Have you ever thought it would be cool to live in outer space on a planet other than Earth?
Well, new research suggests that this fantasy is impossible for a large portion of the population. Scientists from the UK’s University of Manchester, Netherlands, and Germany have determined that the circadian rhythm of animals relies on the rotational speed of the Earth. Their study is the first to determine the value of having an internal body clock that is in tune with Earth’s 24-hour interval rotation.
The researchers compared normal mice with 24-hour circadian rhythms to mice with a gene variation causing them to have 20-hour circadian rhythms. These mice, initially equal in number, were released into outdoor pens with access to food and water. Over a period of 14 months, the researchers reported that the population of mice with 20-hour circadian rhythms gradually reduced in number until the normal mice outnumbered the mutant mice in a 4:1 ratio. The researchers hypothesized that the mice with a 20-hour circadian rhythm were not as physically fit as the mice with normal circadian rhythms; as a result, the number of these mice gradually diminished. These results support previous research that showed an association between people who have abnormal body clocks, because of insomnia or late-night work shifts, and the chance of developing diseases such as type-2 diabetes.
Image Source: Fanatic Studio
Professor Andrew Loudon from the University of Manchester added that “a correctly ticking body clock is essential for normal survival in the wild, and this has to be in phase with the rotation speed of the earth.” Additionally, he mentions, “Animals with clocks that do not run in synchrony with earth are selected against … thus, the body clock has evolved as an essential survival component for life on earth.” Circadian rhythms influence many aspects of the human body. Without an internal clock that matches this 24-hour interval, sleep cycles, hormone balances, body temperature, and various other bodily functions suffer.
These results impose a challenge for future space exploration or colonization. Even if a hospitable planet were discovered within human reach, humans may not be able to survive there in the long term. For instance, the Martian day is only 37 minutes longer than that of Earth’s, but Professor Loudon proposes that “the rotation speed of Mars may be within the limits of some people’s internal clock, but people with short running clocks, such as extreme morning types, are likely to face serious intractable long-term problems and would perhaps be excluded from any plans NASA has to send humans to Mars.”
Feature Image Source: Statue of Abu Rayhan al-Biruni by David Stanley
