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Cows Give Daughters More Milk* Ancient Plague Identified* Extreme Speeding Stars* Dogs Catch Cancer* Earliest Human Tooth Decay* How Snakes Fly

CBC Radio | Posted: February 1, 2014 5:00 AM | Last Updated: February 1, 2014

This week, we'll learn about research that shows that cows give more milk(external link) to their daughters than their sons; we'll hear about a new genetic study that links the famous Black Death to the less well-known but equally deadly Justinian Plague(external link); we'll find out how some stars are flinging themselves right out of our galaxy(external link); we'll learn about a canine cancer(external link) that's contagious; we'll meet a scientist who has discovered the earliest evidence of tooth decay(external link) among hunter-gatherers; and finally, we'll make your skin crawl with a study on how flying snakes fly(external link).

Cows Give Daughters More Milk
Many human parents try hard to treat their sons and daughters equally. But when it comes to making milk, many mammals can be a bit unfair. Cows, for example, make significantly more milk for their daughters than their sons. Dr. Katie Hinde(external link) , an evolutionary biologist at Harvard University, discovered that, when she and her colleagues examined millions of dairy records. The study suggests that the bias begins during pregnancy, since dairy calves are separated from their moms at birth. The result seems to contradict a popular theory that moms with extra resources will favour their sons over their daughters, since the fittest males have the potential to leave far more offspring than the fittest females. But Hinde thinks humans may also tailor their milk production for sons or daughters and that could have implications for how we feed our babies.
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Ancient Plague Identified

Eight hundred years before the notorious Black Death plague, another pandemic devastated Europe. The Justinian plague wiped out up to half the population and is thought to have contributed to the fall of the Roman Empire. But not that much had been known about it -- until now. Dr. Hendrik Poinar(external link), an evolutionary geneticist at McMaster University, analysed the teeth of people thought to have died of the Justinian Plague. He managed to uncover its cause: Yersinia pestis, the same bacteria responsible for the Black Death. But it is a completely different strain than the one that caused the Black Death, and it is now extinct.
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Extreme Speeding Stars

Stars like our sun travel in orbits within galaxies, such as the Milky Way. But about 15 years ago, scientists discovered some huge, hot stars that were going so fast that they were flying right out of our galaxy. Dr. Kelly Holley-Bockelmann(external link), an astronomer at Vanderbilt University, leads a research team that discovered, for the first time, smaller, sun-like stars going fast enough to leave the Milky Way. But unlike the big hyper-velocity stars, which come from the centre of the galaxy and are thought to have been kicked out by black holes, these small stars come from all directions. Researchers are stumped about why they're going so fast.
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Dogs Catch Cancer
Canine transmissible venereal tumor , or CTVT , is an unusual contagious cancer that affects dogs around the world. Live cancer cells are transmitted from dog to dog during mating. Dr. Elizabeth Murchison(external link) , a cancer geneticist at Cambridge University, has sequenced the genome of this cancer. The results suggest that it has survived continuously for 11,000 years. The genome also reveals a lot about the cancer's original host, which turns out to be an ancient dog with a dark coat and pointy ears that was similar to an Alaskan malamute.
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Earliest Human Tooth Decay
The diet of hunter-gatherers living in Morocco, between 13 and 15 thousand years ago, contributed to tooth decay. The remains of 52 individuals were studied, and all but three suffered from tooth decay. The research -- led by Dr. Louise Humphrey from the Department of Earth Sciences at the Natural History Museum in London, England -- found that a diet heavily based on starchy food, including sweet acorns and pine nuts, was the cause. When the nuts were cooked, the sugars became sticky and more likely to remain on - and in - the teeth. The results were a surprise because it had previously been thought that tooth decay arrived with farming and an increase in food processing, 10,000 years ago.
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How Snakes Fly
It is well known how quickly and efficiently snakes can slither across the ground. But a group of snakes called Chrysopelea use similar movements to help them sustain flight. These one-metre-long snakes use their signature 'S' shape to swim through the air, as they glide down from the tree-tops in the rainforests of south-east Asia. But that's not all. Dr. Jake Socha(external link), an Assistant Professor in the Department of Engineering, Science and Mechanics at Virginia Tech University, has found that these snakes change their body shape while in the air, in order to increase aerodynamics. By moving their ribs forward and closer to their spine, the snake's body flattens to allow it to slice through the air. This same reconfiguration creates a concave trough along its underbelly to help maintain loft.
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Theme music bed copyright Raphaël Gluckstein, (external link)Creative Commons License by-nc-nd-2.0(external link)

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