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Last Updated: Nov 18, 2006 - 12:32:53 PM |
Special Topics
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Evolution
New approach will pinpoint genes linked to evolution of human brain
Six million years ago, chimpanzees and humans diverged from a common ancestor and evolved into unique species. Now UCLA scientists have identified a new way to pinpoint the genes that separate us from our closest living relative � and make us uniquely human.
Nov 14, 2006 - 5:46:00 PM
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Evolution
New genetic analysis forces re-draw of insect family tree
The family tree covering almost half the animal species on the planet has been re-drawn following a genetic analysis which has revealed new relationships between four major groups of insects. Scientists have found that flies and moths are most closely related to beetles and more distantly related to bees and wasps, contrary to previous theory.
Oct 29, 2006 - 10:26:00 PM
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Evolution
Giant insects might reign if only there was more oxygen in the air
The delicate lady bug in your garden could be frighteningly large if only there was a greater concentration of oxygen in the air, a new study concludes. The study adds support to the theory that some insects were much larger during the late Paleozoic period because they had a much richer oxygen supply, said the study's lead author Alexander Kaiser.
Oct 12, 2006 - 4:52:00 AM
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Evolution
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Reproduction
Infection Status Drives Interspecies Mating Choices in Fruit Fly Females
Hybridization is a constant possibility for two closely related species. Geographic isolation prevents interbreeding in some cases, but when the range of the two overlap, other mechanisms must come into play if they are to remain genetically distinct. Behavioral isolation is one such mechanism. If members of each group preferentially mate with their own kind, the two species can remain distinct even while residing together. Over time, such isolating behaviors may become more pronounced, and the genes governing them more widespread, a phenomenon termed �reinforcement.�
Oct 11, 2006 - 5:25:00 AM
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Evolution
Mother birds give a nutritional leg up to chicks with unattractive fathers
Mother birds deposit variable amounts of antioxidants into egg yolks, and it has long been theorized that females invest more in offspring sired by better quality males. However, a study from the November/December 2006 issue of Physiological and Biochemical Zoology shows that even ugly birds get their day. Providing new insight into the strategic basis behind resource allocation in eggs, the researchers found that female house finches deposit significantly more antioxidants, which protect the embryo during the developmental process, into eggs sired by less attractive fathers.
Sep 26, 2006 - 10:38:00 PM
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Evolution
Mammals Evolve Faster on Islands!
The notion of islands as natural testbeds for evolutionary study is nearly as old as the theory of evolution itself. The restricted scale, isolation, and sharp boundaries of islands create unique selective pressures, often to dramatic effect. Following what’s known as the “island rule,” small animals evolve into outsize versions of their continental counterparts while large animals shrink. Once restricted to islands, small animals often lacked predators and the competition between species that constrained the growth of their relatives on the mainland. Large mammals, on the other hand, no longer had access to vast grasslands and other abundant food sources and grew smaller to survive. Giant tortoises and iguanas still inhabit the Galápagos and a few other remote islands today, but only fossils remain of the dwarf hippopotami, elephants, and deer that once lived on islands in Indonesia, the Mediterranean, and the Pacific Ocean.
Sep 13, 2006 - 3:48:00 AM
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Evolution
A Bacterial Protein Puts a New Twist on DNA Transcription
For organisms to adapt, develop, and simply live, they must regulate hundreds to thousands of genes, making fine-tuned, precisely timed adjustments to produce the specific complement of proteins required for the occasion. For bacteria, this task falls largely to proteins called sigma factors. These small proteins associate with RNA polymerase, the enzyme that mediates gene transcription, to form a complex called the holoenzyme. The holoenzyme, guided by the sigma factor, recognizes promoter regions, which are specific DNA sequences that precede protein-coding sequences and mark the transcription start site. Sigma factors also contribute to transcription by facilitating DNA strand separation, which must occur before RNA polymerase can begin copying the DNA code. Once transcription begins, the sigma factor disengages from the RNA polymerase, becoming available for new joint ventures with different RNA polymerases.
Aug 16, 2006 - 9:16:00 AM
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Evolution
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Reproduction
Why Does Sex Exist?
