Why does being cunning make people smarter?

"Flower-headed" is often used to describe treacherous schemes or people with treacherous intentions. For example, we often hear people say "so-and-so has a head full of flower-headed." Hey! How come our common language associates "brain" with "intestines" (Figure 1)?

Figure 1 Intestines in the stomach

You know what? The brain and the gut are really connected! They are both really related to the mind.

There is a huge network of neurons in our gastrointestinal tract, which is often called our " second brain ". It is located in our abdomen, so it is also called the " abdominal brain " or " gut brain " (Figure 2).

Figure 2 The “gut brain” in the stomach

The brain on top of the head weighs about 3 pounds, and the "gut brain" in the stomach weighs about 3-4 pounds. The weight of these two brains is similar, and their functions are not inferior to each other! The "gut brain" is located in the nerve plexus of the gastrointestinal wall. It is a very complex neural network containing about 100 billion nerve cells, which is equal to the number of cells in the brain, and the cell types, organic substances and receptors are extremely similar to those of the brain. The two "brains" correspond to each other, just like a pair of twins. As long as one of them feels uncomfortable, the other will also have a similar feeling.

In 1998, Professor Mike Gerson, an expert in anatomy and cell biology at Columbia University in the United States, proposed the "second brain" theory in his monograph "The Second Brain", thus establishing the discipline of neurogastroenterology. Professor Mike Gerson's research shows that the nervous system in the intestines can perceive, receive signals, and respond independently of the brain, making people feel happy or uncomfortable, and can even participate in intellectual activities such as learning like the brain.

Professor David Wingott, consultant of the Royal Hospital of England and gastrointestinal expert of the University of London, said: The two brains in the human body are formed with the process of biological evolution. The original nervous system is divided into two parts: the brain nerve center and the gastrointestinal nervous system . They maintain a loose connection through the vagus nerve system, and the vagus nerve system sends only a small part of the information of the brain nerve center to the intestinal nervous system; in most cases, the "second brain" independently performs its own functions and is very sensitive and direct to emotions. For example, the function of the internal anal sphincter is not controlled by the brain, but it actually functions under the control of the "intestinal brain"; not only that, the entire digestion, absorption, and excretion process are all carried out independently under the control of the "intestinal brain". For example, when you are angry, you will have abdominal distension and pain, when you are sad, your appetite will decrease, when you are nervous, you will have abdominal pain and diarrhea, when you are hungry, you will lose your temper, and after a feast, you will feel satisfied, etc., which are all related to the nerve perception of the "intestinal brain". With the evolution of life, the nerve center has been developed and improved. Since a series of survival activities such as foraging and mating constitute the main content of animals' lives, the role of the intestinal system is particularly important. However, all of this must be commanded by the brain, and the distance between the "control station" and the "position" seems to be a little far. For advanced animals, this requires the intestinal nervous system to be able to exercise command and control functions relatively independently. This actually reveals the mechanism of the formation of the "second brain".

Researchers have long known about the complex network of the " gut-brain axis " (Figure 3), which connects intestinal function to the emotional and cognitive centers of the brain. This two-way communication system is regulated by neural activity, hormones, and the immune system. The most common example is that when pain occurs in a certain part and painkillers are used, the pain is often relieved, but dizziness, nausea, and vomiting occur - dizziness is a reaction of the brain, while nausea and vomiting are reactions of the gastrointestinal tract; in the modern society with a fast pace of life and high work pressure, nine out of ten people have experienced or are experiencing gastrointestinal discomfort. There is also a saying among the people that "nine out of ten people have stomach problems." Happiness, anger, worry, sadness, fear, and shock, these emotional and intellectual activities are not only related to the brain, but also to the gastrointestinal tract.

