f learning makes new connections, then remembering that learning will strengthen those connections. As our brains create these structural changes, our thoughts produce neurotransmitters, a mixture of neurochemicals that create emotions.

Playing with a dog, cat, or other pet can elevate levels of serotonin and dopamine, which calm and relax.

triad

Maze told me that his team’s latest research (not yet published) has also found this type of epigenetic marking in the brain tissues of people with major depressive disorder. Perhaps this connection even explains why antidepressant drugs take so long to be effective: If the drugs work by activating this epigenetic process, rather than just supplying the brain’s missing serotonin, it can take days or even weeks before these genetic changes become apparent.

serotonin has another function: It can act as one of those molecular Post-it notes. Specifically, it can bind to a type of histone known as H3, which controls the genes responsible for transforming human stem cells (the forerunner of all kinds of cells) into serotonin neurons. When serotonin binds to the histone, the DNA unwinds, turning on the genes that dictate the development of a stem cell into a serotonin neuron, while turning off other genes by keeping their DNA tightly wound. (So stem cells that never see serotonin turn into other types of cells, since the genetic program to transform them into neurons is not activated.)

smooching on the first date could be improving the mental health of Aussie singles