Tag Archives: Biomedical/Ethics

The Real Lesson of Sweden’s Laissez-Faire COVID-19 Response

Post Syndicated from Afzal S. Siddiqui original https://spectrum.ieee.org/tech-talk/biomedical/ethics/swedens-actual-covid-policy-herd-immunity

This is a guest post. The views expressed here are solely those of the author and do not represent positions of IEEE Spectrum or the IEEE.

The COVID-19 pandemic, now in its second year, has prompted a great deal of debate and reflection on the tension between personal civil liberties and the collective good. A surprising amount of this soul searching has offered up Sweden as either a shining example or a cautionary tale, depending on the viewpoint of the onlooker. 

In Europe, America, and elsewhere, politicians ostensibly arguing for individual liberty and economic growth have weighed in against mandates on business restrictions and the wearing of masks. Some scientists have also joined the fray. For example, Scott Atlas (former advisor on the White House Coronavirus Task Force) and Sunetra Gupta (co-author of the Great Barrington Declaration) favor looser measures in order to preserve civil liberties and to attain herd immunity as a byproduct. 

Sweden figures in all this because of its largely voluntary approach to quarantining and social distancing. Indeed, for much of 2020, Sweden’s strategy was spearheaded not by politicians but by a health official, Anders Tegnell, the state epidemiologist at the Public Health Agency of Sweden. In advocating for a light-touch approach, Tegnell noted in September 2020 that controlled spread of the virus over the population should provide Sweden with greater protection in the second wave vis-à-vis its Nordic neighbors, who opted for conventional strategies. Thus, the cost of a high death rate in the first wave would be more than offset by the benefit of a low death rate in the second wave. 

So, has this hypothesis been upheld? Were the voices championing individual liberties correct all along?

No. If they had been correct, then during the second half of 2020, excess mortality in Sweden—from all causes and not just COVID-19—should have ticked lower in comparison to that of the other Nordic countries. In fact, no such thing happened.

During weeks 46 to 52 of 2020, Sweden’s standardized excess mortality rates were persistently above the “normal range” (Figure 1, above). By contrast, all of Sweden’s Nordic neighbors combined had just three instances of excess mortality outside the “normal range” during weeks 36 to 52. In terms of actual COVID-19 deaths per million inhabitants, Sweden has done no better than the U.K. and the U.S. for much of the so-called second wave (Figure 2, below). Hence, the data for the final few months of 2020 contradict the individualists’ case.

Faced with such sobering statistics, champions of a hands-off approach should respond with humility. Yet, instead of adapting their hypothesis to fit the facts, they twist the numbers in order to suit their beliefs.

For example, Tegnell claimed in December 2020 that Sweden’s immigrants have been “driving” its higher death rate. However, on a national TV appearance, Tegnell provided no evidence to back up this statement. Others, too, have misleadingly cited Sweden’s relatively high percentage of foreign-born residents to make a case that Sweden did not fare too badly if you take into account the fact that the country has a higher proportion of more-vulnerable people than its immediate neighbors. In making this argument, though, some cited figures as high as 25 percent for Sweden’s foreign-born population. But, this 25 percent estimate includes not only the foreign born but also people born in Sweden to two foreign-born parents. In fact, just 13.9 percent of the Swedish population is born outside the EU, EEA, and U.K., according to Eurostat. This is a critical distinction because only immigrants from low-and-medium-income countries tend to have the kinds of jobs and lifestyles that make them more vulnerable to infection.

Furthermore, consider the Norrland region in northern Sweden. Immigrants from outside the EU/EEA/U.K. constitute 8.2 percent of its population, not far off the 6.6 percent share seen in the neighboring Nordic countries. Yet as of 29 November, Norrland had a COVID-19 death rate that was 4.8 times higher than the average in those Nordic countries. During the so-called second wave (weeks 45 to 48), the discrepancy was starker still: Norrland’s COVID-19 death rate then was over six times as high as the neighboring Nordic countries’ average. All of which suggests that policy—not demographics—explains the outcome.

Some on the right have long trotted out Sweden as a job-killing, high-tax nanny state. Although there was scant empirical evidence for such a caricature, it conveniently suited a particular worldview. Now, during the COVID-19 pandemic, some civil libertarians and others have serendipitously found Sweden’s laissez-faire public-health strategy amenable to their ideology and rushed to embrace it while again brushing aside other facts.

If these people insist on using Sweden as an exemplar when debating governance, then may I suggest that they take a look at the country’s environmental policy? At €110 per metric ton of COemitted, Sweden’s carbon tax is the highest in the world. More important, there is empirical evidence that the carbon tax has, indeed, reduced CO2 emissions from transportation. In this domain, Swedish authorities have long acknowledged the obvious: that laws and regulations do affect human behavior. They further recognize that polite entreaties to firms and households to curb CO2 emissions would not work. The reason for this ineffectiveness is that the cost that an individual consumer incurs for using fossil fuel is lower than the cost that society bears.

If you want people to behave in a way that reflects the full cost of their actions to society, then you must change incentives. This is true whether you are dealing with environmental policy or with a public-health crisis. In a world where data are widely available, evidence-based best practices and not ideology should inform public policy. Framing the discourse in any other way is disingenuous at best and a willful obfuscation at worst.

