SEA FOOD

Michael Crawford, Ph.D.

Director, Institute for Brain Chemistry and Human Nutrition, London Metropolitan University

Author, The Driving Force:

 

Food, Evolution, and the Future

Presentation Summary

"...We heard somebody right at the beginning of this meeting saying, Fish are good for the protein, or we need protein from fish. Ladies and gentlemen, I don’t think protein is important. Fish is important for its trace elements—iodine, selenium, all the rest of it, copper, zinc, manganese—and it’s important for its lipids, not for its protein. This animal gets all the protein it needs from its simplest food resource, namely grass. It achieves a velocity of body growth—and we know protein’s important for body growth—it achieves a velocity of body growth to reach one-ton body weight in four years. This big problem is, it doesn’t have much of a brain. You can look inside the skull, and it doesn’t get the lipids that it needs for a brain. You can look inside the skull and take the brain out, and it fits in the palm of your hand.

 

What we’re interested in is homo sapiens. In this picture, you can see, the brain case of this little one-year-old fellow is nearly the same size as the mother’s. What that tells you is that the priority of human development is the brain; it’s not the body. Look at the size of the child’s hand compared to the mother’s. We know all about this, and I’m not going to dwell on it, but the priority is unquestionably, in homo sapiens, the brain. Physiological requirement is the brain, nutritional requirement priority is the brain, and the brain is made of lipids, so we’ve got to get these lipids to make our brains. That is the chemistry of the human brain. It’s exactly the same as a cow brain or any other brain that you want to look at. The difference is, we’ve got a bit more than a cow...."

 

 

The Role of Seafood in Human Evolution

K. Dun Gifford: Introduction

…I have known Michael Crawford since the early 1990s, when he dazzled a group of the leading foodies and food intellectuals in Seville, Spain, when we were celebrating the 500th anniversary of the Columbus discovery of America by going to Spain and pigging out, to be honest with you. Michael talked to us way back then about the role of seafood in evolution. It was a subject not much on anybody’s radar screen at the time. I think he sensed that as he was getting deep into his subject. With the skill of a light heavyweight boxer, he did some footwork and started to talk about how the great civilizations of the world have always grown and expanded and flourished on the edges of bodies of water.

 

He stopped—I remember this so distinctly, Michael—he stopped, and you could hear the way those little buzz starts to go, and everybody said, Oh, yes, edges of water. Maybe they were fishing. And he smiled, just like he did just then. Michael, I always like to be in your company, and you always bring a high level of discourse to the meetings. We welcome you and we thank you for coming here to us from your cozy abode in the United Kingdom. We look forward to you educating us about other reasons, additional reasons, further reasons, why eating seafood is a very good idea. Welcome.

 

Michael Crawford:

 

Dun, thank you for that introduction. I remember well [the]1492 celebrations in Seville, and yes, evolution and seafood—not much has happened since then, to be honest with you, but you’ll forgive me for repeating my talk that I gave in Seville, with a few bit of extras in, just for good measure.

 

The point I would like to make after saying how grateful I am to all the people who have invited me here to this conference—which I found most fascinating and stimulating—and meeting new friends and meeting old friends again. It’s such a wonderful thing to be here, and I’m very grateful for all the organizers who’ve made this possible. I want to start by reminding people that Darwin, in his book on evolution, discussed the two forces that were responsible for evolution. Natural selection was one, and conditions of existence was the other. Now, most people only think about natural selection, but Darwin actually considered these two forces operated in evolution. He said, of the two, the conditions of existence is the greatest and the most powerful. That has a message for us today, because the conditions of existence are changing. The changes that are taking place today could have a serious impact on the future of humanity. I will be discussing this possibility later in my talk.

 

The unfortunate event was that Weissman decided he didn’t like this second condition of Darwin’s, especially it being the most powerful. So he did an experiment where he cut the tails off some unfortunate rodents. And because they kept on breeding new generations with tails, he said, “The conditions of existence is not in the ball game; forget it.” From then on, ladies and gentlemen, Darwin’s most powerful force of evolution has been dropped by evolutionary biologists. We really need to bring it back into the discussion, because you cannot explain the rise in cardiovascular disease at the beginning of last century from a rarity to number one killer on a change in the genome. We’re talking about a change of the conditions of existence. And it has changed our species. We now are much taller, we’re much fatter, we have changed in one century in terms of not only our disease pattern but our shape and size.

 

Now, I’d just like to take a trip down memory lane to the sun, which is one of these days- it’s a nuclear powerhouse that is making all the elements, and one day it’ll go bang and become a supernova. Well, it may not quite make it to that, but never mind, that’s the sort of idea. That’s the way that elements are produced and distributed and thrown across the space. Of course, they condense into planets and so on.

 

One of the planets, Titan, I think, is a very nice example, because it has a very rich nitrogen atmosphere. It appears to be—from the latest NASA research work on it—it appears to be full of organics. Of course, our planet at the beginning would have been rich in elements and organics in the same way as Titan. Something like three billion years ago, life evolved out of that organic mixture, and it evolved in the sea. Now, again, the interesting concept that Darwin had about the conditions of existence comes up here, because for the best part of two billion years—two and a half billion years, even—nothing happened. We just had blue/green algae, and a lot of viruses and small life particles. So it was all basically mono cellular living systems. There was no real substantive change over that two-and-a-half-billion-year period.

