> So one of the groups, either the "in Africa group" or the "out of Africa" group still should have the "old style brains" unless magically the changed happened

> So one of the groups, either the "in Africa group" or the "out of Africa" group still should have the "old style brains" unless magically the changed happened in both groups at simultaneously. Just because one group migrated earlier doesn't mean they were genetically isolated. Presumably there were subsequent migrations, counter-migrations (of large populations and smaller groups) and associated interbreeding between them.