According to legend, if the groundhog sees his shadow on February 2nd, there will be six more weeks of winter; if not, an early spring is predicted.

Of course groundhogs – also known as woodchucks – don’t emerge at this time just to be furry weather predictors. So what’s the real reason? Research into groundhog biology shows they have other priorities in early February than mingling with the people of Punxsutawney, Pennsylvania.

It’s Groundhog Day!

Groundhog Day appears to have European roots. Early February is midway between the winter solstice and the spring equinox, and throughout history this seasonal crossroads has been celebrated. The ancient Greeks and Romans observed a mid-season festival on February 5th in anticipation of spring. In the Celtic tradition, this period was celebrated as the festival of Imbolog to mark the beginning of spring. Early Christians in Europe embraced this tradition and celebrated Candlemas Day on February 2nd, to commemorate the purification of the Virgin Mary. Customarily on this day, clergy would bless candles and distribute them to the people in the dark of winter in anticipation of spring.

In northern Europe, farmers needed some indication when to start spring planting. They looked for the emergence of hibernators, such as the hedgehog or badger, to signal the coming of spring. Since their emergence occurred in early February, it was believed that if Candlemas Day was sunny, and the hibernator saw its shadow, more wintry weather was ahead. But if it rained or snowed on Candlemas Day, the rest of the winter would be mild.

This tradition was brought to America by the Germans who migrated to eastern Pennsylvania. They found groundhogs in profusion in many parts of the state and decided this mammal was a perfect replacement for the hibernators they’d left behind in Europe. Thus, the tradition continued in America.

Hibernation helps survival

In my study area in southeastern Pennsylvania, the average date groundhogs emerge from their burrows is February 4. This fits the folklore and the timing of Groundhog Day. However, predicting the weather is not their objective.

The real reason is related to Darwinian fitness – a measure of an organism’s ability to contribute its genes to the next generation. The process defines natural selection and is based on an organism’s ability to survive and to reproduce successfully. High Darwinian fitness suggests an individual will pass on its genes to many healthy offspring.

Hibernation contributes to Darwinian fitness value. It enhances survival by saving energy during times of limited food availability. The ability to hibernate is found in several mammalian groups, including all marmots, many species of ground squirrels, chipmunks, hamsters, badgers, lemurs, bats and even some marsupials and echidnas. Curled up in their burrows, they pass the winter months, when food would be hard to come by.

Hibernation: alternating torpor and arousal

Hibernation is characterized by a significant drop in body temperature and metabolic function. This process is commonly called torpor. During torpor, body functions including heart rate, breathing rate, and brain activity are reduced. The overall benefit for the animal is saving metabolic energy at a time when it isn’t eating.

However, for some still unexplained reason, hibernators arouse periodically during their hibernating season. These arousals come at a great energy cost. Therefore, arousing must be critical to survival in some way or animals wouldn’t waste the energy on it. Some possibilities include maintaining cellular functions or disposing of bodily wastes.

In Pennsylvania, these bouts of torpor and arousal continue throughout the hibernation season, starting on average in mid-November and ending by the beginning of March; a total of about 110 days. In one study, an average of 15 bouts of torpor occurred during this period, with arousals in between. Groundhogs aroused for about 41 hours and then returned to torpor for about 128 hours for males and 153 hours for females.

In a 2010 study, we determined that the hibernation periods for groundhogs increase in length with increasing latitude. The hibernation period matches winter’s duration. The celebration of Groundhog Day would need to change by latitude in order to perfectly match groundhog emergence.

It all boils down to sex

One of the drawbacks of hibernation is the reduced time available for reproduction. Thus, hibernators have developed mating strategies to maximize reproductive success. Groundhog mating strategies involve temporary emergence in early February, mating in early March during during their final arousal, and giving birth in early April. This behavior enhances reproductive success because young are born as early as possible (but not too early) and are able to start feeding in May when lots of food is available. That way they have enough time to gain sufficient weight to survive their first winter hibernation.

But why do groundhogs emerge in February, when mating won’t occur until next month? The answer lies in their social structure. Most of the year, male and female groundhogs are solitary and antagonistic against each other. They aggressively maintain a feeding territory around their burrows and rarely have any contact with each other. February is used to reestablish the bonds necessary for mating and ensures that mating can then proceed without delay in early March.

So for the animals themselves, Groundhog Day is more like Valentine’s Day. On February 2nd, groundhogs don’t emerge to predict the weather, but to predict whether their own mating season will be a success!

Stam Zervanos, Emeritus Professor of Biology, Pennsylvania State University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Suppose you were told that there is something responsible for nearly 1 of every 5 deaths of Americans, and that it is completely avoidable. Would you believe – today – that “something” is cigarette smoking?

If you’re a college graduate, you might not believe it. You don’t smoke. Your friends and colleagues don’t smoke. You never see smoke in your workplace, nor in the restaurants and bars you frequent. Like many of the nation’s most educated citizens, you may well regard the problem of smoking as largely solved. Because the educated population is also the most politically engaged, cigarette smoking has virtually disappeared from the nation’s health policy agenda.

I’m not a smoker, although like many of you I was one (45 years ago, in my case). As a student of tobacco policy for over 40 years, I have helped to document the remarkable progress we have made against smoking. But I also appreciate why smoking remains our nation’s most avoidable cause of disability and premature death. The lack of policy attention to smoking is a public health tragedy.

The good news and the bad news

No one can deny the extraordinary victories against smoking. Since the 1964 Surgeon General’s report on smoking and health, adult smoking prevalence has dropped by two-thirds, from 43 percent to 14 percent.

