Probably not. Consider: 90% of the cells in your body are non-human. The 23,000 human genes in your body are outnumbered by millions of microbial genes, doing who knows what. The variety of microbe species that lives on and inside of us is still beyond our ability to detect. In short, we have been overwhelmed by alien species our entire lives, and we have barely begun to understand the implications.
One prominent researcher called human skin a “virtual zoo of bacteria.”5 Another compared the diversity in the human gut to a rain forest.6 The human gut alone contains on average: 40,000 bacterial species,7 9 million unique bacterial genes and 100 trillion microbial cells.8 According to Asher Mullard, “Between them [the bacteria in our bodies], they harbor millions of genes, compared with the paltry 20,000 estimated in the human genome. To say that you are outnumbered is a massive understatement.”9
The global initiative known as the Human Microbiome Project currently estimates that the microorganisms that live inside or on Homo sapiens outnumber somatic (body) and germ cells [germ cells as in gametes, not bacteria] by a factor of ten.10 To this point, only approximately 1% of this microbiota has been characterized and identified.11 The Human Microbiome Project aims to catalog the balance using an array of molecular sequencing techniques over the coming years.12 The combined genetic contributions of these microbes — in excess of 1,000,000 protein-coding genes — provide traits not encoded in our own genomes.13 __ Microbiota
We have long known that the microbes in our gut provide many functions and substances that humans need to thrive. We are beginning to discover other functions of these alien invaders:
… around 90 percent of our cells are actually bacterial, and bacterial genes outnumber human genes by a factor of 99 to 1. But those bacteria, most of which perform helpful functions, weren’t always with us: a baby is essentially sterile until it enters the birth canal, at which point the bacteria start to arrive — and they don’t stop. From a mother’s vaginal microbes to hugs and kisses from relatives, the exposures of newborns and toddlers in their earliest years is critical to the development of a robust microbiome.
… swapping one mouse’s gut bacteria with that of another can significantly alter behavior. Researchers transplanted microbes from one group of mice, which were characterized by timidity, into the guts of mice who tended to take more risks. What they observed was a complete personality shift: timid mice became outgoing, while outgoing mice became timid. “It’s good evidence that the microbiota houses these behaviors,” Foster said.
… In one Japanese study, for instance, researchers were only able to change the baseline stress characteristics of germ-free mice until nine weeks of age. After that, no variety of bacterial additions to the mice’s guts could properly regulate stress and anxiety levels. The explanation for this phenomenon might lie in what’s known as “developmental programming” — the idea that various environmental factors, to which we’re exposed early on, greatly determine the structure and function of organs including the gut and the brain.
“There are changes that happen early in life that we can’t reverse,” said John Cryan, a neuroscientist at the University of Cork in Ireland and a main investigator at the Alimentary Pharmabiotic Centre. “But there are some changes that we can reverse. It tells us that there is a window when microbes are having their main effects and, until this closes, many changes can be reversed.”
… researchers at UCLA showed that healthy women who consumed a drink with four added probiotic strains twice daily for four weeks showed significantly altered brain functioning on an fMRI brain scan. The women’s brains were scanned while they looked at photos of angry or sad faces, and then asked to match those with other faces showing similar emotions.
Those who had consumed the probiotic drink showed significantly lower brain activity in the neural networks that help drive responses to sensory and emotional behavior. The research is “groundbreaking,” Cryan said, because it’s the first trial to show that probiotics could affect the functioning of the human brain. Still, he notes that the results need to be interpreted with care.
… scientists still aren’t sure exactly which microbial species are part of a healthy microbiome, nor do they know whether certain bacterial strains are absolutely vital to mental functioning, or whether the right balance is what’s key. Furthermore, research still hasn’t parsed which illnesses might be affected by the microbiome and, therefore, treatable using probiotics. “There are beginning to be suggestions that this type of probiotic treatment is worth pursuing,” Bienenstock said. “Whether we can use this to improve people’s lives, well, the door is just beginning to open on this.” __ Gut Feelings
It is best to be cautious in the early stages of any type of research. But considering how badly our genes are outnumbered by microbial genes, it would not be surprising to find that these foreign genes have a powerful influence on health and behaviours.
To emphasise the level of our genetic ignorance, researchers funded by the US NIH are beginning to discover some genetic overlap between different types of mental illness.
The overlap in heritability attributable to common genetic variation was about 15 percent between schizophrenia and bipolar disorder, about 10 percent between bipolar disorder and depression, about 9 percent between schizophrenia and depression, and about 3 percent between schizophrenia and autism.
The newfound molecular genetic evidence linking schizophrenia and depression, if replicated, could have important implications for diagnostics and research, say the researchers. They expected to see more overlap between ADHD and autism, but the modest schizophrenia-autism connection is consistent with other emerging evidence. _ Psypost
A lot of inherited and non-inherited variation in mental disorders remains to be explained. How much of this variation could be explained by a complete study of both the human genome combined with the millions of active genes in the microbiome? Hard to say, but the idea is intriguing.
Most human traits exhibit complex inheritance that has been difficult to explain, when study is limited to the human genome and the human environment. No doubt some of this variation will be explained by a more thorough understanding of epigenetics — including non-coding RNA and DNA, copy number variants, and other still poorly understood influences on gene expression. But ignoring millions of active genes, working constantly in the background, might not be the wisest long-term approach.
Boston psychiatrist James Greenblatt is beginning to treat patients using an approach that Al Fin has been recommending publicly for several years: he is filling their guts with health promoting bacteria. Not just physical health-promoting bacteria, but also mental health-promoting bacteria. That is not even a fraction of the vision that Al Fin has laid out for this type of treatment, but at least it is a start.
Some research indicates that the most profound uses of gut microbial transplantation might only be achieved in infancy — when a “critical period” of sorts is in effect — these limitations have not yet been explored.
Besides promoting cognitive health and overall physical health, this approach may also lend itself to the treatment of a wide range of disease — perhaps including the degenerative diseases of ageing, and even ageing itself.