Headlines of the day
Speeding driver tries escape police by hiding in dirt hole (the obscure store)
Super-Sized Autopsy Tables Needed For Big Corpses (Local6.com in Orlando)
One was The Beatles appearing on the Ed Sullivan Show
Two Explosive Evolutionary Events Shaped Early History Of Multicellular Life
ScienceDaily (Jan. 4, 2008) — Scientists have known for some time that most major groups of complex animals appeared in the fossils record during the Cambrian Explosion, a seemingly rapid evolutionary event that occurred 542 million years ago. Now Virginia Tech paleontologists, using rigorous analytical methods, have identified another explosive evolutionary event that occurred about 33 million years earlier among macroscopic life forms unrelated to the Cambrian animals. They dubbed this earlier event the "Avalon Explosion."
The discovery suggests that more than one explosive evolutionary event may have taken place during the early evolution of animals.
The Cambrian explosion event refers to the sudden appearance of most animal groups in a geologically short time period between 542 and 520 million years ago, in the early Cambrian Period. Although there were not as many animal species as in modern oceans, most (if not all) living animal groups were represented in the Cambrian oceans.
"The explosive evolutionary pattern was a concern to Charles Darwin, because he expected that evolution happens at a slow and constant pace," said Shuhai Xiao, associate professor of geobiology at Virginia Tech. "Darwin's perception could be represented by an inverted cone with ever expanding morphological range, but the fossil record of the Cambrian Explosion and since is better represented by a cylinder with a morphological radiation at the base and morphological constraint afterwards."
Darwin reckoned that there should be long and hidden periods of animal evolution before the Cambrian Explosion, Xiao said.
But paleontologists have not found such evidence, and recently scientists have learned that biological evolution has not been moving on a smooth road. "Accelerated rates may characterize the early evolution of many groups of organisms," said Michal Kowalewski, professor of geobiology at Virginia Tech.
To test whether other major branches of life also evolved in an abrupt and explosive manner, Virginia Tech graduate students Bing Shen and Lin Dong, along with Xiao and Kowalewski, analyzed the Ediacara fossils: the oldest complex, multicellular organisms that had lived in oceans from 575 to 542 million years ago; that is, before the Cambrian Explosion of animals. "These Ediacara organisms do not have an ancestor-descendant relationship with the Cambrian animals, and most of them went extinct before the Cambrian Explosion," said Shen. "And this group of organisms -- most species -- seems to be distinct from the Cambrian animals."
But how did those Ediacara organisms first evolve, Shen asked. Did they also appear in an explosive evolutionary event, or is the Cambrian Explosion a truly unparalleled event"
"We identified 50 characters and mapped the distribution of these characters in more than 200 Ediacara species. These species cover three evolutionary stages of the entire Ediacara history across 33 million years," said Shen.
The three successive evolutionary stages are represented by the Avalon, White Sea, and Nama assemblages (all named after localities where representative fossils of each stage can be found). The earliest Avalon stage was represented by relatively few species.
Surprisingly, however, as shown by Shen and colleagues, these earliest Ediacara life forms already occupied a full morphological range of body plans that would ever be realized through the entire history of Ediacara organisms. "In other words, major types of Ediacara organisms appeared at the dawn of their history, during the Avalon Explosion," Dong said. "Subsequently, Ediacara organisms diversified in White Sea time and then declined in Nama time. But, despite this notable waxing and waning in the number of species, the morphological range of the Avalon organisms were never exceeded through the subsequent history of Ediacara."
Kowalewski said their research team had not anticipated the discovery. "Using the scientific literature, we were trying to create a more rigorous reconstruction of the morphological history of Ediacara organisms," he said.
The process involved adapting quantitative methods that had been used previously for studying morphological evolution of animals, but never applied to the enigmatic Ediacara organisms. "We think of diversity in terms of individual species. But species may be very similar in their overall body plan. For example, 50 species of fly may not differ much from one another in terms of their overall shape -- they all represent the same body plan. On the other hand, a set of just three species that include a fly, a frog and an earthworm represent much more morphological variation. We can thus think of biodiversity not only in terms of how many different species there are but also how many fundamentally distinct body plans are being represented. Our approach combined both those approaches," said Kowalewski.
"In addition, the method relies on converting different morphologies into numerical (binary) data. This strategy allows us to describe, more objectively and more consistently, enigmatic fossil life forms, which are preserved mostly as two-dimensional impressions and are not understood well in terms of function, ecology, or physiology," Kowalewski said.
