The husband-wife team of Mary and Harold spent almost two decades working among native American Indian communities, becoming fluent in Spanish, Aztec, Tacanan and Cayubaba (now an extinct language). Both Keys earned their respective PhD's at the University of Texas, in Austin. They raised 3 children in Mexico and South America, then took up teaching positions. Mary fought for her post as full professor at UCI by pointing out that she had published more and better material than male professors who were paid more and elevated above her. Yet she turned down law firms who wanted to bring gender discrimination suits, and instead continued her academic work.
She founded and edited the first intercontinental "newsletter" uniting linguists around the globe. This evolved into the famous Intercontinental Dictionary Series, the largest comparative lexicon of languages in the world.