Bacteria determine people's lifespan?

The bacteria that live in and on the human body may have evolved towards reducing the number of elderly people in the population, according to a new study.

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According to scientists' calculations, the number of bacterial cells in a human body is 10 times greater than the number of cells of that person. In recent years, researchers have discovered that this microbe has a huge effect, from regulating weight gain, mood to cognitive function.

Dr. Martin Blaser, a microbiologist at the Langone Medical Center, New York University (USA), began to doubt the effects of bacteria on the age structure of people. He found that Helicobacter pylori can live in the human intestine for decades without causing any harm to them, but can also cause stomach ulcers and stomach cancer - a risk. muscle increases with age.

According to researchers, bacteria may have evolved in favor of young people.(Photo: Thinstock)

"I began to think that symbiosis is really a creature that keeps you alive when you're young and kills you when you get older. It's obviously not good for you, but good for species," Dr. Blaser said.

To examine the effects of microbes on people as they age, Blaser and his colleagues created a mathematical model to simulate a group of hunters - gatherers living in ancient times.

In this model, the research team assumes that the group has the maximum life expectancy equivalent to modern people today, about 120 years old; Although ancient hunters and gatherers actually have a lower life expectancy than us due to many factors, such as childhood illnesses, incurable body wounds and new bacterial diseases. can be cured with antibiotics.

The research team divided the simulated subjects into 3 groups: young people, people of reproductive age and those who are over-age. Then, they observed how this population group changed based on differences in fertility and mortality.

To record the effects of bacteria, they manipulated fatal factors associated with different types of bacteria. For example, in a version of the model, they increase the popularity of Shigella, a bacterium that causes food poisoning and can kill young children. That made the population fall.

In another version, the team increased the effects of Helicobacter pylori and found that it created a stable population with fewer elderly people. They discovered that this situation allows minors to enjoy more share of food and resources, facilitating population growth and stabilization. In contrast, H. pylori-free populations have a higher proportion of older people and gradually decline in population.

The team concluded, bacteria may have evolved to attack older people in the population. This phenomenon is not only beneficial for human populations, but also for the bacteria itself because they depend on stable host supplies.