When were false teeth first made?

The Etruscans in Italy were the first people known to build and use false teeth. As early as 700 BC they were constructing ivory or bone teeth, secured with bridgework made out of gold, good enough to eat with. Such sophisticated work was not seen again until the 1800s. In the 1700s false teeth were secured to any remaining original teeth or held in place by spring-loaded mechanisms. The latter sometimes resulted in embarrassing accidents, as sets of teeth might suddenly pop out, springing into the air. Such cumbersome dentures had to be removed during eating, since they were not designed for chewing. Today crowns (false teeth cemented to existing teeth) and dentures are far more comfortable and practical. It is even possible to implant artificial teeth directly into the jaw. More about the history of dentistry: http://www.smiledoc.com/smiledoc/dentist/denhis.html

How does Africa make Florida dusty?

Because of the strong, persistent trade winds that blow across the equatorial Atlantic Ocean, each year millions of tons of reddish-brown dust from Africa settle over Florida, sometimes forming a thin coating on cars and other surfaces. These fine dust particles make it hard for some Florida cities to meet federal clean air standards. The dust is swept up from the Sahara Desert during storms. It can rise as high as 15,000 feet (4,600 meters) before it gets carried out to sea. While the clouds of dust cross the Atlantic Ocean, most of the large particles fall out and sink into the water. But the smallest remain aloft, sometimes causing hazy skies and health problems for Floridians. Dust from Africa also affects the Caribbean region: http://www.usatoday.com/weather/walm3.htm Dust can be swept up from China and dropped in California: http://daac.gsfc.nasa.gov/CAMPAIGN_DOCS/OCDST/asian_dust.html

What organism has the smallest number of genes?

A bacterium of the genus Mycoplasma has the smallest number of genes of any known self-reproducing organism. (Some viruses have fewer genes, but they need to use another cell's DNA machinery to reproduce.) Mycoplasma's DNA was recently sequenced (spelled out in detail). It contains only about 470 genes, meaning that Mycoplasma can make at most only 470 different kinds of proteins within its cells. Most bacteria can make thousands of kinds of proteins, and human cells can make hundreds of thousands. Because Mycoplasma is a parasite, it can steal many important substances from its host, so it doesn't need to make the proteins that the host uses to make those substances. Over millions of years, the genes that code for those proteins have disappeared from its DNA. More about Mycoplasma: http://www.ncgr.org/gsdb/mycoplas.html http://www.whitman.edu/Departments/Biology/classes/B206/BacterialGenome/MgDisease.html A complete color map of the genome: http://www.tigr.org/tdb/mdb/mgdb/mgdb_genome_pic/mgdb_pic.html

What's the most remote island on Earth?

The volcanic island group of Tristan da Cunha is 1,180 miles (1,900 km) from the nearest neighbor, the island of St. Helena. It is in the South Atlantic Ocean between the southern tips of Africa and South America. There are five islands in the Tristan da Cunha archipelago, but only the main island of Tristan is inhabited. The islands are surrounded by deep waters on all sides. Tristan's highest point is a volcano that erupted in 1961. Below the volcano is a small but fertile shelf of land, where potatoes and other crops can be grown. Around the rest of the island, high cliffs face the sea. Tristan was discovered in 1506 by a Portuguese explorer named Tristao d'Acunha, but he was not able to land there. Permanent settlement began in 1810. Fewer than three hundred people live there today, farming potatoes and catching "crawdads" (rock lobsters) in the waters around the island. Some people enjoy living on the world's most remote island: http://geowww.gcn.ou.edu/~bweaver/Ascension/tdc.htm http://www.wndrland.demon.co.uk/tristan_da_cunha/tristan_history.html

When did the first flies evolve?

The first true flies were Tanyderid crane flies that flew 225 million years ago. They looked something like today's mosquitoes, and their larvae lived in swamp mud or wet sand. Crane flies appeared during the Triassic Period, when the first large dinosaurs were alive. Since then, the true flies (members of the order Diptera) have evolved into over 100,000 different species, on every continent except Antarctica. Flies are the most widespread insects on the planet. Today, the most primitive crane flies are quite rare, but other kinds of crane flies that evolved more recently are more common. Maybe you have seen them attracted to lights at night, like huge mosquitoes with extremely long legs. More about the very first flies: http://www2.sel.barc.usda.gov/Diptera/tanyder.htm Crane flies make good fishing bait, according to these fishermen: http://www.troutunlimited.org/cranfly.htm http://fly-fish.com/cranefly.html Previous Cool Facts about flies: http://www.cool-fact.com/archive/1998/09/01.html http://www.cool-fact.com/archive/1999/01/20.html http://www.cool-fact.com/archive/1998/07/21.html

How long are your blood vessels?

