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The first-known contraceptive was crocodile dung, used in Egypt in 2000 BC. Condoms were also reportedly used, made of animal bladders or intestines.
Chronic marijuana use can damage the white blood cells and reduce the immune system's ability to respond to disease by as much as 40%. Without a strong immune system, the body is vulnerable to all kinds of degenerative and infectious diseases.
The modern decimal position system was the invention of the Hindus (around 800 AD), involving the placing of numerals to indicate their value (units, tens, hundreds, and so on).
Essential fatty acids have been shown to be effective against ulcers, asthma, dental cavities, and skin disorders such as acne.
The immune system needs 9.5 hours of sleep in total darkness to recharge completely.
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