 

Then what happened was, the blue/green algae have been excreting oxygen. They polluted their atmosphere and, of course, that was the end of them, but that gave birth to the animal phylum that could use oxygen. Round about six hundred million years ago, all 32 animal phyla appeared on the planet. That is a beautiful example of Darwin’s conditions of existence. Now, the interesting point about this change was that it was a time when the photosynthetic apparatus of the blue/green algae changed from making proteins, carbohydrates into making electricity. By making electricity, it caused the primitive organizations to move. Of course, they would move, when they were facing the sun and hence, they would move to the surface, where the food was, where all the algae were producing the food.

 

This was the beginning of the evolution of the visual system. The interesting thing about that, ladies and gentlemen, is we can study the dinoflagellates today who are representatives of what was happening at that time 600 million years ago. What is fascinating about that is that they soaking in docosahexaenoic acid. DHA was- accounts di-DHA phosphoglycerides are present in the eye spot of the dinoflagellates. This is fascinating, because what it actually means is that it was docosahexaenoic acid and retinol that gave birth to the visual system that we now know. It is still, today, the same chemistry that is used in your eyeball and my eyeball. So for 600 million years, there’s been no change, despite the massive differences in genetic organizations of the different species. There’s been no change in the chemistry of the photoreceptors, as far as we can gather.

 

The interesting thing about that—and I’ll come back to it later—is, of course, that it gave rise to the synapse. The same thing applies to the synaptic junction, that there’s no living system that we know about in terms of the mammals, the fish, the birds, or the reptiles, or the amphibia. There’s none of those in which the synapse is not very rich in docosahexaenoic acid, and docosahexaenoic acid phosphoglycerides are used for the synaptic transmission systems.

 

Now, I began to first worry about the conventional wisdom about this origin of humans on the savannahs of Africa quite a long time ago. one of the reasons for this is, it’s been raining on the planet. The rain, as you see here on Mount McKinley, gets frozen. In the summertime, it washes down to the estuaries, where the marine food chain takes place in earnest. Here we have our friends eating the frutta del mare, which you get from these estuaries. What now happens is, if you look at today, the situation of the world today, there are 1.6 billion people at risk to iodine-deficiency disease. It’s almost certain that this is associated with a wide range of other trace element deficiencies, including selenium, which people have been talking about during these last two days.

 

Now that gives you the impression that it’s going to be difficult for inland populations to evolve a large brain, because as you know, iodine-deficiency disease is the simplest way to produce children that are mentally retarded. Today, in Indonesia, where I had to do some work for the World Health Organization, 60 percent of the school children have got palpable goiter. They have 1.5 million severely mentally retarded children and 800,000 cretins. You do not find one in the fishing villages. It’s a very simple message. That questions the ability of homo sapiens to have evolved on inland situations.

 

Now, Bill Harris has given us a good explanation about the essential fatty acids, what they are, so I’m not going to dwell on this picture, other than to impress on you the fact that they did- delta 60 saturation in particular, [which] is a very slow reaction. This has been shown by several workers throughout the last three decades. What this means is that the conversion of linoleic or alpha linolenic acid upwards to docosahexaenoic acid is a slow process and very inefficient. When we did the studies in the ‘70s, we found using radioisotopes, dual-labeled radioisotopes, that if you looked up the DHA that was incorporated into the brain compared to the DHA made from the linolenic acid, there was a 30-to-1 difference in efficiency of incorporating the pre-formed DHA.

 

Now, this is fundamentally important to what I’m going to talk about later. I was interested in the possibility that different species have different brain sizes, and so why is that? We did a study on some 42 different mammalian species, and we looked at the liver lipids, and they’re all over the place, as you can see here. But when you looked at the brain, there was an identity. The thing that was different in the brains of different species was not the chemistry but the extent to which it evolved. It was the extent- the brain size, not the chemistry, that changed between species, and you could relate- and if you looked at the intimate details, which I’ll show you in a minute, you could relate that to the availability of the food chain and to certain metabolic differences in those different species.

 

That’s the chemistry of the photorecptor, just to show you. This was shown by Gene Anderson and Nicholas Bazan in the early ‘70s, very heavily dependent on docosahexaenoic acid. Now, I want to do a little trip down memory lane for some of the early studies that we did, because people have been complaining about how people discover things and nobody pays any attention to them. Well, in 1973, we had evidence in capuchin primates that were deprived of omega-3 fatty acids and given a lot of omega-6, that they had serious skin problems, liver problems, and they had serious behavioral pathology as well. There’s a picture of the capuchins that we found. You can see the obvious one which was the control and the obvious ones which have showing the loss of hair as a result. You re-feed them with alpha linolenic acid, and that all repairs and goes back to normal.

 

There’s a picture of the fatty liver, which is interesting now, because they’re now finding the same kind of hepatic pathology in people with bipolar disorders. It’s also interesting that nobody seems to have followed this up, and we certainly haven’t, that elastic tissue in the vascular system seem to vanish in these animals.

 

The other thing that’s not been talked about today, or during this conference, has been this question of Alzheimer’s disease. I just wanted to show you this data, because we’ve been having a study down on the brains of people who have died with Alzheimer’s disease. We’ve been looking at the healthy areas of the demyelinating areas of the brain. There are a lot of people who are currently doing this same kind of work, but they’re looking at total lipids. You don’t really see very much when you look at total lipids, but when you look at the individual molecular species, as you can see here, the molecular species with stearic acid and docosahexaenoic acid is severely hit in the region of the brain that is demyelinating. I’m just mentioning this because I think that in terms of studying these lipids, we need to go into a bit more detail than people are currently doing in the literature.

