Professor Tim Spector

And that's why...

Poor hygiene, if you're not flossing properly, you're double the risk of getting dementia as well, interestingly.

So there's a real link between microbes here that if they're eating plaque and other stuff that you're leaving around in your gums, gets inflamed, that...

creates an environment where nasty microbes that love inflammation live.

And for reasons we don't know, they seem to pass from your mouth into your brain and trigger inflammation in the brain, which then increase your risk of dementia.

Yes, this is really new science showing that just how important getting the right bugs in the right place and avoiding the ones who are in the wrong place really is.

Well, you've got a sort of human-centric view of the world, Stephen.

True.

We evolve from microbes.

We used to be one.

And it turns out that most of our bodies are...

Remnants of microbes.

Microbes obviously fuse to cause human cells.

So that was the whole origin of how multicellular creatures came together, these single-celled microbes.

Some of them fused to do that.

Others stayed as single cells.

There was always this link between the single-celled guys and their multicellular ancestors, if you like.

And so as we...

co-evolved into more complicated beings, the two were always together.

And it turned out that, again, as we're formed as embryos, the gut is the first thing that this tube is the first thing that comes out of the design system.