Frozen caribou feces offers look at virus evolution
![700-year-old caribou feces preserved in ice core](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2014/10/frozen20caribou20poo_free.jpg?fit=860%2C460&ssl=1)
Intact samples of ancient viruses are hard to find. Extracting them from an ice core containing 700-year-old caribou feces (shown) has helped scientists better understand the diversity and evolution of the infectious agents.
Courtesy of Brian Moorman