 

Now, the big question really is, how do we get from this little chimpanzee to the brain size of that girl? That’s what I want to discuss now. We separated out- the geneticists tell us we separated from the chimpanzees seven and a half million years ago. What is quite interesting, the recent discoveries in Herto, in Ethiopia, quite close to where they found all the stone artifacts in the coastline in Eritrea. In fact, beside what was at the time these people were living there, beside part of the sea, the brain size of the people at Herto is over 1.4 kilograms. It’s actually bigger than the modern brain case today, so we need to worry about that.

 

What is this savannah hypothesis that people have talked about? This origin that we’re supposed to have evolved on the savannahs of Africa? It is described as arriving that we developed a big brain through fierce competition with the top carnivores, and that’s really what led to the expansion of our intellect. That’s good, classical, selective- the one part of Darwin’s story, not the second part of the conditions of existence. What I’m going to tell you is that the conditions of existence on the savannahs is totally inappropriate for the evolution of a big brain. But that’s the story that people talk about.

 

The second thing is upright stance came from the need to see over the tall grasses and throw spears and kill animals and this kind of thing. To be honest with you, ladies and gentlemen, my view about this concept of the savannahs is, it’s very Lamarckian, but leave that aside. Finally, hairlessness, according to Richard Dawkins, says that hairlessness came from males choosing to copulate preferentially with females. Now, Alistair Hardy, many years ago in 1960, put quite a different view about hairlessness. He said, Hairlessness arose because we had an aquatic phase, and like the marine mammals, we lost our hair. We have a requirement for water. We need to drink water because we lose water in the savannahs of Africa, because I’ve measured this, at 1.5 liters an hour. The savannah animals do not sweat like that. This is a silly idea, if you’re living on the savannahs. So they don’t sweat; they have other techniques of conserving water, but certainly not sweating.

 

So Alistair Hardy said, Hey, guys, all the marine mammals have lost their hair, so maybe we had an aquatic phase, and he put forward a number of physiological ideas as to why this aquatic phase could have been important during human evolution. So I’m really talking about the brain. Now, just to get back to part of this story of the upright stance to throw spears at animals, I took this photograph. As you can see, it’s taken with an ordinary 50-millimeter lens. I can assure, ladies and gentlemen, if you stand upright, you do not get that close to these wild animals. A cat, a big cat, will actually try to emulate a moving carpet by getting right down on all four floors and just vanishing into the ground. So far as an upright-stance person is concerned, again, I can assure you that to get that close to these sorts of animals, you have to crawl on the ground, and it’s not a very nice idea for fellows like myself who have upright stance. It’s not a natural thing. I just don’t believe this idea that we evolved a big brain and upright stance because we wanted to see over the grass and throw spears. Because as soon as you stood up to throw a spear, these animals would run away. They’re very sensible.

 

The other thing is this: that the rhinoceros is another very good example of where I think nutrition went wrong last century. We heard somebody right at the beginning of this meeting saying, Fish are good for the protein, or we need protein from fish. Ladies and gentlemen, I don’t think protein is important. Fish is important for its trace elements—iodine, selenium, all the rest of it, copper, zinc, manganese—and it’s important for its lipids, not for its protein. This animal gets all the protein it needs from its simplest food resource, namely grass. It achieves a velocity of body growth—and we know protein’s important for body growth—it achieves a velocity of body growth to reach one-ton body weight in four years. This big problem is, it doesn’t have much of a brain. You can look inside the skull, and it doesn’t get the lipids that it needs for a brain. You can look inside the skull and take the brain out, and it fits in the palm of your hand.

 

What we’re interested in is homo sapiens. In this picture, you can see, the brain case of this little one-year-old fellow is nearly the same size as the mother’s. What that tells you is that the priority of human development is the brain; it’s not the body. Look at the size of the child’s hand compared to the mother’s. We know all about this, and I’m not going to dwell on it, but the priority is unquestionably, in homo sapiens, the brain. Physiological requirement is the brain, nutritional requirement priority is the brain, and the brain is made of lipids, so we’ve got to get these lipids to make our brains. That is the chemistry of the human brain. It’s exactly the same as a cow brain or any other brain that you want to look at. The difference is, we’ve got a bit more than a cow.

 

Now, I want to get back to this slow growth business, slow metabolism, because if you look here, we have a study we did some time ago in guinea pigs and rats. Fed the same diet, except the guinea pigs got a bit of vitamin C, which the rats don’t need. What effectively you see is that, in the rat, the level of linoleic acid is quite low, but the level of arachidonic acid, by contrast, is high. Converse at the same time, the level of linolenic acid in the rat is low, but the level of docosahexaenoic acid is quite high. But when you look at the guinea pig data it’s the reverse. There is much more linoleic acid than arachidonic acid, and there’s quite a lot of alpha linolenic acid still there, but nothing like the amount of docosahexaenoic acid. This is the difference, just in the difference in velocity of body growth between the rat and the guinea pig. So that shows metabolic business.

 

Now, you go into bigger animals, and what effectively you find is that docosahexaenoic acid falls out of the picture. It blocks up the docosapentaenoic acid in the omega-3 series. So you get stuck at 22, with five double bonds and you can’t make this next conversion in any significant amount. The 22, with six double bonds. So this suggested to us, Hey, wait a minute, these are all animals with small brains. So maybe docosahexaenoic acid has got something to do with it. That’s the buffalo, which is different—I could show you hundreds of these, they’re not quite- now, the interesting thing, of course—the giveaway—was the big cats, because what they do is to eat the lifetime’s effort of another animal at one meal, like we had tonight. When you look at the big cats, they have a quite different composition, because they’ve got a lot of arachidonic acid, and they’ve got much more docosahexaenoic acid, although there still is not a huge amount, and there’s still a lot of docosapentaenoic acid.

