Tuesday, October 8, 2013

Environment and Community

 Sandpiper, foraging for larval mole crabs and other zooplankton
Kitty Hawk, North Carolina
 photograph by the author

We are used to the idea of mankind altering his environment to make it more suitable for him. We not only build houses; we landscape areas, dig ditches, build highways, and so on. But it may come as a surprise to readers to hear that microorganisms routinely alter their own environment to make it suitable for themselves. The creatures that depend on them — ourselves, for example — also alter their own environments, believe it or not, to make them more suitable for the microorganisms that they need.

We're going to take one of the most striking examples of that today, although there will be more to look at later on. We've already explained that human beings require a healthy, and wide variety, of microorganisms in their gut in order to digest foods properly. Without them, we die.

Where do we get those microorganisms? Well, of course, we swallow some from our environment. But more importantly, we inherit some of them — quite literally inherit them, since we acquire them from our mother during the process of natural birth.

As peculiar as it may seem, the birth canal — the vagina — is a rich environment for bacterial growth, and in the days just before birth, it turns out, this environment is heavily populated with bacteria from the mother's own gut bacteria community. She has, in other words, a range of all the microbes that the child will need for its digestive system waiting for it in her birth canal. When the child finally leaves the sterile environment of the amniotic fluid — when the water breaks and birth begins — the infant moves through the vagina, opening and closing its mouth, and inevitably swallows billions — perhaps even trillions — of the bacteria that it will need to populate its gut with. So the first organisms it needs other than its mother are, logically enough, bacteria. And the very first act of its life, before it even leaves the birth canal, is to set up housekeeping with them.

Obviously, children that are born by cesarean section don't get this benefit. The rising tide of children born in this matter in modern Western societies is leading to a large number of children who don't start life out with the correct gut bacteria populations. This has long-term implications, since the developmental well-being of the child depends in large part on making sure it has the right gut bacteria from the moment it begins to ingest foods. Otherwise, it's digestive processes don't work properly, and, in addition, the immune system doesn't develop properly. This can lead to all kinds of overreactive immune system situations in later life, and may well lead to diseases such as autism, diabetes, and other maladies such as bipolar disorder and other psychological deficits.

Oddly enough, this could all be corrected by taking children born by cesarean, swabbing the mother's vagina, and making sure that some of that liquid was put in the child's mouth. But no one seems to think of things this obvious.

It gets a little more complicated than that. Breast milk, it turns out, has essential proteins in it which, although they don't do much for the child — it can't digest them — are in fact perfect for the gut bacteria developing the child's intestines. And it furthermore carries an additional wide population of bacteria that are absolutely necessary for the well-being of the child. Follow the links for some fascinating insights into this.

The point is that there is nothing passive about the way that bacteria are delivered to an infant so that it's gut bacteria populations develop properly. Nature is arranging things specifically so that the bacteria are not only present, but have exactly the right environment to support the growth of the organism. So you human beings don't just have bacteria; nature makes certain that they have bacteria, and it makes certain they have the right bacteria. It creates conditions ideal for those bacteria, delivers them, and then nurtures them. This is an example of bioengineering that goes to the root of what community means. Nature, and life, is a community, not a collection of individuals who act independently of one another. The perception of independent action is largely illusory, yet we endorse it as one of the foundations of our social contract.

Nature teaches us otherwise.

 Of course, human beings are far from the only organisms that do this. Think about this: every single organism with a gut has bacteria in it, and every single one of them undoubtedly has similar mechanisms to ensure that it has the right bacteria in it. The entire animal world is engaged in this activity — unseen, and underappreciated. Unfortunately, the action of chemicals in the environment and the accelerating spread of foreign bacteria into new environments is guaranteeing greater and greater disruption of this system, which leads to all kinds of diseases. Because we don't understand how the  system is constructed, many of these diseases don't, at least at first, appear to be linked to the microbial population, but most of them are, in one way or another. The situation becomes more serious every decade, with disturbing diseases such as psychological and immune system disorders becoming more and more prevalent.

We keep looking for the causes of these diseases in our genes; but it may well be that the causes of them lie in our microbial populations, a place we have only just recently started to look at more seriously.

 These arrangements do not stop with animals, which we will discuss in the next post.

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