Free-radicals?<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Free-radical_theory_of_aging#Mitochondrial_theory_of_aging" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Free-radical_theory_of_aging#M...</a>