Table 1.

Comparison of traits exhibited by the TB bacillus in terms of the behavior expected of a symbiont versus a pathogen.

Trait	Symbiont	Pathogen
Low virulence rate with
High dormancy/persistence	√	X
Nicotinamide secretion	√	X
Nicotinamide role in brain growth	√	X
Self-regulation to prevent host death	√	X
Origin should coincide with major brain expansion	√	X
Capacity to switch from NAD production to extraction	√	X
Trade-off with meat consumption	√	X