Is there always another human being in you?

Once upon a time, your origins were explained very easily. Your father met your mother, they had a little fun together, and from a tiny egg fertilized, you screamed and cried in harmony with the world. You are half of your mother, half of your father - that's 100% of you.

Is there always a second person in each person?

But, this simple story has become much more complicated. In addition to the genes from parents, you are also a reservoir of viruses, bacteria - and most likely components of other people.

Indeed, if you are a twin, your body and brain are very easy to contain something from your twin. The strange thing is, they can affect how you act.

"People are not separate personal entities, but super-institutions, organizations , " said Peter Kramer of the University of Padua (Italy). " There are many other human and non-human factors (factors) that exist and struggle within our bodies."

Recently, Mr. Kramer wrote an article in Psychological Science, calling on psychologists and psychiatrists to study this issue, to assess how they affect the behavior of we.

This may sound scary, but we have long known that our bodies are a mess of different organisms and bodies. For example, bacteria in the gut can produce transmitters that change your mood; Some scientists even argue that these bacteria make you "greedy" , craving for the foods that bacteria love.

In nature, the bacteria act on the rat's brain, causing the mouse to become attracted to cats, and in turn, after eating rats, the cat's body becomes a new shelter for the regenerating bacteria. People can also be infected and controlled like this, such as bacteria that seem to make someone risky, thereby increasing the likelihood of being schizophrenic or depressed and suicidal.

In the past 6 years, photographer Ariko Inaoka has always captured a special connection between the twins of Iceland, Erna and Hrefna.

This is to say that our actions are not entirely decided by us. Of course, you will doubt the so-called identity of each person , but the penetration of external factors influences the action, our personality is even more bizarre when you realize that, Your brain is not only affected, invaded by tiny bacteria - but also affected by others.

The most obvious example is the case where conjoined twins share a brain, says Kramer, but even normal twins can "share" organs, even though they Don't really realize this. During the fetal period, cells can travel between twins or triplets.

Once viewed as a rare phenomenon, now statistical science has shown that it is common: there are about 8% of twins and 21% of births have not only one but two blood types: A blood group is produced by their own cells, and a blood group is produced by the cells "alien" absorbed from their twin. In other words, this sharing can happen in many different agencies, including the brain.

A combination brain like this can have serious consequences. For example, we know that the arrangement of brain regions is important for its function - but the presence of the foreign tissues containing different genes has different "intrigues" , and there are can make the brain design fall into chaos. This may explain why twins are rarely as right-handed as most people. Perhaps the existence of "two people" in a body has broken the balance in the brain hemispheres.

Growing up together in a fetus, twins often have special sharing about cells.

Even if you don't have twins, you can still get into other people's cells. For example, when you are formed in the womb, you may be one of two fetuses in the uterus at the time, but during the initial development, the twins are combined. Because it occurs in the early stages of pregnancy, everything seems to grow normally, even though the fetus itself contains the genetic characteristics of another person.

"You look like just one person, but you have another person's cell inside you - in fact, there are always two people who exist in you," Kramer said. In some cases, a woman was surprised to be told that she was not the biological mother of two children she was born with. The reason is, the cells of another sister existed in this woman's body, and they managed to get into the fetal body when the woman was pregnant.

Even Lee Nelson, from the University of Washington, discovered that even as an adult, you can get inside your body. A few years ago, Nelson and William Chan of the University of Alberta in Edmonton studied women's brain tissue and discovered about 63% of male cells.

"We found not only male DNA in the female brain, but also found them in many brain regions , " Chan said. In other words, the brains of women in this study had cells from a man's body. In this case, the conclusion may be: when pregnant with his son, the son's stem cells sought to cross the placenta and reside in the mother's brain. Strangely, this seems to benefit the mother, helping the mother reduce the risk of Alzheimer's disease - although the exact reason is still a mystery. Some researchers have even begun to wonder if those cells can affect a mother's thinking during pregnancy.

Our knowledge of "super-bodies" in the human body is still very new, so many conclusions are still completely theoretical. Kramer's goal is not to give clear answers, but to emphasize to psychologists and neurologists about what determines who we are. "We cannot understand human behavior by considering only one individual," Kramer said. "Finally, we have to understand why we behave like that."

For example, scientists often compare twins to understand the origin of behavior, but in fact even identical twins can have each other's brain tissue. We need to be especially careful when using studies of twins to learn about cases like schizophrenia arising from the brain organism that is faulty, Kramer said.

However, in general we do not feel hatred towards those " strangers " who enter our bodies - because after all, these strangers have also contributed to making us human. "I think these natural immigrants stay with us for a long time, for better or worse , " Nelson said. And I think there are many "better" reasons than "worse".