These are babies and toddlers with rapidly growing brains. Much larger drops are observed in slightly worse daycare/orphanage/foster situations, so a drop of 16

These are babies and toddlers with rapidly growing brains. Much larger drops are observed in slightly worse daycare/orphanage/foster situations, so a drop of 16% isn't surprising to me. In the bad situations, brain structure is significantly changed. https://www.livescience.com/21778-early-neglect-alters-kids-brains.html https://www.livescience.com/21778-early-neglect-alters-kids-... https://en.wikipedia.org/wiki/Romanian_orphans https://en.wikipedia.org/wiki/Romanian_orphans There is simply no substitute for a good mother. Being affluent tends to mean being industrious, conscientious, intelligent, and educated. It isn't popular for such women to stay home and raise lots of kids, but it makes a huge difference in the kids' lives and for the society that those kids will someday grow up to run.