ريتشارد دوكنز's Blog, page 656
October 24, 2015
Science Is Best When The Data Is An Open Book
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Data needs to be an open book if science is to be made more reliable. Quinn Dombrowski/Flickr, CC BY-SA
It was 1986, and the American space agency, NASA, was reeling from the loss of seven lives. The space shuttle Challenger had broken apart about one minute after its launch.
A Congressional commission was formed to report on the tragedy. The physicist Richard Feynman was one of its members.
NASA officials had testified to Congress that the chance of a shuttle failure was around 1 in 100,000. Feynman wanted to look beyond the official testimony to the numbers and data that backed it up.
Maternal Instinct And Biology: Evolution Ensures We Want Sex, Not Babies
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Natural selection favours mechanisms that ensure reproduction - most significantly, the sexual urge. Courtney Carmody/Flickr, CC BY
Many women hear an ominous ticking of their “biological clock” when they reach their 30s, while others never hear it at all.
Some believe the compulsion to bear babies is biologically inbuilt – even suggesting women who refuse their supposed evolutionary duty are being selfish.
Ecotourism Could Be Making Animals Less Scared, And Easier To Eat
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While ecotourists enjoy the warm waters of the Cuiaba River in Brazil, our presence in natural areas like this may have unanticipated costs for local wildlife. Author provided
Wildlife populations are suffering death by a thousand cuts as a result of human activities. Wildlife are being hunted, fished, and poached. They are suffering from climate change and pollution. Diseases take their toll, as do newly invasive species. They are also being fragmented as a function of increased habitat destruction.
These are obvious culprits of environmental disruption. But there is one realm where we may be having an unanticipated impact on wildlife: nature-based tourism.
What Is The Secret To Being Good At Maths?
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Why do Asian children perform so well at maths? Creativa Images/Shutterstock
There is a common belief that Asians are naturally gifted at maths.
Asian countries like Singapore and Japan lead the ranks in first and second position on maths performance in the Program for International Student Assessment (PISA) tables – an international survey that ranks education systems worldwide – while Australia sits around 12th.
What is the secret to being good at maths? Are you simply born clever, or is it the result of a lot of hard work?
First-Ever Field Observations Of Rare And Elusive Whale
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The Omura's whale was only officially described in 2003. Salvatore Cerchio
Only officially recognized as a separate species in 2003, very little is known about Omura’s whales. For decades, the few individuals caught were misidentified as “pygmy” or “dwarf” Bryde’s whales, as both live in the tropical waters of the Indian Ocean and have a very similar appearance. Even then, it was only known from around eight individuals caught by Japan in the 70s, and a handful that had washed up on beaches.
October 23, 2015
What We’re Reading
A cousin catching up with the literature
Here are some of the stories that caught NCSE’s eye this week. Feel free to share articles that crossed your screen in the comment section, or e-mail us directly during the week with things that caught your eye. We’ll add the best to our weekly posts.
Baby Dinosaurs Found in “The Dragon’s Tomb,” Laelaps, October 19, 2015 — Brian Switek is obsessed with “adorable” baby hadrosaurs—and who could blame him? Cute “tiny squeakers that probably tottered around the nest for a while before exploring the wider Cretaceous world”! And because infant dinosaurs are rare in the fossil record, they’re scientifically important, too.
Back to the Future Day, in Climate Trends, Climate Central, October 21, 2015 — In the Back to the Future movies, Marty McFly visited 1885, 1955, 1985, and 2015 in his customized DeLorean. How did the climate change? “Over that period, temperatures, sea level, and carbon dioxide levels have all risen steadily.” And I still don’t have my hoverboard.
New Species of Galápagos Tortoise is Identified, The New York Times, October 21, 2015 — Darwin visited the Gálapagos Islands in 1835, and scientists are still making discoveries there one hundred eighty years later. Pam Belluck introduces us to Chelonoidis donfaustoi, named after a recently retired park ranger who spent his career helping to save endangered tortoises.
In Ancient DNA, Evidence of Plague Much Earlier than Previously Known, The New York Times, October 22, 2015 — Yersinia pestis, the microbe responsible for the Black Death, was active in the Bronze Age, but it wasn’t then able to infect fleas! “By comparing the ancient Yersinia to more recent strains, the scientists also were able to reconstruct its evolutionary history,” Carl Zimmer explains.
The Deadly Legacy of HIV Truthers, Gizmodo, October 22, 2015 — Science denial can be fatal, Charlie Jane Anders observes: “The story of the HIV denialist movement demonstrates that scientific agreement is not necessarily enough. Thousands of people died because the conspiracy theory was able to outrun the facts.”
A Look at the Professional Creationists and Anti-Creationists, BioLogos, October 22, 2015 — Sociologist Tom Kaden interprets the creationism/evolution controversy as “a play of a small number of specialized elite actors,” including NCSE, and suggests that it helps to provide “an answer to the question why public talk about creationism seems so detached from social scientific findings about it.”
