Barbara Finlay, ‘maverick’ of evolutionary neuroscience

In 1995, Barbara Finlay proposed a rule to explain the structure of every mammalian brain: The size of each region scales with overall brain size, and when a region begins to develop dictates how large it will grow.

At the time, the prevailing idea was that brain structure mirrored a species’ functional adaptations. So a species with a large visual cortex must have sharp vision, for instance, whereas one with a small auditory cortex would have poor hearing.

Finlay reasoned that evolution could not shape brains in such a freewheeling way but instead had to contend with the rigid rules of development. For her proposal, she drew on her knowledge of those constraints and gathered published data from 131 species. The resulting Science paper she published with her colleague Richard Darlington revealed that brain structures scale together, with different growth curves dictating their ultimate size. Structures born later in development grow larger than those born earlier because there is a larger pool of progenitor cells available to build them. The pair used this rule to predict when neurogenesis begins for different brain regions in many species of mammals.

This expansive approach was typical of Finlay, who died on 12 September at the age of 75. “She was someone who brought together vast amounts of knowledge and literature into new concepts,” with great originality and creativity, says Gaby Maimon, professor and head of the Laboratory of Integrative Brain Function at Rockefeller University and a former undergraduate researcher in Finlay’s lab.

“Barb was a maverick,” says Alexander Ophir, professor and chair of the psychology department at Cornell University. “If you paid attention to her work, it pushed you to think differently about everything that you were studying,”

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inlay was born on 25 October 1950 in Pittsburgh, Pennsylvania. Her younger siblings—a set of fraternal twins, Kathy and Bill—were born less than two years later.As a child, science was not on her radar—she was more interested in history and politics, she said in an interview in 2025. Yet she jumped at the chance to spend a summer out of town, away from her parents at a high school science training program at Indiana University in 1967.

The program included a six-week stint working in a laboratory. Finlay ended up assisting an optometry master’s student with their thesis, measuring how easily people could discriminate triangles from circles and circles from octagons. The project didn’t excite her, but she read up on the field anyway in a library copy of “The Perception of the Visual World,” by James J. Gibson, she said in the 2025 interview. “It knocked my socks off.”