Scientists are still unsure what were the driving forces behind the rapid morphological expansion during the Avalon explosion, and why the morphological range did not expand, shrink, or shift during the subsequent White Sea and Nama stages.
"But, one thing seems certain -- the evolution of earliest macroscopic and complex life also went through an explosive event before to the Cambrian Explosion," Xiao said. "It now appears that at the dawn of the macroscopic life, between 575 and 520 million years ago, there was not one, but at least two major episodes of abrupt morphological expansion."
Oh, we thought you said “Video Killed The Radio Star.”
Insect Attack May Have Finished Off Dinosaurs
ScienceDaily (Jan. 4, 2008) — Asteroid impacts or massive volcanic flows might have occurred around the time dinosaurs became extinct, but a new arguemet is that the mightiest creatures the world has ever known may have been brought down by a tiny, much less dramatic force -- biting, disease-carrying insects.
An important contributor to the demise of the dinosaurs, experts say, could have been the rise and evolution of insects, especially the slow-but-overwhelming threat posed by new disease carriers. And the evidence for this emerging threat has been captured in almost lifelike-detail -- many types of insects preserved in amber that date to the time when dinosaurs disappeared.
"There are serious problems with the sudden impact theories of dinosaur extinction, not the least of which is that dinosaurs declined and disappeared over a period of hundreds of thousands, or even millions of years," said George Poinar Jr., a courtesy professor of zoology at Oregon State University. "That time frame is just not consistent with the effects of an asteroid impact. But competition with insects, emerging new diseases and the spread of flowering plants over very long periods of time is perfectly compatible with everything we know about dinosaur extinction."
This concept is outlined in detail in "What Bugged the Dinosaurs? Insects, Disease and Death in the Cretaceous," a book by George and Roberta Poinar, just published by Princeton University Press.
In it, the authors argue that insects provide a plausible and effective explanation for the slow, inexorable decline and eventual extinction of dinosaurs over many thousands of years. This period is known as the famous "K-T Boundary," or the line between the Cretaceous and Tertiary Period about 65 million years ago. There is evidence that some catastrophic events, such as a major asteroid or lava flows, also occurred at this time -- but these provide no complete explanation for the gradual decline of dinosaur populations, and even how some dinosaurs survived for thousands of years after the K-T Boundary.
Insects and disease, on the other hand, may have been a lot slower, but ultimately finished the job.
"We don't suggest that the appearance of biting insects and the spread of disease are the only things that relate to dinosaur extinction," Poinar said. "Other geologic and catastrophic events certainly played a role. But by themselves, such events do not explain a process that in reality took a very, very long time, perhaps millions of years. Insects and diseases do provide that explanation."
Poinar and his wife, Roberta, have spent much of their careers studying the plant and animal life forms found preserved in amber, using them to re-create the biological ecosystems that were in place millions of years ago. They are also authors of "The Amber Forest: A Reconstruction of a Vanished World."
As a semi-precious gem that first begins to form as sap oozing from a tree, amber has the unique ability to trap very small animals or other materials and -- as a natural embalming agent -- display them in nearly perfect, three-dimensional form millions of years later. This phenomenon has been invaluable in scientific and ecological research, and among other things, formed the scientific premise for the movie Jurassic Park, for the "dinosaur DNA" found in mosquitoes.
"During the late Cretaceous Period, the associations between insects, microbes and disease transmission were just emerging," Poinar said. "We found in the gut of one biting insect, preserved in amber from that era, the pathogen that causes leishmania -- a serious disease still today, one that can infect both reptiles and humans. In another biting insect, we discovered organisms that cause malaria, a type that infects birds and lizards today.
"In dinosaur feces, we found nematodes, trematodes and even protozoa that could have caused dysentery and other abdominal disturbances. The infective stages of these intestinal parasites are carried by filth-visiting insects."
In the Late Cretaceous, Poinar said, the world was covered with warm-temperate to tropical areas that swarmed with blood-sucking insects carrying leishmania, malaria, intestinal parasites, arboviruses and other pathogens, and caused repeated epidemics that slowly-but-surely wore down dinosaur populations. Ticks, mites, lice and biting flies would have tormented and weakened them.
"Smaller and separated populations of dinosaurs could have been repeatedly wiped out, just like when bird malaria was introduced into Hawaii, it killed off many of the honeycreepers," Poinar said. "After many millions of years of evolution, mammals, birds and reptiles have evolved some resistance to these diseases. But back in the Cretaceous, these diseases were new and invasive, and vertebrates had little or no natural or acquired immunity to them. Massive outbreaks causing death and localized extinctions would have occurred."
