Symbiotic Microbes may shape our evolution!

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From issue 2899 of New Scientist magazine, page 30-34.

Far from being passive hangers-on, symbiotic microbes may shape the evolution of the plants and animals that play host to them

DISPOSING of corpses can be tricky. Bury them in a shallow grave and hungry animals are liable to dig them up. Our body faces a somewhat similar problem when it comes to disposing of unwanted substances. One of the ways the liver purifies blood is by adding the equivalent of a “chuck this out” label to molecules, but this label is made of a kind of sugar – and the bugs in our gut have a sweet tooth. Some produce a special enzyme that allows them to cut off the sugar and eat it, which often results in compounds being recycled within the body rather than disposed of.

Back in the 1980s, Richard Jefferson used the enzyme to develop a powerful technique now relied upon by thousands of genetic engineers around the world. At the same time, he was intrigued by the enzyme’s normal role. Its recycling effect helps determine the blood levels of many compounds, including important substances such as sex hormones. Jefferson realised that the bacteria within us, far from being passive hangers-on, must affect us in profound ways.

In the past decade, this view has started to become mainstream. Study after study has shown how the microbes living in us and on us – the microbiome – can affect our health and even happiness. But back in the 1980s, Jefferson took this idea even further. If microbes are so important, he reasoned, they must play a big role in evolution too. He came up with what he called the hologenome theory of evolution. “The hologenome is the biggest breakthrough in thinking I’ve had in my life,” he says.

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Symbiotic Microbes may shape our evolution!

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