Showing papers in "American Scientist in 2008"

Evolution "for the Good of the Group The process known as group selection was once accepted unthinkingly, then was widely discredited; it's time for a more discriminating assessment

Abstract: Is evolution a team sport, or is the contest f r survival played out strictly between individuals? There's no question that natural selection acts on individual organisms: Those with favorable traits are more likely to pass along their genes to the next genera tion. But perhaps similar processes could operate at other levels of the bio logical hierarchy. In this way natural selection could perpetuate traits that are favorable not to an individual but to a social unit such as a flock or a col ony, or to an entire species, or even to an ecosystem made up of many spe cies. The underlying question is: Can biological traits evolve "for the good of the group"? Many early biologists accepted the idea of group selection without think ing very critically about it. For exam ple, herds of grazing animals might be described as evolving to conserve their food supply over the long term. Herds

Fifty Years of Earth Observation Satellites: Views from above have lead to countless advances on the ground in both scientific knowledge and daily life.

Abstract: A half a century ago, the launch of Sputnik-1 saw the start of an era where we began to launch artificial satellites into orbit to tell us what we look like from above. Hundreds of Earth-observing satellites have followed, and this extensive remote sensing has provided both iconic views and unprecedented insights into our planet. Tatem, Goetz and Hay review the development of these satellites over the past 50 years, as well as the data they have produced, which has lead to a greater understanding of Earth's terrestrial, aquatic and atmospheric processes. They examine current trends and speculate on what the next 50 years of satellite remote sensing may bring

Salivary Diagnostics: Amazing as it might seem, doctors can detect and monitor diseases using molecules found in a sample of spit.

Abstract: Saliva carries different meanings around the world. In most of the United States, for example, the act of spitting is taken as an insult, whereas in some other cultures it can be considered a blessing. And although most Americans do not have a problem with the occasional wet kiss on the lips, they react with revulsion when they see objects covered with saliva. This seeming double standard arises because people perceive a difference between the saliva in their mouths and the saliva out-side their bodies, according to Gordon Allport, a Harvard psychologist who penned an influential 1960 publication on the subject. People won’t drink their own saliva, explained Allport, who hypothesized that this fluid becomes nonself and alien to the mind the moment it exits the mouth. Maybe this aversion explains why the biomedical community has been slow to recognize that saliva doesn’t just help one to chew and swallow—it also contains information about the physiological states of the body. Like blood, saliva contains many protein and RNA molecules, both of which are encoded by genes. Scientists can identify several abnormal conditions if they know which genes are active and at what levels—information that can in many instances be gleaned from a sample of a person’s blood. Saliva, however, is far easier and cheaper to collect and doesn’t expose health-care workers to blood-borne diseases. Oral fluids are also simpler to handle because they don’t clot, lessening the manipulations required. Furthermore, it’s possible that diagnoses that use saliva could be made outside of a doctor’s office, which is attractive for people who can’t afford to see a physician or for people living in places where there are none. Several tests that use saliva are already on the market. Three years ago, the U.S. Food and Drug Administration approved a product called OraQuick for detecting HIV-1 or HIV-2 infection. The assay, which is sensitive to anti-HIV antibodies in oral fluid or blood, indicates the result with one or two colored lines, similar to a home pregnancy test. The FDA authorized the use of OraQuick in clinical settings, but future versions may be sold over the counter. Commercially available kits can gauge the levels of a handful of hormones, including estrogen, testosterone and cortisol, from a sample of saliva. And other, yet unapproved, methods can screen for hepatitis viruses. In addition to these simple measures, saliva has the potential to diagnose diseases with more complex origins, including cancer and diabetes. In recent years, my colleagues at the University of California, Los Angeles, and I have studied the RNA and protein molecules in saliva as indicators of disease. We’ve found that we can diagnose early-stage oral cancer and Sjogren’s Syndrome, a systemic autoimmune disease marked by dryness of the mouth and eyes. Salivary diagnostics for serious illnesses affecting other parts of the body may be just around the corner. But to understand how biomedical researchers can perform such feats, one must first have a clear understanding of the makeup of this remarkable bodily fluid.

