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New Research Shows That Humans Spread Plague Long Before Fleas

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The flea's bad reputation may be somewhat undeserved, according to new research. In the 14th century, the insect played a major role in the spread of bubonic plague, which killed tens of millions of people in Asia, Europe, and Africa. But the results of a new study published in the journal Cell suggest that plague was present in human populations twice as long as previously thought, and that it was initially spread by human-to-human contact.

The bacteria that causes plague,Yersinia pestis, was recently found in human teeth dating from 2800 to 5000 years ago. In studying the DNA, researchers found that while the bacteria could not have led to bubonic plague, specifically, it could have caused pneumonic and septicemic plague, resulting in significant population declines in the 4th and 3rd millennia BCE. "By sequencing the genomes, we find that these ancient plague strains are basal to all known Yersinia pestis," the researchers write. "Our findings suggest that the virulent, flea-borne Y. pestis strain that caused the historic bubonic plague pandemics evolved from a less pathogenic Y. pestis lineage infecting human populations long before recorded evidence of plague outbreaks."

The researchers believe that the older strand of Yersinia pestis could not have caused bubonic plague because six of the seven samples were missing key components found in modern samples. A University of Cambridge press statement explains the significance of the missing ymt gene and a mutation of the pla gene in the ancient samples: 

The ymt gene protects the bacteria from being destroyed by the toxins in flea guts, so that it multiplies, choking the flea’s digestive tract. This causes the starving flea to frantically bite anything it can, and, in doing so, spread the plague. The mutation in the pla gene allows Y. pestis bacteria to spread across different tissues, turning the localized lung infection of pneumonic plague into one of the blood and lymph nodes. 

In other words: Fleas likely had nothing to do with the spread of earlier plagues, because back then, the bacteria hadn't evolved the traits it needed to survive inside fleas' digestive tracts. What's more, thanks to a genetic mutation, modern-day Y. pestis is far more likely to have systemic effects than its prehistoric counterpart. 

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Medicine
Why Haven't We Cured Cancer Yet?
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Walkathons, fundraisers, and ribbon-shaped bumper stickers raise research dollars and boost spirits, but cancer—the dreaded disease that affects more than 14 million people and their families at any given time—still remains bereft of a cure.

Why? For starters, cancer isn't just one disease—it's more than 100 of them, with different causes. This makes it impossible to treat each one using a one-size-fits-all method. Secondly, scientists use lab-grown cell lines cultivated from human tumors to develop cancer therapies. Living masses are far more complex, so potential treatments that show promise in lab experiments often don't work on cancer patients. As for the tumors themselves, they're prone to tiny genetic mutations, so just one growth might contain multiple types of cancer cells, and even unique sub-clones of tumors. These distinct entities might not respond the same way, or at all, to the same drug.

These are just a few of the challenges that cancer researchers face—but the good news is that they're working to beat all of them, as this TED-Ed video explains below.

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Health
Skipping Breakfast Could Be Bad for Your Heart
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There are mountains of evidence supporting the claim that breakfast really is the most important meal of the day. Getting something in your stomach in the first hours of the morning can regulate your glucose levels, improve your cognition, and keep your hunger in check. Now new research published in the Journal of the American College of Cardiology points to another reason not to wait until lunchtime to break last night’s fast. As TIME reports, people who skip breakfast are at an increased risk for atherosclerosis, a disease caused by plaque buildup in the arteries.

Researchers surveyed over 4000 men and women between the ages of 40 and 54 living in Spain. After looking at the dietary habits of each participant, they broke them into three groups: people who consumed more than 20 percent of their daily calories in the morning; those who got 5 to 20 percent; and those who ate less than 5 percent.

The subjects who ate very little in the a.m. hours or skipped breakfast all together were 2.5 more likely to have generalized atherosclerosis. This meant that plaque was starting to collect on the walls of their arteries, hardening and narrowing them and increasing the risk for heart attack or stroke. People who fell into the 5 to 20 percent calorie category were also more likely to show early signs of the disease, while those who ate the most calories in the morning were the healthiest.

These results aren’t entirely surprising. Previous studies have shown a connection between skipping breakfast and health problems like high blood pressure, high cholesterol, diabetes, and unwanted weight gain. A possible explanation for this trend could be that waiting several hours after waking up to eat your first meal of the day could trigger hormonal imbalances. The time between getting into and out of bed is the longest most of us go without eating, and our bodies expect us to consume some calories to help kickstart our energy for the day (drinking straight coffee doesn’t cut it). Another theory is that people who don’t eat in the morning are so hungry by the time lunch rolls around that they overcompensate for those missing calories, which is why skipping breakfast doesn’t make sense as a diet strategy.

But of course there are many breakfast skippers who aren’t motivated by health reasons either way: They just don’t think they have the time or energy to feed themselves in the morning before walking out the door. If this describes you, here are some simple, protein-packed meals you can prepare the night before.

[h/t TIME]

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