Is this why they need babies?

An injection of “new blood” is a phrase long used as a metaphor for the revitalizing effect of fresh minds on a stagnant organization. But research now suggests it also applies in a literal sense. In a development that calls to mind both vampire lore and stories of bathing in blood, young blood appears to in fact rejuvenate old brains.

https:// www.scientificamerican.com/article/fountain-of-youth-young-blood-infusions-ldquo-rejuvenate-rdquo-old-mice/