In similar fashion, the researchers suggest, insects would have played a major role in changing the nature of plant life on Earth -- the fundamental basis for all dinosaur life, whether herbivore, omnivore or carnivore. As the dinosaurs were declining, their traditional food items such as seed ferns, cycads, gingkoes and other gymnosperms were largely being displaced by flowering plants, which insects helped spread by their pollination activities. These plants would have spread to dominate the landscape. Also, insects could have spread plant diseases that destroyed large tracts of vegetation, and the insects could have been major competitors for the available plant food supply.
"Insects have exerted a tremendous impact on the entire ecology of the Earth, certainly shaping the evolution and causing the extinction of terrestrial organisms," the authors wrote in their book. "The largest of the land animals, the dinosaurs, would have been locked in a life-or-death struggle with them for survival."
The confluence of new insect-spread diseases, loss of traditional food sources, and competition for plants by insect pests could all have provided a lingering, debilitating condition that dinosaurs were ultimately unable to overcome, the researchers say. And these concerns -- which might have pressured the dinosaurs for thousands of years -- may have finished the job, along with the changing environment, meteor impacts and massive lava flows.
"We can't say for certain that insects are the smoking gun, but we believe they were an extremely significant force in the decline of the dinosaurs," Poinar said. "Our research with amber shows that there were evolving, disease-carrying vectors in the Cretaceous, and that at least some of the pathogens they carried infected reptiles. This clearly fills in some gaps regarding dinosaur extinctions."
My, what a fabulous little virtual world you have there.
Gay Men Navigate In A Similar Way To Women, Virtual Reality Researchers Find
ScienceDaily (Jan. 3, 2008) — Gay men navigate in a similar way to women, according to a new study from researchers at Queen Mary, University of London.
Dr Qazi Rahman, from Queen Mary’s School of Biological and Chemical Sciences used virtual reality scenarios to investigate if spatial learning and memory in humans can be linked to sexual orientation.
Differences in spatial learning and memory (our ability to record and recall information about our environment) are common between men and women. It has been shown that men consistently outperform women on tasks requiring navigation and discovering hidden objects; whereas women are more successful at tests which require them to remember where those objects lie in a particular space.
This is the first study to investigate if those differences are also true for gay, lesbian and straight individuals.
Dr Rahman used virtual reality stimulations of two common tests of spatial learning and memory, designed by researchers at Yale University. In the Morris Water Maze test (MWM), participants found themselves in a virtual pool and had to escape as quickly as possible using spatial clues in the virtual room to find a hidden platform. In the Radial Arm Maze test (RAM), participants had to traverse eight ‘arms’ from a circular junction to find hidden rewards. Four of the arms contained a reward, four did not.
Dr Rahman and his research assistant, Johanna Koerting, found that during the MWM test gay men and straight women took longer to find the hidden platform than did straight men. However, both gay and straight men spent more of their “dwelling time” in the area where the hidden platform actually was, compared to straight and lesbian women.
Dr Rahman explains: “Not only did straight men get started on the MWM test more quickly than gay men and the two female groups, they also maintained that advantage throughout the test. This might mean that sexual orientation affects the speed at which you acquire spatial information, but not necessarily your eventual memory for that spatial information.
“In previous studies we have also found that gay men tend to use similar navigation strategies to women, like using land-marks, and we now want to explore whether navigation strategies on these virtual navigation tasks are also the same for gay men and women. In particular, we are interested in whether heterosexual men are using a unique strategy from their first attempt at traversing a new environment, which accounts for why they are so quick off the mark.”
The researchers also found that gay and straight men were similar in their performance on the Radial Arm Maze. “This suggests that sexual variation in spatial cognition is not straightforward – gay people appear to show a ‘mosaic’ of performance, parts of which are male-like and other parts which are female-like,” adds Rahman.
Dr Rahman also commented that it would be interesting to see if these sexual differences change with age. “We know that spatial ability declines more rapidly in men with age than in women, and this might be related to changing hormone profiles. This may have some relevance to sex differences in ageing-related diseases of cognitive functioning, such as dementia.
“If we can understand more about how people of different sexes and sexualities differ in spatial performance, we might be able to tailor cognitive remediation therapies more effectively to specific groups within an ageing population.”
This research was recently published in the journal Hippocampus.
A lesser person would make a cheap joke about where the study was done. Not us.
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