October 2017 Discover

October 2017^ DISCOVER^3

Contents

OCTOBER 2017

VOL. 38, NO. 8

26 This

Old Brain

A 69-year-old writer

explores the aging

process of his own brain.

BY JEFF WHEELWRIGHT

32 What

Once

Was Lost

Though challenges

remain, neural stem cells

are beginning to fulfill

their promise for people

with brain injuries and

degenerative diseases.

BY LINDA MARSA

FEATURES

SECTIONSPECIAL

40 Unraveling

a Secret

Forget pen and paper. How

did the Inka use knotted

cords to keep their records?

BY BRIDGET ALEX

48 Think Like

a Hacker

Smart devices make our

lives easier, but beware:

Cybervillains are everywhere.

BY STEPHEN ORNES

56 The Great
Takeover
Invaders from distant
waters are overwhelming the
Great Lakes, and scientists
are worried. BY DAN EGAN
ERNIE MASTROIANNI/DISCOVER

Quagga mussels cling

to a rope dangled in

Lake Michigan for a year.

Learn how these invasive

creatures are destroying

the Great Lakes’ ecosystem

on page 56.

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