#496 95-Year-Old Scientist Reveals the Nutrient Behind Human Brain Evolution - Dr Michael Crawford

Michael Crawford (0:00)

Trouble is being established by chemically that the ability to make DHA is rate-limited. It's a very slow process. So what happens effectively, that as your velocity of body growth increases, your ability to make DHA diminishes. And we proved this. And so what you see is that as land-based mammals get bigger and bigger and bigger, the cranial capacity shrinks. You have these these tiny little animals, squirrels and so on and so forth, 2.5%.

You get up to something like a rhinoceros, and it's about 0.1%.

But brain size in relation to body weight just shrinked without exception on the land system. And that was the difference, of course, between the marine system, where in fact brain capacity seemed to keep pace, more or less. The evidence is home and dry, that this was the reason for the cerebral expansion.

Siim Land (0:58)

Dr. Crawford, welcome to the show.

Michael Crawford (1:01)

Yes. Well, thank you.

Siim Land (1:03)

I'm very honored to have you on the show, and I'm very excited to talk with you about Omega 3s and how important they are to just overall human health and how big of a role they had in the human evolution. So I'm super pleased to have you here. Maybe we can start with you giving us a little bit of backstory of you've been in the field, in the science field for many decades. So how did you get into it and how did you start investigating Omega 3s in particular?

Michael Crawford (1:39)

Well, that's an interesting question because that requires a trip down memory lane. It all happened when I was appointed to head the Department of Biochemistry at the Nuffield Institute of Comparative Medicine in London. And I was given a brand new laboratory with money for equipment and so on and so forth and stuff. And so I sat down with Andrew Sinclair and others and we said, what are we going to do? I've been working in Africa and in Africa, of course, the big problem was protein bio-nutrition and it was fascinating because it was clear that the chronic diseases in East Africa, Uganda, particularly where I was, was totally different to what we saw in the UK. For example, there was no cardiovascular disease, there was no heart disease as we have it. But they had endomyocardial fibrosis, which was the commonest cause of death from heart failure. A host heard of endomyocardial fibrosis in the UK. It's very clear that they also didn't have any breast cancer or colon cancer to speak of.

Eventually, it tumbled that really it was the complete difference in the food structure that was eaten by the people of Uganda compared to the people of the UK. And so that had taught me that nutrition was fundamentally important to health and longevity. And so when we sat down and thought about having returned from Africa and being offered this job, when we sat down and thought, what are we going to do about this? It seemed to me that really to simplify the story, that really what was happening was that was lipid malnutrition in the UK. Everyone was talking about fats being the problem, and protein malnutrition in Africa. So the question was, what are we going to do about lipids? And everybody seemed to be doing things about lipids and heart disease. So we said, ah, the brain, what about the brain? That's full of fat. It's 60% fat. So let's start working on the brain. So the first question was, what is the brain made of in terms of its lipids? And we did a study of 32 mammalian species to examine the lipids of the brain. And what it turned out was that they were all the same. There was no difference from one to the other. What was different was the extent to which the brain had evolved. We have big brains and small brains, and they were all the same.

But chemistry was absolutely identical. But the size of the brain, which is what had mattered, that meant that the chemistry of the brain was a really determinant of brain size and brain function. And that led us into the question of identifying dacosahexaenoic acid as a very principal component of the brain as well as arachidonic acid. And that these two fatty acids between them were so singularly important for brain growth and evolution. And that's what set us off on the story of omega-3, because the arachidonic acid was available from the land food base, but dacosahexaenoic acid was not. The source of the dacosahexaenoic acid was, or the omega-3, if you like to call it that, was the marine foot web. And of course, the singularly important issue here was that the brain evolved in the sea. It evolved in the sea 500 million years ago. And it evolved from a few small cells that were electrically active. And they, they, they expanded. And they, they developed over 500 million years to the brains that we have today. And what, what may I ask? Nourished that evolution. What nourished that evolution? Well, the only thing that was available was the marine foot web. And dacosahexaenoic acid was singularly important in the signalling systems, not only of the brain, but also of the eye. Gene Anderson produced evidence of that about the same time, working at the Cullen Eye Research Institute in Houston, Texas. So, that's really what started it all.