Why those indentations above your butt are named after Venus
Those two small indentations some people have on their lower back, just above the buttocks, have a proper anatomical name: the dimples of Venus, after the Roman goddess of beauty. In Latin, they’re called fossae lumbales laterales, or “lateral lumbar indentations.” The name has been accepted within the medical profession for so long that nobody knows who first made the connection to Venus. Presumably, someone thought they were attractive enough to warrant a divine association.
According to Wikipedia, the dimples mark the sacroiliac joints, where your spine connects to your pelvis. They’re created by a short ligament stretching between bone and skin, and they’re largely genetic — you either have them or you don’t, though body fat percentage affects how visible they are. Research suggests they’re most prominent at around 22 percent body fat in women and 32 percent in men.
Surgeons use these dimples as landmarks when placing screws during spine surgery. Studies have examined the relationship between dimples and lower back pain but have found no statistically significant correlation.
In the 2010s, the dimples became a popular spot for transdermal piercings — small jewelry embedded in the skin.
Feynman mentions them from his playboy painter phase.