 

What you actually see is that there’s a kind of biomagnification from what’s happening in the herbivore to the carnivore, with the docosahexaenoic acid going up in the carnivorous species. Throughout the whole of evolution, all of the carnivorous species have been in advance of the herbivores. Just for example, to compare the big cat—a lion—with the buffalo, the buffalo’s peripheral nervous and vascular system ends in a pretty dead end of a hoof, whereas in the cat’s it ends in an articulated claw, which requires quite a significant degree of motor neurons and peripheral nervous system to control that.

 

The same thing with regard to vision, that these guys can see at night. If natural selection had anything to do with it, a buffalo would have a good idea, Maybe if I saw at night, I’d be able to avoid being caught by these big cats. But it never did it. The point really is that on the conventional natural selection, you cannot explain the fixity of these two different lines, which you can explain if you use Darwin’s conditions of existence. Because even if the buffalo had the genetic change to turn it into a lion, it couldn’t do it, because it hasn’t got the lipids that it would need for a visual system or a peripheral nervous system.

 

If you’ll then look at the relationship between brain weight and body weight, you start off with small animals like the squirrel, cebus monkey, roughly about 2 percent of the body is brain. As you go into bigger animals—these are the body weight—relative brain size diminishes. This, ladies and gentlemen, is absolutely universal throughout all land-based species. There’s no exception to this, that there’s a logarithmic decline in relative brain size as the animals have all bigger bodies. You can even see it going from the chimpanzee to the gorilla. Chimpanzee has about 450 grams of brains; the bigger gorilla’s only got about 250 grams of brain. Again, the proportion is correspondingly down.

 

There’s a big question: If this was the universal law on land, how could homo sapiens escape the trap of evolving- losing brain size as he got bigger? Quite clearly, the answer to that is likely to become the biochemistry that we know. Likely to be that he would probably have found an ecological niche which provided a good source of preformed docosahexaenoic acid, because, again, throughout the universal land data, you see this decline in docosahexaenoic acid, availability for the fetus and fetal brain growth, etc., as you go up the size scale. There you are; there’s point made. That’s all the brain inside that rhinoceros’s skull. That is a very good illustration of the collapse of relative brain size amongst these large mammals, universal on the land-based system.

 

Let’s put homo sapiens back into that picture. There we are. That’s homo sapiens. You can either argue that he lost brain size down to about here and clawed it back up again, which is rather a difficult thing, I’d imagine, to do, or that he simply found an ecological niche during the evolution after he separated from the apes. If he’d gone and left the apes in the forests and woods and things like that, where would he really be separate? Well, of course, at the coastline, at the estuaries. That’s where he’s been right away from them.

 

There, you see, is the only parallel example of a large brain on this planet, which is a marine mammal, namely the dolphin. If we look at the dolphin, dolphin has a very superior brain—it’s got 1.8 kilograms of brain—and it uses it not only for retinal processing of the visual system, but also for sonar. The huge amount of the brain is occupied in three-dimensional sonar interpretation. It also has a language. If you compare a land-based animal with the chemistry availability, huge quantities—about the same size as a zebra—huge quantities of linoleic acid, and almost negligible amounts of docosahexaenoic acid, whereas these are the EPA and DHA in the liver of the dolphin. That really is the big giveaway that you really do need a preformed source of docosahexaenoic acid to explain the evolution of the human brain, how the humans escaped the universal trap of loss of brain size as we evolved bigger bodies.

 

Now the paleoanthropologists say, Hey, we’ve got no fossil evidence for this. Of course, one of the problems about fossil evidence of a coastal evolution is that the coastlines have been moving backwards and forwards, so the only place they really find them are in central Africa, around the Rift Valley. The interesting thing, one of my co-authors happened to be a geophysicist, and what she says—Leigh Broadhurst says—is that at the time the guys were living down that line, the Red Sea and Gulf of Aden was attempting to make an ocean right down the Rift Valley. It didn’t succeed because the plate tectonics moved up and separated the Rift Valley from the Gulf of Aden and the Red Sea. But this is where Herto Man’s been found, and it’s down in the [unintelligible] estuary. There is absolutely incontrovertible evidence of humans exploiting the marine food chain, dating at the time of most significant cerebral expansion of about 150,000 years ago. Of course, we now have the skull at Herto, which will be much the same kind of category, and indeed, there’s been significant finds in Eritrea as well.

 

The fossil evidence is now tumbling in. In fact, what one says to the paleoanthropologist is that all this Rift Valley stuff was anyway people who were living beside water, beside lakes and rivers and things like that. Olduvai Gorge, what was it? It was a river. There you are. That’s so much for the fossil evidence argument.

 

Now we’ve got Chris Stringer of the British Museum saying that the way that humans populated the planet was to migrate out of Africa along the coastlines, and that’s his drawing, which he published in Nature. Now, they certainly weren’t eating buffalos when they went around these coastlines. That’s absolutely sure. I’m not saying that they didn’t hunt and kill animals, but the point really is that, if you’re thinking about the way in which the brain would have developed inside a woman, what’s the point of a woman going out and killing animals? They have to rely on the men to do it. But in any case, while they were all away, mucking about in the bush somewhere, hopefully, all she had to do was to walk to the rocks and pick up the oysters and the mussels and the fish that had got left in the rocky pools and so on and so forth. The children would have done the same thing, as your children do when you take them to the seaside.