If you could stretch out all of a human's blood vessels, they would be more than long enough to go around the world twice. There are over 62,000 miles (99,800 kilometers) of veins, arteries, and capillaries inside of each of us. The thickest are as thick as a forefinger, while the thinnest, which are called capillaries, are as thin as a hair. By far the largest part of the total length is the length of the capillaries. Arteries (which carry blood away from the heart) and veins (which carry blood back to the heart) are not just simple tubes. Their walls are lined with muscles that squeeze the blood inside, providing part of the blood pressure (the rest is provided by the heart). Interactive diagram of an artery and a vein: http://www.innerbody.com/image/c1.html The physics of blood pressure: http://www.physics.uq.edu.au/ph128/3a.html Some previous Cool Facts about blood: http://www.cool-fact.com/archive/1997/02/28.html http://www.cool-fact.com/archive/1998/04/28.html

How many stars are there in most star systems?

Most stars belong to double (binary) or multiple systems, in which two, three, or even more stars orbit around each other. Orbital periods range from hours to centuries, depending on the masses of the stars and distances between them. The closest-orbiting binaries are called contact binaries. In these very fast-orbiting pairs, the two stars actually touch. Each member of a contact binary system is shaped like a pear, with the small end touching the other star. They may actually exchange mass at the point of contact. There are many multiple star systems with four, five, or even more members. Clusters of stars exist, numbering in the tens or hundreds, and there are also much larger "globular clusters," which can contain hundreds of thousands of stars. More about binary and multiple stars: http://www.oma.be/KSB-ORB/D2/index.html http://www.phy.mtu.edu/apod/ap970219.html http://astrosun.tn.cornell.edu/courses/astro201/binstar.htm A giant globular cluster containing 300,000 stars: http://antwrp.gsfc.nasa.gov/apod/ap981017.html

Which ancient king benefited from "modern" plumbing?

The palace of King Minos of Knossos in Crete featured a number of early plumbing innovations. The palace, built around 1700 BC, had tightly sealed terra cotta drain pipes, and a large underground sewer system that discharged into the river Kairatos. Also at the palace were some of the earliest known bathtubs, made of painted terra cotta. Unlike today's tubs, these had no drains, and were filled and emptied by hand. The palace was also home to the first known flushing toilet. It was a private chamber, walled off by gypsum panels. It was flushed by rainwater, or by cisterns poured by hand. More about ancient Minoan plumbing: http://www.theplumber.com/crete.html

How can matter particles travel faster than light?

Very radioactive elements are surrounded by a deep, blue glow when they are submerged in water. The glow, which is called Cerenkov radiation, is produced by high-energy, electrically charged particles moving faster than light. Isn't faster than light travel impossible? The speed of light in a vacuum is an ultimate limit, but when light travels through a dense medium like water, it slows down. If a matter particle travels fast enough in such a medium, it can leave light photons behind. Such a particle leaves a "wake" of light as it penetrates the medium. The wake is similar to the shock wave that follows an airplane moving faster than sound. The faster the particle travels, the sharper (brighter) the wake becomes, and the smaller the average wavelength of light in the wake. Nuclear reactor cores show ultraviolet and blue Cerenkov light: http://nova.nuc.umr.edu/~ans/cerenkov.html

What kind of crustacean has three eyes?

The aquatic crustacean Triops (the name means "three eyes") in the subclass Branchiopoda has three eyes. It has two ordinary compound eyes, and between them a third simple eye. This is the nauplius eye, which is retained from the larval stage. Triops are also known as phyllopods or tadpole shrimp. Triops is a very ancient life form. Fossils have been found from the Permian Period, more than 250 million years ago. In those days, primitive reptiles and amphibians walked on land, but the dinosaurs had not yet evolved. Triops can be a pest in rice paddies, where the finger-size creatures dig in the mud. They have a shell-like cover over the front of the body, as many as 71 pairs of legs, and a forked tail. Closely related creatures live in vernal ponds near San Francisco: http://www.r1.fws.gov/sfbnwr/tadpole.html Another Cool Fact about a creature with three eyes: http://www.cool-fact.com/archive/1997/07/21.html

How big are most asteroids?

