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Asthma is the most common chronic childhood disease in the world. Most children who develop asthma have symptoms before they are 5 years old.
More than 150,000 Americans killed by cardiovascular disease are younger than the age of 65 years.
The average human gut is home to perhaps 500 to 1,000 different species of bacteria.
The first-known contraceptive was crocodile dung, used in Egypt in 2000 BC. Condoms were also reportedly used, made of animal bladders or intestines.
Egg cells are about the size of a grain of sand. They are formed inside of a female's ovaries before she is even born.
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