Althea was born eight years after her parents arrived in Iowa's Garnivillo Prairie from New York, via Wisconsin. She and her siblings--Julia Sherman St. John, E. Amelia Sherman, and Mark R. Sherman--all attended Oberlin College. A member of the Class of 1888, Mark did not graduate, although he went on to practice law in Chicago. Both Julia and Amelia graduated--in 1873 and 1874, respectively--and both became practicing physicians.
Althea's passion was art, and after earning a bachelor's degree in that subject at Oberlin in 1875, she held a general teaching position for a few years, until her passion got the better of her. She continued her training, studying at the Art Institute of Chicago and earning an Oberlin master's degree in 1882, and she went on to teach art at Carleton College and in the Tacoma, Washington, schools, where she was a supervisor of art.
Althea's friend Arthur J. Palas described her work in the foreword to the 1952 edition of Birds of an Iowa Dooryard: "Her art efforts were not in the direction of modern art. Much of modern art is not to paint what is seen, rather to have the work of art carry a thought or theme, something to carry the mind of the observer beyond the pigment and its arrangement on the canvas. It is doubtful that she would ever have depicted cheerfully what she had not seen. Her mind was of a scientific bent. . . . She tried to present to us, as nearly as she could, what she actually observed. Her theme was the truth and truth was thrill enough."
Althea did not give up her interest in art after returning to the Sherman Homestead in 1895, but her increasing interest in ornithology and her increasing confidence is apparent in her correspondence with Oberlin, now housed in the College archives. From 1875 until 1895, she answered College questionnaire inquiries as to occupation with "teaching art." Seven years after returning to Iowa she began describing her occupation as "student of birds."
The questionnaires asked recipients to list articles and publications, and Althea's first response came in 1908, when she noted "only unimportant articles on the subject of birds." By 1925, though, she overran the allotted space, and she added her field notes to the list. "In including field notes in the bibliography given above I have tried to conform to your request as I have understood it," she explained. "Much of the more important of my studies remain yet to be published."
The College sent another questionnaire to alumni in 1935. Althea's answer to the occupation inquiry: "(old age) Study of birds continued." She died eight years later.