Asteroids are rocky or metallic bodies that orbit the sun, mostly between the orbits of Mars and Jupiter. There are probably more than a million of them. Most asteroids are smaller than a medium-size city, and the vast majority are just boulders or pebbles. The largest asteroid is Ceres, which is at least 580 miles (930 kilometers) across. The mass of Ceres is just a bit more than 1/100 of the mass of the moon, and probably about one quarter of the mass of all the asteroids combined. The second largest asteroid is Pallas, with less than half of the mass of Ceres. Vesta is the third largest, but is much brighter than Ceres or Pallas. Are asteroids the smashed debris of an ancient planet, or are they uncombined leftovers of the time when the planets formed? Closer examination of more asteroids by upcoming robot missions may help answer the question. More about asteroids: http://www.ntv.it/nineplanets/asteroids.html http://www.iki.rssi.ru/solar/eng/asteroid.htm http://nssdc.gsfc.nasa.gov/planetary/planets/asteroidpage.html

When were punched cards first used for data storage?

The first punched data cards were invented before there were any computers in the world. They were used in the Jacquard Loom, a weaving machine invented in 1801 by Joseph-Marie Jacquard. The cards were carried in linked chains, and they controlled the weaving pattern by influencing the position of the needles. Small sensing pins detected the presence or absence of holes in the cards, and determined whether or not a needle would pick up a thread. On seeing Jacquard's punched card system, the mathematician Charles Babbage was inspired to use the same principles to design a mechanical calculating machine, the forerunner of modern computers. More about Jacquard looms and early mechanical computation: http://www.csc.liv.ac.uk/~ped/teachadmin/histsci/htmlform/lect4.html A picture of the loom: http://www.ce.vt.edu/evd/Htmls/P415420.html

What are the fastest matter particles in the universe?

The fastest known matter particles are ultra-high energy cosmic rays. These are mostly atomic nuclei of various elements, which come zipping down into the Earth's atmosphere at nearly the speed of light. Cosmic ray energies are measured in electron volts. One electron volt is the amount of energy that an electron gains when it moves across an electric field of one volt. The fastest cosmic rays can carry more than 100,000,000,000,000,000,000 (one hundred quintillion) electron volts of energy. How much energy is that? Pick up a rock about the size of your fist, and throw it as hard as you can. This gives the rock roughly the same energy as a single cosmic ray particle When such a super-particle crashes into the atmosphere, it explodes into an "air shower" of thousands of less energetic particles. The air shower can be detected from the ground by the faint light it emits. Introduction to cosmic rays: http://helios.gsfc.nasa.gov/cosmic.html More about ultra-high energy cosmic rays: http://www.sciam.com/0197issue/0197swordy.html

Why are elephants in Africa being born without tusks?

Ivory poachers in Africa have provided a dramatic demonstration of how evolution works. By killing only those elephants that bear large, valuable tusks, they have allowed elephants with smaller tusks or none at all to multiply. A survey conducted in Uganda's Queen Elizabeth National Park found that up to 30 percent of the elephants had no tusks, up from one percent in the 1930s, and many of the rest had greatly reduced tusks. The same trend is happening all over Africa, as a result of selective culling by poachers. Elephants use their tusks to help them tear apart vegetation, dig in the ground for important dietary minerals, and to help them compete for mates. Without tusks, they are forced to rely on other sources for food and minerals, and their mating process must change. Researchers believe that the elephant population is on the rise again after years of severe poaching. The tuskless elephant population is on the rise across Africa: http://www.gaiabooks.co.uk/environment/elephants_tuskless.html

How does the emperor penguin keep its eggs warm?

