Jul 31, 2013


It’s the form of visible electric discharge between rain clouds or between a rain cloud and the earth. The discharge is seen in the form of a brilliant arc, sometimes several kilometers long, stretching between the discharge points. The discharge also sets up a sound wave that is heard as thunder.

How rain clouds become charged is not fully understood, but most rain clouds are negatively charged at the base and positively charged at the top. The various hypotheses that explain how the polarization occurs may be divided into two categories: those that require ice and those that do not. Most meteorologists believe, however, that ice is a necessary factor, because lightning is not usually observed until ice has formed in the upper layers of thunderclouds. Experiments have shown that when dilute solutions of water are frozen the ice gains a negative charge but the water retains a positive charge. If, after freezing has started, rising air tears small droplets of water away from the frozen particles, the droplets are concentrated in the upper part of the cloud and the larger ice particles fall toward the base. On the other hand, experiments have also shown that large, swiftly falling drops of water become negatively charged whereas small, slowly falling drops become positively charged. The polarization of a thundercloud may thus be due to the rates at which large and small raindrops fall. However formed, the negative charge at the base of the cloud induces a positive charge on the earth beneath it, which acts as the second plate of a huge capacitor. When the electrical potential between two clouds or between a cloud and the earth reaches a sufficiently high value—about 10,000 volts (V) per centimeter (cm) or about 25,000 V/in. (a volt is a measure of electrical potential; for comparison, the potential supplied by an ordinary electrical outlet in the United States is 110 V)—the air becomes ionized along a narrow path and a lightning flash results. Many meteorologists believe that this is how a negative charge is carried to the ground and the total negative charge of the surface of the earth is maintained..

Jul 30, 2013

How Monday got its name

The Romans called the second day of the week dies lunae, or day of the moon. Modern languages that come from Latin have similar names- lundi; in French, and lunes in Spanish. But the groups that spoke Germanic languages substituted their own word for the moon and came up with Monandag, which developed into the modern English Monday.

In ancient times, Monday was considered an unlucky day. This may have been because there were many superstitions about the moon. Some people even thought that gazing at the moon could drive a person insane. (In fact, the word "lunacy" comes from the Latin word for moon.) Monday was unpopular for another reason in days gone by. It was washday - and washing all a family's clothes by hand was a lot of work.

Even today, Monday is an unpopular day. This has less to do with superstition than with the fact that Monday marks the end of the weekend. After two days off, most people have to wake up early and head back to school or work. But some Mondays are better - in the United States and a number of other countries, many holidays fall on Mondays. And that gives everyone a three-day weekend. (Grolier New Book of Knowledge Encyclopedia)

Jul 29, 2013

The Disarming Armadillos – helped us with the discovery of leprosy vaccine

On the surface, the armadillo hardly seems like celebrity material. Its body looks like a conglomeration of some of nature's most bizarre features: the figure of an overgrown sow bug, possumlike ears, turtle feet, lizard skin, and a dinosaur's tail. Draped over its back is a thick, medieval-looking cape called a carapace. Patches of coarse hair cover its armored body, and scent glands at the base of its tail give off a pungent, musky odor. "You could say it's not an animal we humans can easily relate to," says armadillo expert Eleanor Storrs, a professor of biology at the Florida Institute of Technology in Melbourne. Even so, a remarkable discovery she made in the 80’s thrust the creature from the shadows of anonymity into the glare of scientific fame: the armadillo is one of the few creatures besides people that can contract leprosy.

The discovery toppled a barrier that had stalled research on the disease for more than a century, and in the process pushed the armadillo into a position of importance. Now, however, many researchers believe the leprosy connection may just scratch the surface of the animal's trove of secrets.

"It's really a remarkable animal, and there's still so little known about it," says Storrs, who first became fascinated by the creatures nearly three decades ago. Since then the 62-year-old biochemist, who is director of the school's Comparative Mammology Laboratory, has found that under the armadillo's primitive upholstery lies a shy but intriguing animal with a vast repertoire of unusual traits. The more she peers under the armor, she says, the more remarkable it becomes.

Jul 28, 2013

Birth of a Tornado

A mesocyclone (or supercell) is a highly developed and dangerous thunderstorm. As its central updraft spirals skyward at 60 miles per hour, reaching heights of more than 45,000 feet, a bulging wall cloud starts protruding from the storm's base. The wall cloud's core may begin to rotate rapidly, leading it to lower a spinning funnel, which usually evolves into a tornado.

