What do we inherit? And from whom?

Our parents don’t just give us our genetics. They also give us microbes. Add on top of that the factors of epigenetics and environment that our parents give us and it makes one wonder about the complexity of it all.

Microbes are fascinating. Our entire life is dependent on them. And they make up a large part of our body mass. They don’t just impact our health but also our moods and who knows what else.

Or consider parasites. There is the toxoplasmosis gondii parasite which can have major impact on mammalian psychology, at least for rats and humans. Like rabies, toxoplasmosis changes behavior of the infected in order to spread the infection to others. These little buggers literally control your mind. Conniving clever creatures!

This gives a whole other perspective to parasite load. Parasites are more common in warm regions. It isn’t accidental that some of the poorest countries are also the warmest, as their populations have higher parasite loads. This effects both physical and mental health, stunting development and lowering IQ, among much else.

We’ve barely even researched this area. Most microbes and parasites remain unstudied. We have no clue what they do, good or bad. Most of the genetic material we carry in our bodies isn’t human, and that isn’t even including RNA with its bacterial origins. That should give you pause.

Anyway, genetics are only around 2% of the human genome, the rest being so-called Junk DNA, but scientists have come to realize it serves other purposes. By the way, viruses living in us like to snip out pieces of our DNA and mix them up, just for shits and giggles.

What all of this might mean genetically and epigenetically (i.e., across generations) is entirely up in the air. We live in a fascinating time of ignroance and discovery. Genetic determinists can put that in their pipe and smoke it.

On a positive note, this inheritance isn’t fatalism, as much of it can be changed as an adult. In particular, it should be relatively easy to improve gut health. Just introduce new microbes. And new foods that they like. Be sure your microbes are happy!

‘The Diet Myth,’ ‘The Good Gut’ and ‘The Hidden Half of Nature’
By Sonia Shah, NYT

“Using the improved detection capacity of genetic sequencing techniques, scientists have discovered that 100 trillion microscopic creatures live in and on the body, influencing everything from the intensity of our immune responses and our moods to our dietary preferences and propensity to gain weight.”

‘Infectious Madness,’ by Harriet A. Washington
By Meghan O’Rourke, NYT

“Indeed, a handful of researchers are wondering whether mental illnesses are really caused by our immune system’s response to powerful microbial infections. As Harriet A. Washington reports in her new book, “Infectious Madness: The Surprising Science of How We ‘Catch’ Mental Illness,” some researchers in the field believe microbes may be responsible not only for clear-cut diseases like typhoid and tuberculosis, but also for mental illnesses such as anorexia, obsessive-­compulsive disorder and schizophrenia — but in a less tidy manner. As she reports, research has found that 10 to 20 percent of mental illnesses, including autism, are partly caused by pathogens.”

20 thoughts on “What do we inherit? And from whom?

  1. It occurred to me that this post might not seem all that interesting to others. Or that they might not see its relevance and significance. There are implications that might not be obvious to a casual glance of the data.

    We often think about things as being distinct and separate. But science beginning to question and doubt this paradigmatic bias.

    Microbes (and parasites) exist in us and in our environment. We inherit them from everyone and everything we come in contact with. Our entire biological functioning is dependent on microbes and specific microbes determine how our biology functions, including our nervous systems and brains.

    This wouldn’t just shape us as individuals. It would also shape everyone who shares our environment. This might be a major contributing factor to why so many similarities exist between people in the same families, neighborhoods, communities, and societies.

    It wouldn’t just be which microbes we have (or that have us) but what we eat that feeds which microbes. I should be noted that microbes will make us crave the foods they need. It is a symbiosis of organisms in a larger ecosystem of interrelationships.

    This obviously touches upon culture. People of different cultures like different foods and have different microbes that eat those different foods. Maybe those microbes are fundamental to culture in a very direct sense.

    This might also explain why changes of food correspond with vast societal changes. Colonial imperialism spread certain food items across many countries and created an entire new era of civilization. Sugar particularly comes to mind. What kind of society and culture is created with mass consumption of refined sugar? Which microbes love refined sugar and how do they alter our biological and neurological functioning?

    If we wanted to create a new society, maybe that would require new foods to encourage different microbes. And what would happen if we introduced new microbes into a population?

