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Vaccines cause herd immunity. If the majority of people in a community have been vaccinated against a disease, an unvaccinated person is less likely to get the disease since others are less likely to become sick from it and spread the disease.
Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.
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.
Atropine, along with scopolamine and hyoscyamine, is found in the Datura stramonium plant, which gives hallucinogenic effects and is also known as locoweed.
It is believed that humans initially contracted crabs from gorillas about 3 million years ago from either sleeping in gorilla nests or eating the apes.