This article is mind-blowing: there’s no hard proof, but a lot of intriguing evidence that two little girls are in some way sharing each other’s consciousness.
Born with an extremely rare (the rarest- there are no other cases in medical history) form of conjunction at the head (craniopagus), Krista and Tatiana Hogan seem to share mental and physical experience through a thalamic bridge. Their neurosurgeon hypothesizes that when either of the girl’s bodies experiences sensory input, the signal passes to both brains.
It’s hard not to speculate on the big questions this medical anomaly engenders: on the nature of the self, and on the nature of consciousness. And these big philosophical questions are ones that Krista and Tatiana have to negotiate continually at a very practical level: what pronoun should the girls use to refer to themselves, and what does it mean? What if their connectivity extends beyond basic sensory input, to higher-order thoughts and preferences? There are some good links in the article to philosophers and neurobiologists who had been thinking about these kinds of problems before the extraordinary case of Krista and Tatiana.