    All of this reminds me of the issue of ancient societies. They had different foods, lived in different environments, and of course had different microbes. Maybe there is more going on with their cultures having been so different and their portrayals of reality seeming so strange.

    BTW with global warming, ancient microbes will be released from glaciers, permafrost, and ancient frozen lakes. The environmental conditions will also change. Different microbes will prefer those changes. We have no clue what we are doing or what any of it might mean.

    • In traditional societies, cultured foods are common. They were common in our society until recent generations. Ketchup, for example, used to be a cultured food.

      Cultured foods are perfect. They give you happy little microbes and the food they like to eat. In consuming cultured foods on a regular basis, you help create the microbial ecosystem in your gut.

      That has to be one of the greatest innovations in social development. Our intake of microbes in the distant past was random. Once we learned to control our food sources, we could control our microbial intake. As we domesticated wild animals, we domesticated wild microbes.

      In the process, we domesticated ourselves. And we created domesticated societies. Each society domesticated its different animals, plants, and microbes. Maybe this was part and parcel in creating particular cultures and mindsets.

    • http://www.nature.com/news/bacteria-bonanza-found-in-remote-amazon-village-1.17348

      “An isolated American Indian group in the Venezuelan Amazon hosts the most-diverse constellation of microbes ever discovered in humans, researchers reported on 17 April in Science Advances1. Surprisingly, the group’s microbiome includes bacteria with genes that confer antibiotic resistance — even though its members, part of the Yanomami tribe, are not thought to have been exposed to the drugs. […]

      “When researchers analysed the microbial DNA in those samples, they found that the average Yanomami’s microbiota had twice as many genes as that of the average US person. More surprisingly, the Yanomami microbiome was even more diverse than those reported for other indigenous groups in South America and in Africa4.”

    • yeah, well, at this level of understanding – even at this low level of understanding – our selves are not some active deity in the picture, like we’re in charge of any of it. I think for the most part, once we enter the sciences of human nature or behaviour, we’re just treated like any other creature that we couldn’t interview, that we couldn’t ask what we’re doing and why. We’re just black-boxing ourselves and making empirical observations, right? I mean, we’re not expected to know what we’re doing, we’re just an opportunistic lifeform like any other, right? We don’t expect any other species to anticipate the effects of their activities . . . but i guess that’s your point. We have no clue just like mosquitos have no clue. Yes, the complexities reach beyond the sphere of our reality, beyond as far as our little minds can reach.

      • Cluelessness was my general point. I sometimes am fascinated by human ignorance and at other times appalled. But the reality is that ignorance simply shows how we aren’t all that different from any other species. We adapt, evolve, and survive or else we go extinct. Knowledge is mostly irrelevant to this process, despite our liking to think we are above it all. The world is a messy place and we are right down in the muck of earthly life.

  2. http://www.livescience.com/933-study-cat-parasite-affects-human-culture.html

    A parasitic microbe commonly found in cats might have helped shape entire human cultures by manipulating the personalities of infected individuals, according to a new study.

    Infection by a Toxoplasma gondii could make some individuals more prone to some forms of neuroticism and could lead to differences among cultures if enough people are infected, says Kevin Lafferty, a U.S. Geological Survey scientist at the University of California, Santa Barbara.

    In a survey of different countries, Lafferty found that people living in those with higher rates of T. gondii infection scored higher on average for neuroticism, defined as an emotional or mental disorder characterized by high levels of anxiety, insecurity or depression.

    His finding is detailed in the Aug. 2 issue of the journal for Proceedings of the Royal Society, Biology.

    Manipulating behavior

    T. gondii infects both wild and domestic cats, but it is carried by many warm-blooded mammals. One recent study showed that the parasite makes normally cautious rats outgoing and more prone to engage in reckless behavior, such as hanging around areas frequently marked by cat urine, making the rats easy targets.

    Scientists estimate that the parasite has infected about 3 billion people, or about half of the human population. Studies by researchers in the Czech Republic have suggested T. gondii might have subtle but long-term effects on its human hosts. The parasite is thought to have different, and often opposite effects in men versus women, but both genders appear to develop a form of neuroticism called “guilt proneness.”