Why does sex exist? A long-popular view holds that sexual reproduction creates new gene combinations that help the next generation resist rapidly co-evolving parasites. Each species constantly changes to achieve the same result�evolutionary advantage�prompting evolutionary biologists to dub this hypothesis the Red Queen (who tells Alice in Through the Looking Glass �it takes all the running you can do, to keep in the same place�).
Aug 7, 2006 - 1:51:00 PM
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Evolution
Pseudogenes Research Reinforces Theory of Evolution
Scientists led by a Children�s Hospital of Pittsburgh geneticist have found new evidence that a category of genes known as pseudogenes serve no function, an important finding that bolsters the theory of evolution.
Aug 2, 2006 - 11:54:00 AM
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Evolution
Non-human primates may be linchpin in evolution of language
When contemplating the coos and screams of a fellow member of its species, the rhesus monkey, or macaque, makes use of brain regions that correspond to the two principal language centers in the human brain, according to research conducted by scientists at the National Institute on Deafness and Other Communication Disorders (NIDCD) and the National Institute of Mental Health (NIMH), two of the National Institutes of Health. The finding, published July 23 in the advance online issue of Nature Neuroscience, bolsters the hypothesis that a shared ancestor to humans and present-day non-human primates may have possessed the key neural mechanisms upon which language was built.
Jul 24, 2006 - 7:33:00 PM
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Evolution
Primates developed close-up eyesight to avoid a dangerous predator
The ability to spot venomous snakes may have played a major role in the evolution of monkeys, apes and humans, according to a new hypothesis by Lynne Isbell, professor of anthropology at UC Davis. Primates have good vision, enlarged brains, and grasping hands and feet, and use their vision to guide reaching and grasping. Scientists have thought that these characteristics evolved together as early primates used their hands and eyes to grab insects and other small prey, or to handle and examine fruit and other foods.
Jul 22, 2006 - 7:15:00 PM
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Evolution
Parsing the Functional Fields of the Auditory Cortex
No self-respecting concertgoer of a certain era would consider wearing earplugs at a show, but that was long before Pete Townsend and other rock icons spoke out about the risk of deafness. Today, most people recognize that high-intensity noise causes hearing loss�except maybe for those iPod users who routinely blast earsplitting music straight into their brains.
Jun 23, 2006 - 12:43:00 AM
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Evolution
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Reproduction
Declining Human Fertility is Evolutionary Adaptation
Before society criticises teenage girls for having sex behind the bike sheds and becoming pregnant, or women in their 60s for seeking IVF treatment, it is important to consider fertility not just in terms of the 21st century but in the context of the past 150,000 years.
Jun 21, 2006 - 2:52:00 PM
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Evolution
Study shows that threat displays may prevent serious physical harm
In a paper from the July issue of The American Naturalist, Kristopher Lappin (Northern Arizona University), Yoni Brandt (University of Toronto), Jerry Husak (Oklahoma State University), Joe Macedonia (Arizona State University), and Darrell Kemp (James Cook University), demonstrate that a threat display can provide accurate information about the performance of a weapon.
Jun 20, 2006 - 11:17:00 PM
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Evolution
How animals learn from each other
In an exciting study that provides new understanding of how animals learn--and learn from each other--researchers have demonstrated that bats that use frog acoustic cues to find quality prey can rapidly learn these cues by observing other bats. While numerous examples are known of instances where predators can use so-called "social learning" to learn new visual and olfactory cues associated with prey, this kind of learning of an acoustic cue had not been previously described.
Jun 20, 2006 - 12:33:00 AM
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Evolution
Thermal Adaptation in Bacterial Viruses
Assuming the absence of a massive asteroid strike, gamma ray burst, or other globally devastating event, the survival of a species depends on its ability to adapt to environmental changes. To understand how such adaptations occur in nature, scientists study much simpler systems in the lab. A classic lab evolution experiment uses evolutionary responses to temperature as a model for studying how an environmental variable affects the physical expression (phenotype) of an organism's genes. Biologists have typically focused either on the range of physiological responses to temperature or on the genetic changes underlying variations in temperature.