Tornadoes can strike anywhere in the United States, which has more tornadoes than any other country. (A tornado is any rapidly rotating column of air that touches the ground. In the air, it's called a funnel cloud.) Tornadoes are most apt to occur during the late-afternoon and evening hours in the spring and fall, when the air is least stable.

"First there has to be a favorable area for thunderstorms to form - an unstable air mass in which the wind direction turns with height," says NSSL meteorologist Dr. Edward Brandes. "If the air is then lifted by a passing cold front or rises because of daytime heating, a mesocyclone - a severe thunderstorm with a powerful rotating updraft -may develop." With few exceptions, tornadoes are born mesocyclones. Once they spot a mesocyclone, forecasters know they're dealing with a fierce storm that produces 3/4-inch (1 3/4-centimeter) hail and winds blowing at a minimum of 60 miles (96.5 kilometers) per hour. Says NSSL meteorologist Doug Forsyth: "It also means there's a fifty-fifty chance of a tornado."

Jul 27, 2013

Probiotics & Prebiotics

Probiotics are beneficial bacteria in your intestinal tract that can improve health. And probiotics can also help improve immune system function. Probiotics interact with a specific part of your small intestine called the Peyer's patches, which directly signal your immune system to be vigilant.

"Some probiotic drink mixes out there contain beneficial probiotic organisms," says Patricia David, MD, MSPH, president of Healthy U in Columbus, Ohio. "And those are great if you're on the go. But I encourage people to obtain their probiofics directly from food sources whenever possible - these food sources include yogurt, buttermilk, goat's milk, coconut water, soy milk, miso, kim chi, and sauerkraut. For optimum probiotic exposure, look for yogurts and other probiotic products that contain bifldobacterium and/or lactobacilli.

Another way to increase your levels of beneficial immune-bolstering bacteria is to consume prebiotics - nondigestible food components that selectively stimulate the growth of "good" bacteria in the gastrointestinal tract, says Dr. David. "Natural sources of prebiotics include dandelion greens, spinach, kale, artichokes, legumes, onions, leeks, garlic, oatmeal, flaxseed, barley, and soy yogurt." she says. (‘The Doctor’s Book of Food Remedies’, by Selene Yeager and the Editors of ‘Prevention’ magazine)

Jul 26, 2013

Foods for Defense

The most powerful protection that you can give your immune system is to eat a well-balanced diet containing a variety of fruits, vegetables, whole grains, seeds and nuts, and seafood, says Dr. DiMilia. These foods are high in nutrients that can help keep your immune system healthy. What's more, some of these nutrients are antioxidants, which may help give the immune system an added boost.

Here's why antioxidants are so important. Every second, immune cells in your body are hit by a barrage of free radicals, harmful oxygen molecules that are created in enormous numbers every day. Since free radicals are missing an electron, they rush through your body, stealing electrons wherever they can find them. And every time they grab an electron, another cell is damaged.

The antioxidants in such foods as brightly colored fruits and vegetables, however, literally come between free radicals and healthy immune cells, offering up their own electrons. This neutralizes the free radicals, stopping them from doing further harm. In the process, your body's immune cells stay protected and strong.

Jul 25, 2013

Other Victims of Nazism

These Gypsy children were
sent to Auschwitz
In addition to Jews and the mentally and physically handicapped, the Nazis targeted several other groups for elimination. These included the Roma and the Sinti (Gypsies); homosexual men; and, to a lesser extent, Jehovah's Witnesses. The reason for their persecution was that, in one way or another, all of these groups threatened the purity of the German master race.

The Nazis' treatment of the Roma and Sinti in many ways mirrored their treatment of the Jews: Gypsies were considered racially inferior and targeted for genocide. A special camp was set up for them within Birkenau, where families were permitted to stay together until they were exterminated together. In the meantime, Dr. Josef Mengele performed brutal pseudoscientific experiments on many of the inmates. The Roma word for the Holocaust is Porajmos, meaning "the devouring."

With regard to gays, the Nazis were able to take advantage of the same sort of long-standing hatred and prejudice that many Germans felt toward Jews. In 1871, the year of Germany's unification, Paragraph 175 was added to the Criminal Code, stating, "Unnatural fornication, whether between persons of the male sex or of humans with beasts, is to be punished by imprisonment." During the sexually liberated Weimar period, an active campaign was undertaken to remove Paragraph 175 from the Criminal Code, but the effort failed. Thus, when the Nazis came to power in 1933, they didn't have to enact new laws to imprison homosexual men; they merely had to enforce the law already on the books.

