Fast-Moving Predator

A. There’s nothing about the Opah that says “fast-moving predator”. Tuna, sharks, and swordfish are fast-moving predators and accordingly, their bodies look like streamlined torpedoes. By contrast, the Opah looks like a big startled frisbee, with thin red fins stuck on as an afterthought.

It’s pretty (silver body and red fins) and big (up to two metres long), but fast? Nicholas Wegner, from the National Oceanic and Atmospheric Administration, certainly didn’t think so when he first started studying it. Since then, he has discovered that the Opah is an active predator, which has a trait that no other fish possesses. It is warm-blooded.

B. Most fish have body temperatures that match the surrounding water. A small number of them can warm specific parts of their bodies. Swordfish, Marlins, and Sailfish, can temporarily heat their eyes and brains, sharpening their vision when pursuing prey. Tuna and some sharks, including the Mako and Great White, can do the same with their swimming muscles, going into turbo mode when they need to. But none of these animals can heat their entire bodies. Their hearts and other vital organs stay at ambient temperature, so while they can hunt in deep, cold waters, they must regularly return to the surface to warm their innards.

The Opah has no such problem. It can consistently keep its entire body around 5 degrees Celsius warmer than its environment. It doesn’t burn as hot as a bird or mammal, but it certainly outperforms its other relatives.

C. Wegner discovered its ability by accident. His team just happened to catch more Opah during one of their research trips, and they used the opportunity to learn more about this little-known species. As they dissected the animals, Wegner immediately noticed that its gills contain a beautiful and intricate tangle of red and blue blood vessels. “That was when we realised what it was capable of,” he says. Wegner had seen blood vessels like those before. They’re called "retia mirabilia" Latin for “wonderful nets”—and they’re the secret behind the heating systems of Tuna and Shark.

D. All animal muscles produce heat when they contract, but in most fish, that heat is almost immediately lost to the environment through the skin or the gills. The gills are especially problematic. No matter how much insulation a fish has, the blood that runs through the gills has to make close contact with the seawater. A Tuna can produce as much heat as it likes in its swimming muscles, but as soon as the blood from those muscles reaches the gills, as it must do to be reloaded with oxygen, it ought to quickly cool. But it doesn’t, because of these wonderful nets.

In those nets, the veins that carry warm blood away from the hot muscles are interwoven with the arteries that carry cold blood in from the gills. They run so close that the veins offload their heat onto the arteries before it can reach the gills and disappear. Through these “countercurrent exchangers”, the tuna can retain whatever heat it generates. But since its "retia mirabilia" are located in its swimming muscles, those are the only body parts that stay warm. That’s why its heart still runs cold.

E. The Opah’s wonderful nets are in its gills, and that makes all the difference. The blood vessels carrying warm blood from the heart to gills flows next to those carrying cold blood from the gills to the rest of the body, warming them up. So, while a tuna or shark might isolate its warm muscles from the rest of its cold body, the Opah flips this arrangement. It isolates the cold bits—the gills—from everything else. This allows its huge pectoral muscles, which generate most of its heat, to continuously warm the rest of its body. It also keeps that heat with the help of thick layers of fat, which insulate the heart from the gills, and the pectoral muscles (which produce most of the animal’s heat) from the surrounding water.

F. Wegner’s team confirmed this by catching Opah, implanting them with small thermometers, and then releasing them. The instruments inside the fish recorded consistently higher temperatures than those dropped into the surrounding water. The Opah’s brain is warm. Its muscles are warm. And perhaps most importantly, its heart is warm—a first for a fish. Not even a Great White Shark has a warm heart. “That’s why Opah can stay at depth,” says Wegner. “These guys are specialised for living deeper than those other predators.”

G. So, it’s fast, then? Despite the somewhat comical physique? “That’s what’s really blew my mind about this discovery,” says Wegner. “Just from looking at it, I really thought it was a slow, sluggish, deep-water fish that doesn’t do very much. But all indications are that this is a very fast fish and an active predator.

