CORRECTION: The number of countries that Ethnologue tracks is 226, not 156.

The full text of my recent Science piece can be found here. It begins like this:

After a long day in the field, deep in the mountains of southwestern China near the border with Vietnam, retired environmental health professor Gary Shook was surprised to meet another American, Jamin Pelkey, staying in the same government guesthouse. The two exchanged pleasantries.

"I'm collecting tiger beetles," explained Shook, who had found four new species in the region. "What about you?"

"I'm collecting new species of languages," replied Pelkey, then a graduate student at La Trobe University in Australia doing fieldwork for his dissertation...