I find issue with the conclusions of the report in that it does not address a well-known dietetic issue related to Chinese height variance. In the northern climes of China where wheat is more prevalent the heights are statistically superior to those in the southern climes where rice is the prevalent staple.
The findings sound plausible, but I believe that the conclusions are unsupported.
I could understand an argument that states inferior/reduced agricultural production later in history led to a decline in height. However, what I see here is an evolutionary assumption that 'as production capabilities increased man's height must also increase' being challenged. Correlation does not make for causation. Therefore the conclusions are unsupported within the article as presented.
That's preposterous. Wheat vs. Rice.
You don't need to go to China. Go to Europe. People in Northern Europe like the Dutch, Scandinavians, Scots, etc. are a couple of inches taller than the Spaniards, Italians, Portugeuse, etc.
You take any animal, and you'll find the members of the same species living at higher latitudes to be bigger in size.
Or hell, just look here in America. Ever wonder why Native Americans here in the states are often 6'+, but amongst Mexicans of predominantly Indian blood 6 footers are rare? Same phenomenon.
Of course, there are exceptions to this rule. Eskimos tend to be short and stocky, which helps hold in heat at the extreme latitudes. And certain tribes in Africa are very tall, but unlike the tall Northern Europeans, their height is an alternate adaptation, and that is to dissipate body heat through their thin limbs.
The Northern Chinese diet will contain more beef and lamb than a southern diet based on fish and pork.