A world without retirement

We are entering the age of no retirement. The journey into that chilling reality is not a long one: the first generation who will experience it are now in their 40s and 50s. They grew up assuming they could expect the kind of retirement their parents enjoyed – stopping work in their mid-60s on a generous income, with time and good health enough to fulfil long-held dreams. For them, it may already be too late to make the changes necessary to retire at all.

In 2010, British women got their state pension at 60 and men got theirs at 65. By October 2020, both sexes will have to wait until they are 66. By 2028, the age will rise again, to 67. And the creep will continue. By the early 2060s, people will still be working in their 70s, but according to research, we will all need to keep working into our 80s if we want to enjoy the same standard of retirement as our parents.

This is what a world without retirement looks like. Workers will be unable to down tools, even when they can barely hold them with hands gnarled by age-related arthritis. The raising of the state retirement age will create a new social inequality. Those living in areas in which the average life expectancy is lower than the state retirement age; south-east England for instance has the highest average life expectancy, whereas Scotland the lowest; will subsidise those better off by dying before they can claim the pension they have contributed to throughout their lives. In other words, wealthier people become beneficiaries of what remains of the welfare state.

Retirement is likely to be sustained in recognisable form in the short and medium term. Looming on the horizon, however, is a complete dismantling of this safety net.

For those of pensionable age who cannot afford to retire, but cannot continue working – because of poor health, or ageing parents who need care, or because potential employers would rather hire younger workers – the great progress Britain has made in tackling poverty among the elderly over the last two decades will be reversed. This group is liable to suffer the sort of widespread poverty not seen in Britain for 30 to 40 years.

Many now in their 20s will be unable to save throughout their youth and middle age because of increasingly casualised employment, student debt and rising property prices. By the time they are old, members of this new generation of poor pensioners are liable to be, on average, far worse off than the average poor pensioner today. A series of factors has contributed to this situation: increased life expectancy, woeful pension planning by successive governments, the end of the final-salary pension scheme (in which people got two-thirds of their final salary as a pension) and our own failure to save.

It is not news that the population is ageing. What is remarkable is that we have failed to prepare the ground for this inevitable change. Life expectancy in Britain is growing by a dramatic five hours a day. Thanks to a period of relative peace in the UK, low infant mortality and continual medical advances, over the past two decades the life expectancy of babies born here has increased by some five years.

In 2014, the average age of the UK population exceeded 40 for the first time – up from 33.9 in 1974. In little more than a decade, half of the country’s population will be aged over 50. This will transform Britain – and it is no mere blip; the trend will continue as life expectancy increases. 2015 marked a demographic turning point in the UK. As the baby-boom generation (now aged between 53 and 71) entered retirement, for the first time since the early 1980s there were more people either too old or too young to work than there were of working age. The number of people in the UK aged 85 or more is expected to more than double in the next 25 years. By 2040, nearly one in seven Britons will be over 75. Half of all children born in the UK are predicted to live to 103. Some 10 million of us currently alive in the UK (and 130 million throughout Europe) are likely to live past the age of 100.

The challenges are considerable. The tax imbalance that comes with an ageing population, whose tax contribution falls far short of their use of services, will rise to £15bn a year by 2060. Covering this gap will cost the equivalent of a 4p income tax rise for the working-age population.

It is easy to see why governments might regard raising the state retirement age as a way to cover the cost of an ageing population. A successful pursuit of full employment of people into their late 60s could maintain the ratio of workers to non-workers for many decades to come. And were the employment rate for older workers to match that of the 30-40 age group, the additional tax payments could be as much as £88.4bn. According to PwC’s Golden Age Index, had our employment rates for those aged 55 years and older been as high as those in Sweden between 2003 and 2013, UK national GDP would have been £105bn – or 5.8% – higher.

There are, of course, problems to this approach. Those who can happily work into their 70s and beyond are likely to be the privileged few: the highly educated elite who haven’t spent their working lives in jobs that negatively affect their health. If the state pension age is pushed further away, for those with failing health, family responsibilities or no jobs, life will become very difficult.

