Full Idea
In the 1950s a great deal became known about biochemical and neurophysiological processes, especially at the level of the cell, and none of it gave any evidence for the existence of special forces not found elsewhere in nature.
Gist of Idea
Modern biological research, especially into the cell, has revealed no special new natural forces
Source
David Papineau (Thinking about Consciousness [2002], A 6)
Book Reference
Papineau,David: 'Thinking about Consciousness' [OUP 2004], p.253
A Reaction
Papineau says that this plus the conservation of energy makes the closure of physics faily conclusive. I would think the similar failure of modern research into the brain to find evidence of weird forces strengthens the case.