 

If would have been very simple for a woman- the whole savannah hypothesis is male-centered. They never thought about the woman. But actually, it’s the woman who’s going to create the next generation, and bit by bit, a bigger and bigger brain, and a bigger and bigger body, and all in sympathy, a good harmony of growth.

 

Just recently, we’ve got some- a good publication of mitochondrial DNA. Evidence suggests that the coastal trail that Stringer talks about was likely the only route taken during the Pleistocene settlement to populate the rest of the planet. So this is pretty good confirmation of this idea that we were, in fact, coastal and not savannah species. Just a little bit of pictures to show you: This is Norway, rock drawings 5,000 B.C., an otter, and I was interested in Helsinki recently when I was giving a lecture. Went to the museum, and there’s a fishing net there, which was found in a bog; it’s 35 meters long and one and a half meters deep. It has knots in it that are the same as the fishermen use today, and it’s been carbon-dated to 10,000 years ago, before the pyramids. People up in the Scandinavian regions were fishing a long time before- but about the same time that people in the Euphrates region were trying to domesticate animal and grow cereals.

 

Seafood has been a consistent driving force throughout 150,000 years at least. Way before the Egyptians and the Romans. The Romans were dead keen on fishing, and I could talk a lot about that. The Vikings, Rule Britannia, you name it, all the way down to today. Even Columbus discovering America, for heaven sakes. These guys learned their seafaring out of the fishing boats—that’s where it all came from. Not only that, we have all five—this is going back to Seville—all five origins of the written languages, which were the keynote for the beginnings of civilization, were all beside water, the Euphrates, the Ganges, the Nile, and the Tiber. There you have it.

 

If you want an example of contemporary people who live the way probably that people would have done throughout human evolution, we have the Moken. They’re sometimes called the Sea Gypsies. They actually live by the sea. The children are born in the water. They have incredible visual acuity, and they can see things on the floor of the sand—in amongst the sand—that you can’t see with goggles on. The children swim, and eventually, about three or four years of age, they learn to walk on the land. For about the first three years, they’re gathering their own food from the sea floor. They’re quite incredible, and unbelievable visual acuity, as indeed you might expect from that kind of food resource. one interesting snippet of information about the Moken was that when the tsunami came, not one of them was killed because they were so familiar with the waves of the oceans and all that kind of thing, they saw the tsunami coming before it came. They saw the water receding, and they said, Hey, wait a minute, this is the wave that kills, and they all ran inland. Not one of them died. Their houses were washed away, but they all survived.

 

The answer really is that children swim when they’re born. When I was in New Zealand, my daughter had a young son, and she’ll be talking about all of this stuff, and she’s a great believer in her father, you see, and so we were at the swimming pool, and she said, Well, if all this is true, then Oliver will be able to swim, because he was only two months old at that time. I swallowed and said, It is true, but let’s not try it with Oliver. Again, the faith of a daughter in her father is phenomenal; she just took Oliver and pushed him underwater. He opened his eyes, and paddled with his arms like this, floated to the surface, then put his head on one side and took a breath. It’s a natural instinct that at the early age, children don’t have to learn to swim; they swim instinctively. What is more is that if you don’t keep them swimming like the Moken do, of course, then they lose it, because as the brain expands and myelination takes place, they actually lose the instinct that they’re got, that they’re born with.

 

This doesn’t prove anything. I think the real proof of the matter lies in the necessity to have a rich source of docosahexaenoic acid that would have given the coastal dwellers the advantage over the people like Neanderthals who were meat-eaters and lived more inland. Indeed, there’s a paper recently been written on the Neanderthals, which shows that there are significant evidence of iodine deficiency in the skeletons. Now, that really puts an important distinction between the savannah hypothesis and the coastal hypothesis, because the savannah hypothesis has no predictive value. Coastal hypothesis and the dependence of the brain for 600 million years on docosahexaenoic acid has predictive value.

 

Indeed, in 1972, when we first started talking about this, we were struck by the idea that there was a significant relationship between dietary fats and vascular disease. If that was the case, then ultimately, the brain would be affected, because the human fetus requires a massive input of blood from the placenta and from the cardiovascular system, which develops before the brain. If you don’t have- you have 70 percent of all the energy that’s going into the human fetus is devoted to human brain growth. To deliver that, you need a really efficient vascular system. So that prediction was a perfectly logical one.

 

What has now happened is that the people in the Karolinska in Sweden have done an assay—an audit rather—of all the costs of ill health throughout the European Union. For the 25 member states, the cost of brain disorders have now overtaken all other costs of ill health. It is now, ladies and gentlemen, a total sum of $386 billion for the 25 member states. Now, I guess the population in the United States and the 25 member states of Europe are probably quite similar, which would mean that you’re probably looking at a very similar cost in the United States, and nobody’s talking about it. The predictive value of the concept of a nutritional dependence, Darwin’s conditions of existence, driving the evolution of the human brain is important, because just as it can drive it forward—as with the land animals, which universally lost [unintelligible] brain capacity—it can also drive it backwards. That, ladies and gentlemen is a very worrying thought.

 

I will give you four recommendations from this.

