Is the response to calorie restriction purposeful? A challenge to life history theory

If the response to calorie restriction (CR) is purposeful, the purpose being to postpone aging in the face of diminished resources, this has implications for theories as to the causes of aging. If the response to CR is not purposeful, being merely the cessation of aging, this represents a challenge for life history theory, which holds that organisms respond to certain changes in their environments through modifications in growth, reproduction, and maturity.