Some minor points: - The pineal gland isn't the only organ in the brain directly sensitive to the bloodstream. The base of the hypothalamus, specifically at th

Some minor points: - The pineal gland isn't the only organ in the brain directly sensitive to the bloodstream. The base of the hypothalamus, specifically at the arcuate nucleus, can sample blood-born hormones via the Hypophyseal portal system, which is the same permeabilized brain region responsible for the pineal glands' exposure to the bloodstream. - Its also the hypothalamus that senses light levels, via the suprachiasmatic nuclei located just above the optic nerves. Its those neurons that sense light levels via retinal photoganglion cells. The SCN maintains the clock but then signals the pineal on its own. https://www.ncbi.nlm.nih.gov/pubmed/15193530 https://www.ncbi.nlm.nih.gov/pubmed/15193530 I find the calcification hypothesis interesting. Certainly damage to the arcuate nucleus (gliosis) has been implicated in hypothalamic aging and obesity, and I contend that other forms of brain damage due to blood-born exposures are possible. It would be neat to try correlating water flouride levels to millions of fitbit accounts .... if only encouraging people to donate their data for science was easier....