knowledge

     A recent study suggests that the same vitamins in spinach that perform instant wonders for Popeye’s biceps might pack longer-lasting effects, such as dictating the hair color and health of future generations. Your lunch order could make a bigger difference than you think. A 2006 study led by David Martin, an oncologist at the Children’s Hospital Oakland Research Institute in California, tested whether a mouse’s diet alone can affect its descendants. The researchers fed meals high in minerals and vitamins—such as B12, which fortifies leafy greens—to pregnant mice that have a gene that makes their fur blond and also increases the Likelihood that they will grow obese and develop diabetes and cancer. On the new diet, the mice produced brown-haired offspring that were less vulnerable to disease. Even when the second-generation mice were denied the supplements, their offspring retained the improved health and still grew dark fur coats.         Mar...

      On March 10, 2010, Eyjafjallajökull volcano, a caldera in Iceland covered by an ice cap, erupted. It sent plumes of clouds across most of Europe and the Atlantic Ocean. Photos of the eruption show lightning originating and ending in the cloud of ash that hovered over the volcanic opening.    The largest volcanic storms are similar to supercell thunderstorms that spread across the American Midwest. But while those thunderstorms are fairly well understood, volcanic lightning still remains mysterious. The remote location of volcanoes and infrequent eruptions make volcanic lightning difficult to study. In general, lightning occurs through the separation of positively and negatively charged particles. Differences in the aerodynamics of the particles separate the positive and negative. When the difference in charge is great, electrons flow between the positive and negative regions. A lightning bolt is a natural way of correcting the charge distributi...

    Historians have traced the earliest reference to this rumor back to the beginning of the 20th century, when it was perpetuated by self-help gurus promising to expand people’s mental abilities. However, like so many things hucksters have told us, the brain claim is false. “There’s no question,” says Marcus Raichle, a neurologist and professor of radiology at Washington University in St. Louis, “you’re using every little bit of this thing.”      Even when you’re sleeping or just watching TV, your brain is burning a surprising amount of energy for its size.  Although your brain constitutes about 2 percent of your body weight, it accounts for 20 percent of the total energy that your body consumes. Scientists know that most of your brain’s energy is used for basic upkeep and communication between neurons. The rest, they speculate, might go toward preparing the brain to receive information by making predictions based on past experiences. For example, instea...

      Virulent infectious diseases and parasites have long been shown to be a significant cause of decline in biological populations. But can disease lead to the actual extinction of the host species—such as humankind?    Scientists attempt to determine the extinction-threatening effects of disease by first studying its role in historical extinctions. But proving that infectious disease is responsible for past extinctions is tricky business. After all, the extinct species is not around for scientific investigation. Even if a pathogen or parasite were discovered in a disappearing population, it would not prove that the pathogen itself was responsible for the decline.      However, reasonable evidence exists that historical extinctions and extirpations—local extinctions in which a speciesc eases to exist in the specific geographic area of study—are at least partlya ttributable to infectious disease. Avian malaria and bird pox are believe...

     Ever since Darwin first made headlines, scientists have been pondering why humans lost their natural coats as they evolved from apes. The theories range from lice to cannibalism.       The traditional theory—refined by scientists over the past 40 years—proposes that humans gradually became furless in order to withstand the brutal heat of the African savanna or to prevent over heating while chasing prey. One alternative idea, put forth in 2003 by evolutionary biologist Mark Pagel of the University of Reading in England, is that as humans learned to keep warm by making clothing and building shelters, they no longer needed heavy body hair. This hairlessness prevented parasites, such as mites and ticks, from sticking to their bodies. Avoiding parasites led to healthier humans, Pagel posits, and because there’s nothing as attractive as a bug-free hominid, hairlessness became a desirable feature in a mate, and natural selection drove the hairier ...

  The collapse of the Mayan civilization at the end of the so-called classic period, between 200 and 900, is a persistent archaeological mystery. The classical Maya were the most advanced of the pre-Columbian civilizations, anchored by a collection of city-states in the lowlands of modern-day Guatemala, Belize, and the Yucatan Peninsula. But around 700, these citystates began an inexorable decline that ended in their total abandonment. While the independent Maya survived until the Spanish conquest in the late 17th century, the postclassical Maya were a less urban and populous civilization. Archaeologists have posited a number of theories explaining the decline of the classical Maya, from foreign invasion to disease epidemic to a collapse in trade with neighboring cultures, but one of the oldest and most persistent theories centers on drought. The Yucatan Peninsula and Petén Basin were already particularly susceptible to variability in rainfall—the soil is thin and sandy...

    Thanks to recent breakthroughs in genetics research, we may be on the verge of discovering a fountain of youth in our own genetic material In 2009, three researchers—Elizabeth Blackburn of the University of California, San Francisco, Carol Greider of Johns Hopkins University, and Jack Szostak of Massachusetts General Hospital—won the Nobel Prize in Medicine for their work linking the aging process to telomeres. Telomeres are clusters of DNA that cap the chromosomes of complex organisms, protecting the rest of the genetic code during cell division. As cells age, these caps grow smaller, exposing the DNA to breaks and mutations that can lead to cancer or cell death.          These discoveries hint at a connection between telomeres and the broader aging process. People of an advanced age do tend to have cells with shorter telomeres when that cell is of a type that replicates frequently. Analysis of the white blood cells of Hendrikje van A...

     Humans store their genes in 23 pairs of chromosomes, 22 of which are identically matched. The 23rd is a two-sided biological coin—twin Xs mean you’re female; an X and a Y, male. Chromosome pairs often trade bits of DNA in a process called recombination, the purpose of which is to keep genes functioning properly. Talk of men’s path toward extinction began in the late 1990s, when it was discovered that the human Y chromosome, which is stumpy compared with the X, does not share enough genetic material with the X to practice recombination. Left without a way to renew damaged genes, the Y would continue to degrade and would eventually disappear, geneticists announced. They slapped an expiration date on the male half of the species of sometime in the next 5 to 10 million years. To get a perspective on this prediction, scientists looked to our closest genetic relatives—the chimps. Because humans and chimpanzees shared a common ancestor 6 million years ago, genet...

     The main functional unit of the brain is a type of nerve cell called the neuron, of which the human brain possesses roughly 100 billion. The human body contains three types of neurons, each different in function. Sensory neurons carry signals from the outside world into the central nervous system. Motor neurons carry signals from the central nervous system to muscles and glands. Interneurons form a connection between other neurons; they are neither sensory nor motor. Each sensation, memory, thought, and movement we experience is the result of electrochemical signals that pass Through neurons. The ability of our brain to function is the result of the 24/7 activity of neurons.         The human brain consists of the brain stem, the cerebellum, the cerebrum, and the limbic system.The BRAIN STEM contains the medulla, which regulates heart rate and breathing; the pons, which links to the cerebellum to help with movement and posture, as well...

        Few of us ever experience significant supernatural phenomena, but 60 to 80 percent of us do report having the strange sensation that we’ve already experienced something that we consciously we are actually experiencing for the first time. Like feeling you’ve had the same exact conversation with someone before. Or walking into a room you have never been in before, and sensing that you’ve been there in the past. If you’ve ever had feelings such as these, you’ve experienced déjà vu, the sense of having experienced something previously, although it is, in reality, entirely new. Déjà vu comes from the French term meaning “already seen.”         The phenomenon of déjà vu is difficult to study because it occurs only briefly and without notice, and it fades quickly. In addition, there is no physical manifestation of the experience, leaving scientists little to work with other than self-reported descriptions. So although researchers have...