Jun 10, 2006 - 1:16:00 PM
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Evolution
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Reproduction
Genetic quality of sperm worsens as men get older
New research indicates that the genetic quality of sperm worsens as men get older, increasing a man's risk of being infertile, fathering unsuccessful pregnancies and passing along dwarfism and possibly other genetic diseases to his children. A study led by scientists at Lawrence Livermore National Laboratory (LLNL) and the University of California, Berkeley, found a steady increase in sperm DNA fragmentation with increasing age of the study participants, along with increases in a gene mutation that causes achondroplasia, or dwarfism. The first changes were observed in men in their early reproductive years. Earlier research by the same team indicated that male reproductive ability gradually worsens with age, as sperm counts decline and the sperm lose motility and their ability to swim in a straight line. In the current study, the researchers analyzed DNA damage, chromosomal abnormalities and gene mutations in semen samples from the same subjects � 97 healthy, non-smoking LLNL employees and retirees between 22 and 80 years old � and found that sperm motility showed a high correlation with DNA fragmentation, which is associated with increased risk of infertility and a reduced probability of fathering a successful pregnancy.
Jun 8, 2006 - 4:46:00 PM
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Evolution
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Reproduction
Songbirds boost size of eggs when hearing sexy song
When the females started egg-laying they varied the size of their eggs in the nest according to the attractiveness of the male's song. That is, the more attractive the song, the larger the eggs.
Jun 8, 2006 - 6:04:00 AM
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Evolution
Why women live longer than men
Despite research efforts to find modern factors that would explain the different life expectancies of men and women, the gap is actually ancient and universal, according to University of Michigan researchers. This skewed mortality isn't even unique to our species; the men come up short in common chimps and many other species, Kruger added. Kruger and co-author Randolph Nesse, a professor of psychology and psychiatry and director of the Evolution and Human Adaptation Program, argue that the difference in life expectancy stems from the biological imperative of attracting mates.
May 10, 2006 - 12:49:00 PM
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Evolution
Fruitfly study shows how evolution wings it
In the frantic world of fruitfly courtship, the difference between attracting a mate and going home alone may depend on having the right wing spots. Now, Howard Hughes Medical Institute researchers have learned which elements of fly DNA make these spots come and go in different species. Their studies have also uncovered surprising new evidence supporting the idea that evolution is an incessant tinkerer when it comes to complex traits.
Apr 20, 2006 - 3:56:00 PM
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Evolution
Tantalizing clue to the evolutionary origins of light-sensing cells
Lizards have given Johns Hopkins researchers a tantalizing clue to the evolutionary origins of light-sensing cells in people and other species. Published in the March 17 issue of Science, their lizard study describes how the �side-blotched� lizard�s so-called third, or parietal, eye, distinguishes two different colors, blue and green, possibly to tell the time of day. Specialized nerve cells in that eye, which looks more like a spot on the lizard�s forehead, use two types of molecular signals to sense light: those found only in simpler animals, like scallops, and those found only in more complex animals like humans.
Apr 15, 2006 - 6:04:00 PM
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Evolution
Relationship of brain and skull more than just packaging
People usually think of the skull as packaging for the brain and researchers usually investigate them separately, but a team of researchers now thinks that developmentally and evolutionarily that the two are incontrovertibly linked. The researchers, including biological anthropologists, physicians and a computer scientist, looked at the CT scans and MRIs of infants with particular types of craniosynostosis � a condition where one or more of the sutures -- fibrous bands that connect the bones -- of the baby's skull close too early and deform the skull and brain.
Apr 14, 2006 - 11:17:00 PM
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Evolution
What Does Evolution Do with a Spare Set of Genes?
A hundred million years ago, a molecular twist of fate endowed an ancestor of today's baker's yeast (Saccharomyces cerevisiae) with an extra copy of every gene it owned�the equivalent of a factory one day finding double the number of workers reporting for duty. What did the yeast and the forces of evolution do with this treasure trove of potential? Did the extra gene-workers simply double the output? Did the original crew and the duplicates divvy up the ancestral functions? Or did they take on new tasks? That's what Gavin Conant and Kenneth Wolfe sought to find out in their study of the networks of interactions among genes and other cellular components that emerged in the wake of that landmark event.
