Natural Science Forum / Biology / Paleontology / December 2004

Is Aging an Altruistic Adaptation?
Programmed death theory challenges Darwin
By Liz Brown
Betterhumans Staff
9/27/2004 4:29 PM

Credit: Scott Rothstein
Killer countdown: Yeast findings support a theory that aging is
programmed to help species survive

A new aging theory has challenged Charles Darwin by proposing that
aging is an altruistic adaptation that helps groups of organisms
survive.

Developed by molecular gerontologist Valter Longo of the University of
Southern California in Los Angeles, the theory hinges on natural
selection through "group" selection.

In Darwinism, natural selection happens on the individual level.
Organisms better suited to their environment survive and reproduce,
and beneficial mutations lead species to change over time.

In Longo's theory, however, the majority of a population dies
prematurely to provide nutrients for surviving members, who have
genetic mutations that increase their chances of reproducing.

"We're not saying Darwin was wrong," says Longo. "We're just saying
that there appear to be some big missing pieces in his theory."

Numbered days

Longo's theory is supported by observations of programmed aging in
baker's yeast.

The programmed aging theory suggests that an organism's lifespan is
determined even before it's born. The theory suggests that growing old
and dying is caused by genes or the decline of organ systems, and is
predetermined.

The theory has many critics. But while there are several theories on
aging, most researchers agree that growing old and dying is somehow
related to changes in gene expression that affect systems responsible
for maintenance, repair and defense. These changes can be caused by
internal or external factors.

In studies on yeast, Longo and colleagues have discovered that large
portions of yeast populations die long before expected in order to
provide nutrients for mutants within their own population. "Billions
of organisms die early so that a few better-adapted individuals can
grow," he says.

Dying too early

The findings could have important implications for human aging because
the molecular pathways that regulate longevity in yeast are possibly
similar to those in humans. "Basically, it is the first demonstration,
to our knowledge, that aging is programmed and altruistic," says
Longo.

Still, Longo admits that programmed human aging is just a possibility.
"We don't know whether it's true yet or not," he says. "But if aging
is programmed in yeast, and the pathway is very similar, then isn't it
possible that humans also die earlier than they have to?"

Longo admits there are many unanswered questions in his theory and
plans to look closer at aging in humans and mammals.

The research is reported in the journal Cell Biology (read abstract).