In this week’s Discovery newsletter, we think twice before going on a gluten-free diet, go diving to find lost history ... and explore the wide-reaching effects of penguin divorce.

 PHOTOGRAPH BY AILEEN SON, THE NEW YORK TIMES/REDUX 

Only a small percentage of the population actually needs to avoid gluten, yet millions have jumped on the trend. Here’s what science says about the risks and benefits of going gluten-free.

Related: Fruits and vegetables are less nutritious than they used to be

LAST CHANCE: Get $10 off a National Geographic subscription

 PHOTOGRAPH BY WAYNE LAWRENCE, NAT GEO IMAGE COLLECTION 

PHOTOGRAPH BY KATIE ORLINSKY 

Did you know that declining numbers of free-ranging caribou herds led Alaska to send for hundreds of domesticated reindeer to roam the great north as a new food source. When did these first domesticated reindeer ship from Europe to Alaska? 

A. 1867
B. 1881
C. 1898
D. 1911

Today’s Soundtrack: Easier Said Than Done, Thee Sacred Souls 

Today’s newsletter was edited and curated by David Beard and produced by Amanda Williams-Bryant. Sign up here to get tomorrow’s Top Ten stories of the week or catch Sunday’s Photo of The Week.