98.6 Is Not Normal

The assertion that 98.6F is the normal body temperature was based on research done in 1851.

A new study indicates that:

  • Average body temperatures have decreased by a little more than 1 degree between 1851 and 2020;
  • That body temperature readings are affected by age, gender, body mass, and time of day. Thus “normal temperature” is a range, not a number.

A decline in the rate of metabolism is probably the cause of a decline in body temperature. This in turn could be the result of reduces rates of inflamation and better or more consistent home heating.


  1. Myroslava Protsiv, Catherine Ley, Joanna Lankester, Trevor Hastie, Julie Parsonnet. Decreasing human body temperature in the United States since the industrial revolution. eLife, 2020; 9 DOI: 10.7554/eLife.49555
  2. Stanford Medicine. “Human body temperature has decreased in the United States.” ScienceDaily. ScienceDaily, 8 January 2020. <www.sciencedaily.com/releases/2020/01/200108090328.htm>

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