How many hairs does the average person have on his or her head and how much does human hair grow in a year?

The amount of hair covering varies from one individual to another. An average person has about 100,000 hairs on their scalp. Most redheads have about 90,000 hairs, blonds have about 140,000, and brunettes fall in between these two figures. Most people shed between 50 to 100 hairs daily. Each hair grows about 5 inches (12.7 centimeters) every year. (The Handy Science Answer Book, compiled by the Science and Technology department of the Carnegie Library of Pittsburgh)

Can a person get a suntan through a window?

No. The ultraviolet radiation that causes suntan does not pass through glass. A tan is the skin 's natural defense against these harmful sun rays. Pigment cells in the lower skin level make more pigment and melanin to absorb the ultraviolet rays. As the pigment spreads into the top layer of the skin, it becomes darker. (The Handy Science Answer Book, compiled by the Science and Technology department of the Carnegie Library of Pittsburgh)

The original meaning of the word “scapegoat”

As described in Leviticus 16:1-27, part of a Hebrew ritual on the Day of Atonement involved the presentation of two male goats at the altar of the tabernacle. After lots were cast, one goat was sacrificed to the Lord; the other, the  ‘scapegoat’, was set aside for Azazel, an evil spirit of the wilderness. The high priest transferred the sins of the people onto this goat and sent it away into the desert. (The Book of Answers, by Barbara Berliner)

What to do when you get sick -- making the right decisions

When you get sick, you must decide what course of action to take in order to recover your health. If you do not accept this responsibility, others will decide for you and will not necessarily make the best choices. The most important decision is whether visits to health professionals will help or hinder your own healing system. You will need to understand the nature of your illness and to know whether conventional medicine can do anything for it without reducing the possibility of spontaneous healing. You will also want to know whether any alternative treatments exist that might be of benefit.

A good place to start is with a review of what conventional medicine can do effectively and what it cannot. For example, it is very effective at managing trauma, so that if I were in a serious automobile accident, I would want to go directly to an urgent care facility in a modem hospital, not to a shaman, guided imagery therapist, or acupuncturist. (Once out of danger, I might use those other resources to speed up the natural healing process.) Conventional medicine is also very good at diagnosing and managing crises of all sorts: hemorrhages, heart attacks, pulmonary edema, acute congestive heart failure, acute bacterial infections, diabetic comas, bowel obstructions, acute appendicitis, and so forth. You must be able to recognize symptoms of potentially serious conditions, so that you will not waste time before getting needed treatment. In general, symptoms that are unusually severe, persistent, or out of the range of your normal experience warrant immediate investigation.

Color Blindness

Color blindness is a defect of vision affecting the ability to distinguish colors, occurring mostly in males. It involves a person’s inability to distinguish one or more of the three colors red, green, and blue. It is noteworthy to know that the ability to see color exists in only a few vertebrates, including, among others, man and the other primates, fish, amphibians, some reptiles, and some birds; and in bees and butterflies.

The first detailed report on this condition was written by the British chemist John Dalton, who was himself afflicted with it. Total color blindness, in which all hues are perceived as variations of gray, is known as achromatopsia or monochromatism. This condition is congenital, extremely rare, and affects men and women almost equally. Partial color blindness, called dichromatism, consists generally of the inability to differentiate between the reds and the greens or to perceive either reds or greens; infrequently, the confusion may involve the blues or the yellows. Dichromatism is the most common form of color blindness, affecting about 7 percent of men and less than 1 percent of women. Dichromatism is identified as a sex-linked hereditary characteristic. Color blindness also may occur as a temporary condition following a serious illness.