet, MD, says that we grew up learning that 98.6 degrees is our normal body temperature is wrong.
The 98.6F number was established by a German physician Carl Reinhold August Wunderlich in 1851. Modern studies suggest that the number is too high. A more recent study found that the average body temperature for 25,000 British people averaged 97.9 F.
The researchers say that they have explored the body temperature trends and concluded that the temperature changes are a true historical pattern rather than measurement errors or biases. The researchers propose that the decrease in body temperature is the result of changes in the environment over the past 200 years.
Data used in the study came from several data sets covering distinct historical periods. The last set was of data between 1862 and 1930 from Union Army veterans of the Civil War. Data from the U.S. National Health and Nutrition Examination Survey I contains data from 1971 to 1975. The final data was gathered from 2007 through 2017. The data held 677,423 temperature measurements.
The team found that the average body temperature of men born in the 2000s was, on average, 1.06 F lower than men born in the early 1800s. For women born in the 2000s, body temperature was on average 0.58 F lower than women born in the 1890s. The team says that the reduction in temperature could be due to a reduction in metabolic rate due to a population-wide decline in inflammation. The team also thinks that comfortable lives at a constant ambient temperature, thanks to central heating and air, could contribute. General access to medical treatments and better food could also contribute.