#Wikidata it hurts when you are cheating. For us a human is singular; he or she has a date of birth, maybe a date of death and that is what we expect to find in "20th-century births" and all its subcategories.
We could argue that a horse, a cat or a dog has a date of birth as well but really, Scott Alexander and Larry Karaszewski for instance is not one human or singular. Together they do not have a date of birth, they have two.
Because of the problems articles like the one about Scott and Larry generate, we put them on a "black list". We make them a "group of people". In this way we will not consider them for all kinds of subsequent statements. We will not make them an alumni or give them an occupation. That is reserved for humans.