    Other studies have also found links between the parasite and schizophrenia. T. gondii infection is known to damage astrocytes, support cells in the brain that are also affected during schizophrenia. Pregnant women with high levels of antibodies to the parasite are also more likely to give birth to children who will develop the disorder.

    In light of such studies, Lafferty wondered whether high rates of T. gondii infection in a culture could shift the average personality of its individuals.

    “In populations where this parasite is very common, mass personality modification could result in cultural change,” Lafferty said.

    The distribution of T. gondii could explain differences in cultural aspects that relate to ego, money, material possessions, work and rules, Lafferty added. In some countries, infections by the cat parasite are very rare, while in others nearly all adults are infected.

    Adding to cultural diversity

    To test his hypothesis, Lafferty looked at published data on cultural dimensions and average personalities for different countries. The countries examined also kept records of the prevalence of T. gondii antibodies in women of childbearing age. Countries with high prevalence of T. gondii infection also had higher average neuroticism scores.

    “There could be a lot more to this story,” Lafferty said. “Different responses to the parasite by men and women could lead to many additional cultural effects that are, as yet, difficult to analyze.”

    Lafferty thinks that climate could be an important factor in determining which human populations are infected by T. gondii. The parasite’s eggs can survive longer in humid, low-altitude regions, especially at mid latitudes that have infrequent freezing and thawing.

    Other factors could also influence infection rates, including how a culture’s attitudes about having cats as pets and the hygiene practices of its people.

    Despite its association with neuroticism, Lafferty doesn’t think all of the cat parasite’s effects on human culture are bad.

    “After all, they add to our cultural diversity,” he said.

  3. http://www.nature.com/news/a-mouse-s-house-may-ruin-experiments-1.19335

    You are what you eat

    Nutrition can also determine whether a mouse study succeeds or fails, yet Brayton says that many researchers cannot even say where their animals’ feed comes from. Some mouse foods contain oestrogens and endocrine-disrupting chemicals that can affect research on cancer, among other diseases1. And the high-fat, high-sugar food used in obesity studies goes rancid quickly; when it does, mice may stop eating and lose weight without researchers realizing why.

    Food choices can also alter a mouse’s gut microbiome. Catherine Hagan Gillespie, a veterinary pathologist at the Jackson Laboratory in Sacramento, California, has found that species of bacteria in the gut vary widely between mice from different vendors2. In another, unpublished, study, she found that mice with different assortments of gut bacteria showed different anxiety levels in behavioural tests.

    But few behavioural scientists think about running microbiology assessments, says Hagan Gillespie. Even when they do, the extra work involved can increase the complexity and cost of the study. Yet the mouse microbiome is sensitive to a wide array of factors, such as air quality, maternal stress and immune function.

    Differences in the gut microbiome may explain why mice with the same genetic mutation can have different characteristics, or phenotypes, says George Weinstock, associate director for microbial genomics at the Jackson Lab’s site in Farmington, Connecticut. Jackson Lab, which breeds and supplies mice for use in studies around the world, tightly controls factors such as the type and quantity of food and the pH of water that animals receive. Even so, it finds differences between the mice at its three sites. Weinstock says that the company has begun researching ways to standardize its customers’ experiments by providing special food and care instructions for the mice that it provides.

    But even when improved mice and food are available, some researchers resist using them out of concern that it will affect their results, says Graham Tobin, former technical director of the mouse-diet vendor Teklad in Alconbury, UK. Yet he argues that standardizing results across labs is worth this inconvenience to individual scientists. Tobin also notes that researchers rarely resist adopting other new technologies — such as improved DNA sequencers — that can throw older data into question.

    • That article was the basis of my most recent post:


      The issue of that post was about research. The confounding factors, from environments to microbes, are obviously problematic for scientists. But they are also problematic for everyday life, for politics and social policies and the economic system. These are the things that shape not only individuals but also families, communities, and entire societies.

      Scientists who want to study larger issues of humanity and human nature are dealing with a mess of confounding factors that can’t be disentangled, often can’t even be fully detected and discerned. And that feeds back into society and public debate. Scientists study such things because they want to further knowledge and promote progress. If we aren’t clear in these issues, our beliefs will to that extent be disconnected from or at least have a confused relationship to reality.

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