The author is a professor in the Department of Computer and Systems Sciences, Stockholm University, Sweden, and an Adjunct Professor in the Department of Mathematics and Systems Analysis, Aalto University, Finland.

This article was edited on 1 March, 2021, to more clearly describe Swedish immigration statistics and competing theories about their effect on COVID-19 infection rates.

Don’t be Too Quick to Judge Sweden’s Covid-19 Policy

Post Syndicated from Vaclav Smil original https://spectrum.ieee.org/biomedical/ethics/dont-be-too-quick-to-judge-swedens-covid19-policy

In 2008, I concluded that the next major pandemic would arrive before 2021. The very year after this forecast saw a minor event—involving the H1N1 influenza virus—but the 2019 pandemic obviously qualifies as a major global outbreak.

This was no remarkable feat of forecasting, just a simple recognition that pandemics reappear rather frequently. A regrettable corollary is that we remain repeatedly unprepared for their spread and that we mismanage our responses on truly grand scales. But this does not prevent people from making simplistic judgments.

Sweden’s response to the COVID-19 virus is a perfect example of this habit. The response has not been decided by politicians, it has not involved major adjustments, and all key decisions have been left to the state epidemiologist, Anders Tegnell, who has relied on appealing to his compatriots to behave responsibly.

Even in Sweden, his approach has not remained unchallenged, but abroad it has elicited two remarkably divergent criticisms. Some say, “They did not resort to any panicky lockdowns, and they are none the worse for it,” while others say, “They did not lock down anything, and the consequences have been catastrophic.” Neither statement is true, but even an interim appraisal, made in November 2020, shows an outcome that is as singular as it is a part of a larger piece.

To begin with, Sweden shut down high schools and universities, but not grade schools and kindergartens; it restricted very large gatherings, allowed restaurants, shops, and services to remain open, while leaving to the individual the responsibility of limiting smaller gatherings. The early consequence of these decisions seemed severe: Excess mortality began to rise steeply in late March, and in April it reached levels far higher than in any of the country’s immediate Nordic neighbors. But by midsummer, cumulative mortalities divided by the size of the population were considerably lower in Sweden than in several populous European nations. By the middle of November, cumulative death rates were twice as high in Belgium, 45 percent higher in Spain, 25 percent higher in the United States, United Kingdom, and Italy (the country with extensive restrictive lockdowns) and 12 percent higher in France. On the other hand, the mortality rate in Finland and ­Norway was only about 10 percent that of Sweden, and Denmark’s rate was about 80 percent lower.

There is no doubt that Sweden’s numbers were inflated, in part, by the relatively high share in its population of the foreign born (who are more vulnerable to infection)—a quarter of the people are immigrants, and nearly a third have at least one parent born abroad. Similarly, comparisons of excess all-cause mortality (a rate that is better able to capture the actual death toll attributable to the pandemic) show that in October 2020 the Swedish rate was marginally lower than in France, 30 percent lower than in the United States, only half as high as in Spain—but 2.5 times higher than in Finland and five times higher than in Germany.

EuroMOMO, which monitors mortality, shows Swedish deaths rising substantially above normal from the 13th to the 21st week of 2020, returning within normal range by the 27th week, and steadily declining afterward to below the normally expected rate by the 40th week of 2020. By the 45th week, Swedish mortality remained well below the expected level and even below the Norwegian rate.

Meanwhile France, Italy, Spain and Belgium had, once again, high excess mortalities, and only the Finnish mortality was well below the Swedish rate. The final verdict about Sweden’s relative success or indefensible failure is still many months in coming.

Obviously, you can use these comparisons to portray Sweden as either a success (vis-à-vis Spain, the U.K., or the United States) or a failure (vis-à-vis Germany or Finland). But we will have to wait until the second wave of the pandemic has fully asserted itself to see how such comparisons will fare.

This article appears in the January 2021 print issue as “Sweden’s COVID Response.”

DNA Databases in the U.S. and China Are Tools of Racial Oppression

Post Syndicated from Thor Benson original https://spectrum.ieee.org/tech-talk/biomedical/ethics/dna-databases-in-china-and-the-us-are-tools-of-racial-oppression

Two major world powers, the United States and China, have both collected an enormous number of DNA samples from their citizens, the premise being that these samples will help solve crimes that might have otherwise gone unsolved. While DNA evidence can often be crucial when it comes to determining who committed a crime, researchers argue these DNA databases also pose a major threat to human rights.

In the U.S., the Federal Bureau of Investigation (FBI) has a DNA database called the Combined DNA Index System (CODIS) that currently contains over 14 million DNA profiles. This database has a disproportionately high number of profiles of black men, because black Americans are arrested five times as much as white Americans. You don’t even have to be convicted of a crime for law enforcement to take and store your DNA; you simply have to have been arrested as a suspect.

Bradley Malin, co-director of the Center for Genetic Privacy and Identity in Community Settings at Vanderbilt University, tells IEEE that there are many issues that can arise from this database largely being composed of DNA profiles taken from people of color.

