Jaime “Ka Diego” Padilla (R), spokesperson of the Melito Glor Command of the New People's Army (NPA), and Ka Kathryn (Comrade Kathryn) (L) react during their 50th founding anniversary celebration at an undisclosed location in the mountains of Sierra Madre, Philippines, 31 March 2019. (Photo by Alecs Ongcal/EPA/EFE)

Fire fighters attend a drill session during the Jilin Fire Fighting Emergency Rescue Drill On Setpember 28, 2011 in Changchun, Jilin Province of China. (Photo by ChinaFotoPress/Getty Images)

Mohamed Mostafa, 35, carries dyed yarns at a dye workshop in old Cairo, Egypt, March 17, 2016. Egypt's hard currency crisis and competition from modern factories in Asia and at home threaten one of the last dye workshops in Egypt. But one of its owners takes comfort in the trade's ancient resilience. Mohamed Mostafa boasts that the profession dates back 3,000 years, so it can survive anything. (Photo by Amr Abdallah Dalsh/Reuters)

FaceResearch.org, a site run by two psychologists at the University of Aberdeen in Scotland, features software that can average together faces from thousands of photos. These images purportedly show the average face of women from 40 different nationalities.

Hwang Bo-young (L), a North Korean defector who was a member of the North Korean National female ice hockey team, prepares for practice with South Korean teammates on March 13, 2006 in Seoul, South Korea. Young, 27-years-old, became a captain of the South Korean National Female Ice Hockey Team. (Photo by Chung Sung-Jun/Getty Images)

Inmates dressed as Santa Claus prepare to participate in an event ahead of Christmas celebrations at Santa Monica female prison in Lima December 19, 2014. (Photo by Enrique Castro-Mendivil/Reuters)

A female forest guard carries a tranquillizer gun in the Gir National Park and Wildlife Sanctuary in Sasan, in Gujarat December 2, 2014. The sanctuary, which is home to Asiatic lions in India, has an area of 1,412 sq km in which female guards were employed for the first time in India in 2007. The guards fetch a monthly salary of around $148 for working almost 12 hours a day, six days a week, said one of the female guards. (Photo by Anindito Mukherjee/Reuters)