Climate Change is Here, National Geographic, November 2015 — Accompanying a special issue of the print magazine is a spectacular website explaining that climate change is here and addressing the questions How do we know it’s happening? How do we fix it? and How do we live with it? Bill Nye “The Science Guy” (a member of NCSE’s Advisory Council) is featured throughout.
How Hurricane Patricia Quickly Became a Monster Storm
Hurricane Patricia, the strongest hurricane ever recorded in the Western Hemisphere, is plowing toward Mexico’s west coast. The Category 5 storm was a modest hurricane just two days ago but has quickly become a monster, seemingly out of nowhere.
As the Mexican government in three states scrambles to evacuate thousands of people, meteorologists are watching nervously to see what the storm will do next. Patricia, they say, is shaping up to be not only the most powerful but the fastest-growing on record. Twenty-four hours ago, the winds were an impressive 130 miles per hour. Now, at 200 miles per hour, the winds are comparable to the strongest tornadoes.
“The wind damage is going to be something extraordinary,” says Jeff Masters, a meteorologist at the Weather Underground. “We’re talking like a high end EF4, low end EF5 tornado that’s 15 miles wide hitting the coast, if it stays at this strength.” (An EF5 tornado is extremely damaging, and tornadoes are rarely more than a mile wide.)
How did a seemingly moderate hurricane turn into such a beast? Three factors affect the creation of a hurricane. First, and most important, is the temperature of the ocean’s surface water. Right now the water in the Eastern Pacific is more than 30 degrees Celsius, roughly a full degree higher than it normally is this time of year, according to David Adams, a scientist at the National Autonomous University of Mexico, in Mexico City. “Just the difference of a degree or two” can really pump up the energetics of a hurricane, he says.
Second, the speed of atmospheric winds (not part of the hurricane) moving across the upper reaches of the storm formation is low. If the wind there is high, it can divert a hurricane or shear it apart. But over the past few days, the winds along Mexico’s west coast have been unusually calm.
Finally, there is the humidity. A powerful hurricane needs moist air to feed it. “The relative humidity was 80 percent there,” Masters says. “We’re used to seeing relative humidities lower, like in the 60 and 70 percent range.”
Over the last 24 hours, these factors have combined perfectly to build a truly frightening hurricane that the Mexican National Weather Service is calling “the most dangerous storm in history.”
Meteorologists say it is not a surprise that this storm comes during a time when El Nino, a set of atmospheric and oceanic conditions over the Pacific, is especially strong. Generally, a period of significant El Nino conditions will bolster Pacific hurricanes while sapping strength from those in the Atlantic. What is unusual is that such a huge storm comes this late in the hurricane season, when ocean temperatures and humidity tend to drop off.
In September 2013, Hurricane Manuel rocked a similar segment of Mexico’s coastline, which includes the cities of Manzanillo and Acapulco. Although weaker than Patricia, that hurricane caused massive flooding, which resulted in prolonged looting and lawlessness in Acapulco. Patricia could repeat that, though with much stronger winds.
“The forecasts are that it will move in pretty quickly and dissipate, because it’s going to hit head-on with the really high mountains that are around Jalisco and Michoacán. That tends to destroy the structure of the hurricane. But of course that’s going to lead to really hideous amounts of rainfall,” Adams says.
In that case, the storm could cause damage as far away as the inland city of Guadalajara and be felt as far away as South Texas. Adams says that would actually be a preferable scenario to the alternative, which would be if the storm simply stays just off the coast, wreaking havoc on the cities there for many hours.
It’s still not clear exactly how Patricia grew so quickly. Like Hurricane Katrina that drowned New Orleans, it could have hit an especially warm patch of water at just the wrong time, Masters notes. But because Patricia has not been as closely monitored as Katrina was, he adds, scientists may never know for sure.
Nor can they say what role climate change could have had on a single weather event like a hurricane. But Adams says Patricia might be a glimpse at the kinds of storms a warmer climate might produces. “This may be a preview of what could happen if you increase, summarily, sea surface temperatures on the order of a degree or so.”
Additional reporting by Sally Rios Kuri
Rise of the Microglia
Microglia, the immune cells of the brain, have long been the underdogs of the glia world, passed over for other, flashier cousins, such as astrocytes. Although microglia are best known for being the brain’s primary defenders, scientists now realize that they play a role in the developing brain and may also be implicated in developmental and neurodegenerative disorders. The change in attitude is clear, as evidenced by the buzz around this topic at this year’s Society for Neuroscience (SfN) conference, which took place from October 17 to 21 in Chicago, where scientists discussed their role in both health and disease.
