Is the way pythons control their own genes the future of medicine? Pythons can expand and retract the size of their organs as they feast and fast, write Carl Zimmer and Wes Fraser.

By scrutinizing the cardiac muscle of recently fed pythons, researchers have revealed how the reptiles reshape their hearts in greater detail.

Instead, genes’ activity — whether they are expressed or not, for instance, or the length of protein that they encode — depends on myriad external factors, from the diet to the environment ...