How do you prove that Earth is older than 10,000 years?

Re:How do you prove that Earth is older than 10,000 years? by jdmichal on Thursday November 23, 2017 @05:59PM (#15768387)

I wonder why you feel that singular they is informal? There's nothing wrong with the construction. It's attested as far back as 14th century. And, as you mention, it certainly fills a void in the language.