Over the past century, the median body temperature for humans have body temperature slightly declined. Scientists attribute this to a slowdown in metabolism with the modern and comfortable living conditions we have today.
If you search for “normal body temperature” in a search engine you will get the result 37°C or 98.6°C. But it seems that this classic figure is out of date. This conclusion comes from Julie Parsonnet and her colleagues at Harvard Medical School, and they published an article in eLife magazine about the change.
The median”healthy” body temperature term was coined by German physician Karl Wunderlich in 1851. However, data from recent years shows that the median body temperature is less than what the scientific community accepted back then.
Scientists associate the recent findings with environmental changes caused by the industrial revolution in the recent centuries, and changes to human physiology related to it.
Scientists examined three extensive sources of information about body temperature measurements in US residents from different historical eras – medical records of Civil War veterans (1862-1930), data from the first National Health and Nutrition Study (NHANES, 1971-1975), and also a file cabinet at Stanford University Medical Center (2007-2017).
The authors summarized more than 677,000 individual temperature measurements. After statistical processing of these data, the downward trend was confirmed. Calculations showed that normal body temperature of a human is decreased at a rate corresponding to 0.03°C or 0.05°F per decade.
Of course, these results can also be associated with the improvement of temperature measurement technologies. However, by dividing the participants of the first sample by age, scientists found exactly the same decrease, although all measurements were carried out with the same tools available at that time.
Scientists attribute this trend to a general decrease in metabolic activity. In their opinion, the development of hygiene and medicine, the availability of food and domestic comfort led to the weakening of the chronic inflammatory processes. The development of heating systems in homes has also reduced the normal energy needs of the body, and as a result, its temperature.
The team from Stanford, found that the median body temperature of men who was born in the 2000s was on average 1.06°F lower than men who was born in the beginning of 1800s. Same applied for women that was born in the 2000s, body temperature was on average 0.58°F lower than the women born in the 1890s.