The Surgeon General’s Report

Not long ago the idea of repairing the brain’s wiring to fight addiction would have seemed far-fetched. But advances in neuroscience have upended conventional notions about addiction—what it is, what can trigger it, and why quitting is so tough. If you’d opened a medical textbook 30 years ago, you would have read that addiction means dependence on a substance with increasing tolerance, requiring more and more to feel the effects and producing a nasty withdrawal when use stops. That explained alcohol, nicotine, and heroin reasonably well. But it did not account for marijuana and cocaine, which typically don’t cause the shakes, nausea, and vomiting of heroin withdrawal.

The old model also didn’t explain perhaps the most insidious aspect of addiction: relapse. Why do people long for the burn of whiskey in the throat or the warm bliss of heroin after the body is no longer physically dependent?

The surgeon general’s report reaffirms what the scientific establishment has been saying for years: Addiction is a disease, not a moral failing. It’s characterized not necessarily by physical dependence or withdrawal but by compulsive repetition of an activity despite life-damaging consequences. This view has led many scientists to accept the once heretical idea that addiction is possible without drugs.

The most recent revision of the Diagnostic and Statistical Manual of Mental Disorders, the handbook of American psychiatry, for the first time recognizes a behavioral addiction: gambling. Some scientists believe that many allures of modern life—junk food, shopping, smartphones—are potentially addictive because of their powerful effects on the brain’s reward system, the circuitry underlying craving.

For years Childress and other scientists have tried to unravel the mysteries of addiction by studying the reward system. Much of Childress’s research involves sliding people addicted to drugs into the tube of a magnetic resonance imaging (MRI) machine, which tracks blood flow in the brain as a way to analyze neural activity. Through complex algorithms and color-coding, brain scans are converted into images that pinpoint the circuits that kick into high gear when the brain lusts.

Childress, who has flaming red hair and a big laugh, sits at her computer, scrolling through a picture gallery of brains—gray ovals with bursts of color as vivid as a Disney movie. “It sounds nerdy, but I could look at these images for hours, and I do,” she says. “They are little gifts. To think you can actually visualize a brain state that’s so powerful and at the same time so dangerous. It’s like reading tea leaves. All we see is spots that the computer turns into fuchsia and purple and green. But what are they trying to tell us?”

The reward system, a primitive part of the brain that isn’t much different in rats, exists to ensure we seek what we need, and it alerts us to the sights, sounds, and scents that point us there. It operates in the realm of instinct and reflex, built for when survival depended on the ability to obtain food and sex before the competition got to them. But the system can trip us up in a world with 24/7 opportunities to fulfill our desires.

Desire depends on a complex cascade of brain actions, but scientists believe that the trigger for this is likely to be a spike in the neurotransmitter dopamine. A chemical messenger that carries signals across synapses, dopamine plays wide-ranging roles in the brain. Most relevant to addiction, the flow of dopamine heightens what scientists call salience, or the motivational pull of a stimulus—cocaine, for instance, or reminders of it, such as a glimpse of white powder. Each drug that’s abused affects brain chemistry in a distinct way, but they all send dopamine levels soaring far beyond the natural range.

How powerfully? Consider the strange side effect of medications that mimic natural dopamine and are used to treat Parkinson’s. The disease destroys dopamine-producing cells, primarily affecting movement. Dopamine-replacement drugs relieve the symptoms, but about 14 percent of Parkinson’s patients who take these medications develop addictions to gambling, shopping, pornography, eating, or the medication itself. A report in the journal Movement Disorders describes three patients who became consumed by “reckless generosity,” hooked on giving cash to strangers and friends they thought needed it.

Through learning, the signals or reminder cues for rewards come to provoke surges of dopamine. That’s why the aroma of snickerdoodles baking in the oven, the ping of a text alert, or chatter spilling out the open door of a bar can yank a person’s attention and trigger craving. Childress has shown that people who are addicted don’t have to consciously register a cue for it to arouse their reward system. In a study published in PLoS One she scanned the brains of 22 recovering cocaine addicts while photos of crack pipes and other drug paraphernalia flashed before their eyes for 33 milliseconds, one-tenth the time it takes to blink. The men didn’t consciously “see” anything, but the images activated the same parts of the reward circuitry that visible drug cues excite.