Mercury Could Have Once Been as Big as Our EarthThere are several problems with studying the planet Mercury. It's so close to the sun that space probes have to follow indirect routes in order to avoid being pulled by the sun's gravity. The journey also very hot, which requires very hardy spacecraft. So scientific probes are few and far between. But the data that we have about the tiny planet shows us that it may have once been much larger and much further from the sun than it is now. This is mainly evident in Mercury's core, which is unusually large for a small planet, covered with a small mantle and an extremely thin crust. Mercury's crust contains thorium, which should have been blown away by the heat of the early solar system -unless Mercury wasn't as close to the sun then as it is now. Scientists have been studying the composition and the relative mineral makeup of Mercury from both the data gleaned by probes and by rare analogue minerals found on earth that may have come here from an event in Mercury's history. The hypothesis is that Mercury was once a much larger planet, and was knocked off its orbit by some event like a collision, then settled in as a remnant of itself in its current orbit close to the sun. Read how the evidence points to this possibility at BBC Future. -via Damn Interesting​(Image credit: A loose necktie) 
Everything You Ever Wanted to Know About Dental CavitiesDental cavities, or caries, is caused by lactic acid dissolving tooth enamel. The acid is produced by bacteria that thrive on the carbohydrates you eat, as some of it is left on your teeth after eating. This is why we brush our teeth, to deprive bacteria of anything to work with. But there's a lot about tooth decay that you probably don't know, like the name of the main bacteria responsible for causing caries, Streptococcus mutans. Once it takes hold in your mouth, this germ is part of your permanent biome, and you probably got it from your mother. Tooth decay didn't bother the dinosaurs. In fact, it doesn't show up in the fossil record of our ancestors until primates evolved. But it really took over when humans began cultivating and eating carbohydrates -grain, that is, and it got worse when we achieved unrestricted supplies of sugar. Brushing your teeth is the best way to prevent decay, but not for the reason you might think. Brushing doesn't really do much unless you have a toothpaste containing fluoride. You might be surprised at how many people never see a dentist, but it makes sense when you think of the expense, and regular health insurance doesn't cover it. Oh, but there's a lot more involved in the science of tooth decay. Read the research behind all the above facts and a lot more you should know about tooth decay at Cremieux Recueil. -via Damn Interesting ​(Image credit: Jonathan Rolande via Flickr) 
Why Drinking is More Dangerous for Older PeopleAs the Baby Boom generation us retiring, the US is seeing an uptick in injuries, illness, and deaths related to alcohol in people over age 65. A lot of that uptick is due to the fact that Boomers always drank more than their parents, in addition to using drugs. And the cohort is still huge. But there are extra dangers in drinking as an elderly person that you might not realize. The amount of alcohol required to become intoxicated is lower for older people, because their metabolisms are slowing down, and people over 65 retain less water in their bodies than they did when they were younger. Many common prescription medicines taken by older people can magnify the effects of drinking. And even at the same levels of intoxication, older people are more likely to fall down, with greater consequences because their bones are more brittle. Alcohol use is likely to depress one's immune system response as well. Retired people have more time on their hands, but that time shouldn't be filled with alcohol. The healthiest option would be to decrease the amount of alcohol consumed instead. Read more about the effects of aging on alcohol tolerance at CNN. -via Fark​(Image credit: Matti Blume) 
Type 3 Diabetes is Not a ThingType 1 diabetes, once called juvenile diabetes, is when the body does not have the ability to produce adequate insulin, which is crucial in processing sugar to feed our organs. Type 2 diabetes is when our bodies develop a resistance to insulin and the insulin regulation system goes haywire. You may have heard about Type 3 diabetes, a term that is only beginning to be used, and maybe it shouldn't be. The idea of Type 3 diabetes comes from research into Alzheimer's disease. This research shows that the brain cells of Alzheimer's patients have a resistance to insulin. Glucose and insulin have a profound effect on the energy-hungry brain. So does a kind of diabetes cause Alzheimer's disease? That's only a big maybe for now. Alzheimer's is a very complex condition, and there appears to be many causes, yet we still haven't found the one main cause, if there is one. So if you hear the term Type 3 diabetes, this is the research they are talking about. But it's still in the preliminary research phase. We shouldn't popularize a term of disease unless and until the scientific community can come to some consensus over it. Read more about the connection between insulin and Alzheimers at Science-Based Medicine. -via Real Clear Science​(Image credit: Computer Graphics Laboratory, University of California, San Francisco) 
The Future of the Earth, With or Without UsWe've studied a lot about the earth's past, and we are concerned about what is happening to the planet now. But that concern is mainly about what's going to happen to humankind and the civilizations we've built. While catastrophe may wipe out humans, suddenly or slowly, our extinction will be just another phase for the world as a whole. We can look much further ahead if we want, by extrapolating how the world has changed in the past, assuming the same forces will continue into the future. Sure, we have some say in certain trends that affect the earth, but the planet was around a long time before there were humans, and it may be here a long time after we are gone. Who knows? Maybe some other species will take over and treat the world better. PBS Eons looks at the near future, 10,000 years or so, when human actions will still have serious effects on the world. But if you go further, like 10 million years or 300 million years into the future, it's as if we were never here at all. This video is a little over nine minutes long; the rest is promotional.
Brain Cell Transplants Show Promise in Treating EpilepsyThis may sound like the plot of a science fiction horror film, but scientists are transplanting human cells into the brains of epilepsy patients. But it seems to be working so far. Epileptic seizures occur when electrical discharges in the brain's neurons run wild, causing abnormal and excessive storms of brain activity. People who suffer these seizures cannot take part in certain jobs and activities, such as driving, and can also suffer from poor memory and cognitive decline. If epilepsy cannot be controlled by medication, surgery is an option that involves cutting parts of the brain that can sometimes result in permanent brain damage. In a new experiment, stem cells were harvested from a human embryo created via IVF. They were grown and coaxed into becoming “inhibitory interneurons” that secrete a chemical called GABA that quiets brain activity. In a trial involving five epilepsy patients, these cells were injected into each subject's hippocampus. Three subjects showed significant improvement in the number and severity of seizures, enough to change their lives. One patient showed no improvement, and one patient showed quick improvement that may have been caused by something else. Read about the possibilities of stem cell therapy for epileptic seizures at MIT Technology Review. -via Damn Interesting(Image credit: GDJ)