For almost 2000 years, from ancient Greece to the nineteenth-century, the most common procedure performed by surgeons was bloodletting. The doctors would cut the patient to allow blood to drain because they thought this would drain disease from the body. In truth, if it didn’t kill the patients, bloodletting at least left them weaker. The medical establishment didn’t realize that life is in the blood.
Even though William Harvey disproved the effectiveness of bloodletting in 1628, doctors (and barbers) still practiced it for another 200 years. It can take a long time for false ideas to be abandoned, even by doctors and scientists. In some areas such as China and the Middle East, people still practice a form of bloodletting today known as hijama or cupping.
While they were still practicing bloodletting, doctors began to experiment with blood transfusions. Early experiments in the seventeenth-century involved transfusions of animal blood into humans, usually with disastrous results. Doctors didn’t realize that there are different blood types among humans and even among animals. Different blood types have a different molecular structure in the red blood cells. If a patient is given blood of the wrong type, it can cause a reaction that can be fatal, because the patient’s immune system attacks the foreign blood cells as invaders.
In 1901 Karl Landsteiner found that mixing blood from different patients sometimes caused clotting. This led him to classify blood into three types—A, B, and O. Scientists have discovered more blood groups since then, making transfusions much safer today.
If those who practiced bloodletting had paid more attention to the Bible, they might have realized much sooner that it was a bad idea. “The life of every creature is in the blood” is stated twice in Leviticus 17 verses 11 and 14. With that admonition, God commanded the ancient Israelites to refrain from eating blood and to sacrifice the blood of animals to cover their sins. But the final redemption for sins came when “God presented Christ as a sacrifice of atonement, through the shedding of his blood” (Romans 3:25). Life is in the blood, and eternal life is in the blood of Christ.
— Roland Earnst © 2021
The cover story of the June (2019) issue of Reader’s Digest lists 50 features of your amazing human body. The article gives some evolutionary guesses as to how some of those features could have developed. We thought it was especially interesting that science has not explained nine of the 50: