Shrinking Brains

Shrinking Brains

In a recent media article (Seafood’s Role in Dementia Prevention – SCA) we commented on National Press Club presenter, Professor Henry Brodaty AO (scientist, clinician, and advocate) who challenged all Australians to adopt a “slip, slop, slap” approach to brain health. We have followed up on this issue and communicated with Professor Michael Angus Crawford, PhD, FRCPath, MRSC, FRSB.

Michael is renowned for his pioneering research into the role of seafood—especially omega-3 fatty acids—in human nutrition and brain health. Throughout a career span of over five decades, Crawford’s relentless advocacy has shaped our understanding of how seafood impacts both the brain and the heart, and why its decline in modern diets spells trouble for global mental health and intelligence.

Early Discoveries: The Essentiality of DHA

Crawford was the first to confirm, in the early 1970s, that docosahexaenoic acid (DHA), a long-chain omega-3 fatty acid primarily found in seafood, is a critical building block for the brain.

Michael Crawford and Andrew Sinclair in 1971 published the first evidence that docosahexaenoic acid (DHA) was essential for the brain. This landmark research was identified in the Sunday Times 5th November 1972 by Graham Rose who reported on Michael's claim that if attention was not given to this evidence on the nutrition of the brain there would be a catastrophic failure in mental health (the words were more colourful ‘we will become a race of morons’!!).

This landmark research at the Nuffield Institute of Comparative Medicine. London, UK, demonstrated that the brains of all mammals, including humans are rich in DHA and that brain size varies significantly according to dietary DHA supply. He showed that human milk is naturally high in DHA and that deficiencies in omega-3 intake led to behavioral pathologies in a primate, including self-harm. Hence the importance of breastfeeding mothers!

Additionally, in 1973, Gene Anderson, working at the Cullen Eye Research Institute (Houston, Texas), provided robust evidence that deficiency of DHA in rats caused loss of visual function in terms of retinal electrical function.

The strong evidence for a DHA requirement by the brain, has multiplied since then, resulting in the 2008-10 FAO-WHO joint expert consultation on the role of dietary fatty acids in human nutrition to conclude that the evidence of its essentiality for the brain was supported at the highest level of confidence.

Professor Crawford is keen to give credit to his close research partner in these endeavours in the early seventies, Emeritus Professor Andrew Sinclair. Most Australians are unaware that in Andrew we have one scientist to thank for our most important nutritional knowledge – especially the importance of eating seafood, particularly oily fish, like sardines and salmon – for maintaining good health.

Brain Evolution, Health, and the Waterside Ape Theory

In his influential book, The Shrinking Brain and the Global Mental Health Crisis, Crawford explains how the shift in human evolution from forest to shoreline environments allowed early Homo sapiens to consume a diet plentiful in brain-specific nutrients from land and sea. He underscores that our 1,600cc brains evolved from humble beginnings (about 350cc in chimpanzees) not due to genetic factors (our genome differs just 1.5% from chimps), but primarily due to abundant access to seafood—mussels, oysters, crabs, and fish. The “waterside ape theory,” supported by figures like Sir David Attenborough, suggests our cognitive leap was directly fueled by the consumption of these marine foods.

Evidence abounds on the benefits of Omega-3’s in preterm infants, essential as the brain growth spurt is incomplete when children are born early. See our earlier blog Omega-3 Testing in Pregnancy – SCA on that issue.

How the Modern Diet is Shrinking Brains

Crawford continued his activities to present the case for the expansion of cranial capacity from a chimpanzee size of 340cc, to a peak of 1,500-1,700cc in Cro Magnon 28.000-32,000 y.a. proving that it could only have happened if early hominids, made use of the aquatic food web to provide DHA and the essential trace elements, including iodine which are also richest in marine foods. There is little in foods from the land and almost none in intensively produced land-based foods commonly available in our supermarkets nowadays.

Proof of the marine connection came from studies of John Parkington [12] and Curtis Marean [11] who have reported on incontrovertible evidence of exploitation of the marine food web by early Homo 160,000 -200,000 y.a. along the coastline of Cape Town and Pinnacle Point in South Africa. Around the same time, fossilised skulls were discovered in Herto, which at the time would have been coastal Ethiopia. Cranial capacity had by then reached 1,450cc. like today.

