12-17-2016, 04:11 PM
(11-01-2016, 10:58 AM)X_4AD_84 Wrote:(11-01-2016, 09:50 AM)Warren Dew Wrote: The Flynn effect appears to have reversed starting with birth cohorts around 1980 or a little before. I know of papers showing reversal in at least Denmark, Germany, Finland, and the UK, and no papers showing it continuing. The fact that it can reverse convinces me that it's real. I suspect the timing matching that of the end of the 20th century height increases is not coincidental, either.
In my opinion, the Flynn effect reversal is most likely due to changes in nutrition - first improved nutrition, but since 1980, poorer nutrition. More junk food may be a reason for the recent decline, as pbrower2a suggests, and perhaps government recommendations that emphasize carbohydrates over the fats needed for brain development also contributed.
None of the above. It's due to "browning."
People from Asia, Latin America, the Middle East - are short. The tall Northern European genes are being bred out.
There is little evidence for average height differences between different popuations due to genetics. Almost all of the difference is environmental. largely nutritional. For example in the nineteenth century Americans were the tallest nation while the Dutch were diminutive. Today the Dutch are the tallest.
The tallest people in the Guinness Book of Records in 1973 was some African tribe (I can't remember which one). They have been surpassed by the Dutch. Hunter-gathers tend to be healthier than agricultural or industrial populations. So as recentlly as forty years ago (assuming Guinness is right) hunter gathers still had pride of first place. The Dutch have finally achieved the first recovery from the Neolithic and Industrial Revolutions. Americans unfortunately have been defeated by these revolutions.