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Mammals No Strangers to Chemical Warfare.
Toxins as a defense strategy are well documented in the reptile and insect worlds. However, this New York Times article discusses the many instances where mammals have evolved a chemical strategy of their own. Take for instance the African crested rat. It is big and sports a flamboyant coat of black and white fur. It is also poisonous. This giant rat takes advantage of a convenient local resource for its chemical arsenal: the Acokanthera tree. By chewing the bark of the tree, the African crested rat builds up a potent chemical in its system that is toxic to predators. Moreover, the crested rat wants to be seen and its fur coat, visible even in low light, is a warning to predators. A video clip from Is That Skunk? is featured in the article. Watch the full episode of Is That Skunk? online.
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Horse DNA Has a Story to Tell About Us.
Analyzing the mitochondrial DNA of horses from all over the world, scientists are developing a clearer picture not only as to their history, but also the history of human domestication of horses. Mitochondrial DNA is a sort of clock in which mutational changes can be traced back in time. What horse DNA reveals is that modern horses evolved from a common ancestor between 130,000 and 160,000 years ago. However, around 10,000 years ago, 18 separate mitochondrial DNA lineages emerged. Scientists believe this relatively sudden branching indicates that horses were being domesticated by humans in separate groups in different regions of Asia and Europe.
Read more at Discovery.
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The Trouble With Pythons.
Because owners of exotic pets, such as python snakes, often discard them into the wild, Florida has a big problem. In the areas where these former pet Burmese pythons have established themselves, they are killing small mammals to the point of local extinction. According to the researchers, “observations of raccoons have crashed by 99.3 per cent, opossums by 98.9 per cent and bobcats by 87.5 per cent. Rabbits have vanished completely.” It is believed that because pythons are a recently introduced species, many animals in the areas affected, including predators, have not developed strategies to avoid them. The federal government has recently banned the importation of Burmese pythons, but that measure may be too late for some locations in Florida.
Read more at New Scientist.
Watch the full episode of PBS Nature’s Invasion of the Pythons which addresses the issue of pythons in the Everglades.
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A Third Ancient Human Group May Have Interbred With Modern Humans.
The technology of genetic sequencing has become cheaper and faster. This has enabled paleontologists to analyze more ancient human remains, more quickly, in their quest for genetic markers that shed light on our ancestry. Scientists now believe that modern humans and their Neanderthal cousins interbred and that non-African human DNA is about 2.5% Neanderthal. Even more striking, after analyzing a pinky finger from the 40,000-year-old human remains in a Siberian cave, scientists conclude that a third group, which they call the Denisovans, also contributed to the DNA of modern humans. As much as 5% of the genome of people from Oceana (South Pacific) contains Denisovan DNA.
Read more at New York Times.
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NASA Study Attributes Global Warming to Human Activity, Not Solar Variations.
NASA has weighed in again on the continuing controversy over climate change. A new study looked at the solar activity between 2005 and 2010. Even though solar activity during that period was lower than usual, the earth warmed nevertheless.
Read more at Red Orbit.
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Teen Scientists Capture Rare Hummingbird Photos.
They may just be young teenagers, but the Shank brothers, ages 9 to 16, have already made an impressive contribution to the study of nature. They waited over a week to photograph a rare albino ruby-throated hummingbird. The brothers utilized several cameras and took numerous photographs of the bird in August 2011. Of course, their inspiration probably runs in the family. Their father, Kevin Shank, publishes the Nature Friend Magazine in Virginia.
See images at Global Animal.
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Good News For the World’s Rarest Gorilla.
The “Cross River Gorilla” is the world’s rarest, with a population of only about 300. In an effort to determine how sustainable its habitat is in west central Africa, between Nigeria and Cameroon, conservationists resorted to high resolution satellite imaging of the areas the gorilla is known to frequent. The scientists examined satellite images pixel by pixel and also relied on ordinary survey work to estimate the amount and quality of the gorillas’ remaining habitat. The good news is that the situation is better than expected. Assuming that vital corridors between mating areas can be kept open and protected, there is ample suitable habitat for these gorillas at the present time.
Read more at Red Orbit.
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Afraid of Animals – It’s Literally All in Your Head.
Research into epilepsy has allowed scientists some insight into a region of the brain that appears to be hard-wired to react to images of animals, and only animals. The amygdala is the part of the human brain that is thought to control emotions and basic responses, such as fight or flight. Epilepsy patients were being treated with electrodes implanted in their brains. When they were showed a group of pictures, a small number of neurons in a specific portion of the right amygdala responded to images of animals. The remainder of the patients’ brains showed no reaction. The development has led to speculation about the evolutionary roots of the amygdala and the importance of animals in the lives of our ancestors.
Read more at Scientific American.
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Fish Get the TSA Treatment.
An article in Scientific American makes available a slide-show of fish that have been x-ray photographed. The slide-show is based upon an exhibit at the Smithsonian National Museum of Natural History. “X-ray Vision: Fish Inside-Out,” will be on display until August, 2012.
Read more at Scientific American.
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Why Middle East Unrest Is Bad News For Elephants.
From 1998 to 2005, international cooperation and tough enforcement led to an encouraging fall in the production and sale of ivory products in Egypt. Unfortunately, recent unrest as well as new demand from abroad may be the undoing of elephants. The first part of this two-punch assault derives from civil unrest, which has markedly decreased enforcement of Egypt’s ivory protection laws. The second is from increased demand. A marked uptick in illegal ivory sales has been detected in major cities in Egypt. Demand from Chinese buyers, especially, is driving a new surge of ivory sales and its concomitant encouragement of illegal elephant pouching. According to the article on TRAFFIC’s website, “One ivory vendor told the investigators that Chinese buyers would sometimes spend USD 50,000 on ivory during one bargaining session.”
“The Dirt: This Week in Nature” curated and written by Robert Raciti.