Even the EXIF metadata on the photo wouldn't always be reliable for assessing that date. Some people resort to uploading screenshots of pictures found elsewhere online. Through the Facebook meme, most people have been helpfully adding that context back in (“me in 2008 and me in 2018”) as well as further info, in many cases, about where and how the pic was taken (“2008 at University of Whatever, taken by Joe; 2018 visiting New City for this year’s such-and-such event”).
In other words, thanks to this meme, there’s now a very large dataset of carefully curated photos of people from roughly 10 years ago and now.
Facial recognition's potential is mostly mundane: Age recognition is probably most useful for targeted advertising.
Ad displays that incorporate cameras or sensors and can adapt their messaging for age-group demographics (as well as other visually recognizable characteristics and discernible contexts) will likely be commonplace before very long.
In other words, it would help if you had a clean, simple, helpfully labeled set of then-and-now photos.
What's more, for the profile pictures on Facebook, the photo posting date wouldn’t necessarily match the date the picture was taken. They might have uploaded pictures multiple times over years.
I’ll offer three plausible use cases for facial recognition: one respectable, one mundane, and one risky.
The benign scenario: Facial recognition technology, specifically age progression capability, could help with finding missing kids.
"This is a user-generated meme that went viral on its own," a Facebook spokesperson responded.
"Facebook did not start this trend, and the meme uses photos that already exist on Facebook.