Brace yourself for a mind-bending discovery! A recent study published in Science journal has unveiled the secret behind the shrew’s record-breaking resting heart rate of 1,020 beats per minute – that’s 17 beats per second, over 10 times faster than the average human. This tiny mammal’s heart is truly a marvel of nature, and the research team, led by William Joyce and Professor Kevin Campbell, has uncovered the evolutionary adaptations that enable this exceptional feat.
Decoding The Shrew’s Superpowered Heart
The research investigate the mechanisms of shrew heart function, looking in particular at a key protein that regulates how well (or poorly) the heart beats and relaxes with each beat: ‘cardiac troponin I’.
The scientists found that in shrews and their close cousins the solenodons, a key part of this protein “brake” on heart relaxation is missing. In essence, the pace-limiting brake on heart relaxation has been ‘bred’ out of the human genome by evolution and we don’t yet know how to replace it. By contrast, the human average heart rate fluctuates between 60 and 100 beats per minute — placing the shrew far off of normal heartbeat numbers.
Why Rapid Heartbeats Are Evolutionarily Superior
This also offers clues as to how the remarkable heart rate of the shrew has evolved. There, they discovered that some bat species — which can top 1,000 beats per minute — by in essence “skip” the gene encoding the two ‘brake’ amino acids in the cardiac troponin I protein during protein synthesis. This modification makes for higher heart rates still.
The scientists suggest that the ancestors of shrews and moles underwent a similar evolutionary process in which deletion of this gene region came to be selectively advantageous. This adaptation bestowed meaning to these little critters, allowing them an astonishingly high HRrest. This evolutionary development could have been key in helping the shrews support their also already very active life styles, as their fast heart rates place them at a significant energetic disadvantage, even when not moving.
Putting These Discoveries Forward into Biomedical Innovation
The findings take mammalian biology to new areas, beyond the quotidian world of most lab rodents and house pets; but its reach is far greater than describing what might be a tiny tumor suppressor gene mutant at work in an even tinier shrew. The project is now looking into how these results can be adapted into potential biomedical applications, specifically in the context of heart health.
The researchers hope to be able reproduce the changes they observed in bats, in a model organism and someday, perhaps human hearts. Exploring the processes that make such rapid heart rates possible could provide new leads for therapies aimed at helping to replicate any benefits seen on the heart, and perhaps even push it to work better. These findings may in fact pave the way for an improved practice of medicine for cardiovascular health and perhaps groundbreaking treatments that improve human health.