 

Firstly, Bill Lands talks about prevention, and I one hundred percent agree with him. The Global Forum on Health in Geneva has estimated that, of the research that’s going into biomedical systems, 90 percent of it is devoted to only 10 percent of the burdens of ill health. It’s a completely distorted picture, and they’re calling for a re-evaluation of the way that people fund research work to try to address the real issues [of worldwide] ill health. Now, they have a prediction that puts mental ill health in the top three burdens of ill health worldwide by 2020. I would also suggest that schoolchildren need to be educated. The top-down approach of governments saying, This is what you should do, hasn’t worked.

 

The Lancet had an editorial…[published] 6th of March, 2004…[titled] The Catastrophic Failures of Public Health. This is true, ladies and gentlemen. Despite all the money that’s gone into biomedical research, we’re seeing increases in obesity, mental ill health amongst young children, and diabetes and stroke. It’s not a particularly valuable system, simply talking down to people. You’ve got to empower people with knowledge, and I see no reason why children shouldn’t leave school with the same amount of knowledge that I have about nutrition, certainly at the higher levels of what we call A-level. I believe that we used to teach children about nutrition, health, and hygiene, but they closed all the colleges of domestic science in the 70s and 80s. That was a disastrous mistake.

 

We need to restore the land food chain to something giving us a better balance of omega-3 to omega-6, for whatever that means.

 

Lastly, I would just put it to you that we need to invest in the oceans. We’re not investing sufficiently in the oceans. We need to agriculturalize the oceans….When you stop and think about the oceans, they are really pretty good and pretty big, and we don’t know half the stories, what’s in the ocean.

 

Just to say—we did have a lot of people who tried to shoot us down on this story, but Phillip Tobias, who’s probably the greatest living paleoanthropologist, wrote that, My generation grew up steeping in what more recently has been called the savannah hypothesis. Of that, he says, We were profoundly and unutterably wrong. Now, for a great man—after he’s lived his whole life preaching the savannah hypothesis—to say, We were profoundly and unutterably wrong, shows that he is a really great man. The trouble is, there are a lot of people who will not listen to the biochemical evidence, which, to me, is the most compelling bit of evidence about the coastal origins of homo sapiens.

 

In summary, I just want to remind you that two-thirds of the planet’s surface is ocean. That we really need to consider the conservation of that resource and its future utilization. At the moment, we’re just hunters and gatherers, the way were in the land 10,000 years ago. We really need to start thinking seriously about what the oceans could offer us, because it’s an enormous resource, which, I believe, has not been properly tapped and is not being properly utilized.

 

Finally, I’ll just say this: That the stakes of considering the predictive value of the story that comes from the origin of humans dependent on a coastal resource—the brain evolved in the sea, we still require docosahexaenoic acid for it, and without it, we could run into trouble. If mental ill health rises this century the way cardiovascular disease rose last century, we’re in for very serious trouble. Just finally, what is at stake is the future health and ability of children that are about to be born. Thank you for listening to me.

 

 

© Seafood and Health Alliance 2005

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Seafood and Your Health

 

Answers to Concerns about Toxins, Contaminants, and the Benefits of a Fish Diet

What's so healthy about eating fish?

 

Fish is a high-protein, low-fat food that provides a range of health benefits. White-fleshed fish, in particular, is lower in fat than any other source of animal protein, and oilier fish contain substantial quantities of omega-3s, or the "good" fats in the human diet. In addition, fish does not contain the "bad" fats commonly found in red meat -- called omega-6 fatty acids.

 

Why are omega-3s good for your health?

 

A growing body of evidence indicates that omega-3 fatty acids help maintain cardiovascular health by playing a role in the regulation of blood clotting and vessel constriction. They are important for prenatal and postnatal neurological development, and may reduce tissue inflammation and alleviate the symptoms of rheumatoid arthritis. Other maladies in which omega-3 may play a beneficial role include cardiac arrhythmia (irregular heartbeat), depression and irritable bowel syndrome.

 

There are three main omega-3 fatty acids: ALA, EPA and DHA. EPA and DHA (which are longer molecules than ALA) appear to provide the greatest health benefits. In the ocean, ALA is made by marine algae, or phytoplankton. Small invertebrate animals, or zooplankton, eat the phytoplankton and elongate their ALA to EPA and DHA. In turn, when finfish and shellfish (fish higher up the food chain) eat plankton, they accumulate even higher concentrations of omega-3s. Fish high in omega-3s that are caught or farmed in an ecologically sound manner and are low in contaminants (see What Are Contaminants?) include wild salmon from Alaska (fresh, frozen and canned), Atlantic mackerel and herring, sardines, sablefish, anchovies and farmed oysters (see Best & Worst Choices).

 

What about fish oil supplements?

 

Besides eating fish, another way to consume omega-3 fatty acids is by taking store-bought fish oil supplements. Some fish oils come from fish caught as food for humans; others are made from small fish caught for animal feed, such as South American anchovies. However, since the same contaminants (mercury, PCBs, dioxins, pesticides) that accumulate in fish also accumulate in fish oil, you should buy capsules that are made from purified fish oil (more on contaminants in fish oil supplements and the results of an Environmental Defense survey).

 

What are other sources of omega-3 fatty acids?

 

Alternative sources of the shorter omega-3 fatty acid ALA include flaxseed, walnuts, wheat germ and plant-based omega-3 tablets. However, since humans do not readily convert ALA to the more beneficial EPA and DHA, the omega 3s in terrestrial plants probably do not provide as a great a health benefit as the longer omega-3 fatty acids found in marine products.

