Gary is Manx and grew up in Douglas on the Isle of Man. He received his first degree in Physiology and Pharmacology from Sheffield University in 1986, then worked on his doctoral thesis in Stephen B. McMahon’s lab at St. Thomas's Hospital Medical school in London. He received his Ph.D. in February of 1990.

He then moved to the lab of Professor Lorne Mendell in New York at Stony Brook. He worked in Lorne's lab for almost four years and in the last year he was appointed Research Assistant Professor. It was in Lorne Mendell’s laboratory that Gary discovered that NGF is a critical mediator of hyperalgesia and pain. These findings formed the mechanistic basis of anti-NGF medication, like Tanezumab, that still hold great promise for the treatment of inflammatory pain. 

In 1993 he received a von Humboldt Fellowship to work in the department of Neurobiochemistry at the Max-Planck Institute for Psychiatry in Munich under the directorship of Professor Yves-Alain Barde. In February of 1996 he took up an appointment as an independent Group Leader at the MDC in Berlin. The projects in his lab first focused on the molecular basis of sensory neuron mechanotransduction and sensory ion channels. In 2003 Gary obtained a joint appointment at the Charité University Medical Faculty as a full Professor. The lab recently developed small drug-like molecules that can interfere with touch sensation and can be used to treat pain. 

Over the last 15 years the Lewin lab has pioneered the molecular exploitation of extreme physiology observed in the naked mole-rat and other African rodents. The lab has broadened its outlook and now looks at molecules that may promote metabolic health inspired by the phenomenal fitness and longevity of the naked mole-rat.