My colleague and I have fecal samples from mandrills. It's pretty far outside my usual interests, but I was trying to research to see if there is a way to determine age of the animal from the feces (hormone contents, metabolite concentrations, etc). I haven't had any luck in primates or any other taxa, but I highly doubt that there isn't any research on this. Does anyone here have experience with aging individuals based on fecal samples?