 

What are contaminants?

 

Despite their valuable qualities, fish can pose considerable health risks when contaminated with substances such as metals (e.g., mercury and lead), industrial chemicals (e.g., PCBs) and pesticides (e.g., DDT and dieldrin). Through increased testing, many of our oceans, lakes and rivers are now known to be surprisingly tainted. As a result, some fish are sufficiently contaminated that Environmental Defense recommends limited or no consumption. (View our Health Alerts chart for adults and children.)

 

Where do contaminants come from?

 

Contaminants enter the water in a variety of ways. Industrial and municipal discharges, agricultural practices, and storm water runoff can all deposit harmful substances directly into the water. Rain can also wash chemicals from the land or air into streams and rivers. These contaminants are then carried downstream into lakes, reservoirs and estuaries.

 

Fish take in these substances in several ways, and their contaminant levels depend on factors like species, size, age and location. Mercury, for example, is naturally converted by bacteria into methylmercury. Fish absorb methylmercury mostly from their food, but also from the water as it passes over their gills. Generally, larger and older fish have had more time to bioaccumulate mercury from their food and the water than smaller and younger fish. In addition, large predatory fish (like sharks and swordfish) near the top of marine food chains are more likely to have high levels of mercury than fish lower in marine food chains due to the process of biomagnification.

 

Fish can also absorb organic chemicals (such as PCBs, dioxins and DDT) from the water, suspended sediments, and their food. In contaminated areas, bottom-dwelling fish are especially likely to have high levels of such toxins because these substances run off the land and settle to the bottom. These organic chemicals then concentrate in the skin, organs and other fatty tissues of fish. Wild striped bass, bluefish, American eel, and seatrout tend to be high in PCBs, since they are bottom-tending fish often found in contaminated rivers and estuaries.

 

What are the risks of eating seafood contaminated with industrial pollutants?

 

Contaminants such as mercury, PCBs and dioxins build up in your body over time. Health problems that may result from eating contaminated fish range from small, hard-to-detect changes to birth defects and cancer. It can take 5 years or more for women in their childbearing years to rid their bodies of PCBs, and 12-18 months to significantly reduce their body burden of mercury. Mothers who eat contaminated fish before becoming pregnant may have children who are slower to develop and learn. Developing fetuses are exposed to stored toxins through the placenta. Women beyond their childbearing years and men face fewer health risks from contaminants than children do. Following the advice below will minimize your exposure and reduce the health risks associated with these contaminants.

 

What about mercury in canned tuna?

 

The two most popular types of canned tuna – white and light – vary greatly in their average mercury content. Canned white tuna consists of albacore, a large species of tuna that accumulates moderate amounts of mercury. Consequently, Environmental Defense recommends that adults and children limit their consumption of canned white tuna.

 

Canned light tuna usually consists of skipjack, a smaller species with approximately one-third the mercury levels of albacore. Therefore, Environmental Defense only recommends that young children (ages 0-6) limit their consumption of canned light tuna. However, recent news reports suggest that some canned light tuna actually contains yellowfin tuna, a species that is similar in size and mercury content to albacore. These products are sometimes (but not always) labeled ‘gourmet’ or ‘tonno’, and their consumption should be limited by adults and children. Overall, it’s best to exercise caution in how much tuna you (or especially your children) consume.

 

Do the health benefits of omega-3s outweigh the risks associated with contaminants in seafood?

 

There is no definitive answer to this question, but the information provided here can help you decide for yourself. For young children and women of childbearing age, consumption of mercury-contaminated fish can severely impact a child's development. However, other sub-populations (older women and men) may find it an acceptable tradeoff to exceed recommended seafood meal limits to increase their omega-3 intake. For our advisories concerning PCBs, dioxins and pesticides, the cancer risk (1 in 100,000 - the level recommended by the EPA) may not outweigh the benefits of omega-3s for people at high risk of cardiovascular disease. However, these chemicals are known to cause serious health problems besides cancer, so the tradeoffs are not simple.

 

I've heard that the high amount of selenium in seafood counteracts the harmful effects of mercury. Is this true?

 

There is limited evidence to date that selenium in seafood provides significant protection against the negative effects of methylmercury (the toxic form of mercury found in fish).

 

Selenium, an essential nutrient, is present in the cells of all mammals. When bound to certain proteins, selenium acts as an antioxidant by detoxifying free radicals. (Free radicals are highly-reactive atoms or molecules that can damage cells.) Organ meats and seafood are the best sources of selenium, and the USDA ranks 16 different seafood sources in the top 25 selenium-containing foods.

 

A form of selenium – selenide – has also been shown to neutralize the toxicity of some forms of mercury. As part of its 2006 report Seafood Choices: Balancing Benefits and Risks, the Institute of Medicine reviewed the scientific evidence that selenium reduces the risks associated with methylmercury in seafood.

 

The expert panel concluded that although selenium may diminish some of the toxic effects of some forms of mercury and other heavy metals, the mechanisms for these interactions are poorly understood. In addition, there was little or no evidence showing that selenium affected the toxicity of other seafood contaminants such as PCBs or dioxins. Therefore, it is premature to conclude that selenium acts as a safeguard against methylmercury. Choosing fish that are low in contaminants is still the best course of action (see our list of best and worst choices).

 

Why did you use EPA rather than FDA methodology? Isn't the FDA in charge of monitoring the nation's seafood supply?

