|
|
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.
Bacteria have flourished on the earth for over three billion years. They were the first life forms on the planet.
People often find it difficult to accept the idea that bacteria can be beneficial and improve health. Lactic acid bacteria are good, and when eaten, these bacteria improve health and increase longevity. These bacteria included in foods such as yogurt.
People about to have surgery must tell their health care providers about all supplements they take.
Sperm cells are so tiny that 400 to 500 million (400,000,000–500,000,000) of them fit onto 1 tsp.
![Prostate cancer. In this example, a large mass has grown into the urinary bladder. Prostate cancer i](https://biology-forums.com/gallery/47/medium_14755_16_10_12_12_26_16_94272360.jpeg)
![The skulls of living haplorhines differ from those of strepsirhines by having large brains, an enclo](https://biology-forums.com/gallery/47/medium_274477_04_02_15_12_29_04_20594136.jpeg)
![Edward Bellamy, author of the utopian novel Looking Backward (1888) Bellamy’s socialism worried many](https://biology-forums.com/gallery/47/medium_27_24_08_15_1_27_04_223942387.jpeg)