Jul 24, 2013

Why is spilling salt considered bad luck?

One reason is because salt was once valuable and difficult to obtain. According to an old Norwegian superstition, a person is doomed to shed as many tears as it takes to dissolve the spilled salt. Another reason is the belief that spilled salt refers to the devil. In the German superstition, whoever spills salt engenders enmity: It is thought to be a direct act of the devil. And both the French and the Americans toss salt over the left shoulder to hit the devil in the eye. (The Book of Answers, by Barbara Berliner)

Jul 23, 2013

Is That So?

"[It's a] myth [that] people who eat vegetarian diets are healthier than people who eat meat." (National Cattlemen's Beef Association, displayed on the Web site of the National Cattlemen’s Beef Association in 2001)

"Studies indicate that vegetarians often have Lower morbidity and mortality rates...Not only is mortality from coronary artery disease lower in vegetarians than in non-vegetarians, but vegetarian diets have also been successful in arresting coronary artery disease. Scientific data suggest positive relationships between a vegetarian diet and reduced risk for...obesity, coronary artery disease, hypertension, diabetes mellitus, and some types of cancer." (American Dietetic Association Position Paper on Vegetarian Diets, Journal of the American Dietetic Association 97 (1997):1317-21)
(The Food Revolution: how your diet can help save your life and our world, by John Robbins)

Jul 22, 2013

What did the swastika stand for before Hitler appropriated it?

Before it became the Nazi symbol of Aryan superiority, the swastika had several meanings, all positive. In Sanskrit, the word swastika means "conducive to well-being." The Aryans of India believed swastikas represented the sun's motion across the sky, a symbol of its goodness and regenerative power. The Greeks and Persians believed it represented prosperity and happiness. Early Christians disguised the cross as a swastika to avoid persecution. North American Indian tribes used a similar symbol as a sign of peace. (The Book of Answers, by Barbara Berliner)

Jul 21, 2013

Where does earth end and space begin?

The answer isn't as simple as it may seem. The US government awards wings to astronauts who have flown in a powered vehicle to a height of 50 nautical miles (about 80 km) above Earth's surface. The rest of the world recognizes a spaceflight boundary of 100 kilometers; but even at this altitude, a spacecraft can circle Earth only a few times before its orbit decays due to atmospheric drag. To maintain orbit for a day or longer, a spacecraft must attain an altitude of at least 80 nautical miles (about 130 km). This may sound high up, but if Earth were a peach, then this altitude would be right at the top of its fuzz.

Even at an altitude of 300 kilometers, there's more than enough atmosphere to make knowledge of its effects essential. Beyond the drag it causes on spacecraft, the atmosphere at that height has a different composition than the air at sea level. Significantly, it contains a much higher percentage of atomic oxygen. Unlike molecular oxygen, which consists of two oxygen atoms bonded together, atomic oxygen is highly reactive and will attack spacecraft components susceptible to oxidation (rust), weakening and eroding them.

Jul 20, 2013

Sources of fuel worldwide – up until utilization of petroleum oil

When the steam engine was invented at the beginning of the 18th century, most sources of fuel worldwide were the same as they had been for centuries: wood for cooking, oil for lighting, coal for heating and industry. The advent of commercially successful steam power in 1712 allowed for machinery and engines that were larger and more capable than any machines had ever been, catalyzing the dramatic changes of the Industrial Revolution. During the 19th century, continuous improvements to steam engine design transformed factories and built railroads across Europe and the Americas. Both inventors and engineers knew, however, that steam power had significant limitations. Steam must be generated by burning fuel, usually coal: and steam engines were large and bulky to allow for a furnace. The first steam-powered locomotive, invented in 1804 by the English engineer Richard Trevethick, was so heavy it broke the rails it rode on. From the earliest days of the Industrial Revolution, engineers looked for alternatives to steam that would allow for lighter, more powerful engines.

Internal combustion provided one such alternative. For centuries, inventors had imagined and tinkered with internal combustion engines; the medieval Arab scholar Al-Jazari described twin-cylinder reciprocating pistons in 1206, and Leonardo da Vinci  sketched compressionless engines in 1509. The modem combustion engine was the British inventor Robert Street's 1794 model, which used exploding gas to drive the pistons.

Jul 19, 2013

The discovery of Iron

The so-called Iron Age marks the period when iron replaced the use of bronze, toward the end of the 2nd millennium B.C. The discovery of iron was, however, made much earlier. A recent translation of a text from the Fayoum region shows that the Egyptians were capable of extracting iron ore some 3500 years B.C., but the technique used was rather rudimentary.

