Going to try the answer the old question “Why are the Japanese so…..Japanese?” in the sense of patient, nonviolent, guileless. And I think the answer is related to another stereotype: their immaculate skin, the root cause in both cases being high levels of omega-3 fatty acids. 
The Japanese are the world record holders in circulating levels of EPA+DHA. Here's a list which shows published samples with the highest level of these fatty acids circulating in plasma. The UK average is about 4-5%. This was taken from sciencedirect.com/science/articl…
The obvious association that exists between fish consumption and omega-3 level is not as obvious as it first might appear: for example a Korean study found only a very weak correlation of .269 between fish intake and EPA+DHA in serum.
A study done on Finnish fishermen looked at a populations that consumes fish at about the average Japanese level (70kg per year) and yet their circulating omega-3s (7% of total fat) were lower than 6 out of 7 general Japanese samples and only about half the Japanese peak.
In other words, it is very difficult for a typical European to match Japanese omega-3 levels, even when eating an ungodly amount of fish.
There’s likely a feedback loop here: populations that eat more fish evolve with time to better process EPA+DHA and this makes the beneficial physical and mental effects of stuff much more salient for them.
Someone would need to demonstrate this, but I think I’ve noticed a tendency for the Japanese to remain relatively immune to diminishing marginal returns here: every extra fish eaten does less and less for an Englishman, but there’s no end to what the Japanese can metabolize.
Population geneticists have detected recent strong natural selection acting on carbohydrate metabolism in Europeans and genes which facilitate ketogenesis in the meat eating peoples of the Arctic. I think it’s unlikely that something similar has not gone on in the Japanese.
There has a lot of recent research on the cognitive effects ofomega-3 and the most rock solid findings are that they dramatically aggression and the risk of developing schizophrenia. There’s a national correlation -0.63 (strong) between seafood consumption and homicide rate.
The effect of omega-3s on aggression is powerful enough that it has also been noticed in dogs: link.springer.com/article/10.100…
The Japanese are impossibly peaceful people. The country with +1 million people in Europe with the lowest homicide rate is Norway with 0.47 deaths per 100,000 people and Japan is down to just 0.26.
The Norwegian tendency toward non-violence is very old:
Like the Japanese, the Norwegians have some of the world’s highest level of circulating omega-3 and they also have a famous tendency to produce women with immaculately clear, shiny skin.
There is a large body of research showing that fish oil substantially increases a person’s sunburn threshold, which goes a long way toward answering the British question of why pale Scandinavians seem to tan so easily while they burn up: sciencedirect.com/science/articl…
Another similarity between Japs and Scandinavians is that they have smoothly vibrating, calming voices. The Japanese tendency here is well known enough that I won’t litigate it, but here is Sissel Kyrkjebø, who also did the Hymn to the Sea from Titanic:
HBDers try to explain the differences between violent Vikings and peaceful Norwegians with bad theories about migration, but I think old and new Scandos are more alike than different. A pathological modesty, a feeling that one’s own life is worthless, so why not Valhalla?
The Japanese are so timid and respectful in person, but ferociously brave in battle. In the Pacific they never broke and ran as even Marines do when pushed. A Japanese or a Norwegian cannot leave his friends behind, because to do so is immodest.
There’s one more speculative parallel between the Japanese/Koreans and Scandinavians I want to talk about and that’s their weird dominance of competitive video gaming, virtually any game really, which might extend into chess.
Re congitive effects: "The mood profile was improved after Omega-3 with increased vigour and reduced anger, anxiety and depression states. This was associated with an effect on reactivity with a reduction of reaction time in the Go/ No-Go and Sustained Attention tests"
"results are confirmed by the EMG data that showed the Omega-3-related reduction of RT was not owing to peripheral effects on muscles, such as improved speed of
contraction, but to decreased EMG latency, which was probably influenced by a higher efficiency of central mechanisms"
contraction, but to decreased EMG latency, which was probably influenced by a higher efficiency of central mechanisms"
In other words, one of the effects high omega-3 levels have is that they allow a person to make faster and more accurate decisions on tests of inhibition and executive function like Go/No-Go, which I think has applications in many kinds of real world mental tasks.
End. Going to keep grinding these out until the lockdown ends, got something stuff coming on implications of lactose tolerance in NW Europe and an attempt to explain West African creativity.
