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Medical Forum / General / Nutrition / June 2005PUFAs & brain size
SURVIVAL OF THE FATTEST The Key to Human Brain Evolution Stephen C Cunnane Research Center on Aging Université de Sherbrooke Canada http://www.worldscibooks.com/lifesci/5769.html How did humans evolve larger and more sophisticated brains? In general, evolution depends on a special combination of circumstances: part genetics, part time, and part environment. In the case of human brain evolution, the main environmental influence was adaptation to a 'shore-based' diet, which provided the world's richest source of nutrition, as well as a sedentary lifestyle that promoted fat deposition. Such a diet included shellfish, fish, marsh plants, frogs, bird's eggs, etc. Humans and, and more importantly, hominid babies started to get fat, a crucial distinction that led to the development of larger brains and to the evolution of modern humans. A larger brain is expensive to maintain and this increasing demand for energy results in, succinctly, survival of the fattest. Contents: The Human Brain: Unique Yet Vulnerable: Human Evolution: A Brief Overview The Human Brain: Evolution of Larger Size and Plasticity Defining Characteristics: Vulnerability and High Energy Requirement Fatness in Human Babies: Insurance for the Developing Brain Nutrition: The Key to Normal Human Brain Development Iodine: The Primary Brain Selective Nutrient Iron, Copper, Zinc and Selenium: The Other Brain Selective Minerals Docosahexaenoic Acid: The Brain Selective Fatty Acid The Shore-Based Scenario: Genes, Brain Function and Human Brain Evolution Bringing the Environment and Diet into Play The Shore-Based Scenario: Why Survival Misses the Point Earlier Versions The Evidence How Would It Work? Survival of the Fattest Readership: General, and those with an interest in origins of humans, especially human intelligence. 368pp Pub.date: May 2005 ISBN 981-256-191-9 US$68 / £41 ISBN 981-256-318-0 pbk US$32 / £20 Marc Verhaegen http://www.onelist.com/community/AAT http://groups.yahoo.com/group/AAT1 > SURVIVAL OF THE FATTEST > The Key to Human Brain Evolution [quoted text clipped - 15 lines] > humans. A larger brain is expensive to maintain and this increasing demand > for energy results in, succinctly, survival of the fattest. I don't know that I can buy this. In some environments--the jungle comes to mind--being fat could be rather disadvantageous. When trying to catch prey, or avoiding predators, a slender body is highly advantageous. When you look at humans living in similar environments today, you will note that as a general rule, these individuals are thin, not fat. Brain size, on the other hand, would have come as an advantageous trait that allowed humans to adapt to a great variety of environments, in many cases by intentional modification of those environments. Finally, fat storage came as an adaptation to survive very harsh environments, where seasonal availability of nutrients meant those able to set fat aside for a dry day would increase the probability of their survival. It is only when our brain activity allowed us to modify our environment to the point where we could sustain a sedentary lifestyle and have more reliable, sustainable food sources that we started piling on the fat. So I would arrive at quite the opposite conclusion: brain size/capacity led to us being fat. You can find plenty of such claims. They come and go, but there's not enough of a scientific basis for them to regard them as anything more than cute ideas. In an anthropology book I own, the point is made that palm and coconut were likely staple foods in the diet of early humans, and we all know that's it's easy to catch shellfish, as opposed to fish, and shellfish is high in cholesterol but low in PUFAs. If they would learn some biochemistry and biophysics, it would help - they would at least realize how foolish they appear. > You can find plenty of such claims. They come and go, but there's not > enough of a scientific basis for them to regard them as anything more [quoted text clipped - 4 lines] > would learn some biochemistry and biophysics, it would help - they > would at least realize how foolish they appear. Fact 1. Humans cannot introduce fatty acid double bonds into lower positions than 9. Fact 2. Major proportion of brain membrane phospholipids (40% of the dry weight of human brain) contain double bonds in positions 3 and 6. Fact 3. Numbers such as 3 and 6 are smaller than 9. Conclusion: n-3, n-6 fatty acids must come from food. > You can find plenty of such claims. They come and go, but there's not > enough of a scientific basis for them to regard them as anything more [quoted text clipped - 4 lines] > would learn some biochemistry and biophysics, it would help - they > would at least realize how foolish they appear. People who say something before informing a little bit are the foolish ones. 1) Why don't you read the book first? 