Scientists have made the first embryonic stem cell lines from human skin cells.
Bees could build flat honeycombs from just three shapes: squares, triangles or hexagons. But for some reason, bees choose hexagons. Always “perfect” hexagons. Why?
The ocean abyss is truly our last frontier outside of space.
Patients like the ones in the study, who relapse after chemotherapy, usually have only a few months left, Dr. Sadelain said. But now, three of the five have been in remission for 5 to 24 months. Two others died: one was in remission but died from a blood clot, and the other relapsed. The survivors have gone on to have bone-marrow transplants. Their prognosis is good, but relapse is still possible, and only time will tell.
From couch potatoes to Olympic athletes, everyone has a physical capacity for exertion, beyond which the body becomes stressed and begins to feel bad. How much stems from genetic factors—things like lung capacity, oxygen transport and the rate at which oxygen is used in the muscle cells—is still a subject of scholarly debate. Estimates vary from 10% to 50%, says Panteleimon Ekkekakis, a professor of kinesiology at Iowa State who has been studying the psychophysiology of exercise.
But many sedentary people push beyond their intrinsic range when they try to exercise too quickly or intensely, which can make them hate the activity and want to stop, says Dr. Ekkekakis.
The idea hinges on something called the “ventilatory threshold.” Normally when people breathe, they expel an amount of carbon dioxide that is equal to the amount of oxygen taken in. But beyond the ventilatory threshold, the release of carbon dioxide begins to exceed the body’s intake of oxygen. This excess release of carbon dioxide is a sign that the muscles have become more acidic, which the body finds stressful.
For most individuals, the ventilatory threshold is around 50% to 60% of the way to their maximum capacity, though there is tremendous individual variation. For elite athletes, the threshold may be as high as 80%, while sedentary people may hit it at 35%.
By using tricks such as listening to music, people can continue to feel good even slightly past their ventilatory threshold, Dr. Ekkekakis and his colleagues have found. As people approach their maximum capacity, however, the feel-bad reaction is unavoidable.
And while both ventilatory threshold and maximum capacity can be slowly increased, people have to have enough positive experiences to stick with exercise over time so they actually can boost these limits.
In continuing studies of obese, sedentary but otherwise healthy middle-aged women, Dr. Ekkekakis found that some individuals reach their ventilatory threshold after just one minute at a slow pace on a treadmill. Some women’s thresholds are so low that they would reach their maximum capacity simply by doing the dishes or cooking, says Dr. Ekkekakis.
This means that though many weight-loss interventions suggest walking as the primary form of physical activity, it is probably too hard for many people.
I suspect people would know more of these things if it weren’t for the taboo nature with which we regard sex.
A humorous and educational video about the chameleon.
In recent years, biologists have recognized that birds engage in play. Juvenile Common Ravens are among the most playful of bird species. They have been observed to slide down snowbanks, apparently purely for fun. They even engage in games with other species, such as playing catch-me-if-you-can with wolves, otters and dogs. Common Ravens are known for spectacular aerobatic displays, such as flying in loops or interlocking talons with each other in flight.
They are also one of only a few wild animals who make their own toys. They have been observed breaking off twigs to play with socially.
Keep it together, Tessa.
Co-Discoverer of Evolution by Natural Selection: Alfred Russel Wallace Letters Go Online
Alfred Russel Wallace may not be a name as well-known as Charles Darwin, but London’s Natural History Museum is one of many institutions that believes it should be.
The reason why is simple: ask the average person in the street who discovered natural selection, they will say, “Darwin”. In fact it was discovered by Darwin and Wallace — both scientists arrived at the conclusion independently in the 19th century, and in fact the original publication of the theory featured both of their names on the cover.
A hundred years after his death, the Natural History Museum (NHM) is hoping to address this and to make 2013 the “Year of Wallace”. By doing so, it hopes to publicly reinstate the Victorian as the co-discoverer of one of the most important discoveries in the history of science.
The NHM has this week launched Wallace Letters Online, a website that showcases for the first time the correspondence Wallace had during his life and research. All surviving letters have been scanned and transcribed by museum volunteers and staff, and can be freely read and downloaded.
Who was Alfred Wallace?
One need only speak to George Beccaloni, NHM curator and director of the Wallace Correspondence Project, to discover why Wallace was such an important character in the scientific history books.
“When he died it’s been said that he was the most famous person in the world,” Beccaloni tells Wired.co.uk. “Every newspaper around the world ran obituaries about him and called him the last of the great Victorians.
“Wallace received a lot of credit in his lifetime for being the co-discoverer [of natural selection]. He was awarded every honour that it’s possible for a biologist to receive in Britain, including the most prestigious honour of the Royal Society, the Copley Medal.”
Problematically, natural selection was a distinctly controversial topic when it was proposed, and so after his death in 1913, Wallace’s name devolved into relative obscurity.
“It was only when modern genetics and population ecology emerged in the late-1930s that people realised that natural selection was the key to evolution,” says Beccaloni. “People got interested in the history of the subject and in where the idea came from and they looked back and saw Darwin’s ‘On the Origin of Species’ and didn’t look any further.”
Beccaloni is something of a Wallace evangelist, but he’s not alone. He recently travelled with fellow Wallace fan Bill Bailey to Indonesia to film a two-part documentary for the BBC about the late scientist’s discoveries. (“I went out as a sort of personal Wallace fact checker,” says Beccaloni.) The documentary is set to be broadcast later this year.
For an insight into the life of Wallace, the Natural History Museum’s Wallace Letters Online website is now open to the public.
It’s long overdue.
A decoy spider hangs below its much smaller builder, suspected to be a new species in the genus Cyclosa (Photo: Phil Torres) The decoy attracts predatory birds that, for obvious reasons, are more likely to notice it than the actual spider a tenth its size. Fascinating! Source: Weird Science
There are only about 4,000 tigers, at most, remaining in the wild. Yet there are probably tens of thousands of captive tigers around the world (there is no official census). This would appear to make a compelling case for the existence of zoos and private collections. If tigers can survive and breed well in captivity, then perhaps more can be introduced to the wild when safe habitat becomes available. Yet that system isn’t working the way we think it does. A huge number of the captive tigers are hybrids of various subspecies and are so inbred that they will never be suitable for reintroduction to the wild. No tigers are more emblematic of this problem than white tigers.
I recently asked friends on Facebook to write down their thoughts about white tigers without searching for any new information. Some very intelligent people were under the impression that white tigers are a variety of Siberian tiger, camouflaged for a snowy climate. Others applauded zoos with white tigers for supporting conservation of white tigers while lamenting a lag in reintroduction efforts. Only one out of 27 respondents knew that white tigers are not a subspecies at all but rather the result of a mutant gene that has been artificially selected through massive inbreeding to produce oddball animals for human entertainment.