Why do people have different color skin?

Skin color—which ranges from light pink to dark brown—is determined by the amount and type of the pigment melanin there is in the skin. Melanin comes in two types: phaeomelanin (red to yellow) and eumelanin (dark brown to black).

Both amount and type are determined by four to six genes. One copy of each of those genes is inherited from your father and one from your mother. Each gene comes in several coding sequences, which results in a variety of skin colors around the world.

Why do we say “Goodnight, sleep tight”?

Sometime during the sixteenth century, British farmers moved from sleeping on the ground to sleeping in beds. These beds were little more than straw-filled mattress tied to wooden frames with ropes.

To secure the mattress before sleeping, you pulled on the ropes to tighten them, and that’s when they began saying, “Goodnight, sleep tight.”

How many computers are there in the world?

According to statistics from technology research companies such as Gartner Inc., in April 2002 the billionth personal computer (PC) was shipped. The second billion mark (some being ordered as replacements for older PCs) was reportedly reached in 2007. With personal computers becoming more popular around the world, research companies estimate that there will be more than two billion PCs in active use by 2015.

In the United States, more than half of the people who use a computer are also connected to the Internet.

What is a disability?

The word “disabled” usually refers to a person who has a physical or mental handicap that keeps him or her from doing certain tasks—or makes performing them unusually difficult. Most physical disabilities, like blindness or paralysis, are easily noticed, but many mental disabilities are harder to detect. Mental disabilities can include diseases like schizophrenia, which causes severe disturbances in people’s thoughts and emotions.

Another type of disability is a learning disability, such as dyslexia, which is a learning disorder that makes reading very difficult because the brain reverses the order of letters and words. Many disabled people prefer the term “differently abled,” a description that doesn’t divide people into categories like “normal” and “disabled” but addresses the idea that every person has different abilities.

What’s a charley horse?

A charley horse a muscle cramp, or sudden, uncontrolled contraction of a muscle. This type of pain is generally felt in the legs, sometimes after heavy exercise, and usually lasts just a few minutes.

The expression probably came from the word “charley,” which is used to describe a horse that is lame.

What are the origins of April Fool’s Day?

Up until 1564, the French celebrated New Year’s between March 25 and April 1, but with the introduction of the new Gregorian calendar the festival was moved to January 1.

Those who resisted became the victims of pranks including invitations to nonexistent New Year’s parties on April 1. Soon the April 1 celebration of a non-occasion became an annual festival of hoaxes.

What it the largest flower in the world?

The flower with the world’s largest bloom is the rafflesia, which grows in the rain forests of Indonesia. It can grow to be 3 feet (0.91 meters) across and weigh up to 15 pounds (6.8 kilograms). It is a parasitic plant, with no visible leaves, roots, or stem. It attaches itself to a host plant to obtain water and nutrients.

When in bloom, the rafflesia gives off a repulsive odor, similar to that of rotting meat. Although people do not want to come near it, the strange odor attracts insects that pollinate the plant.

Why are there wars?

Wars have taken place since the beginning of recorded history, and they surely occurred before that as well. A war begins when one group of people (the aggressors) tries to force its will on another group of people, and those people fight back. War frequently springs from the differences between people, or from the desire of one group to increase its power or wealth by taking control of another group’s land. Often the aggressors feel that they are superior to the group they want to dominate: they believe that their religion, culture, or even race is better than that of the people they wish to defeat. This sense of superiority makes them feel that it is acceptable to fight to take the land, possessions, and even lives of the “inferior” group, or to force their ways on the dominated people.

Because countries can be very different from one another in government, religion, customs, and ideology (ways of thinking), it is not surprising that nations disagree on many things. But great efforts are usually made to settle the disagreements through discussion and negotiation—a process called diplomacy—before they result in anything as destructive as a war. War usually occurs when diplomacy fails. Because science and technology have allowed us to create such powerful and destructive weapons that can result in such devastating wars, we now have international organizations that work all the time to try to keep peace among nations.

How did we start celebrating Mother’s Day?

In 1907 Miss Anna Jarvis of West Virginia asked guests to wear a white carnation to the church service on the anniversary of her mother’s death. But Mother’s Day became increasingly commercial, and Miss Jarvis spent the rest of her life trying to restore its simplicity.

The strain of her efforts to stop Mother’s Day and what it had become led her to an insane asylum, where she died alone in 1948.

What type of people help make a community operate well?

Firefighters, police officers, ambulance drivers, garbage collectors, mail carriers, crossing guards public-school teachers, school-grounds and maintenance workers, public librarians, bus drivers, and parks and recreation workers are just a few of the city-service people that make a town or city run well. Every day, these and hundreds of other workers labor to make communities across the United States safe, clean, and healthy.

Many of these workers are paid for their jobs, but many also volunteer (work without pay) to help their neighborhoods be safe. The government estimates that about 60 million people volunteer each year, most often in religious, educational, youth, or community service organizations. Volunteers commonly perform activities such as firefighting, coaching, campaigning, fundraising, delivering goods, and serving on boards or neighborhood associations.