It means theory of natural destruction.
जायन्ते हेतुवैषम्याद्विषमा देहधातवः| हेतुसाम्यात् समास्तेषां स्वभावोपरमः सदा||२७|| प्रवृत्तिहेतुर्भावानां न निरोधेऽस्ति कारणम्| केचित्तत्रापि मन्यन्ते हेतुं हेतोरवर्तनम्||२८||
Discordance of the causative factors results in disequilibrium of the tissue elements (dhatu) of the body. Conversely, concordance of tissue elements is restored by means of restoring the concordance of causative factors. However, the resolution / destruction of the existing always happens naturally in the course of time. (Cha.Su.16/27-28)
The theory of natural destruction was first proposed by Punarvasu Atreya while answering a query of Maitreya.