Life's Little Mysteries

Why Do We Die?

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Death happens as cells die. (Image credit: Stephanie Pappas, LiveScience.com.)

We die naturally because our cells die.

After they’ve done their job, billions of cells in your body die each day and make way for new cells.

Old cells age us. Inside a cell, telomeres at the end of each chromosome contain genetic information that gets clipped away with each cell division. At first, telomeres are long enough that they can handle a snip here and a trim there. But after they hit a certain length, the information is lost.

Related: What exactly does it mean to die from 'natural causes'?

When programmed cell death goes haywire, it can lead to diseases such as cancer and Alzheimer's disease.

Damage from exposure to ultraviolet light and free radicals also age cells.

But don’t despair. Scientists have extended the lives of flies, worms and mice through genetic tinkering or technology that mimics the effects of caloric restriction. Some research suggests humans could one day live to 140 years of age.

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Corey Binns
Corey Binns lives in Northern California and writes about science, health, parenting, and social change. In addition to writing for Live Science, she's contributed to publications including Popular Science, TODAY.com, Scholastic, and the Stanford Social Innovation Review as well as others. She's also produced stories for NPR’s Science Friday and Sundance Channel. She studied biology at Brown University and earned a Master's degree in science journalism from NYU. The Association of Health Care Journalists named her a Centers for Disease Control and Prevention Health Journalism Fellow in 2009. She has chased tornadoes and lived to tell the tale.