Figure 3 Gut-brain axis network system

The latest research shows that the intestinal flora living in the digestive tract can achieve two-way communication and interaction with the brain through the intestinal flora-gut-brain axis . On the one hand, emotional changes can cause structural changes in the intestinal flora by activating the intestinal immune system; on the other hand, the intestinal flora can affect the structural and behavioral changes of the brain through multiple pathways such as acting on the vagus nerve, immune system, and endocrine system. Therefore, the intestinal flora-gut-brain axis is a new pathway for two-way communication and interaction between the intestinal flora and the brain .

Clinically, it has been found that many digestive system diseases are closely related to mental factors, such as functional dyspepsia and irritable bowel syndrome, which seriously affect people's quality of life and work efficiency. The aggravation of symptoms of patients with ulcers or the occurrence of complications such as bleeding and perforation often occur after people's emotions are hit. When people suffer from anxiety, impatience and Parkinson's disease, they can cause abnormal symptoms in the "brain" and "gut brain". In patients with Alzheimer's disease and Parkinson's disease, the same tissue necrosis is often found in the head and abdomen; patients with mad cow disease usually have mental disorders due to brain damage, and at the same time, the intestinal organs are often extremely damaged. Those who are cheerful, open-minded and tolerant have a low incidence of stomach diseases. For thousands of years, Chinese medicine has touched on the relationship between intestinal health and human health, and even mentioned the situation of "fecal toxins entering the blood, and all kinds of diseases arise".

Wisdom and loneliness appear to affect the diversity of intestinal microbes, and the latter also appears to have an impact on the former, according to a new study by researchers at the University of California, San Diego School of Medicine, published in the journal Frontiers in Psychiatry on March 25, 2021. Their results found that lower levels of loneliness and higher levels of wisdom, compassion, social support, and engagement were all associated with greater phylogenetic richness and diversity in intestinal microbial communities. Reduced microbial diversity generally represents poorer physical and mental health and is associated with a variety of diseases, including obesity, inflammatory bowel disease, and major depressive disorder. The relationship between loneliness and microbial diversity is particularly evident in older people. Loneliness may lead to changes in the intestinal microbiome; similarly, a deterioration in the intestinal environment may make a person lonely.

Although humans are made up of billions of incredibly coordinated human cells, these cells are easily outnumbered by the bacteria that live on and in our bodies, adding an extra 2kg to our body mass. These bacteria are not just freeloaders; many actively help us digest our food and prevent infection. More importantly, these microbes have a profound impact on the brain.

Scientists have shown through animal and human experiments that intestinal microbial populations do affect brain function . The human intestinal microbiome is composed of trillions of microorganisms residing in the digestive tract - bacteria, viruses, fungi. The bacteria in the intestines can help normal brain development; without the presence of microbial populations, the structure and function of the human brain will undergo major changes.

Why can bacteria in the gut affect the brain? Information about what the body senses is transmitted between organs in several different ways. Information may be transmitted through hormones in the blood, immune cells, or the vagus nerve, which runs from the brain to the gut. Through these pathways, the behavior of one organ can affect another.

So, can we adjust these microorganisms to make us healthier, happier, or even smarter? The answer is yes. Diet may be the biggest factor affecting the composition of the intestinal microbiome. A diverse diet will give you a diverse microbiome (Figure 4). Studies have found that IQ is related to the intestinal flora during infancy. What affects IQ is not the number of intestinal flora, but whether the flora combination is optimal. Generally speaking, infants have the most bifidobacteria in their intestines. And bifidobacteria mainly come from the mother, so the mother's intestinal flora affects the baby's IQ. This also corresponds to the folk saying: "Children's personality follows their father, and intelligence follows their mother", "Nephew (intelligence) is like his uncle" (because it is inherited from the mother).

Figure 4 Diverse microbial populations in the “intestinal tract”

In daily life, if you want to be a winner in life, you should compete with your intestinal flora from birth; intestinal flora can also determine the quality of your future life . Maintain a positive, optimistic, tenacious, hardworking, scientific and pragmatic attitude towards life, eat more variety, and the intestinal flora will be more diverse. Only then will the "colorful intestines" grow and develop more easily, and people will be smarter ! I wish you all have a "colorful intestines"!

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Flowery intestines