Final answer:
Proximate causes of aging refer to immediate biological mechanisms like cellular damage, while ultimate causes relate to evolutionary and genetic factors. The free radical theory of aging serves as an example of both proximate causes with oxidative stress leading to cellular damage and ultimate causes relating to the broader evolutionary consequences of such damage.
Step-by-step explanation:
In the context of theories of aging, proximate causes refer to the immediate biological factors, such as molecular and cellular changes, that contribute to aging, also known as primary aging. These can include damage-related factors like oxidative stress. In contrast, ultimate causes pertain to broader and more distal evolutionary explanations of why aging occurs. These can include programmed factors such as genetics and evolutionary pressures that have shaped the lifespan of organisms. For instance, modernization theory suggests that societal changes that devalue the elderly could be an ultimate cause of age-related decline in social power and influence.
The free radical theory of aging, originally proposed in the 1950s, illustrates both proximate and ultimate causes. The proximate version asserts that aging is a direct result of oxidative damage to cells, while the ultimate version posits that oxidative damage leads to age-related disease and a secondary form of aging. While the theory remains under debate, evidence indicates that oxidative stress contributes to aging, and that reducing such damage can extend lifespan in certain organisms. However, in primates, calorie-restriction, which reduces oxidative stress, has not shown an increase in lifespan, highlighting the complexities of aging processes.