Thursday, May 13, 2021

The Story of the Human Body: Evolution, Health, and Disease

The human body has evolved in a different environment than it exists in today. We have many innovations that make our life "easier" today. However, these same innovations also take away some of the needed stresses that help our body body to properly develop and fight of ailments. 

The book starts with the origins of humans. Early hominids started to walk upright millions of years ago. This created many challenges, but also gave some advantages. (After all, they did not become extinct.) Brain size also increase. (There is still debate as to what caused what.) Eventually, homo sapien spread across the world, primarily as a hunter-gatherer society.

The human body is fairly well optimized for hunting and gathering life. This type of life required a great deal of physical exercise. It also required a lot of chewing (Which helped lead to good dental appearance.) Sweet food was prized and stored up. Humans store more fat than many other animals, giving advantages in survival. People have infrequent births, but a higher likelihood of a child living longer. Birthing is not easy. However, the wider hips allow for larger babies to be born, though they still need more attention after birth.

Our ailments today often come from "too much" or "too little". We have processed food to give us the primary energy that we crave. Our genes encourage us to stock up on this food and store it away. Alas, this lead to obesity and a number of other ailments. On the too little side, we don't move enough. Our bones and muscles are strengthened by stresses. 

Our medical system focuses on treating symptoms rather than making lifestyle changes to reduce causes. This has inadvertently resulted in some negative evolution of disease. Social evolution has a curious interaction with different conditions. (Is near-sightedness more common because of related benefits? Or is it because it has little harm and is easily fixed?) Many diseases today also appear later in life, causing little negative pressure on reproduction.  

Looking at the "long" picture provides an interesting insight into the human condition as well as some concerns about the way we are practicing medicine today.

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