I know this is a very strange thing to ask but why do we, you know, pooh? Why were we made this way? It stinks? Was it not possible to design us so we do not have to do this and produce a horrible smell. That is another thing? Why do we smell? You know like after a run. I am not seeking explanations as to what happens to our body that makes us smell but why would God make us so that we sometimes smell bad?
Hi Wojciech:
I do not know if this is the answer you are seeking, but I thought I’d have a go at it. I believe the reason all organisms (including humans) excrete waste is closely tied to a scientific principle known as the law of entropy. This is a mathematical law governing “disorder”, or “randomness”, if you will, in the universe. Basically, it says that in any defined closed system (such as an animal in its ecosystem, say), the entropy (disorder) of that system always increases, or at best, can only remain constant. This explains why chemical reactions occur in specific directions, releasing free energy for the animal to use (say, the process of cellular respiration in the cell); to run them in the opposite direction, you need to put energy back into the system.
Now that being said, animals such as ourselves need energy to operate, and given that the law of entropy restricts the ability of our bodies to extract energy from the foods we eat (there is never 100% conversion, or efficiency), it logically follows that there must always be some left-over, unextracted energy available in those food products. Organisms lower on the food chain can use some of these leftovers (indeed, I am told much of our solid waste products contain undigested food, materials secreted by our digestive tract, and bacteria) and the energy from these waste products can of course be utilized by other organisms lower on the food chain (plants, decomposers, and so on). Of course, organisms aren’t really a closed system; they need an external energy source continually pumping energy in (the Sun), and if you take the Earth-Sun system to be closed, even though life appears to contradict the entropy principle, in fact entropy increases overall as the Sun converts its available fuel into energy via nuclear reactions.
So that, at root level, is why we excrete…because we cannot convert matter directly into energy (at 100% efficiency), so there will always be “something left over” that we cannot use from the food we eat. As other commentators have already pointed out, it is “smelly” to us as a learned reaction to avoid fecal contamination (pathogenic bacteria)…if there were 100% conversion, there would be no bacteria in feces at all. But to be honest, I’m not sure I’d be comfortable having a “ideal reactor” operating in my intestines, anyway.
I hope this helps.
Jacques
