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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.
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.
Side effects from substance abuse include nausea, dehydration, reduced productivitiy, and dependence. Though these effects usually worsen over time, the constant need for the substance often overcomes rational thinking.
Bacteria have flourished on the earth for over three billion years. They were the first life forms on the planet.
The human body's pharmacokinetics are quite varied. Our hair holds onto drugs longer than our urine, blood, or saliva. For example, alcohol can be detected in the hair for up to 90 days after it was consumed. The same is true for marijuana, cocaine, ecstasy, heroin, methamphetamine, and nicotine.
![The heavily worn, and sometimes cutmarked, anterior teeth of Neadertals suggest that these teeth wer](https://biology-forums.com/gallery/47/medium_273287_22_02_15_10_32_16_2081617.jpeg)
![Pressure testing the cooling system. A typical hand-operated pressure tester applies pressure equal ...](https://biology-forums.com/gallery/29/medium_548020_29_05_17_11_20_04_295761956.png)