An example of that from fairly recent human history is to be seen in Asia, and China in particular.
It is very common amongst Asian peoples that shortly after drinking even a small quantity of alcohol, they display an 'alcohol flush', rather like a facial blush. People who do this appear to be able to tolerate alcohol better than others.
Researchers at the Chinese Academy of Sciences have discovered that this is caused by a variant allele called ADH1B*47His. Molecular dating techniques have shown that this arose in China around 7-10,000 years ago, exactly when Chinese culture underwent a major (possible the most significant) change when rice was domesticated.
We studied a total of 38 populations (2,275 individuals) including Han Chinese, Tibetan and other ethnic populations across China. The geographic distribution of the ADH1B*47His allele in these populations indicates a clear east-to-west cline, and it is dominant in south-eastern populations but rare in Tibetan populations. The molecular dating suggests that the emergence of the ADH1B*47His allele occurred about 10,000~7,000 years ago.This crop quickly became the staple source of carbohydrate and a good deal of the protein in the Chinese diet and enabled settled agriculture and the growth of cities in and around the Hwang Ho (Yellow River) valley.
Rice can also be fermented to give alcohol which has several uses: It can be used recreationally but ultimately destructively when used in excess; it can also be used to preserve food and enhance it's nutrient qualities, as a disinfectant and medicinally as an analgesic. It is believed that drunkenness may have quickly become a major problem giving both increased food but also increased problems with drunkenness and alcohol-related illness.
So, people carrying ADH1B*47His would have been able to tolerate alcohol and would have suffered less damage from recreational alcohol, whilst benefiting from the positive benefits, giving them a very real advantage.
So here again we see an illustration of the way the environment drives evolution by translating the information in the genome and giving it meaning. Before there was rice being cultivated and the alcohol that was able to be produced by it and with it, the ADH1B*47His allele had no meaning whatsoever. In the presence of rice and alcohol it meant survive and prosper when others are suffering and failing. And so ADH1B*47His increased in the local human gene pool
The presence of rice change the environment of the human population of China and evolution ensured the human population promptly adjusted to fit into this new environment.
When will creationists ever get that simple piece of information into their heads and allow themselves to appreciate the wonder of nature and the awe-inspiring power of evolution by natural selection to fine tune living organisms to harmonize with their environments.
More information: The ADH1B Arg47His polymorphism in East Asian populations and expansion of rice domestication in history, Yi Peng, Hong Shi, Xue-bin Qi, Chun-jie Xiao, Hua Zhong, Run-lin Z Ma and Bing Su, BMC Evolutionary Biology (in press), www.biomedcentral.com/bmcevolbiol/
Read more at: http://phys.org/news183153307.html#jCp