The use of iron was developed in Asia Minor (Mesopotamia). It was introduced into Greece toward 1200 B.C, where it permitted the growth of architecture: buildings could be made with blocks of stone joined by metal bolts. Iron also allowed beams of great length to be constructed because metal girders spread weight evenly. The Propylaea of the Acropolis in Athens are a magnificent example of this. (Inventions and Discoveries)

Jul 18, 2013

Sun's damaging rays

The ozone layer protects the Earth from the sun's ultraviolet rays. But the ozone layer is getting thinner, and more ultraviolet radiation is reaching the Earth. Health officials urge people to protect themselves from the sun's damaging rays. They recommend that people spend less time in the sun; wear protective clothing, including wide-brimmed hats, when in the sun; wear sunglasses that block ultraviolet rays; and apply sunscreen. (Grolier New Book of Knowledge Encyclopedia)

Jul 17, 2013

Food that is totally Rad!

The symbol you see here may look like a flower, but it's actually the symbol for food irradiation. Grocery shoppers in the United States got their first look at the symbol on January 24, 1992 when irradiated strawberries went on sale at a supermarket in North Miami Beach, Florida.

Irradiation is a process in which food is bombarded with low-level radiation in the form of gamma rays. The radiation doesn't make the food radioactive. Rather, it kills harmful bacteria, molds, and insects that cause spoilage and disease. Thus, supporters of the process say, irradiated foods can be shipped greater distances, can stay on supermarket shelves longer, and can protect people from getting food poisoning and other illnesses.

Opponents of food irradiation point out that gamma rays change the chemical structure of foods. This causes food to lose some of its nutritional value. Also , the radiation may create new compounds that are found only in irradiated foods and that haven't yet been identified or tested by scientist.

Jul 16, 2013

October 3rd, 1990: Germany becomes united

After 45 years of separation, West Germany and East Germany were reunited into a single nation. In effect, East Germany was absorbed into West Germany, and the East German government went out of existence. Berlin became the capital of the new Federal Republic of Germany. West German leaders, including President Richard von Weizsacker and Chancellor Helmut Kohl, kept their posts in the new government. (Grolier New Book of Knowledge Encyclopedia)

Jul 15, 2013

The odds of being killed on a motorcycle

1,250 to 1 (The Handy Science Answer Book, compiled by the Science and Technology department of the Carnegie Library of Pittsburgh)

Jul 14, 2013

The leading causes of death for young persons

For persons under the age of 21, accidents are the leading cause of death. Motor vehicle accidents account for almost half of all accidents involving this age group. However, the home appears to be the most dangerous place for infants (0 to 1 years). From birth to age one, the most prominent cause of accidental death is choking on food or objects placed in the mouth. Motor vehicle accidents rank second, and suffocation (from smothering by bedclothes, plastic bags, etc.) is the third leading cause. Fourth are fires, burns, etc.; the fifth is drowning. For children aged 1 to 4 years, the ranking is (1) motor vehicle accidents; (2) drowning; (3) fires and burns; (4) choking; and (5) falls. For ages 5 through 14, the order is (1) motor vehicle accidents; (2) drowning; (3) firearms; (4) poisoning; and (5) fires, burns, etc. From ages 15 to 24, motor vehicle accidents ranked first, drownings and poisoning tied for second and third place, and falls and fires, burns, etc., tied for fourth and fifth positions. (The Handy Science Answer Book, compiled by the Science and Technology department of the Carnegie Library of Pittsburgh)

Jul 13, 2013

Understanding the Neanderthals

Archaeological finds in Israel have shed new light on the role of the Neanderthal in human evolution. Remains of some 400 Neanderthal individuals have been found throughout Europe and in western Asia, dating from between 120,000 and 40,000 years ago. For many years, scientists had believed that either modem humans replaced Neanderthals, out-competing them because of superior intelligence, or that Neanderthals evolved into modem humans. The evidence from the Israel site suggests that modem-type humans coexisted with Neanderthals, possibly for as long as 50,000 years. The evidence also raises questions about interaction, cooperation, competition, and communication between these anatomically different humans.