The phenotypic plasticity of Death Valley's pupfish: desert fish are revealing how the environment alters development to modify body shape and behavior

Abstract: ked even of lichen." For the most part, that description is accurate. As one of the world's harshest desert regions, Death Valley is a land of eroding bad lands, scorching alluvial fans, and bar ren flats of mud and salt. Even maps of the Death Valley region of California and Nevada al lude to the region's sweltering tem peratures. Furnace Creek, the Funeral Mountains, Dante's View, the Devil's Golf Course?the names of its geologi cal features are omens of an extreme landscape. And, in those extremes, Death Valley delivers. Death Valley holds concurrent titles of being the

The Past and Future of the Periodic Table

Abstract: I t graces the walls of lecture halls and laboratories of all types, from universities to industry. It is one of the most powerful icons of science. It captures the essence of chemistry in one elegant pattern. The periodic table provides a concise way of understanding how all known chemical elements react with one another and enter into chemical bonding, and it helps to explain the properties of each element that make it react in such a fashion.

Why Think Up New Molecules

Abstract: S ome theoreticians in chemistry, myself included, like to think about molecules that do not (yet) exist. I use the simple word “think” purposely, for the design need not use fancy-schmancy, computer-intensive, “first-principles” calculations. We conjure up the chemical future in so many ways—through simple model building, qualitative thinking and ever-more-reliable quantum chemical calculations. Even in dreams, as Henning Hopf of the Technische Universität Braunschweig reminded me, referring to the German chemist Friedrich August Kekulé, who worked out the cyclic structure of the carbon-based molecule benzene in the mid-1800s. Kekulé stated that the structure came to him during a daytime reverie about the ouroboric symbol of a snake biting its own tail. But why do we try to imagine new molecules? Aren’t there enough molecules already on Earth, be they natural or synthetic? A potpourri of reasons follows.

Bird Song and the Problem of Honest Communication

Abstract: P may at times be tempted to communicate dishonest information to one another: to exaggerate our income to someone we're dating, for example, or, conversely, to understate our income to the Internal Revenue Service. Although morality does play a role in the degree of truth imparted in the messages that we actually deliver, we also use a rational calculation of costs and benefits to decide whether or not to bend the truth. That lie may be worth it to us if the reward outweighs the punishment for getting caught— we are only human, after all.

Tectonic plates come apart at the seams

Abstract: At a rate of a few centimeters per year, the movement of continents is imperceptible to transient beings like ourselves. But over geologic time, the land masses that define the world of our senses have cruised around the globe, smashing together and ripping apart. Pangea, the supercontinent that broke up more than 100 million years ago, was only the most recent union of Earth's landmasses. Supercontinents and superoceans have been forming and disappearing for 3 billion years. But why do supercontinents split at one site and not another? The answer to this question is several hundred million years older than Pangea, dating back to the breakup of the previous supercontinent. The mountainous sutures of old continental collisions, it seems, carry the seeds of the next continental dispersion.

Jefferson, Buffon and the Moose

Abstract: In 1781, in the midst of the American Revolutionary War, the British army rousted Thomas Jefferson from his home in Monticello. Politically unpopular, he retired from the governorship of Virginia and threw himself into writing. The result was his only book, Notes on the State of Virginia (1785), in which, among other topics, he famously defended his country against those Europeans who said that the Americas (North, South and Central) were unhealthy places populated by lesser animals and plants, compared with those of the Old World, and inhabited by peoples who were similarly weak and degenerate.

Twisting Light to Trap Atoms

Abstract: Scientists are now exploiting orbital angular momentum in various experiments. Orbital angular momentum can arise if phase fronts, such as wave crests, become twisted around the direction of light propagation. Since the phenomenon was confirmed in 1992, researchers have investigated it in many experiments, initially with classical techniques but increasingly on the quantum level. Areas where orbital angular momentum can be used include in optical tweezers to rotate small particles; it can also be transferred from light to ultracold molecules, and it can be used as a model for applications in quantum cryptography.

