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Home / Health / The average body temperature of healthy adults has dropped in the past 20 years-ScienceDaily

The average body temperature of healthy adults has dropped in the past 20 years-ScienceDaily



For nearly two centuries since the German doctor Carl Wunderlich set 98.6°F as the standard “normal” body temperature, parents and doctors have used it as a measure of fever (usually the severity of the disease) Evaluation.

However, with the passage of time, in recent years, the decrease in body temperature of healthy adults has been widely reported. A 2017 study of 35,000 adults in the UK found that the average body temperature was lower (97.9°F), while a 2019 study showed that the normal body temperature of Americans (in any case in Palo Alto, California) Person) is approximately 97.5°F.

A multinational team of doctors, anthropologists and local researchers led by Michael Gurven, professor of anthropology at the University of California, Santa Barbara and chair of the integrated anthropology unit on campus, found that Postdoctoral research also has a similar decline. Tsimane, an indigenous inhabitant of foraging horticulturists in the Amazon region of Bolivia. Researchers have been studying the population in the 1

6 years since Gurven, the co-leader of the Tsimane Health and Life History Project, entered the study population. They have observed a rapid decline in average body temperature-0.09°F per year, so today’s Tsimane body temperature is approximately 97.7°F.

Gulvin said: “In less than two decades, we have seen the same decline as the U.S. has declined in about two centuries.” Their analysis is based on 18,000 of nearly 5,500 adults. A large sample of observations and adjusted for many other factors that may affect body temperature, such as ambient temperature and weight.

The anthropologist’s research is published in the journal Scientific progress.

Gulvin said: “This illuminating study shows that since the Civil War, the normal body temperature drop in the United States has been carried out in a single population. It cannot explain why this drop occurred.” “But it is clear about humans. Certain physiological changes may occur. A major hypothesis is that over time, due to improvements in sanitation, clean water, vaccination and medical conditions, the number of people we are infected decreases. In our research, we can Performing the test We obtained information about the clinical diagnosis and biomarkers of infection and inflammation directly at each patient’s visit.

Gurven pointed out that although some infections are related to increased body temperature, adjusting for these infections does not account for a sharp drop in body temperature over time. He said: “We have used the same type of thermometer in most of our studies, so this is not caused by a change in the instrument.”

Kraft added: “No matter how we perform the analysis, the decline is still there. Even if we limit the scope of the analysis to less than 10% of adults who are diagnosed as fully healthy by doctors, we still observe that over time , The degree of body temperature drop remains the same.”

So, a key question is why both Americans and Tsimane’s body temperature drop over time. The large amount of data provided by the team in a long-term study in Bolivia addresses some possibilities. Gurven explained: “The reason for the decline may be the rise of modern healthcare and the reduction in the duration of mild infections compared to the past.” “But despite the overall improvement in health over the past two decades, Infections are still widespread in rural Bolivia. Our results show that reducing infections alone cannot explain the observed drop in body temperature.”

He went on to say that this may be because people are in a better condition, so their bodies may have less work to fight infections. Or more use of antibiotics and other therapies means that the infection time is shorter now than in the past. Consistent with this argument, Gulvin said: “We found that in the early stages of the study, a respiratory infection caused a higher body temperature than the most recent respiratory infection.”

Although the researchers found that even after analyzing the biomarkers of inflammation, the body temperature still temporarily drops, but more use of anti-inflammatory drugs such as ibuprofen may also reduce inflammation.

Kraft said: “Another possibility is that because there is air conditioning in summer and heating in winter, our body does not have to struggle to adjust the internal temperature.” “Although Timani’s body temperature does vary with the time of year and weather conditions. Changes, but Dimani still does not use any advanced technology to help regulate body temperature. However, they do have more opportunities to wear clothes and blankets.”

The researchers were initially surprised to find that there is no single “magic bullet” that can explain the drop in body temperature. Gulvin said: “This may be a combination of multiple factors, all of which indicate that the situation has improved.”

According to Gurven, the body temperature found in the United States was lower than expected and dropped over time, which caused many people to scratch their heads. Is it a fortunate? In this study, Gulvin and his team confirmed that body temperatures below 98.6°F were found outside the United States and the United Kingdom. “Tsimane in Bolivia lives in rural and tropical areas with very little public health infrastructure.” “Our research also shows for the first time that even in this tropical environment, body temperature has also dropped. In tropical environments, infections still account for Great morbidity and mortality.”

As a vital sign, temperature is an indicator of the physiological condition in the body, very similar to a metabolic thermostat. Gurven said: “We have known for some time that everyone does not have a universal’normal’ body temperature, so I suspect that our findings will affect how clinicians use body temperature readings in practice.” Despite fixing the temperature at 98.6°F, But most clinicians are aware that there is a certain range of “normal” temperatures. From the lowest temperature in the morning to the highest temperature in the afternoon, the body temperature may vary by 1°F throughout the day. It also changes after the entire menstrual cycle and physical activity, and decreases with age.

However, by linking improvements in broader epidemiological and socio-economic conditions with changes in body temperature, the study suggests that body temperature information may provide clues to the overall health of the population, as do other common indicators such as life expectancy . Gulvin said: “The temperature of the human body is easy to measure, so it can easily be added to routine large-scale surveys that monitor population health.”


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