Brittany heartbeat of “more than 1,200 beats per minute”

Brittany DavisJanuary 2018Essay 1Size does in fact, MatterImagine the life of a small hummingbird: quick, flashy, diving at speeds up to 60 mph, with a heartbeat of “more than 1,200 beats per minute” (Galassi, Daily Southtown). This life is fast, rapid, and short-lived. But why? Studies show that mammals with a more rapid heartbeat tend to live shorter lives compared to their counterparts. The reason being, that most living creatures are prone to only live for about 1 billion of their own heartbeats. A new theory has emerged that claims almost every living creature only survives about 1 to 1.5 billion heartbeats before dying naturally. According to theoretical physicist Geoffrey West, “lifespan is connected to size.” He believes that a smaller animal will nearly always live a shorter amount of time than larger ones; the reason being the larger an animal is, the slower their heart rate tends to be.An average chihuahua, for example, lives a life of trembling panic, manic-like energy and is usually restless with an average weight of no more than 6 pounds. These characteristics, similar to the hummingbird, exert a massive amount of energy. They typically survive only about 10 to 15 years, with a heart rate of 200 beats a minute. Their bodies utilize energy less efficiently in relation to a larger creature. Compare them to a blue whale; a much larger mammal. They move slow with majestic leisure, naturally living on average 80 to 110 years, with 8 to 10 heartbeats per minute. For this reason, one can argue that the larger creature, such as a whale or elephant, will naturally always live longer. The reason, however, has little to do with their survival abilities, but more to do with the speed of their heartbeatIn the 1930’s, biologist Max Kleiber founded what is known today as Kleiber’s Law. he believed that “an animal’s metabolic rate scales to the ¾ power of the animal’s mass” (Encyclopedia Britannica). in layman’s terms, this law states that as the size of a creature increases, their lifespan lengthens, while simultaneously, reducing their heartbeats per minute reduce, by about 75 percent. This finding debunked the previously believed theory that stated, as one increased in mass, the reduction of metabolic rate was a one-to-one ratio. For example, a hummingbird, which may be 50 times smaller than a chicken, does not use 50 times the energy of said chicken. Rather the chicken, only 50 times greater, uses 15.8% of the hummingbirds total energy requirements.Although research had been previously conducted on the topic, physicist Geoffrey West, and biologists Jim Brown and Brian Enquist researched the correlation between animals’ energy exertion in relation to size and mass in 2007. Taking into account Kleiber’s Law, what they discovered was that with the ¾ rule on metabolic rate, the average number of heartbeats of each living creature tended to be around 1-1.5 billion in a lifetime.The principle they developed was later named the Quarter Power Scaling, which can be described as a theory that believes smaller animals have fewer cells, which results in fewer connections. “In a little animal, the job is easier. In a big animal, there are so many more blood vessels, moving parts, longer pathways, there is so much more work to do, the big animal could break down much more quickly” (Size Matters: The Hidden Mathematics of Life). Because of this, larger animals have developed more efficient cells than smaller ones.The only outlier in these theories: Humans. With our development of medicines and our knowledge of clean water, healthy foods, and good hygiene practices, we have been the only beings to live longer than predicted by our mass.


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