[2] On 9 October 1936, she married fellow zoology student Ole Gregers Hammer (1911–1996) who later headed Danish beekeeping research.

In the 1930s and 1940s, Marie Hammer collaborated with Statens Vildtbiologiske Undersøgelser (Danish Wildlife Investigations), conducting work on sparrows.

[1] In the late 1940s, she once again embarked on lengthy expeditions to continue her research on moss mites, travelling to Canada, Alaska and the Rocky Mountains (1948), Mexico, Argentina, Chile and Bolivia (1954), Panama, Ecuador, Peru, Chile and Argentina (1957), Hawaii, Fiji, New Zealand and New Guinea (1962), West Pakistan, Indonesia, Tonga, Western Samoa and Tahita (1969) and finally Java and Bali (1973).

[2] In 1982, Hammer was awarded Weekendavisen literature prize for her book Forsker i fem verdensdele (Researcher in Five Continents) in which she describes her travels, her work on moss mites and the people she met.

[7] A biographical novel based on the life and endeavours of Marie Hammer was published in 2021 by Danish author Eva Tind entitled "Kvinden der samlede verden" ("The woman who assembled the world") referring to continental drift after the former supercontinent, Pangaea, and her scientific support of this theory.