333. The growing and wearing away of man.
Verse 36:68 talks of wearing away of man when he lives for longer days, 16:70, 22:5 Allah also talks about this in verses 16:70, 22:5.
Man gradually grows right from his birth, and after a particular period of time gets worn out losing his teeth, his walk, and retires to his bed, just like a child who needs a lot of assistance.
This is what is mentioned in the Quran as a downward phase in the life of man.