The Functionalist's Dilemma

Abstract: The Functionalist’s Dilemma George Lakoff Language, Consciousness, Culture: Essays on Mental Structure . Ray Jackendoff. xxiv + 403 pp. MIT Press, 2007. Science, as Thomas Kuhn famously observed, does not progress linearly. Old paradigms remain as new ones supplant them. And science is very much a product of the times. The symbol manipulation paradigm for the mind spread like wildfire in the late 1950’s. Formal logic in the tradition of Bertrand Russell dominated Anglo­American philosophy, with W.V.O. Quine as the dominant figure in America. Formalism reigned in mathematics, fueled by the Bourbaki tradition in France. Great excitement was generated by the Church­Turing thesis of the equivalence between Turing machines, formal logic, recursive functions, and Emil Post’s formal languages. The question naturally arose: Could thought be characterized as a symbol manipulation system? The idea of artificial intelligence developed out of an attempt to answer this question, as did the information processing approach to cognitive psychology of the 1960’s. The mind was seen as computer software, with the brain as hardware. The software was what mattered. Any hardware would do—a digital computer or the brain, which was called “wetware” and seen (incorrectly) as a general­purpose processor. The corresponding philosophy of mind was called “functionalism”, which claimed that you could adequately study the mind independently of the brain in terms of its functions, as carried out by the manipulation of abstract symbols. The time was ripe for Noam Chomsky to adapt the symbol manipulation paradigm to linguistics. Chomsky’s metaphor was simple: A sentence was a string of symbols. A language was a set of such strings. A grammar was a set of recursive procedures for generating such sets. Language was syntacticized—placed mathematically within a Post system, with abstract symbols manipulated in algorithmic fashion by precise formal rules. Since the rules could not look outside the system, language had to be “autonomous”—independent of the rest of the mind. Meaning and communication played no role in the structure of language. The brain was irrelevant. The idea was called “generative linguistics,” and it continues in many US linguistics departments. By the mid­1970’s, there was another paradigm shift. Neuroscience burst onto the intellectual stage. Cognitive science developed beyond the formalist cognitive psychology to include neural models. And a linguistic theory committed to viewing language in terms of the brain and integrated with other aspects of the mind developed. It was called “cognitive linguistics,” and has been steadily developing into a rigorously formulated neural theory of language based on theory of neural computation and actual developments in neuroscience. Language and thought are seen as physically embodied and carried out biologically, not merely an abstract symbol manipulation system.

The Benefits of a Long Childhood

Abstract: ironic effect: Apollo became one of the Kennedy legacies that could not be eas ily questioned and one that President Johnson was determined to carry out." The last years of von Braun's life were frustrating, because the political will to invest immense resources in space travel dissolved after several Apollo missions landed on the Moon. From our perspec tive this is not surprising, but it was not something that von Braun or many of his contemporaries had anticipated. A thread that runs through the por tion of the book covering von Braun's time in the United States is that his con

Why Is a Raven Like a Writing Desk

Abstract: Many answers have been proposed to the riddle that the Mad Hatter posed to Alice at their famous tea party (for example, because Poe wrote on both) Let me argue for yet another one: the power of convention As I compose this essay, the writing desk I am using is a spanking new Ma cintosh laptop with many gigabytes of storage and enormous computing power Its screen is a marvel of full color clarity; it has a built-in video camera and microphone, and hence allows multiple methods of input and output Yet it has a QWERTY key board Why QWERTY? The QWERTY keyboard, named for the order of the keys on the left side of the first row of letter keys, was in vented in 1873 by Christopher Sholes, a Milwaukee newspaper editor Its purpose was to split up keys that were commonly hit serially so that a too-fast typist would not jam the associated type bars In addition to its primary goal of slowing things down, it also aided left-handed English language typists, for far more words can be typed with only the keys under the left hand than under the right Now, since its purpose has been long anachronistic, why do we still persist in using it? The reason is, of course, the power of convention After it became the conventional keyboard layout and touch typists learned it, they were