[3] After graduating from Harvard, he married and settled at the family farm at Lancaster, thirty-five miles west of Boston.

[8] He used his wealth to sponsor various natural history expeditions and in 1906 he sent Wilmot W. Brown Jr. to Guadalupe Island off Pacific Mexico.

Here, Brown, H. W. Marsden and Ignacio Oroso gathered field data on how the natural vegetation was being destroyed by thousands of goats, to the detriment of the native wildlife.

[8] In 1913, Thayer and other Harvard graduates sponsored an expedition to Alaska and Siberia, with Joseph S. Dixon and Winthrop Sprague Brooks as zoological collectors.

Together, John and Evelyn were the parents of:[12] Thayer died on July 29, 1933, in Lancaster and was buried at Old Settlers Burial Yard there.