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Cancer has been around as long as humankind, but only in the second half of the twentieth century did the number of cancer cases explode.
There are 60,000 miles of blood vessels in every adult human.
Vaccines prevent between 2.5 and 4 million deaths every year.
For about 100 years, scientists thought that peptic ulcers were caused by stress, spicy food, and alcohol. Later, researchers added stomach acid to the list of causes and began treating ulcers with antacids. Now it is known that peptic ulcers are predominantly caused by Helicobacter pylori, a spiral-shaped bacterium that normally exist in the stomach.
Calcitonin is a naturally occurring hormone. In women who are at least 5 years beyond menopause, it slows bone loss and increases spinal bone density.