What does the average human body temperature mean for physiological function, as it decreases year by year?

Beijing time on February 20, according tomedia reports, 37 degrees Celsius is a very important number. Clinical lygo and medical textbooks regard 37 degrees C as the “normal” average temperature of the human body. But a new study suggests that the average body temperature in the United States has now dropped, and researchers think they may know why.

What does the average human body temperature mean for physiological function, as it decreases year by year?

Infographic

Measurement of average body temperature

In 1851, a doctor in leipzig, Germany, called Carl Reinhold August Wunderlich, set a temperature standard of 37 degrees Celsius (98.6 degrees Fahrenheit) for the first time after collecting information on the temperature of about 2,500 people. “He took the temperature of the people he could find, whether they were healthy or not, and wrote a book about the link between body temperature and disease. “Dr. Parsonnett, senior researcher in the study and professor of medicine and health research and policy at Stanford University, said: “It’s not a good thing that we’re going to be working on. Julie Parsonnet. Mr. Windrich’s study also highlights changes in body temperature by sex, age, weight and height, “and his conclusions are almost entirely correct, suggesting that he must have spent a lot of time studying these body temperature data.” “

Since Windrich’s pioneering work, doctors have still used body temperature as one of the key signs to judge someone’s health. Now we know that body temperature can fluctuate up to 0.2 degrees Celsius in a day, young people tend to have higher body temperatures than older people, and women tend to have higher body temperatures than men, depending on the menstrual cycle. In addition, the body’s body temperature is affected by the weather, body activity and eating conditions.

But why does human body temperature generally fluctuate around 37 degrees?

There is evidence that the body maintains a relatively stable body temperature to ensure the smooth functioning of many organs and chemical reactions in the body, as well as to prevent fungal infections. But according to a new study published on January 7th, the ideal temperature may no longer be 37 degrees Celsius. The average Body Temperature in the United States has been dropping since the early 19th century, by about 0.02 degrees Celsius every 10 years. The average temperature of American men born in the 21st century is 0.58 degrees Celsius lower than that of American men in the early 19th century, and that of American women born in the 21st century is 0.32 degrees Celsius lower than that of women born in the 1890s. The question is, why is this happening?

Cold and hot

As an infectious disease researcher, Parsons spent years studying a bacterial infection caused by Helicobacter pylori. Helicobacter pylori can cause esophagus, stomach and small intestine ulcers, and also increase the risk of stomach cancer. However, the rate of H. pylori infection in the United States has declined in recent years.

“I’ve been studying Helicobacter pylori for 30 years, so I’m well aware that fewer people are infected with the bacteria in the United States. “This change reflects a larger trend: modern humans are much less likely to develop infectious diseases than people living in the 19th century. People in the 19th century may suffer from a range of problems such as malaria, long-term wounds, tuberculosis, dental disease, dysentery, etc., but these bacteria are rarely found in modern humans, and the immune system does not need to be overloaded at all times.

And Parsons wanted to find out how the decline in microbes in the body gradually alters the body’s physiological functions. To do this, she and the study’s co-authors analyzed data from data groups dating back to the American Civil War, the 1970s and early 2000s, with a total of more than 677,000 records.

It turns out that the average body temperature of humans has been dropping for years. To rule out the interference of thermometer advances against data, the researchers also analyzed trends within each data set. The results showed that there was a downward trend in body temperature in each data group, regardless of the thermometer used.

“Humans have been evolving over the years, and a lot has changed physically. “Modern humans have become less hypothermia than humans in the 19th century and the last century, Parsennett said. “

Why is this important?

The findings echo those of a 2017 study in the UK. The British study analysed 250,000 temperature records from more than 35,000 patients and found that the average temperature in the UK was 36.6 degrees Celsius, a significant drop from the “normal” average of 37 degrees. It seems that human body temperature is indeed falling, but what does this mean for human physiology?

Mr Parsons said it remained an open mystery. “We haven’t figured out how the lower body temperature affects human health and longevity. “

The decrease in body temperature may reflect a decrease in the prevalence of infection. This trend significantly reduces the incidence of inflammation in the body. Inflammation produces a protein called cytokine, which accelerates the body’s metabolism, which in turn produces heat.

In addition, unlike our ancestors, many people today live in temperature-controlled environments. “We don’t have to bother keeping our body temperature constant because the temperature in the room is always in the 20s. “

Of course, the temperature of residents of other countries may be very different from that of britain and the United States. For example, a 2008 study showed that the average temperature of Pakistanis is still floating around 37 degrees Celsius. But small differences in body temperature in different groups of people do not affect the body’s physiological function.

This may affect the function of microorganisms in the body, but we don’t know much about it. Mr Parsons said. Personally, only drastic changes in body temperature represent health problems, such as fever or hypothermia. Overall, the average body temperature may continue to decline as medicine advances and life expectancy increases.

Parsonst also noted that body temperature is “an indicator of levels of inflammation in the body.” If the average level of a group can be measured, it may be possible to predict its life expectancy. Life expectancy and body temperature may level out for a long time to come, she added.