Another important new discovery about Neanderthals was also made in Israel. At Kebara Cave was found the first well-preserved specimen of a Neanderthal hyoid bone --part of the structure of the throat used for speech. Scientists long had debated whether or not Neanderthals could speak, with part of the argument resting on anatomical differences between Neanderthals and Homo sapiens sapiens. The Neanderthal hyoid's similarity to the hyoid in modem humans would seem to imply a Neanderthal capability to make sounds similar to those of modem humans. (Funk & Wagnalls new Encyclopedia of Science Yearbook)

Jul 12, 2013

Infant Emotions

There is more to a baby's face than meets the eye. Psychologists at Wesleyan University in Middletown, Connecticut, documented greater emotional intensity on the right side of infants' faces while the youngsters smiled or frowned. Curiously, previous studies found emotional expressions are more intense on the left side of the face among right-handed adults.

Researchers think the adult pattern is influenced by the right side, or hemisphere, of the brain, which controls most muscles on the left side of the face and is critical in producing emotional displays. The left hemisphere controls much of the right side of the face, and is thought to inhibit emotional expressions, thus contributing to more intense expressions on the left side.

The examination of babies' faces suggests the right hemisphere matures more quickly during infancy, according to study director Catherine T. Best. At first, it apparently dampens the expression of spontaneous emotions, then gives up that function as the left hemisphere matures during childhood. Further study of facial expressions may clarify the ways in which infant and adult brains handle emotions, Best said.(Funk & Wagnalls new Encyclopedia of Science Yearbook)

Suspension bridge

The Chinese were building suspension bridges in the 6th century, although they existed prior to that in the form of drawbridges and footbridges made from vines. Suspension bridges were not built in the Western world until the 19th century. James Finlay (U.S.) built the first suspension bridge in the United States in 1801, at Union Town, Pa., spanning Jacob’s Creek. (Inventions and Discoveries)

Jul 11, 2013

Kings Canyon National Park

Kings Canyon National Park is a national park in the southern Sierra Nevada, east of Fresno, California. The park was established in 1940 and covers 461,901 acres.  It incorporated General Grant National Park, established in 1890 to protect the General Grant Grove of giant sequoias. (Wikipedia encyclopedia)

Jul 10, 2013

February 11, 1990: Nelson Mandela Walks to Freedom

South African black nationalist leader Nelson Mandela , who spent 27 years in jail for his efforts to end white minority rule, was freed on February 11, 1990. During his years in prison , Mandela had helped focus worldwide attention on the struggle for racial equality in South Africa.

Blacks outnumber whites in South Africa by more than five to one, but whites ruled the country since its early days, until 1994. In 1948, apartheid - "separateness" -- became the government's official policy. Everyone was classified according to race. This classification determined who could vote, where people could live, which schools they could attend. The main goals of Mandela and many other people, including his fellow members of the African National Congress (ANC), were to end apartheid and establish black majority rule.

Jul 9, 2013

The Protestant Revolution

In the world today, the number of people who claim Christianity as their religion number approximately 2 billion. More than 1.1 billion are Roman Catholics; the rest are generally known as Protestants, a term coined in 1528 during the struggle of European Christians seeking a new way to salvation different from the one established and enforced by the Catholic Church for over 1,000 years. Given the fact that the power of the Catholic Church was so deeply entrenched, the success of Protestantism was a landmark event in Western history. Even mote extraordinary is the rapidity with which it took hold. In less than 40 years (1517-55), most of Europe was segregated into Catholic and Protestant towns, cities, and kingdoms. The roots of popular discontent with the church were rooted in a history riddled with corruption and overt sinfulness on the part of the clergy, the bishops, and even the pope himself. (The New York Times ‘Smarter by Sunday – 52 Weekends of Essential Knowledge for the Curious Mind’)

Jul 8, 2013

How often does the human eye blink?

The rate of blinking varies, but on the average the eye blinks once every five seconds or 17,000 times each day or 6.25 million times a year. (The Handy Science Answer Book, compiled by the Science and Technology department of the Carnegie Library of Pittsburgh)

Jul 7, 2013

Is it true that the nails and hair of a dead person continue to grow?

Between 12 and 18 hours after death, the body begins to dry out. That causes the tips of the fingers and the skin of the face to shrink, creating the illusion that the nails and hair have grown. (The Handy Science Answer Book, compiled by the Science and Technology department of the Carnegie Library of Pittsburgh)

Jul 6, 2013

The first time the art of architecture was practiced

Historians generally agree that the art of architecture was first practiced in the Neolithic period (between the 9th and 4th millennia B.C.) in the Near East, where the claylike earth was used to build the first walls. Two series of inventions were to play a decisive role in the development of architecture: iron tools, whose use became widespread from the 10th century B.C., and weight displacement machines such as the pulley and the winch, of which even the most modem machines are merely perfected models. (Inventions and Discoveries)

Jul 5, 2013

Our thoughts can either make us ill or heal us

It is a connection that has been recognized since the beginning of recorded history, says Jeanne Achterberg-Lawlis, Ph.D., author of lmagery in Healing: Shamanism and Modern Medicine. 

