Why Does Aging Happen

The reading for this week is the chapter "Why does aging happen?" from the book, "Why we age: What science is discovering through the body's journey through life".  The book takes categorizes thoughts into three causal theories of aging.  These include: "the good-of-the species theory, the rate-of-living theory and the evolutionary aging theory" (p. 55).  Do you agree with any of these theories?  Are there any other theories out there that you find interesting or have discussed in a class?

For your own blogging this week:
In your own words, how would you explain "Why we age?"

Can you give an example or provide a link to an interesting source that supports your explanation?