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There are more nerve cells in one human brain than there are stars in the Milky Way.
Your skin wrinkles if you stay in the bathtub a long time because the outermost layer of skin (which consists of dead keratin) swells when it absorbs water. It is tightly attached to the skin below it, so it compensates for the increased area by wrinkling. This happens to the hands and feet because they have the thickest layer of dead keratin cells.
Asthma occurs in one in 11 children and in one in 12 adults. African Americans and Latinos have a higher risk for developing asthma than other groups.
In the ancient and medieval periods, dysentery killed about ? of all babies before they reach 12 months of age. The disease was transferred through contaminated drinking water, because there was no way to adequately dispose of sewage, which contaminated the water.
Astigmatism is the most common vision problem. It may accompany nearsightedness or farsightedness. It is usually caused by an irregularly shaped cornea, but sometimes it is the result of an irregularly shaped lens. Either type can be corrected by eyeglasses, contact lenses, or refractive surgery.
![Bluehead wrasse males with yellow females of the species. If the blueheaded male is removed from a t](https://biology-forums.com/gallery/47/medium_33_09_09_11_10_08_14_16931922.jpeg)
![Despite the traditional focus on males, females actively choose mates and are the driving force in t](https://biology-forums.com/gallery/47/medium_269691_26_01_15_5_55_23_204351272.jpeg)
![Bonobo females form close alliances, maintained through sex, but these alliances are lacking in chim](https://biology-forums.com/gallery/47/medium_269691_26_01_15_5_55_54_204501800.jpeg)