Lydia was born on the Island of Nantucket on May 5, 1822, the daughter of Gideon and Eunice Macy Folger. She attended Wheaton Seminary in 1838 and taught there from 1842 to 1844. She received her M.D. degree from Central Medical College of New York in 1850, making her the second woman in the country and the first American-born woman to earn a medical degree. She was the first female professor in an American medical college.
Lydia married Lorenzo Niles Fowler in 1844. They had three daughters: Jessie Allen, Amelia and Lydia. Lorenzo, his brother Orson Squire Fowler, and Samuel Wells were all proponents of phrenology and produced books on this and other subjects at the NY publishing firm of Fowler and Wells.
Between 1852 and 1860 Lydia practiced medicine in New York City and spent part of the time teaching women as a volunteer at the Metropolitan College.
Lydia traveled to Europe in 1860 to address women on physiology and she spent the winter of 1860-61 studying in Paris. In London she was in charge of all obstetric cases at Marylebone Road Hospital before joining her husband to lecture on phrenology and other subjects across Britain. She praised women as mothers, but also taught that education was something which they owed to themselves and to their children.
In 1863 the Fowlers opened an office in London where Lorenzo practiced phrenology and where Lydia assisted, lectured, wrote and was also active in the British Women’s Temperance Society.
Lydia’s publications include: Familiar Lessons on Phrenology (for Young Readers), 1847; Familiar Lessons on Astronomy, 1848; Pet of the Household; and Woman and her Destiny.
Lydia died in London on January 30, 1879 from blood poisoning contracted while caring for the poor.