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Hank Green: Hello, I’m Hank Green and this is SciShow News.

The main event in the US this weekend is the Super Bowl, the championship match of American football and the unfortunate odds are that fans are likely to witness at least one concussion. Nearly every NFL game involves a player suffering a concussion, and while that might not sound like a huge deal, attention from the media, including SciShow News, has heightened public awareness about what’s being called a concussion pandemic.

From tragic high-profile suicides like that of former NFL linebacker Junior Seau to a number of new studies, we’re getting all kinds of indications that repeated concussions by athletes in football, hockey, baseball and other sports can take a drastic toll. The technical definition of a concussion is ‘any trauma caused by sudden jarring of the head that results in temporary loss of brain function’, often seemingly minor, like confusion, dizziness, headache or brief unconsciousness. But after one concussion, a person becomes more susceptible to the next, and with each recurrence, the list of risks grows to include depression, dementia and motor neuron diseases.

For obvious reasons, NFL players are at an especially high risk. In the 2012 season, the league averaged 11 concussions per week, and the damage its athletes suffer has been borne out in study after study. Autopsies of more than 50 ex-NFL players have revealed chronic traumatic encephalopathy, a form of dementia, and a 2012 study showed that NFL players are four times more likely to die of Alzheimer’s or amyotrophic lateral sclerosis, the motor neuron syndrome also known as Lou Gehrig’s disease.

To help prevent these and other conditions, some reforms have been proposed, like new helmets equipped with so-called ‘guardian caps’ which use foam pads to absorb impact, but researchers have yet to test their effectiveness. And last year, two different sports equipment makers unveiled electronic impact indicators which can be worn inside the helmet and alert referees when players receive especially hard hits.

But the simplest solution would be like to enforce the rules of the game. Helmet-to-helmet hits, the hardest and often most dangerous impacts, are actually banned by the NFL, but the rule is often ignored. So, while some things have improved since last I brought this up, serious study into sports-related head injuries remains in its infancy. At least the NFL seems willing to invest in this research. Last week, it said that it was awarding $20 million in grants to universities around the country to fund studies into the long-term effects of concussions and how to better diagnose them.

Turning now to more ancient pandemics, on Monday, scientists revealed the oldest genome of a pathogen ever sequenced, revealing, among other things, that descendents of the germ that caused one of history’s most dangerous plagues could give rise to brand new pandemics today. Led by geneticists from McMaster University, the team sequenced the DNA of bacteria extracted from the teeth of two 1,500-year-old plague victims.

Buried in a Bavarian cemetery, the victims died during the Plague of Justinian, which killed about half of Europe’s population between the 5th and 8th centuries and is sometimes described as the last nail in the coffin of the Roman Empire. The researchers were surprised to find the genome of the Justinian germ was markedly different from that of the previously sequenced Black Death plague, which killed 200 million people in the 14th century.

Because the fact is both outbreaks were caused by the same bacterium, known as Yersinia pestis. The strain that caused the Justinian plague seems to have gone extinct, the researchers report, but descendents of the Black Death strain are still around today with thousands of infections reported every year. So, the discovery of this new flavor of plague suggests that other as-yet-unknown strains could have been what caused many of history’s ancient pandemics, like the Antonine Plague that struck Rome in the 200s, or even the more devastating Plague of Athens in the 5th century BCE.

It also means that another human-infecting strain could be coming into being right now. The fact is, even though we’ve spent thousands of years with this particular germ, we know very little about the rate of genetic change in Y. pestis, so we don’t know how quickly that could happen. Nor we do know exactly why the Justinian strain died out. Some biologists think it might have been eradicated by the cooling climate, which proved inhospitable to the warm-loving bacterium.

So, be sure to share these fun facts at your Super Bowl party. They go great with nachos.

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