The spokesperson said:

"How people share and communicate is changing and things like masks and other effects allow people to express themselves in fun and creative ways. We're excited to welcome the Faciometrics team who will help bring more fun effects to photos and videos and build even more engaging sharing experiences on Facebook."

TC also noted that the acquisition could lead to facial gesture controls, since one of Facebook's goals for its AI research efforts is to "recognize facial expressions and perform related actions." That likely won't happen in the near future, but we're looking forward to a time when we can make faces at our phones to control the Facebook app.

Here is FacioMetrics' full statement about the purchase: