Evolution, the microbiome, and human health

Published on November 4, 2018   49 min

A selection of talks on Microbiology

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I'm Joe Alcock. I am a Professor of Emergency Medicine in the Department of Emergency Medicine at the University of New Mexico. Today, I'll be talking about evolution, the microbiome, and human health.
When you're listening to me you may think that I'm a human and a mammal, and you'd be at least partially right. Recent work has shown that my body and your body, too, is inhabited by as many as 30 trillion microbes, so these are microscopic organisms living in and on your body, mostly in your gut, numbering this vast number of 30 trillion, which is equivalent to the number of human cells in your body. If an alien came down and sampled a gene at random from my body, there's a good chance that it would sample microbial gene because our genes are actually outnumbered by 10 to 1 by microbial genes. So, in some ways, we may be more microbial than human. But, the very least we are more complicated than we thought before, and these microbes have an important impact on our bodies and on our health. Some have suggested that we humans are better thought of as being a meta-organism or, a superorganism- a complex combination of both mammal and microbe. There's a variety of microbes in our guts, and if one took a microbe at random from our intestine would probably fall into either the Firmicutes or Bacteroides.
So, I like this quote by Rob Knight, he's at UC San Diego, and he has said that, "Just over the last five years, it went from being crazy to think that microbes were involved to now being crazy to think that microbes aren't involved in human health and disease." You can fill in the blank with just about any condition that you can think about; there's been an avalanche of recent findings that suggest that microbes are involved in just about every health condition that you can think of. But, these fall into the three main categories that I'm going to talk about today. The three major organ systems and functions of the body that have received a lot of attention recently are the brain: cognition, memory, behavior seems to be impacted by the composition of the microbiota. Pictured on the right is an immune cell, and the immune system is markedly affected both in terms of its development and its function by which microbes are present and what they're doing. It seems like a major function of the immune system is to pay attention to signals from the microbiota and, in some ways, to respond. Then, thirdly, we have the gastrointestinal tract. That's one seems like it is a no-brainer that microbes affect the GI tract because that's where they're found- mostly in the colon or the large bowel. Both gut development and certainly gut function and a wide variety of GI diseases, things like inflammatory bowel disease, are also affected by the composition of the microbiome.