According to an interesting article written by Steven and Michael Meloan for the Huffington post:
A recent study led by Massachusetts General Hospital found that half hour per day of meditative practice over only eight weeks led to increased feelings of compassion, self-awareness, introspection, and reduced stress. The study also reported that changes in brain structure appear to underlie these perceptions. Increases in gray matter density have been observed in structures associated with these compassionate states, as well as areas linked to memory and cognition. Researchers sometimes refer to such measurable changes from meditative practice as “self-directed neuroplasticity.”
All well-and-good you might say, but how does neuroplasticity translate into inter-generational changes characteristic of an ‘evolutionary’ process? Well, it seems that ‘environmental’ (or behavioural) influences have been shown to alter the epigenome; the Meloans’ postulate that the positive benefits of meditation (and by extension ‘contemplative’ forms of prayer) could then be passed down through the generations via this mechanism. The implications of this are enormous and shows that meditative practice (however this is understood) is even more beneficial than previously thought.
You can read the full article here: http://www.huffingtonpost.com/steven-and-michael-meloan/meditation-epigenetics_b_877010.html