Apr 5, 2006 - 6:44:00 PM
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Evolution
Evolutionary biology research techniques predict cancer
In diverse ecosystems, packed with wildly different species, evolution whizzes along. As different species accumulate mutations, some adapt particularly well to their environment and prosper. It happens in marine sediments, mountain forests � and, as a new study illustrates, in precancerous tumors, too.
Mar 27, 2006 - 1:26:00 AM
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Evolution
Something fishy about human brain evolution?
Forget the textbook story about tool use and language sparking the dramatic evolutionary growth of the human brain. Instead, imagine ancient hominid children chasing frogs. Not for fun, but for food. According to Dr. Stephen Cunnane it was a rich and secure shore-based diet that fuelled and provided the essential nutrients to make our brains what they are today. Controversially, according to Dr. Cunnane our initial brain boost didn't happen by adaptation, but by exaptation, or chance.
Feb 19, 2006 - 5:17:00 PM
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Evolution
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Reproduction
Fish have menopause, study determines
A UC Riverside-led research team has found that as some populations of an organism evolve a longer lifespan, they do so by increasing only that segment of the lifespan that contributes to "fitness" � the relative ability of an individual to contribute offspring to the next generation. Focusing on guppies, small fresh-water fish biologists have studied for long, the researchers found that guppies living in environments with a large number of predators have adapted to reproduce earlier in life than guppies from low-predation localities. Moreover, when reproduction ceases, guppies from high-predation localities are far older, on average, than guppies from low-predation localities, indicating that high-predation guppies enjoy a long "reproductive period" � the time between first and last reproduction.
Dec 29, 2005 - 4:19:00 PM
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Evolution
Modeling the Origin and Spread of Early Agriculture
After the last major ice age some 10,000 years ago, things began to look up for early humans. Forbidding climes yielded to more hospitable weather patterns, and people began to settle down and domesticate plants and animals. Archeologist Gordon Childe, who in 1942 called the transition from hunting and gathering to agriculture the Neolithic Revolution, proposed that unchecked population growth triggered economic and social problems among Near Eastern populations and forced farmers and shepherds to search for new lands. In this demic diffusion model, dispersing populations introduced Europeans to the Neolithic lifestyle. Alternately, Europeans may have learned to farm by imitating Neolithic practitioners they encountered through trade or other interactions (the cultural diffusion model).
Dec 29, 2005 - 4:02:00 PM
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Evolution
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Reproduction
Dancing ability determines mate quality
Dance has long been recognized as a signal of courtship in many animal species, including humans. Better dancers presumably attract more mates, or a more desirable mate. What's seemingly obvious in everyday life, however, has not always been rigorously verified by science. Now, a study by scientists at Rutgers, The State University of New Jersey, for the first time links dancing ability to established measures of mate quality in humans. Reporting in Thursday's edition of the British science journal Nature, Rutgers anthropologists collaborating with University of Washington computer scientists describe how they created computer-animated figures that duplicated the movements of 183 Jamaican teenagers dancing to popular music. The researchers then asked peers of the dancers to evaluate the dancing ability of these animated figures. The figures were gender-neutral, faceless and the same size � all to keep evaluators from boosting or dropping dancers' scores based on considerations other than dance moves.
Dec 22, 2005 - 5:11:00 AM
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Evolution
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Reproduction
How sense of smell affects mating and aggression
New research by scientists at UCSF sheds light on how the odor detecting system in mice sends signals that affect their social behavior.
Dec 22, 2005 - 3:42:00 AM
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Evolution
Dog Genome Sheds Light on Human Evolution
An international research team led by scientists at the Broad Institute of MIT and Harvard announced today the completion of a high-quality genome sequence of the domestic dog, together with a catalogue of 2.5 million specific genetic differences across several dog breeds. Published in the December 8 issue of Nature, the dog research sheds light on both the genetic similarities between dogs and humans and the genetic differences between dog breeds. Comparison of the dog and human DNA reveals key secrets about the regulation of the master genes that control embryonic development. Comparison among dogs also reveals the structure of genetic variation among breeds, which can now be used to unlock the basis of physical and behavioural differences, as well the genetic underpinnings of diseases common to domestic dogs and their human companions.
Dec 8, 2005 - 6:38:00 PM
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