I think they area as a result of a rapid gastric emptying and creation of high osmotic gradient in the small intestine that causes a sudden shift of fluid from the blood vessels to the intestinal lumen. Gastrectomy is the removal of part or all of the stomach. A partial gastrectomy involves the removal of a part of the stomach, the lower half is removed mostly, while full gastrectomy involves the removal of the entire stomach.
The health consequences of eating it is highly unknown. Genetically modified foods have no been PROVEN safe. I tried to research but I really didn't find all that much. Sorry if this is not what you were looking for...
Yes, all living organisms evolve and adapt to their environment as a part to natural selection.