I support the Wear and Tear theory for on the surface it makes logical sense to me. If your hard on your body i.e. wearing it down or doing things like substance or alcohol abuse your tearing it down and eventually your body can’t take the beating any longer and will just be worn out and start to shut down eventually leading to ageing and then death.
The reason I found Somatic Mutation interesting and supported it was if your making thousands of copies of something eventually something is not going to copy correctly i.e. a mutation. You get to many bad copies or mutations and the good cells are then outnumbered and can’t keep up with the number of mutation