the study of fecal matter started a long time ago and is still going on. feces are a smelly waste that comes out of your behind and the average human empty's their body 1-3 times a week. the study of flatulence also started a while ago but is still going on. flatulence is a form of smelly gas that comes out of your behind and the average human passes gas 1-25 times a day and if you pass gas more often then that then you are gassy..