If you are the kind of person who examines their poo, firstly, that is just a little bit weird, and secondly, you may have noticed that when you eat corn, it tends to come out pretty much the same as it went in. So what's going on?
The thing is, modern humans are not really built for digesting corn and the reason is all due to evolution. Years ago, when we didn't eat much meat and instead feasted on vegetables, our digestive systems were a little different from how they are today. Our digestive tract was much longer and our appendix actually did something useful. Our teeth were different too - our molars were bigger and our incisors smaller. Today, we don't need such big teeth to chew on tough plant matter and evolution is phasing them out. As our jaws get smaller, our wisdom teeth no longer fit so well (and this explains the huge amount of pain I'm in at the moment).
The reason that early man had such a different digestive system from us modern folk is that plant matter is pretty hard to digest. Plant cell walls all contain a type of carbohydrate called cellulose and this cannot be digested by humans today. Other carbohydrates (like starch in bread) can be broken down by humans because we possess the enzymes that can cut the links between the individual components. The ability to break down cellulose is missing in humans but would have been present in early man. The appendix would have played a big role in the digestion of this plant material. (You know how rabbits eat their poo? Well that's because their intestines contain bacteria that breaks down cellulose - in a sort of rabbit version of our appendix. Lots of important nutrients are released but some are lost in the rabbits' poo, so our fluffy friends do the smart thing - they eat it all over again and absorb the nutrients second time round.)
So today, with our smaller teeth, we tend to not chew our food very well. When eating corn, we often swallow the kernels whole and our poor digestive systems have enough trouble with plant matter any way, never mind tough whole kernels. The kernels aren't broken up by the acid in the stomach (this is mainly there to help us attack proteins) so will pass all the way through our shorter less efficient digestive systems. We could all give our digestive systems a break by chewing our food into a nice smooth mush before swallowing!
