To that end, Dr. Shave and his colleagues went to African nature preserves over the course of several years to scan dozens of chimpanzees’ hearts and check their blood pressures during the animals’ annual veterinary checkups. They also visited zoos to do heart scans on several gorillas (although they did not measure blood pressures).
In the meantime, Dr. Baggish and other researchers scanned the hearts and measured blood pressures of young, male distance runners and football players at Harvard, subsistence farmers in Mexico, and 40 sedentary but healthy young men in Boston. (Only males were included in this study, although the researchers would like to study women and female primates in the future.)
Then the scientists began making comparisons, which turned out to be stark. The hearts of the chimps and gorillas proved to be well adapted for short, sharp bursts of activity, with a rounded shape and thick walls inside their chambers that could withstand and respond to sudden, brief spikes in blood flow but resulted in relatively high baseline blood pressures in the chimps, compared to people (although primates, unlike us, do not seem to experience heart problems from such hypertension).
The human hearts, on the other hand, were more elongated and supple, with thinner chamber walls that could twist and pump greater volumes of blood at lower pressures than in the primate hearts, a necessity during sustained aerobic activities, like walking or jogging.
Perhaps most intriguing, though, were the differences within the various groups of people. The collegiate runners and subsistence farmers, whatever their age, harbored hearts that were endurance-ready, with the thinnest, springiest chamber walls and the lowest blood pressures among the human groups.
The hearts of the football players, meanwhile, whose regular exercise consisted mostly of weight training, and those of the sedentary young Bostonians, whose regular exercise consisted of not doing any, showed relatively thicker chamber walls and greater heart stiffness.
Their hearts had developed a subtly “chimpanzee-like phenotype,” in the words of the scientists.
That slight aping of the hearts of the football players and the sedentary young men was coupled with everyday blood pressures that, while still within the normal range, were higher than those of the runners and farmers.