The Role of the Microbiome in What Makes Us Unique

Everything that exists contains information. What gives identity to things is information. For example, a rock has information about its appearance traits, elements, and molecules that formed it, giving it its distinctive entity. However, environmental factors also impact its appearance, such as its color, shape, and dimensions. In thermodynamics, increasing entropy leads to increasing disorders and decreasing information. Living beings seem to contradict the second law because living organisms exhibit high levels of order and complexity. Living beings, apart from their physical characteristics, exhibit a plethora of traits that define their existence. For instance, a frog embodies intricate information such as its species, gender, life cycle, feeding habits, and more.

Genetics determines the main information of living things

Like other entities, some of this information is stored in atoms and molecules that form living organisms. However, the complexity of living things, particularly mammals, indicates that they should possess a wealth of information. The vast amount of information in humans compels us to consider additional systems to preserve it. Like all other living organisms, humans contain genetic material (DNA or RNA) that stores the necessary information for their growth, development, and function. This information contains instructions for making proteins and controlling biological processes. The genome is the primary source of the necessary information to make a living being.

However, genetics cannot display the complete information of living beings, especially complex mammals. Studies on homozygous twins have revealed that the same genome may not result in identical individuals. When these twins are separated early in life, they exhibit very different biological and psychological traits, despite sharing the same genome. This indicates that environmental factors influence the genes to express their phenotypes.

Living organisms continuously interact with their environment and gather information about environmental conditions, such as temperature, light, humidity, and nutrients. This information helps them react appropriately. Particularly, the impact of environmental factors on personality characteristics is intriguing. Epigenetic information includes chemical modifications of genetic materials that affect gene expression without altering the DNA sequence itself. This process is influenced by environmental factors and experiences. Environmental-associated epigenetic marks are another level of information in living organisms.¹

Also, all living organisms have complex networks of chemical reactions that enable them to absorb energy from their environment and engage in vital activities. These processes involve the conversion of food into energy and are conducted with enzymes that are products of genes. In organisms with a nervous system, information is transmitted in the form of electrical and chemical signals. This information allows organisms to respond to environmental stimuli and display complex behaviors. In the case of humans, traits such as their thoughts, mindsets, habits, behaviors, beliefs, and personalities in general contribute to the vast amount of information required to manifest these traits.

The central nervous system in complicated animals provides another level of information storage

In humans and perhaps other complex mammals, the brain's connectome provides vast information and determines patterns of behaviors, decisions, thoughts, and feelings. The connectome, which is the whole map of neural connections in the brain, evolves throughout life through learning, experiences, and perceptions. Because these connections are unique to each individual, akin to a brain's fingerprint, they may elucidate the distinctive characteristics of each person. The uniqueness of each person's connectome motivates some scientists to explore this map, upload it to a supercomputer, and recreate the information and identity of the connectome owner. However, this theory overlooks the impact of the genome and the variable environment, which influence both gene expression patterns and connectome shape.²

The microbiome is a third factor that determines our characteristics

The human microbiome, comprising trillions of microorganisms (such as bacteria, viruses, fungi, and archaea) residing in and on our bodies, plays a vital role in numerous aspects of human health and offers valuable insights into our biology. Here are some essential ways the microbiome contributes to our comprehension of human health. In addition to its impact on the immune system, digestive system, and metabolism, the gut-brain axis refers to the two-way communication between the gut microbiome and the brain. The microbiome can generate neurotransmitters and other compounds that influence mood and cognition, offering insights into conditions such as depression and anxiety.

Despite a large amount of data about the reciprocal of the microbiome and the brain through the gut-brain axis recently, to avoid doubt about the real effect of gut microbiota in physical and mental states, we should perform controlled experiments directly on humans.

How do we determine the extent to which our informative traits originate from microbes that reside in our body symbiotically but are not part of our body?

Antibiotics provide insight into the crucial role of the microbiome in shaping our identity

Many findings about the microbiome are derived from animal studies due to the challenges of conducting human clinical studies. However, antibiotic consumption provides insight into the role of the microbiome and the balance of gut microbiota in physical and mental health. Antibiotics can disrupt the normal gut flora and destroy some types of microbes, including beneficial bacteria. They impair the balance of bacteria in the gut, a condition known as symbiosis. This imbalance may lead to issues such as diarrhea and opportunistic infections.

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Studies have shown that antibiotics can lead to psychiatric side effects, specifically depression and anxiety. This is due to their off-target effects, particularly through the brain-gut-microbiota axis. Antibiotics can decrease gut microbial diversity, which is linked to a higher risk of depression. Some antibiotics, like isoniazid and minocycline, have been recognized for their potential antidepressant effects. These findings also address the long-term consequences of early-life antibiotic exposure, connecting it to conditions like obesity, asthma, allergies, and attention-deficit/hyperactivity disorder in later life, mediated by the brain-gut-microbiota axis.³

The media is full of news about the microbiome's role in physical health, specifically mental states. Understanding how much of our emotions, thoughts, and behaviors are truly linked to microbiome diversity is important. It seems that beyond genetics, environmentally related epigenetics, and brain circuit networks, the microbiome signature significantly influences our personality and identity. Therefore, the microbiome should be considered the third store of identity information.

Humans carry incredibly complex information. Each person possesses unique information. With more than 8 billion people currently living in the world and the billions who have lived before, it becomes evident that no two individuals are alike, showcasing the remarkable complexity of humans. Therefore, the existence of additional information repositories may cast doubt on the feasibility of transferring a person's mind, encompassing their memories, personality, and cognitive functions, from their biological brain to a digital medium.