Crawford argues that today’s diets contain less than a tenth of the omega-3 fats that shaped our ancestors’ brains. This nutritional shift has resulted in a documented decrease in average brain mass—from over 1,600cc 30,000 years ago to about 1,336cc today. IQ scores are declining globally, and Crawford links these trends to a move away from seafood and toward processed foods, sugars, and refined carbohydrates trend reinforced by outdated fears over dietary fat and heart disease.

He highlights that marine foods remain the single richest sources of DHA, which is not synthesized efficiently from plant-based precursors in the human body. As such, populations and individuals who eat little or no fish are at substantial risk of omega-3 deficiency, with potential repercussions for mental health, learning, and cognitive performance across the lifespan.

The Mental Health Crisis—Evidence and Solutions

Crawford’s work shows a direct connection between poor omega-3 intake and the explosion in mental health issues seen worldwide. Depression, ADHD, autism, and dementia have all increased in parallel with declining seafood consumption. Crawford references research indicating a 20% reduced risk of dementia with increased intake of fish or supplemental omega-3 oils.

Crawford advocates for regular blood testing to ensure adequate omega-3 DHA levels—especially in those following plant-based diets, as algae-derived DHA supplementation becomes crucial for vegetarians and vegans. He also notes that less than 5% of children today meet the basic requirement for seafood-sourced omega-3s, predisposing them to learning and emotional problems.

During pregnancy, he found that a deficiency of DHA means mothers produce oleic acid to substitute in the developing brain, but it is an inadequate replacement. This leads to higher risks of preterm birth and developmental brain deficits. He emphasizes that improving omega-3 and B vitamin status in mothers leads directly to higher IQ and better emotional stability in their children.

Cardiovascular Health and Seafood

While Crawford’s primary focus is on brain health, he has not neglected the profound benefits of seafood for the heart. He has repeatedly demonstrated how omega-3s from fish oil improve blood vessel flexibility and circulation, ensuring adequate oxygen and nutrients are delivered to brain and heart tissues—key for maintaining sharp cognition and robust cardiovascular health.

The Reversal is Possible—A Call to Action

Despite the trend toward “dumbing down," Crawford insists that the process is entirely reversible. His message is clear: return to diets rich in brain-supportive nutrients from the sea. He has lent his name and scientific rigor to public health campaigns and research charities aimed at prevention of dementia, robust brain function, and overall wellbeing through seafood consumption.

In summary, Crawford’s work has awakened the scientific community and broadened public to seafood’s critical role. The implications are vast—failure to restore adequate omega-3 intake could mean worsening mental health and lower intelligence across generations, while restoring such diets promises brighter, sharper, and healthier future generations.

Key Takeaways:

• DHA, abundant in seafood, is essential for brain evolution and ongoing mental health.[3][4]
• Modern dietary shifts away from seafood have led to declining brain size, IQ, and spiraling mental health disorders.[1][5][4]
• Both brain and heart function benefit from regular seafood consumption, supporting cognition and circulation.[2][6][3]
• Ensuring adequate omega-3 intake, especially during pregnancy and childhood, is crucial for optimal development and lifelong brain health.[1][4]

By championing the vital importance of seafood in the human diet, Michael A. Crawford calls on us to remember and reclaim the dietary wisdom that built our remarkable brains, the legacy of the waterside ape. Be sure to include adequate fish/seafood in your diet.

References

1. http://www.nutritiousminds.org/scientific-advisory-board.html
2. https://www.nature.com/articles/s41430-024-01452-6
3. https://pmc.ncbi.nlm.nih.gov/articles/PMC1171703/
4. https://foodforthebrain.org/the-shrinking-brain-are-we-dumbing-down/
5. https://library.fabresearch.org/viewItem.php?id=15748
6. https://aquaasiaapac.com/2023/07/24/slip-slop-slap-for-your-brain-seafoods-role-in-dementia-prevention/
7. https://www.iapss.org/london-october-2023
8. https://www.sciencedirect.com/science/article/abs/pii/S0952327813000707
9. https://pmc.ncbi.nlm.nih.gov/articles/PMC5598976/
10. https://pmc.ncbi.nlm.nih.gov/articles/PMC5203760/
11. https://www.nature.com/articles/nature06204
12. https://www.academia.edu/19735076/Milestones_the_impact_of_the_systematic_exploitation_of_marine_foods_on_human_evolution