 

The FDA's approach is based on relatively old science and balances consumer health risks from seafood contaminants against economic losses to the seafood industry. In addition, the FDA's only consumer seafood advisory is for methylmercury and ignores the risks associated with other seafood pollutants (e.g. PCBs).

 

On the other hand, the EPA's risk-assessment approach is based solely on human health, and stems from more recent and rigorously reviewed science. We feel that our comprehensive compilation of fish tissue data, coupled with the EPA's risk-assessment approach, provides consumers with a powerful tool for avoiding excessive exposure to contaminants in seafood.

 

If the consumption advisories for contaminants are most important for women and children, how come there are instances where women can eat more fish in a month than men?

 

Our advisories are calculated based on average body weight and typical meal sizes for men and for women - the two most important factors in determining intake of contaminants through seafood consumption. Women weigh less on average than men (144 pounds versus 172 pounds), and we assume they eat smaller portions as well (6 ounces versus 8 ounces).

 

The difference in portion size has a greater effect on the calculation than the difference in body weight; therefore in several instances women can safely eat more portions of a particular fish in a month than men (for example, American/Eastern oysters). In the case of mercury, our methodology – taken from EPA – is designed to protect women of childbearing age and children. See our Health Alerts page for more information on the methodology we used to determine consumption advisories.

 

How come there are fish that have consumption advisories for children, but aren't designated as a 'Health Concern'?

 

Our decision was difficult, but we chose not to use the 'Health Concern' designation when there are consumption advisories only for children. Adults are the primary consumers of fish and our designation would be misleading for adults. We urge parents to consult our online advisories, which are specific to children.

 

What about natural toxins in seafood?

 

Besides industrial pollutants and other human-made contaminants, some seafood may also contain natural toxins if fish eat harmful algae or bacteria. In warm tropical waters, a toxin called ciguatera can work its way up the food chain and be present in toxic levels in large, predatory fish. Cooking does not destroy the toxin, and consumption of ciguatoxic fish can cause intense flulike symptoms.

 

In addition, fish like tuna, mackerel, bluefish and mahimahi begin decomposing soon after capture. If not stored properly, they may develop a histamine called scombrotoxin. Eating fish (even cooked fish) with high concentrations of scombrotoxin can cause an allergy-like reaction, which is treatable with an antihistamine.

 

Uncooked shellfish may contain disease-causing bacteria, viruses or parasites. Raw oysters, clams and other shellfish pose a particular risk since they are filter feeders - straining tiny particles from the seawater for food. If the seawater contains disease-causing microorganisms, these accumulate in the shellfish. The Norwalk virus, which causes intestinal illness in humans, is often associated with eating raw oysters and clams. For this reason, it is important to get raw shellfish from a reliable source, or ensure that your shellfish is cooked thoroughly.

 

How can I reduce the risks?

 

Fish consumption is the primary route of exposure to contaminants like mercury and PCBs. Since these substances can damage developing nervous systems and impair learning, seafood contamination is a particular concern for young children and women of childbearing age. The best ways to reduce exposure are:

 

Reduce consumption of fish known to be high in contaminants (see below).

Prepare your fish in a way that cuts down on toxins (see below).

Eat sport fish from a variety of water bodies, and try not to eat the same species of fish more than once a week.

How can I cook fish to reduce toxins?

 

Unfortunately, there are no cooking methods that will reduce mercury levels in seafood since it binds to proteins in fish tissue (including muscle). However, levels of PCBs, dioxins and some pesticides can be reduced by the following cooking methods, since these chemicals build up in fatty tissue.

 

Before cooking, remove the skin, fat (found along the back, sides and belly), internal organs, tomalley of lobster and the mustard of crabs, where toxins are likely to accumulate. This will greatly reduce the risk of exposure to a number of hazardous chemicals.

When cooking, be sure to let the fat drain away, and avoid or reduce fish drippings.

Serve less fried fish. Frying seals in chemical pollutants that might be in the fish's fat, while grilling, broiling or poaching allows fat to drain away.

For smoked fish, it is best to fillet the fish and remove the skin before the fish is smoked.

How can I avoid getting sick from eating seafood?

 

Check fish carefully before buying. Bruises, brown spots and cloudy eyes all indicate decomposition, and possibly bacteria. Buy fish that was frozen or refrigerated immediately after capture (see Buying Guide).

Cook fish and shellfish thoroughly. Handle raw fish as you would handle other raw meat products. Take care not to cross-contaminate cooked food or vegetables with the utensils used to prepare raw fish, and wash utensils and hands thoroughly in-between handling.

Avoid shellfish from untraceable sources, particularly if eaten raw.

What is the government doing about these problems?

 

Two government agencies are responsible for monitoring the nation's seafood supply. National standards and recommendations concerning commercial seafood (what you would find in a restaurant, grocery store or fish market) originate from the Food and Drug Administration (FDA). For recommendations concerning sport fish caught in local waters, individual states work in conjunction with the Environmental Protection Agency (EPA) to test fish and issue fish consumption advisories. EPA's guidance is generally regarded as more protective of consumers than that of the FDA, especially regarding acceptable levels of mercury and PCBs. In addition, many states now also offer their own health advice for commercial fish.

 

What fish should I avoid?

 

Low-contaminant fish are an important part of a healthy diet, and Environmental Defense encourages people to include such fish in their diets, especially if they are caught or farmed in an environmentally responsible manner. However, there are certain species that people (especially women of childbearing age and children) should eat in moderation or avoid altogether (view our Health Alerts chart)