No, seriously, do they?
“Is the placebo effect biologically real? We’re not sure. But, if it is, then it is safe to say that it evolved over time, that it confers some survival advantage, and most importantly, it should also be able to be seen in other organisms. It has been reported in rats on occasion. But, what if we could study the placebo effect in lower organisms like fruit flies (Drosophila melanogaster) or worms (Caenorhabditis elegans)?
In the study of aging, these tiny, but powerful animals who age quickly, make it easier to do many experiments in a shorter period of time. Worms, in particular, are a fantastic model for the field of dietary restriction (DR), a programmed method of reducing calorie intake and the most scientifically sound method of extending lifespan. But in worms, the extended lifespan offered through DR is disrupted by the smell of food which tricks their bodies out of DR mode and stops the extension of life.”