Activated in the diseased brain, microglia find injured neurons and strip away the synapses, the connections between them. These cells make up around 10 percent of all the cells in the brain and appear during early development. For decades scientists focused on them as immune cells and thought that they were quiet and passive in the absence of an outside invader. That all changed in 2005, when experimenters found that microglia were actually the fastest-moving structures in a healthy adult brain. Later discoveries revealed that their branches were reaching out to surrounding neurons and contacting synapses. These findings suggested that these cellular scavengers were involved in functions beyond disease.
The Brain’s Sculptors
The discovery that microglia were active in the healthy brain jump-started the exploration into their underlying mechanisms: Why do these cells hang around synapses? And what are they doing?
During early development, the brain starts off with many more synapses than it needs. Then, through pruning, these networks are refined. Microglia are critical to this process: they gobble up synapses, thus helping to sculpt the brain by eliminating unwanted connections. But how do microglia know which synapses to get rid of and which to leave alone?
New evidence suggests that a protective tag that keeps healthy cells from being eaten by the body’s immune system may also shield against microglial activity in the brain. Emily Lehrman, a doctoral candidate in neuroscientist Beth Stevens’s laboratory at Boston’s Children’s Hospital, presented these unpublished findings at this year’s SfN. The researchers found that this protective tag is highly expressed in the visual system in mice at five days after birth, when synaptic pruning peaks. Removing this protective tag in mice led to excess engulfment by microglia and overpruning of neuronal connections.
But pruning is not always a bad thing. Other molecules work to ensure that microglia remove weak connections, which can be detrimental to brain function. Cornelius Gross, a neuroscientist at the European Molecular Biology Laboratory, and his research group have been investigating the activity of fractalkine, a key molecule in neuron-microglia signaling whose receptors are found exclusively on microglia. “Microglia mature in a way that matches synaptogenesis, which sets up the hypothesis that neurons are calling out to microglia during this period,” Gross says.
His lab found that removing the receptor for fractalkine created an overabundance of weak synaptic contacts caused by deficient synaptic pruning during development in the hippocampus, a brain area involved in learning and memory. These pruning problems led to decreased functional connectivity in the brain, impaired social interactions and increased repetitive behavior—all telltale signs of autism. Published last year in Nature Neuroscience (Scientific American is part of Springer Nature), this work was also presented at the conference.
When Pruning Goes Awry
Studies have also found evidence for increased microglial activation in individuals with schizophrenia and autism; however, whether increased microglial activity is a cause or effect of these diseases is unclear. “We still need to understand whether pruning defects are contributing to these developmental disorders,” Stevens says.
Some findings are emerging from studies on Rett syndrome, a rare form of autism that affects only girls. Dorothy Schafer, now at the University of Massachusetts Medical School, studied microglia’s role in Rett syndrome while she was a postdoctoral researcher in Stevens’s lab. Using mice with mutations in MECP2, the predominant cause of the disease, she found that while microglia were not engulfing synapses during early development, the phagocytic capacity (or the gobbling ability) of these cells increased during the late stages of the disease. These unpublished results suggest that microglia were responding secondarily to a sick environment and partially resolve a debate going on about what microglia do in Rett syndrome—in recent years some studies have shown that microglia can arrest the pathology of disease, whereas others have indicated that they cannot. “Microglia are doing something, but in our research, it seems to be a secondary effect,” Shafer says. “What’s going on is still a huge mystery.”
Return of the Pruning Shears
As the resident immune cells, microglia act as sentinels, sensing and removing disturbances in the brain. When the brain is exposed to injury or disease, microglia surround the damaged areas and eat up the remains of dying cells. In Alzheimer’s disease, for example, microglia are often found near the sites of beta-amyloid deposits, the toxic clumps of misfolded proteins that appear in the brain of affected people. On one hand, microglia may delay the progression of disease by clearing cellular debris. But it is also possible that they are contributing to disease.
Early synapse loss is a hallmark of many neurodegenerative disorders. Growing evidence points to the possibility that microglial pruning pathways seen in early development may be reactivated later in life, leading to disease. Unpublished data from Stevens’s lab presented at the conference suggest that microglia are involved in the early stages of Alzheimer’s and that blocking microglia’s effects could reduce the synapse loss seen in Huntington’s disease.
As a newly burgeoning field, there are still more questions than answers. Next year’s conference is likely to bring us closer to understanding what these dynamic cells are doing in the brain. Once the underdogs, microglia may be the key to future therapeutics for a wide variety of psychiatric and neurodegenerative disorders.
The Pulse with Devon Peacock – Richard Dawkins Interview
Devon interviews evolutionary biologist and best selling author Richard Dawkins about his latest book, Brief Candle in the Dark: My Life in Science.
Interview date: October 23, 2015
Fossil Friday
This week on Fossil Friday, another lovely specimen from Dan Phelps, who has again thoughtfully provided us with a sense of scale.
Rather an interesting sight, right? Somewhat reminiscent of vertebrae. A couple of clues: it’s from the Late Devonian and was found in Kentucky. The first person to identify it wins bragging rights for the week!
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