He was retweeting a study that was not his own. I'll look it up.

edit :

here's the study : https://www.pnas.org/doi/10.1073/pnas.2018840118

here's DS's retweet : https://twitter.com/davidasinclair/status/145775319654643712...

I misrepresented DS's retweet comment and it is not as spectacular as I made it seem. In any case, intresting.