2) Stephen Cunnane is a well-know biochemist (worked with, eg, David Horrobin & Michael Crawford, wote a lot of papers on PUFAs & human evolution). 3) PUFAs are abundant in the savanna IYO?? 4) Coconuts are found in the savanna IYO rather that at the seaside?? BTW, I'm not saying I fully agree with Cunnane's view on brain evolution, I'm only informing about the appearancer of a possibly interesting book on brain evolution. This is my view on human evolution (if you believe you have 1 serious argument against it, I'd like to hear): IMO some time after the Homo-Pan split 7-4 Ma, Homo populations had become seaside omnivores (collected fruits, coconuts, bird eggs, turtles, shell-, crayfish, algae...). This would explain a lot of typically Homo traits (not in apes & australopiths) better than savanna scenarios do: brain size, diving skills, breathing control, vocality, small mouth & chewing muscles, descended tongue bone, projecting nose, longer airway, reduced sense of smell, handiness, tool use, late puberty, long legs, body alignment, reduced climbing, fatness, fur loss, high needs of water, sodium, iodine & PUFAs. This likely happened when Plio-Pleistocene Homo spread along the Indian Ocean & African coasts. 1.8-Ma Homo remains come from Algeria, Iran, Kenya, Georgia, Java... always near lakes or seas, (R.Dennell 2003 JHE 45:421): in spite of sea level changes (Ice Ages), Homo much more than australopith remains have been found amid shells, corals & barnacles, from 1.8 to 0.1 Ma, ie, throughout the Pleistocene, in coasts all over the Old World (Mojokerto, Terra Amata, Table Bay, Eritrea...), even on islands that could only be reached by sea (Flores 0.8 Ma http://allserv.rug.ac.be/~mvaneech/outthere.htm ). If you forgot, this was my original past: SURVIVAL OF THE FATTEST The Key to Human Brain Evolution Stephen C Cunnane Research Center on Aging Université de Sherbrooke Canada http://www.worldscibooks.com/lifesci/5769.html How did humans evolve larger and more sophisticated brains? In general, evolution depends on a special combination of circumstances: part genetics, part time, and part environment. In the case of human brain evolution, the main environmental influence was adaptation to a 'shore-based' diet, which provided the world's richest source of nutrition, as well as a sedentary lifestyle that promoted fat deposition. Such a diet included shellfish, fish, marsh plants, frogs, bird's eggs, etc. Humans and, and more importantly, hominid babies started to get fat, a crucial distinction that led to the development of larger brains and to the evolution of modern humans. A larger brain is expensive to maintain and this increasing demand for energy results in, succinctly, survival of the fattest. Contents: The Human Brain: Unique Yet Vulnerable: Human Evolution: A Brief Overview The Human Brain: Evolution of Larger Size and Plasticity Defining Characteristics: Vulnerability and High Energy Requirement Fatness in Human Babies: Insurance for the Developing Brain Nutrition: The Key to Normal Human Brain Development Iodine: The Primary Brain Selective Nutrient Iron, Copper, Zinc and Selenium: The Other Brain Selective Minerals Docosahexaenoic Acid: The Brain Selective Fatty Acid The Shore-Based Scenario: Genes, Brain Function and Human Brain Evolution Bringing the Environment and Diet into Play The Shore-Based Scenario: Why Survival Misses the Point Earlier Versions The Evidence How Would It Work? Survival of the Fattest Readership: General, and those with an interest in origins of humans, especially human intelligence. 368pp Pub.date: May 2005 ISBN 981-256-191-9 US$68 / £41 ISBN 981-256-318-0 pbk US$32 / £20 Marc Verhaegen http://www.onelist.com/community/AAT http://groups.yahoo.com/group/AAT1 |
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