The decrease among young people has been even more substantial. For example, since smoking peaked among high school seniors 20 years ago, smoking prevalence in the past 30 days has plummeted by nearly 80 percent.

Prompted by tobacco control initiatives, Americans’ decisions to quit smoking and not to start in the first place avoided 8 million premature deaths from 1964 to 2012. The Centers for Disease Control and Prevention considers tobacco control one of the 10 greatest public health achievements of the 20th century and of the first decade of the 21st.

That’s the good news. The bad news is that 1 of every 7 adults still smokes. And smoking kills nearly 500,000 Americans every year. That number exceeds – by a lot – the sum total of all deaths caused by the opioids and other drugs, alcohol, motor vehicle injuries, homicide, suicide, HIV/AIDS and fires.

Who smokes now? The role of education

What accounts for the divergence between common perceptions about smoking and the dismal reality? In large part it is remarkable changes in who is smoking. Increasingly, today’s smokers are those with lower education, lower income and - importantly - a higher incidence of mental illness.

Consider this: In 1966, the smoking rate of Americans who hadn’t graduated high school was just 20 percent greater than that of college grads. By 2017, in contrast, the smoking prevalence of the least educated was nearly four times greater than that of the most educated.

Smoking has declined substantially at both ends of the education spectrum but to a much higher degree among college graduates: by half among Americans lacking a high school degree, but by 85 percent among college graduates.

For college grads, the rate of smoking in 2017 was vanishingly small. For those without a high school degree, and indeed for high school grads too, fully 1 out of 5 remain smokers. The difference matters. Research attributes a fifth to a third of a large education-related gap in life expectancy to differences in smoking.

Money matters

A similar pattern of smoking holds with respect to income classes, themselves highly correlated with educational attainment. According to the latest data, Americans who live below the federal poverty level were three times more likely to smoke than Americans with incomes at least 400 percent above the federal poverty level. The gap has widened since the early 1990s.

There is an enormous difference in life expectancies between the nation’s richest and poorest citizens. Smoking is again a significant factor in this disparity.

Mental health does, too

An enormously important factor in smoking today is that the smoking prevalence of people suffering from serious mental illness is more than double that of the population not so afflicted (28 percent and 13 percent, respectively, in 2014). People with mental health problems or substance use disorders constitute a quarter of the U.S. population but consume 40 percent of all cigarettes smoked. They have more difficulty quitting smoking.

Rates differ by mental illness condition. In 2007, nearly 60 percent of schizophrenics smoked. That was three times the rate of the general population. Smokers with serious psychological distress (SPD) lose 15 years of life expectancy. Nonsmoking victims of SPD lose five years. Research has thus attributed up to two-thirds of the life expectancy reduction of SPD victims who smoke to their consumption of cigarettes.

Sexual orientation, race and ethnicity

Smoking also disproportionately afflicts members of the LGBT community. Among racial/ethnic groups, American Indians and Alaskan Natives had the highest smoking rates in 2016, while Asian Americans and Pacific Islanders had the lowest.

In general, women have substantially lower smoking rates than men. The exceptions are American Indians/Alaska Natives, among whom women have slightly higher smoking prevalence than men, and non-Hispanic whites, among whom men smoke at slightly higher rates.

Marginalized smokers

As these data indicate, the principal victims of smoking are members of marginalized populations. Despite the enormous continuing importance of smoking in U.S. health, the issue is submerged. Smoking no longer afflicts the nation’s most economically advantaged population, and those it does burden lack an effective voice in the nation’s political life.

Besides, smokers tend to blame themselves for the behavior.

In point of fact, smoking is a tenacious addiction, one that the vast majority of smokers acquired in their youth. They were assisted in so doing by an avaricious tobacco industry that marketed aggressively to young people. Kids have been referred to as “replacement smokers,” the new smokers needed to replenish the industry’s customer base as its most loyal customers succumb to smoking-produced diseases.

Restoring tobacco control to the nation’s public health agenda

What can be done? The simple – and incomplete – answer is “more of the same.” Public education has contributed to decreased smoking, as have policy interventions: cigarette taxation, smoke-free workplace laws, prohibitions on product advertising and promotion, and media anti-smoking campaigns. Evidence-based smoking cessation treatments can help as well. Interventions increasingly need to be targeted to specific high-risk groups.

These evidence-based measures are unlikely to be enough, however. A potentially complementary tool may lie in a highly controversial recent development: the emergence of e-cigarettes. Novel reduced-risk nicotine delivery products like e-cigarettes may serve as alternatives to smoking, especially for those smokers otherwise incapable of quitting cigarettes.

Vaping may hold the potential to help significant numbers of Americans to quit smoking. The risks of vaping are clearly substantially less than those of smoking. At the same time, however, there are concerns about the attraction of e-cigarettes to young people and uncertainty about the health effects of long-term vaping.

While the ultimate impacts of e-cigarettes and other novel non-combusted tobacco products remain to be seen, there is widespread agreement that it is the burning of tobacco – primarily in the form of cigarette smoking, with its 7,000 chemicals – that is by far the most deadly method of consuming tobacco.

The enormous successes of tobacco control notwithstanding, smoking remains Public Health Enemy No. 1. Today, the burden of smoking falls primarily on marginalized populations – the poor, the poorly educated, and those suffering from mental health problems. A compassionate public would renew the battle against smoking with a vigor not seen in decades.

Kenneth E. Warner, Professor Emeritus of Public Health, University of Michigan

This article is republished from The Conversation under a Creative Commons license. Read the original article.