A nanosecond pulsed laser beam starts the photoacoustic imaging process. Geoff Story/Courtesy of Washington University in St. Louis hide caption

itoggle caption Geoff Story/Courtesy of Washington University in St. Louis

A daily habit of sugary-sweetened drinks can boost your risk of developing the disease — even if you're not overweight. Ryan Kellman/NPR hide caption

itoggle caption Ryan Kellman/NPR

Giedre (left) and Tal Cohen in March 2013, while Giedre was still healthy. Since then, she's begun having symptoms of Alzheimer's disease. In Giedre's case, the illness is tied to a rare genetic mutation she inherited. Courtesy of Tal Cohen hide caption

itoggle caption Courtesy of Tal Cohen

Women with mild cognitive impairment, which can be a precursor to Alzheimer's, tend to decline faster than men. Lizzie Roberts/Getty Images/Ikon Images hide caption

itoggle caption Lizzie Roberts/Getty Images/Ikon Images

The area around the confluence of the Silverthrone and Klinaklini glaciers in southwestern British Columbia provides a glimpse into how the terrain traveled by Native Americans in Pleistocene times may have appeared. David J. Meltzer/Science hide caption

itoggle caption David J. Meltzer/Science

Lee Perry-Gal measures chicken long bones at the zooarchaeology lab, Zinman Institute of Archaeology, University of Haifa. Courtesy of Guy Bar-Oz hide caption

itoggle caption Courtesy of Guy Bar-Oz

In this colorized image of a brain cell from a person with Alzheimer's, the red tangle in the yellow cell body is a toxic tangle of misfolded "tau" proteins, adjacent to the cell's green nucleus. Thomas Deerinck/NCMIR/Science Source hide caption

itoggle caption Thomas Deerinck/NCMIR/Science Source

Floodwaters from rising sea levels have submerged and killed trees in Bedono village in Demak, Central Java, Indonesia. As oceans warm, they expand and erode the shore. Residents of Java's coastal villages have been hit hard by rising sea levels in recent years. Ulet Ifansasti/Getty Images hide caption

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A family receives treatment for cholera at a clinic run by Doctors Without Borders in Port-au-Prince, Haiti, in October 2011, a year after the overwhelming outbreak began. Ramon Espinosa/AP hide caption

itoggle caption Ramon Espinosa/AP

A bumblebee collects pollen from a flower. New evidence suggests climate change has left bumblebees with a shrinking range of places to live. Yuri Kadobnovy/AFP/Getty Images hide caption

itoggle caption Yuri Kadobnovy/AFP/Getty Images

Even if you don't speak their language, you can likely communicate with these musicians through song and dance: Men from Papua New Guinea; Wiz Khalifa at the 2015 Billboard Music Awards; and Japanese dancers at the Daihanya Festival in Kagoshima City. Ness Kerton/AFP/Getty Images; Ethan Miller/AFP/Getty Images; iStockphoto hide caption

itoggle caption Ness Kerton/AFP/Getty Images; Ethan Miller/AFP/Getty Images; iStockphoto
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