Emperor penguins brood their eggs by holding them on their feet. The single egg is protected from the Antarctic cold by a fold of loose skin called the brood patch. Unlike other penguins, emperors brood their young during the cold, dark winter months. The female lays one egg, passes it to the male, then travels out to sea, where she feeds for about nine weeks. Meanwhile, the male stands still and does not eat, weathering temperatures as low as -65 degrees Fahrenheit (-54 degrees Centigrade). When the female returns, she takes over, receiving the just-hatched chick from the hungry male, who goes out to sea. While he is gone, the chick is fed and raised by the mother penguin. By the time the sea-ice begins to break up, the penguin chick is ready to fend for itself. Emperors are the largest, deepest-diving penguins: http://www.nature.ca/notebooks/english/emperor.htm Penguins are well-adapted for their life in the cold southern seas: http://www.terraquest.com/va/science/penguins/penguins.html http://octopus.gma.org/surfing/antarctica/penguin.html More Cool Facts about penguins: http://www.cool-fact.com/archive/1997/08/22.html http://www.cool-fact.com/archive/1997/11/14.html

What's the largest uplifted land mass?

The Tibetan Plateau of Asia includes over two million square kilometers (780,000 square miles) of land, with an average elevation of over 5000 meters (16,400 feet), making it the largest uplifted area on Earth. It is surrounded by some of the highest, most deeply eroded mountain ranges on the planet. 14 million years ago, the plateau was even higher. It was formed about 50 million years ago by the collision of what is now India with the Eurasian continent. That slow, powerful collision pushed up the Himalayas, and lifted the Tibetan Plateau. Even today, India still moves north about five centimeters (two inches) each year. The elevation of the plateau caused massive changes in the planetary climate, including the annual monsoon pattern, which brings seasonal floods and droughts to southeast Asia. The geology of the Tibetan Plateau: http://vishnu.glg.nau.edu/people/jhw/Tibet/Plateau.html More about the diverse ecosystems of the Tibetan Plateau: http://www.igc.apc.org/ei/tpp/nfabout.htm Another Cool Fact about the slow collision between India and China: http://www.cool-fact.com/archive/1997/11/06.html

Why do body joints make popping sounds?

Do a deep knee bend, and it's very likely you'll hear popping sounds coming from your knee joints. There are also popping sounds when you "crack your knuckles." What causes the popping sounds? Actually, there are two kinds of sounds. The joints in your fingers are enclosed in capsules that contain a lubricating fluid. When the joint is moved near the end of its range, gas that is dissolved in the joint fluid suddenly comes out of solution, forming a small bubble and making the popping noise. The joint can't be "popped" again until the gas redissolves. The knee-bending sounds are most likely made by tendons (fibers that connect muscles and bones) that snap into new positions when the joint moves under stress. This kind of popping noise can be repeated many times, because the tendons shift back and forth as the joint moves. More about popping joints: http://www.sciam.com/askexpert/medicine/medicine11.html

What kind of fish eats stony coral?

The parrotfish is a reef dweller that takes bites out of rock-hard corals, and pulverizes the stony material with its hard beak. It swallows the resulting mixture of coral sand, algae, and living coral polyps. By breaking off chunks of coral, the parrotfish plays an important role in the coral reef ecosystem. It removes surface algae, which might otherwise completely swallow up the reef. The chewed-up coral sand passes through the fish and is released, to fall in drifts between the reefs. It slowly dissolves, and becomes available for use by growing corals. Although the parrotfish chews up living corals, it is no threat to the coral reefs. However, overfishing of parrotfishes by humans is a threat. In some places, parrotfish are now protected from fishing, to preserve the ecological balance of the reefs. More about parrotfish: http://www.usdivers.com/fun_facts/pfish.htm Another Cool Fact about parrotfish: http://www.cool-fact.com/archive/1997/12/04.html

Who designed the first planned cities?

The first system of planned public works was invented and described by the Greek Hippodamus, who redesigned his own city, Miletus, after it was destroyed by the Persians. Hippodamus divided his cities into three sections, for religious, administrative, and commercial uses. He believed that city design was an art, and that mathematical laws of balance and proportion were important. Hippodamus invented the concept of "city blocks." Streets were laid out in regular grids for efficiency. His cities had systems to deliver water and dispose of sewage and garbage. New Greek cities took on his distinctive look, and existing cities were redesigned and rebuilt. Later, the Romans embraced and extended his ideas in their own ambitious public works projects. More about Miletus, one of the first planned cities: http://fhw.uni-muenster.de/projects/bouleuterion/en/katopsis/miletus_intro.html Miletus, Priene, and Didyma all showed features of preplanned design: http://www.turkishodyssey.com/places/aegean/aegean4.htm A Cool Fact about another inventive Greek from Miletus: http://www.cool-fact.com/archive/1999/01/26.html

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Updated Mar 9th 2001



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