Human Brain Evolution: The Influence of Freshwater and Marine Food Resources

[Persej]

I really enjoyed reading this book, so I thought I could recommend it on the forum. From the book cover:

A multidisciplinary treatment of the importance of aquatic foods in human brain evolution

The evolution of the human brain and cognitive ability is one of the central themes of physical/biological anthropology. Based on studies of the modern human brain, certain prerequisites were needed for the development of the early brain and associated cognitive advances. Important prerequisites included polyunsaturated fatty acids and other brain selective nutrients, which are found in highest quantity in fish and shellfish. Early hominins were able to access these foods when frequenting wetlands, particularly lake and river margins. Increased consumption of this high-quality diet over time exaptively diverted energy to the brain, and was a catalyst for brain growth. The later exploitation of marine shellfish and fish is roughly correlated with the emergence of Homo sapiens, and cognitive advance associated with changing human behaviors.

Human Brain Evolution: The Influence of Freshwater and Marine Food Resources documents the energy and nutrient constraints of the modern brain, highlighting the significant role of brain selective nutrients in brain development and the evolution of neural systems. There is a particular focus on two long-chain polyunsaturated fatty acids (LC-PUFA) in brain development and maintenance—docosahexaenoic acid (DHA) and arachidonic acid (AA). These nutrients are found in the highest quantity in fish and shellfish, and this volume further discusses fossil, morphological, and isotopic evidence for hominin consumption of these foods over time.

The contributors to this volume come from several fields—paleoanthropology, nutrition, neurochemistry, archaeology, and paleobiology—providing a multidisciplinary approach to the complex and challenging topic of the evolution of the brain. The first half of this volume focuses specifically on the biochemical and nutritional requirements of encephalization of the human brain, best acquired opportunistically (exaptively) through consumption of fish and/or shellfish. The second half provides multidisciplinary evidence on the exploitation of initially, freshwater and later, marine fish and shellfish, by successive hominin taxa. These persuasive, thought-provoking discussions and arguments provide the basis for a new perspective and help the reader understand the vital role freshwater and marine foods have in human brain function and, hence, evolution.

Human Brain Evolution is essential reading for graduate students, postdoctoral students, and research scientists in physical/biological anthropology, human biology, archaeology, nutrition, cognitive science, and the neurosciences. It is also an excellent supplemental text for biological anthropology or a graduate student discussion seminar.

Amazon.com: Human Brain Evolution: The Influence of Freshwater and Marine Food Resources (9780470452684): Stephen Cunnane, Kathlyn Stewart: Books

Amazon.com: Human Brain Evolution: The Influence of Freshwater and Marine Food Resources (9780470452684): Stephen Cunnane, Kathlyn Stewart: Books

www.amazon.com

The second half of the book (chapters 8, 9 and 10) was not much interesting to me personally, but the first half was very enjoying. I am no expert in these matters, but I think that it fits nicely with what was already discussed on this forum. I don't think that it's perfect, but I do think that most of the presented information is quite valid. Of course, those who are more experienced with these things can prove me wrong.

The book on Amazon is quite expensive, but for some reason, you can get it at Researchgate.

 

[Persej]

I've read another book from the same author, Stephan Cosgrave Cunnane, only this one is written solely by him. Here you have more biological facts, which is exactly what I was looking for, so I enjoyed reading this book as well. Again, I am no expert in this area, but his theory certainly sounds reasonable to me. I don't think that his theory is perfect, though. There is obviously a lack of intelligent design, or a carrier of that design, such as viruses that can enforce mutations in DNA. However, the environment can also play it's part in the mutation of a species. As he wrote in his book Survival Of The Fattest: The Key To Human Brain Evolution:

A changing environment creates selection pressures that are an important
stimulus for evolution. Most major environmental change such as
volcanoes, glaciation, or rifting in the earth's crust involves climate
change affecting temperature and the availability of food or fresh water.
Abundance of food or water could rise or fall with the climate change
and also create selection pressures. How the pressure works depends on
the species involved, i.e. it could favour survival of some while straining
survival of others. To survive, either a sufficient number of individuals
within a species is capable of adapting to the environmental change or
must be capable of moving away from it, probably to face new
challenges.

Those individuals that survive and reproduce do so because they are
already sufficiently adapted, i.e. different, to be able to tolerate the
change. That adaptation, whether it is beak shape, rudimentary standing
ability or whatever, then becomes the focus for the distinctiveness from
the parent population that is the seed of the new species. The concept of
selection pressure can have a negative connotation in the sense that the
environmental change is seen as exposing survival limitations; only a
few individuals are sufficiently different within the species to both be
members of that species but also to survive and reproduce in the
changing new environment.

