A recent respondent of mine asserted that 'service' and 'compassion' were 2 of the 10 yamas and niyamas. I guess ahiṃsā could be indirectly translated as 'compassion' for others by being 'non-violent', however, 'service' as in 'seva' does not find any mention in the PYS list, which is what my respondent was referring to.

While the ideas of 'service' and 'compassion' show a lack of critical understanding of the normative, institutionalised convention, I find it fascinating how these canonised ideas evolve in a meme-like way, unregulated in the minds of yoga practitioners (my respondent is a professional yoga teacher). As many practitioners of modern yoga assume this list has 'stood the test of time' and is as an a priori concept, this has made me think about the historicity and development of the yamas and niyamas as singular ideas, and as a conjoined pair. 

Might it be correct to say that they were first standardised in the PYS as 10? Were there any other lists that had a greater or lesser number prior to the PYS?  (I'm thinking in a similar way to the development of the ṣadcakratantra, and how there were other texts that discussed alternate numbers/locations, etc)

Might someone be able to  lead me to a better understanding of the development of the yamas and niyamas? I looked through the search option of the list but couldn't really find any discussion that pertained specifically to my request. Although the discussions on whether some texts place a concept in the yama as opposed to the niyama category are quite interesting. 

Thank you.