I think parents should just start doing their jobs again and teaching their kids this shit rather than throwing them to the wolves. Maybe even introducing their kids to men or women that will make for good spouses and allow them to have grandkids if need be, but the above is an absolute necessity most parents just neglect to do.
For people, just asking which cartoons they watched in x grade; usually gives a good approximation.
For trees you'll have to check with the owner or get one of those things that extract a section of the trunk with all the rings so you can count them.
If its really really old, carbon dating will be your only option.