In my view, changing environments not only force evolution, they
also permit it. A changing environment may unlock a certain genetic
potential for morphological or physiological change that previously
remained silent. Some individuals within a species and certainly some
species as a whole may be better prepared for and better able to take
advantage of a particular climatic or environmental change than others.
Genetic or physiological preparedness means that a change in the
environment is permissive; the changing environment doesn't necessarily
force change, it allows it.

My hypothesis is that key nutritional changes in a new environment
permitted human brain evolution because the brains of some hominid
species were genetically prepared for such change. There was no
selection pressure. Nothing forced the brain to become larger. Nothing
forced babies to develop body fat. Hominid survival was not at risk;
several survived for million year periods without substantial change in
brain size.

How do Nutrients Affect Gene Expression?

Establishing that gene mutations affecting nutrient metabolism can be
nutritionally managed or altered demonstrates that nutrition and genetics
are not two solitudes. Genes are neither independent of nor more
important than the environment. Whether we are talking about response
to a cold or evolution of the brain, Darwin's 'conditions of existence'
involve a complex dialogue between the genome and the environment.
But how does it work? What is the mechanism by which nutrients affect
gene expression and, ultimately, evolution?

An old but still valid example is one place to get started. In the 1960s,
Myron Winick at Columbia University was one of the first into the yet to
be named field of nutrigenomics. Winick was trying to determine how
indispensible amino acids affect growth and development. He had two
varieties of bacteria, one that could make one of the indispensable amino
acids, histidine, and one that could not. Since the variety that could not
make histidine was in effect lacking an essential nutrient for its growth, it
did not grow well unless histidine was supplied in the culture medium.
However, when the variety lacking the ability to synthesize histidine was
given histidine, it multiplied better than the bacteria that could synthesize
histidine.

One might expect that the two varieties would become equivalent
once histidine was given to those that couldn't make it. On the contrary,
not being able to make histidine was advantageous as long as histidine
was given in the culture medium. Apparently, it was more efficient for
growth in these bacteria to be dependent on the diet for histidine than to
be independent of dietary histidine by being able to make it. Winick's
interpretation was that if the enzymes usually needed to make histidine
synthesis are no longer necessary because histidine is present in the diet,
more DNA and mRNA are available for other requirements of cell
division and growth.

Eliminating instructions for one amino acid from the cramped space
in the bacterial genome frees up that space for other useful information
that, in Winick's example, seems to have conferred an advantage because
the bacteria depending on diet for histidine grew faster than expected.
Bacteria grow and replicate very quickly so they also evolve quickly. In
effect, histidine became a dietary vitamin and nutrition became of direct
importance in regulating the bacteria's gene expression and evolution.
The trade-off is the dependence upon the environment, in this case, for a
nutritional supply of histidine.

Then why not free up as much space as possible in the genome by
depending on the diet for all nutrients? Organisms do indeed depend on
diet for many nutrients. Some nutrients can be made by some organisms
but not by others, i.e. plants can make the vitamins and other organic
nutrients needed by animals. Other nutrients, like minerals, can't be
made by plants, animals (or bacteria).

The trick is to depend on the diet only for substances (nutrients) found
in good supply in your chosen diet. Don't evolve in a habitat that fully
meets your nutrient needs and then move to a habitat no longer meeting
those needs. This is what has happened with humans during the past
century - we now consume diets that do not meet our needs for brain
selective nutrients and enormous numbers of people are paying the
consequences.

And in his opinion those brain selective nutrients can be found in high quantities only in marine environments, like DHA and iodine.

 

[Persej]

I found an article that shows how much of omega 3's you can get in animals if you feed them with omega 3 food:

Analysis of the published results shows that, under the best conditions, feeding animals with extracts of linseed and rapeseed grains, for example, increases the level of ALA acid by 20 to 40-fold in eggs (according to the low or high level of ALA in commercial eggs), 10-fold in chicken, 6-fold in pork and less than 2-fold in beef. By feeding animals with fish extracts or algae (oils), the level of DHA is increased by 20-fold in fish, 7-fold in chicken, 3 to 6-fold in eggs, less than 2-fold in beef. In practise, the effect is considerable for fish and egg, interesting for poultry and rabbit, extremely low for beef, mutton and sheep.

[Effect of increasing the omega-3 fatty acid in the diets of animals on the animal products consumed by humans]. - PubMed - NCBI

So fish, birds and eggs are best sources of DHA.