The Science of Life's Clockwork

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3m 11sec

A Life in the
By Jay Schulkin.
Johns Hopkins Univ. Press. 187 pp. $49.95

As a boy, Curt Richter loved to tinker with clocks and locks, dismantling and reassembling them by the hour. His curiosity about how things work and his finely honed mechanical skill ended up serving him well: During some six decades at Johns Hopkins University’s medical school, from graduate student in 1919 to emeritus professor still doing lab work in the 1980s, Richter made a series of pioneering discoveries, most notably about the internal clockwork that regulates behavior. In this conversationally written book, Jay Schulkin, a research professor of physiology and biophysics at Georgetown University, surveys Richter’s wide-ranging accomplishments and offers an informed perspective on his scientific legacy, though without providing much detail on his life outside the lab.

“Before Richter, there was a paucity of research investigation on animal activity,” Schulkin writes. The few early researchers in biological rhythms had focused on plants. But as a Ph.D. student, Richter constructed rat “mansions,” each with a central room, plus separate chambers for eating, drinking, running, climbing, burrowing, gnawing, and other specific behaviors. He hooked up devices to record the animals’ every movement, which revealed cyclical patterns of behavior as well as sequential relationships between different behaviors, such as eating and resting. In his dissertation, The Behavior of the Rat, published in 1921, Richter asserted that innate mechanisms—not external influences—control behavior.

Richter soon applied his findings to humans by documenting cycles in illnesses, both mental and physical. He recognized that symptoms often wax and wane predictably at different times of the day, month, and year, a finding with important implications for treatment. Today’s widely accepted recognition of seasonal affective disorder, with its depressive states that worsen during winter’s short days, arguably grows out of Richter’s work.

Having hypothesized the existence of an internal clock, Richter set about finding it. In the 1960s, he succeeded. The master clock that regulates daily and other biological rhythms in mammals, he wrote, is located in the brain’s hypothalamus. Although surgical instruments of the time didn’t allow him to pinpoint the clock itself, later scientists confirmed Richter’s finding with more advanced tools. They identified a tiny cluster of timekeeping cells within the hypothalamus, which are activated by light signals transmitted from the retina via a specialized nerve pathway.

Richter’s studies weren’t limited to biological rhythms. In the 1940s, he explored what came to be called “learned helplessness.” He found that wild rats immobilized even for a short while in a secure grip or in a bag wouldn’t struggle when placed in a swimming tank. Having lost “all hope of escape,” he wrote, they simply let themselves drown. This research grew out of public-health efforts to exterminate rats in urban areas, though Richter thought it might also help explain sudden death in humans suffering extreme shock or fear. Richter also found that diets lacking salt, protein, fat, and other nutrients triggered hungers for those substances; and he explored nerve pathways that control motor reflexes in different mammals. He also developed tech­niques to assess spinal damage in American soldiers wounded in World War II, based on skin resistance and perspiration.

The author or coauthor of some 250 scientific papers and two books, Richter continued his lab work into his nineties. He received honorary degrees from the University of Chicago, Johns Hopkins University, and the University of Pennsylvania, and was nominated for a Nobel Prize. When he died in 1988, at 94, he was eulogized as a giant in his field, or, more precisely, his fields—specialists in several disciplines now laud him as a founding father. As Schulkin suggests, Richter dedicated his long life to the pragmatic tradition of American inquiry ex­em­plified by Benjamin Franklin and Thomas Jefferson.

—Lynne Lamberg

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