Very interesting read. just one provoking thought from it:
"It is a sobering thought that the only barrier between you and others is your skin receptors!"

The 'illusion of one unitary self', could it be a deeply embedded memory? We may not know every thing about our origins but still remember/long for ... 'Union'?
Perhaps the scope of the whole picture goes beyond 'neurology', beyond Darwin. Thinking about blissful states ...

"One of the last remaining problems in science"