Socrates said, "There is no illness of the body apart from the mind." But what may have been recognized by healers 2,400 years ago was generally not recognized by most healers of 10 or 20 years ago. For back around the turn of the 20th century, allopathic medicine (based on vaccines and pills) came to so strongly dominate the scene in America that all other medical theories were summarily dismissed.

The allopathic approach emphasized that for every disease there was one germ and there was (or soon would be) one drug that could be administered to kill it. Legislation was enacted to outlaw many traditional healing practices, including those that suggested a patient's thinking might affect his health, says Dr. Achterberg-Lawlis.

In the early 1980s, she and her husband, G. Frank Lawlis, Ph.D., conducted studies at the University of Texas Health Science Center, showing that the life expectancies of terminal cancer patients could be accurately predicted by looking at each patient's attitude. "But nobody wanted to hear about it," she says. "We found it very difficult to get published in medical journals."

Jul 4, 2013

Sagittarius A*: The black hole at the center of the Milky Way galaxy

An infrared portrait of the core of the Milky Way galaxy revealing bright star clusters and hundreds of thousands of massive stars amidst dust and swirls of hot ionized gas. The galaxy’s black hole lurks within the luminous Central cluster at right. (National Geographic)

It's hard to be modest when you live in the Milky Way. Our galaxy is far larger, brighter, and more massive than most other galaxies. From end to end, the Milky Way’s starry disk, observable with the naked eye and through optical telescopes, spans 120,000 light-years. Encircling it is another disk, composed mostly of hydrogen gas, detectable by radio telescopes. And engulfing all that our telescopes can see is an enormous halo of dark matter that they can’t. While it emits no light, this dark matter far outweighs the Milky Way’s hundreds of billions of stars, giving the galaxy, a total mass of one to two trillion times that of the sun. Indeed, our galaxy is so huge that dozens of lesser galaxies scamper about it, like moons orbiting a giant planet…

Jul 3, 2013

Orangutans’ cognitive abilities

Orangutans are on equal cognitive footing with African apes, or even surpass them on some tasks. For those in zoos that have contact with humans, they not only learn how to communicate their thoughts with abstract keyboard symbols, but also demonstrate a “theory of mind” (understanding another individual's perspective) and to make logical and thoughtful choices that show a mental flexibility some chimpanzees lack. In the wild, orangutans keep innovative cultural traditions. Some groups construct foraging tools for extracting insects from tree holes, others use leaves as rain hats or napkins, wad them up as pillows, or line their hands with them when climbing a spiky tree. And in rare instances orangutans will twist leaves into bundles and cradle them like dolls. (National Geographic)

Jul 2, 2013

How fast do fingernails grow?

Healthy nails grow about 0.8 inches (2 centimeters) each year. The middle fingernail grows the fastest, because the longer the finger, the faster its nail growth. Fingernails grow four times as fast as toenails. (The Handy Science Answer Book, compiled by the Science and Technology department of the Carnegie Library of Pittsburgh)

Jul 1, 2013

Trying to understand how our brain works

In the continuing effort to understand the human brain, the mysteries keep piling up. Consider what scientists are up against. Stretched flat, the human neocortex - the center of our higher mental functions – is about the size and thickness of a formal dinner napkin. With l00 billion cells, each with 1,000 to 10,000 synapses, the neocortex makes roughly l00 trillion connections and contains 300 million feet of wiring packed with other tissue into a one-and-a-half-quart volume in the brain.

These cells are arranged in six very similar layers, inviting confusion. Within these layers, different regions carry out vision, hearing, touch, the sense of balance, movement, emotional responses and every other feat of cognition. More mysterious yet, there are 10 times as many feedback connections - from the neocortex to lower levels of the brain - as there are feed-forward or bottom-up connections.

Added to these mysteries is the lack of a good framework for understanding the brain's connectivity and electrochemistry. Researchers do not know how the six-layered cortical sheet gives rise to the sense of self. They have not been able to disentangle the role of genes and experience in shaping brains. They do not know how the firing of billions of loosely coupled neurons gives rise to coordinated, goal-directed behavior. They can see trees but no forest.