We are stardust, we are golden
We are billion year old carbon
And we got to get ourselves back to the garden
— “Woodstock” by Joni Mitchell
Astrophysicist Neil deGrasse Tyson might agree with that 1960’s lyric:
“The atoms of our bodies are traceable to stars that manufactured them in their cores and exploded these enriched ingredients across our galaxy, billions of years ago. For this reason, we are biologically connected to every other living thing in the world. We are chemically connected to all molecules on Earth. And we are atomically connected to all atoms in the universe. We are not figuratively, but literally stardust.”
Beyond the atomic level, molecules combine into increasingly complex arrangements to create cells of various forms and functions to produce us. What exactly are we made of? Discover Magazine looks into human body systems as complex and diverse ecosystems — the microbiome:
Your body is made up of around ten trillion cells, but you harbour a hundred trillion bacteria. For every gene in your genome, there are 100 bacterial ones. This is your ‘microbiome’ and it has a huge impact on your health, your ability to digest food and more. We, in turn, affect them. Everything from the food we eat to the way we’re born influences the species of bacteria that take up residence in our bodies.
Compared to “the bustling metropolis” in your intestines, skin bacteria merely comprise a “tiny country village”:
In a thorough survey of our skin microbiome, Elizabeth Grice identified species from at least 205 different genera. Your forearm has the richest community with an average of 44 species, while your nostril, ears and inguinal crease (between leg and groin) are the most stable habitats.
Michael Pollan says we are more than just human beings. We are “superorganisms”:
In sheer numbers, these microbes and their genes dwarf us. It turns out that we are only 10 percent human: for every human cell that is intrinsic to our body, there are about 10 resident microbes — including commensals (generally harmless freeloaders) and mutualists (favor traders) and, in only a tiny number of cases, pathogens. To the extent that we are bearers of genetic information, more than 99 percent of it is microbial. And it appears increasingly likely that this “second genome,” as it is sometimes called, exerts an influence on our health as great and possibly even greater than the genes we inherit from our parents. But while your inherited genes are more or less fixed, it may be possible to reshape, even cultivate, your second genome.
Our body systems need these bacteria just as much as they need us:
[I]t really is a system, for evolution has aligned the interests of host and bugs. In exchange for raw materials and shelter the microbes that live in and on people feed and protect their hosts, and are thus integral to that host’s well-being. Neither wishes the other harm. In bad times, though, this alignment of interest can break down. Then, the microbiome may misbehave in ways which cause disease.
Indeed, new research points to an unhealthy microbiome as a reason for a myriad of diseases, including obesity, heart disease, diabetes, and autoimmune disorders. Physician and author Andrew Weil examines some factors that can injure our microbiomes’ well-being:
This field is in its infancy, but preliminary findings indicate that our microbiomes are becoming increasingly unbalanced (the technical term is dysbiotic) due to:
- Dietary change toward processed foods.
- Increased exposure to powerful antibiotics from medical treatment and residues in foods.
- Increased incidence of C-section deliveries, which deprives infants of exposure to vital microorganisms in the birth canal that “seed” the gut.
These changes may underlie increased incidence of a wide range of diseases and conditions; everything from allergy and autoimmunity to obesity, type 1 diabetes, asthma, gluten sensitivity, and even psychological and behavioral conditions.
Tomorrow we’ll look at how our individual microbiomes are colonized from birth, and how keeping your microbiome healthy and balanced might be the key to good health.
(Yahoo!Images — The Crab Nebula)