Human body is gradually cooling down:37°C is no longer normal temperature

About 150 years ago, the average human body temperature was higher than it is today. A temperature of 37 degrees Celsius was then considered the standard for normal body temperature. Several studies now show that the average body temperature of a healthy person has fallen to about 36.4 degrees Celsius. According to BBC reports, scientists are trying to understand the reason. Were temperatures measured inaccurately in the past, or has better health and a changing lifestyle led to a decline in body temperature? Experts say both factors could be responsible. Who considered 37 degrees a normal temperature? In the 1860s, German doctor Carl Wunderlich studied fever and body temperature. He measured the temperatures of 25,000 patients over about 15 years. He collected more than 10 lakh readings from them. Based on this data, he reported the average temperature of healthy adults as 37 degrees Celsius, or 98.6 degrees Fahrenheit. Temperatures above 38 degrees were considered a sign of fever. They had a large amount of patient data. This is why 37 degrees became the standard for normal body temperature. Why is the average body temperature lower today? A team led by Julie Parsonnet, an infectious disease specialist at Stanford University, studied temperature-related data from around 1.90 lakh people in the United States. The data was collected between 1862 and 2017. According to the research, the average temperature of American adults today is around 36.39 degrees Celsius. The temperature of American men has fallen by around 0.59 degrees compared with the beginning of the 19th century. This change is not limited to developed countries. The average temperature of the Tsimane community living in the Amazon rainforest was 37 degrees in the early 2000s, but had fallen to 36.5 degrees by 2018. Their way of life also changed during this period. Three reasons for the fall in body temperature Was there an error in measuring temperatures 150 years ago? Experts examined the glass thermometer used during Wunderlich’s time. According to them, this thermometer may have recorded temperatures around 2°C higher than modern instruments. At that time, mercury thermometers were around 30 centimetres long and took 15 to 20 minutes to measure temperature. Wunderlich measured temperature by placing the thermometer in the armpit, whereas temperatures are generally taken orally today. Therefore, it is difficult to make a direct comparison between the old and new figures. Why do scientists consider the old figures accurate? Experts also studied the temperature records of American soldiers from 1862 to 1930. The average temperature of those born earlier was found to be higher than that of those born later. Two other data sets collected between 1971 and 2017 showed the same trend of declining temperatures. This suggests that the decline was not caused solely by old thermometers. What four factors affect body temperature? Is 37°C the right temperature to consider normal? New research has raised questions about considering 37°C the sole standard for normal body temperature. Some medical books and healthcare databases have also incorporated newer average temperature figures. However, experts say that a person’s health should not be assessed on the basis of a single reading. Age, the time of day and the person’s general condition must also be taken into account. Body temperature can vary from person to person and at different times of the day.