Is it true that people have “tongue prints”?

Yes. All human beings have some traits that are the same, but each individual person also has a set of traits that are different from any other. Among these individual traits are fingerprints, tongue prints, patterns in the iris of the eye, and voice patterns. Because fingerprints and tongue prints are unique in every person (even identical twins), they can be used to identify an individual. (But next time someone calls out your name, it’s best to answer rather than stick out your tongue!)

Why do people cry when someone dies?

Crying is a way of expressing sadness. It helps people who have lost someone close to them express their grief and sorrow. (Talking about the dead person also helps.) People cry because they will never again see the person who has died and they know they will miss that person. If the death is unexpected, the tears may also be caused by feelings of shock and anger. During the period immediately following a person’s death, when the loss of that loved one is felt most sharply, grieving people usually are not comforted by the fact that dying is a natural and necessary process that happens to all living things. As time passes, however, many people begin to accept the loss of their loved one, and the pain of that loss becomes a bit easier to bear. Thinking of the person after some time has passed brings less sadness and maybe even some pleasure as good times with the loved one are remembered.

How can a microwave oven cook food so fast?

Unlike other ovens, which cook food with heat waves made from burning gas or electric currents, microwave ovens use special bands of electromagnetic energy called microwaves (similar to light waves) to cook food. While heat waves gradually work their way inside food to cook it, microwaves can travel right through food in an instant. In a microwave oven a device called a magnetron produces a beam of microwaves that pass through a spinning fan, which sends the waves bouncing in all directions. As they travel through food their energy is absorbed by molecules of water. The water molecules vibrate at the same high speed as the microwaves (2.45 billion times per second!) and rub against other molecules. All this movement and friction causes a great deal of heat, cooking the food inside and out. Microwaved food is cooked through a process similar to steaming, which explains why it doesn’t turn brown. But some microwave ovens have traditional heating elements to make food look more appealing—giving it the outer color that we expect in cooked food. Certain materials allow microwaves to pass through (meaning they are not heated by the waves) while other materials absorb the waves and still others reflect them, or bounce them back. For this reason it is important to be careful about the containers and coverings we use in microwave ovens. Microwaves pass through glass and plastic wrap, for example, which are safe to use, as are paper products and most sturdy plastics. But metal containers and coverings like aluminum foil are reflective. Such surfaces keep food from absorbing microwaves, allowing the waves to bounce around so much inside an oven that it may break.

Did dinosaurs communicate?

Dinosaurs probably communicated both vocally and visually. Large meat eaters like Tyrannosaurus rex, with its loud roar, or a Triceratops shaking his head, would have made its intentions very clear. The chambered head crests on some dinosaurs such as Corythosaurus and Parasaurolophus might have been used to amplify grunts or bellows. Mating and courtship behavior and territory fights probably involved both vocal and visual communication. Scientists believe that the sounds created by dinosaurs like Parasaurolophus were so individual that each had a slightly different tone. They also believe that these dinosaurs had different calls, ranging from low rumbles to high-pitched notes, which they used for different situations.

Why did dinosaurs become extinct?

Scientists do not know for sure why dinosaurs became extinct. They have many different theories, some of which explain the extinction as something that happened gradually over a long period of time. Other theories suggest that a single catastrophe, such as fallen asteroid from outer space, caused the dinosaur population to die off rather suddenly. And some scientists believe the dinosaur population had been gradually getting smaller and then was finished off by some dramatic event. Those who believe gradual changes brought about the dinosaurs’ end suggest that, as more and more mammals appeared, the dinosaurs had trouble competing with them for food sources. And these mammals may have eaten dinosaur eggs in such large numbers that fewer and fewer baby dinosaurs were born. Some experts believe that widespread disease killed off dinosaurs. Many suggest that gradual climate changes—from continuously warm, mild weather to seasonal variations with hot summers and cold winters—affected the dinosaurs. Scientists are not sure whether dinosaurs were warm-blooded or cold-blooded (and there may have been some of each). If they were cold-blooded, meaning that their body temperature changed depending on the temperature of their surroundings, it would have been difficult for such large animals to survive extreme temperatures. Smaller coldblooded creatures can burrow under the ground, for example, to escape both heat and cold. But most dinosaurs were simply too large to do that. The scientists who believe that dinosaurs became extinct after a major catastrophe point to evidence that suggests a huge asteroid, perhaps several miles wide, hit Earth. The impact of such an object would have created enormous clouds of dust and other debris. The heat of impact would have started fires over a great area. Between the dust clouds and the smoke from the fires, sunlight would have been blocked, maybe for several months. A lack of sunlight would have caused a dramatic drop in temperature, and much plant life would have died. Without plants, the plant-eating dinosaurs and many other animals would have died; without the planteating dinosaurs and those other animals, the meat-eating dinosaurs would eventually die as well.

What is the federal government?

The federal government is the national government of the United States of America. It includes the executive, legislative, and judicial branches. The executive branch is responsible for enforcing the laws of the United States. Its main components include the president, the vice president, government departments, and independent agencies. The president is the leader of the country and commander in chief of the armed forces; the vice president is the president of the Senate and the first in line for the presidency should the president be unable to serve; the departments and their heads (called Cabinet members) advise the president on decisions that affect the country; and independent agencies help carry out the president’s policies and provide special services. The legislative branch is the lawmaking branch of the federal government. It is made up of a bicameral (or two-chamber) Congress: the Senate and the House of Representatives. The judicial branch, made up of the Supreme Court and other federal courts, is responsible for interpreting the meaning of laws, how they are applied, and whether or not they violate the Constitution.

How did a crushing public humiliation become known as a “Roman holiday”?

The Etruscans of ancient Italy ritually honoured their dead war heroes by sacrificing the lives of all prisoners seized in battle. After conquering the Etruscans, the Romans borrowed and embellished the ritual by having the prisoners kill each other. They turned the slaughter into public gladiatorial games and declared the spectacle a Roman holiday, which became an expression synonymous with any cruel and crushing public destruction.

Why do paratroopers shout “Geronimo” when they jump from a plane?

During the Second World War, Native American paratroopers began the custom of shouting the name of the great Indian chief Geronimo when jumping from a plane because, according to legend, When cornered at a cliff’s edge by U.S. cavalrymen, Geronimo, in defiance, screamed his own name as he leaped to certain death, only to escape both injury and the bluecoats.