Amerika

DNA increasingly looks like a Scantron form that we pass over reality and then look to see which options have been checked. Certain environmental influences trigger genes to express themselves more strongly or weakly.

At the forefront of research, scientists are looking at our gut microbiome, or the collection of organisms that live in our intestines and help us break down food. They also produce useful chemicals, like B vitamins, from the fermenting process.

While it kind of grosses us out to talk about it, we are basically long tubes that consume food, turn it into slime, and then compost it in our intestines in order to efficiently harvest nutrition, and we could do none of this without billions of little organisms.

It turns out that our gut microbiome, in addition to making us survive, triggers genetic conditions so that we respond to our food sources. Among other things, different microbe species can trigger muscle differences:

The relative abundance of Roseburia inulinivorans, but not other Roseburia species, was positively associated with multiple strength measures including handgrip, leg press and bench press in humans. Supplementation of R. inulinivorans in mice significantly enhanced forelimb grip strength, whereas other Roseburia species had no effect. Metabolomic analyses revealed that R. inulinivorans reduced amino acid concentrations in the caecum and plasma, while activating the purine and pentose phosphate pathway in muscle. These changes coincided with increased muscle fibre size and a shift from type I to type II fibres. Accordingly, we observed that the relative abundance of R. inulinivorans is lower in older adults compared with young adults.

R. inulinivorans emerges as a species-specific modulator of muscle strength, linking gut microbiota to muscle metabolism and function. These findings support its potential as a probiotic candidate for nutraceutical interventions targeting age-related muscle-wasting diseases.

If you add one type of microbe to the microbiome of a mouse, its muscles grow differently and it becomes stronger. By the same token, if you remove that microbe from a human, it will become weaker.

Our microbiomes are complicated recipes, like formula, in which the right organisms in the right balance must be there for our traits to develop correctly. If something interrupts them, we lose abilities.

As a side note, antibiotics seem to kill off the gut microbiome, meaning that we become different people afterwards. Doctors are treating some diseases with fecal transplants which introduce missing parts of the microbiome to those who have lost those fauna.

We may be under constant assault and losing what we have, since our gut microbiome is changed by our social group because whoever is around us breathes on us and we pick up their microbes:

Animals are home to diverse bacterial communities that can affect their hosts’ physiology, metabolism, and susceptibility to disease. Here we highlight recent research that reveals surprising and important connections between an individual’s microbiome and its social behavior. We focus on two recent discoveries: (i) that social interactions can affect the taxonomic and genic composition of animal microbiomes, with consequences for microbiome function and potentially host fitness, and (ii) that microbiomes can affect host social behavior by producing chemical signals used in social communication and by directly influencing host nervous systems.

There are probably other less savory ways that microbes spread as well, but since you know these are intestinal microbes, you can let your feverish imaginations loose on that mental image. All smells are particulate.

When you are in a workplace with people where they are breathing, coughing, sneezing, and otherwise emitting mouth and intestinal microbes, your body absorbs those and adds them to your microbiome. You become more similar to those around you through gut genetics.

Microbial sharing of this nature, like a feces transplant, gradually alters your gut microbiome to be like that of your social group:

Using both species-level and strain-level data, we show that microbial sharing occurs between many relationship types, notably including non-familial and non-household connections. Furthermore, strain-sharing extends to second-degree social connections, suggesting the relevance of a person’s broader network. We also observe that socially central people are more microbially similar to the overall village than socially peripheral people.

Even better, as this points out, the more popular you get, the more your microbiome becomes similar to that of everyone around you. The gut microbiome transplants occur as an inherent part of being around other people.

If those people are from another ethnic group or race, they have different gut bacteria, because they are adapted to different conditions and therefore need different gut bacteria. Your traits will be changed by their traits through the changing gut microbiome, which can spread across continents once introduced anywhere in the country:

The researchers also uncovered evidence that particularly competitive bacterial populations can spread rapidly across large geographic distances. In some cases, these populations appear to have expanded across continents within only a few decades.

Patterns like this have previously been observed mainly among pathogens, making the finding especially notable for ordinary gut bacteria.

“Our findings show that gut bacteria are also more dynamic than previously thought. Well-adapted strains can spread internationally and occupy new ecological niches,” says study leader Martin F. Polz from the University of Vienna.

The results suggest that the gut microbiome may be shaped by more than diet, medication and lifestyle. Transmission between people could also be an important force influencing which bacterial populations become established and spread.

Now consider another interpretation: microbes spread deleterious traits as well as positive ones. For example, microbe transfers from smaller organisms can induce lower intelligence, where higher organisms bring greater intelligence.

This shows us the power for social microbe transfer to make a community smarter or dumber, depending on the donor animal brain size (paraphrasing this paper):

Mice that received microbes from large‑brained primates showed higher expression of genes involved in energy metabolism and synaptic plasticity — the core processes that let neurons fire efficiently and rewire with learning. Those given microbes from smaller‑brained macaques showed a different pattern entirely.

The researchers also noticed something more unsettling. Mice colonized with microbes from smaller‑brained primates showed brain gene expression patterns that overlapped with signatures seen in conditions like ADHD, schizophrenia, bipolar disorder, and autism.

Previous human studies have repeatedly linked gut microbiome differences with these conditions, but most of that evidence has been correlational. Here, the transplant experiments suggest a more causal role: changing the microbial community alone was enough to push developing brains toward or away from gene programs associated with altered neurodevelopment.

The authors suggest that if developing human brains are exposed to the “wrong” mix of microbes at critical windows, their wiring and function may shift in ways that show up later as cognitive or behavioral differences.

If you are surrounded by genetically foreign people, by nature their gut microbiome is different than yours. It is being absorbed by your body, however, which means that it will displace some of what you need and also change other gene expressions.

You will become more like the dissimilar organisms among you, thanks to their different gut microbiomes.

This could lead to radical differences in brain function as the microbiomes of the world merge, cancel each other out, and cause traits to drop out of the general population of the first world:

Between 2015 and 2025, reading skills have seen the most significant decline, decreasing by 28 points in OECD countries, and by 16 points in the other participating countries and economies.

Scores in math have dropped by 22 points across the OECD on average, compared to a decline of 8 points in the rest of the world.

In science, the focus of the 2025 PISA assessment, a seven-point decline was measured in OECD countries, while the performances in other countries and economies remained broadly stable.

There are many sources for the competence crisis in the first world, but it is increasingly looking like microbiome chaos, brought on by having people of different ethnicities living around you.

Tags: diversity, genetics, gut microbiome