From the article:

When we think of human development, we usually think of the growth of a fetus or the maturation of a child into an adult. Yet the tightly choreographed transition into middle age is a later but equally important stage in which we are each recast into yet another novel form.

That form is one of the most remarkable of all: a resilient, healthy, energy-efficient and productive phase of life that has laid the foundations for our species’s success. Indeed, the multiple roles of middle-aged people in human societies are so complex and intertwined, it could be argued that they are the most impressive living things yet produced by natural selection.

This is a fascinating article that makes the claim that the "middle age" period of life is the result of human evolution. Though the body deteriorates in predictable ways after age 40 (the author uses skin elasticity and vision as examples) other core functions (cognition, muscular strength) deteriorate much more slowly as the body continues to invest heavily in maintaining those systems.

The idea is that middle-aged humans, though no longer reproducing, were able to invest their remaining years nurturing their (adult) children and their grandchildren. Also, entering a more "supporting" allowed them to focus on teaching the considerable skill they had learned to their descendants, passing along non-genetic information in a way that improved the fitness of their offspring.

Peter Thiel thinks death is a problem that can be solved:

Peter Thiel is financing medical research that would possibly extend the human lifespan to 150 years or more.

"There are all these people who say that death is natural, it's just part of life, and I think that nothing can be further from the truth," says Thiel.

[Read more.]

Organisms that do not reproduce tend to live longer: http://pandawhale.com/convo/2394/dr-john-hatle-what-grasshoppers-can-teach-us-about-food-sex-and-aging