true is the final answer!
The answer is Erasmus Darwin
In the 19th century, Erasmus Darwin, Charles Darwin's grandfather proposed the theory that loss of irritability in the nervous system and a decreased response to sensation or stimuli was associated with ageing.
This is one of the first theories of biological ageing; the others being Hippocrates' and Eli Metchnikoff's.
Hippocrates attributed ageing to the loss of body heat whereas, Eli Metchnikoff associated it with autointoxication. A state caused by the poisoning or intoxication of the body by toxins produced by the body itself.