“I wouldn’t say that they are only collecting information on minorities, but when you have a skew towards the collection of information from these communities, when you solve a crime or you think you have solved a crime, then it is going to be a disproportionate number of people from the minority groups that are going to end up being implicated,” Malin says. “It’s a non-random collection of data, as an artifact, so that’s a problem. There’s clearly skew with respect to the information that they have.”

Some of the DNA in the FBI’s database is now being collected by immigration agencies that are collecting samples from undocumented immigrants at the border. Not only are we collecting a disproportionate amount of DNA from black Americans who have been arrested, we’re collecting it from immigrants who are detained while trying to come to America. Malin says this further skews the database and could cause serious problems.

“If you combine the information you’re getting on immigrant populations coming into the United States with information that the FBI already holds on minority populations, who’s being left out here? You’ve got big holes in terms of a lack of white, caucasian people within this country,” Malin says. “In the event that you have people who are suspected of a crime, the databases are going to be all about the immigrant, black, and Hispanic populations.”

Malin says immigration agencies are often separating families based on DNA because they will say someone is not part of a family if their DNA doesn’t match. That can mean people who have been adopted or live with a family will be separated from them.

Aside from the clear threat to privacy these databases represent, one of the problems with them is that they can contain contaminated samples, or samples can become contaminated, which can lead law enforcement to make wrongful arrests. Another problem is law enforcement can end up collecting DNA that is a near match to DNA contained in the database and end up harassing people they believe to be related to a criminal in order to find their suspect. Malin says there’s also no guarantee that these DNA samples will not end up being used in controversial ways we have yet to even consider.

“One of the problems you run into is scope creep,” Malin says. “Just because the way the law is currently architected says that it shouldn’t be used for other purposes doesn’t mean that that won’t happen in the future.”

As for China, a report that was published by the Australian Strategic Policy Institute in mid-June claims that China is operating the “world’s largest police-run DNA database” as part of its powerful surveillance state. Chinese authorities have collected DNA samples from possibly as many as 70 million men since 2017, and the total database is believed to contain as many as 140 million profiles. The country hopes to collect DNA from all of its male citizens, as it argues men are most likely to commit crimes.

DNA is reportedly often collected during what are represented as free physicals, and it’s also being collected from children at schools. There are reports of Chinese citizens being threatened with punishment by government officials if they refuse to give a DNA sample. Much of the DNA that’s been collected has been from Uighur Muslims that have been oppressed by the Chinese government and infamously forced into concentration camps in the Xinjiang province.

“You have a country that has historically been known to persecute certain populations,” Malin says. “If you are not just going to persecute a population based on the extent to which they publicly say that they are a particular group, there is certainly a potential to subjugate them on a biological basis.”

James Leibold, a nonresident senior fellow at the Australian Strategic Policy Institute and one of the authors of the report on China’s DNA database, tells Spectrum that he is worried that China building up and utilizing this database could normalize this type of behavior.

“Global norms around genomic data are currently in a state of flux. China is the only country in the world conducting mass harvesting of DNA data outside a major criminal investigation,” Leibold says. “It’s the only forensic DNA database in the world to contain troves of samples from innocent civilians.”

Lebold says ethnic minorities like the Uighurs aren’t the only ones threatened by this mass DNA collection. He says the database could be used against dissidents and any other people who the government sees as a threat.

“With a full genomic map of its citizenry, Chinese authorities could track down those engaged in politically subversive acts (protestors, petitioners, etc.) or even those engaged in ‘abnormal’ or unacceptable behavior (religious groups, drug users, gamblers, prostitutes, etc.),” Leibold says. “We know the Chinese police have planted evidence in the past, and now it is conceivable that they could use planted DNA to convict ‘enemies of the state.’”

As Leibold points out, world powers like China and the U.S. have the ability to change norms in terms of what kind of behavior from a major government is considered acceptable. Thusly, there are many risks to allowing these countries to normalize massive DNA databases. As often happens, what at first seems like a simple law enforcement tool can quickly become a dangerous weapon against marginalized people.

Will Protests Increase the Spread of COVID-19?

Post Syndicated from Emily Waltz original https://spectrum.ieee.org/the-human-os/biomedical/ethics/will-protests-increase-spread-covid19-coronavirus

As thousands of individuals continue to gather in U.S. cities to protest racial injustice, computer scientists whose models predict the spread of COVID-19 are considering how these mass gatherings might affect the rate of disease transmission.

COVID-19 AI Challenge: How Are Lockdowns Affecting the Most Vulnerable?

Post Syndicated from Megan Scudellari original https://spectrum.ieee.org/the-human-os/biomedical/ethics/covid19-ai-challenge-how-are-lockdowns-affecting-the-most-vulnerable

In reaction to the rapid spread of COVID-19, over 100 countries worldwide have instituted lockdowns, restricting movement for billions of people. Those restrictions are having major effects, such as a global food crisis, on economically vulnerable populations.

Now, a group of 73 volunteer engineers, students, and policy experts are working to identify and quantify unintended consequences of the COVID-19 lockdown on vulnerable populations.

For two months, the group, organized by Palo Alto-based Omdena, will scour publicly available data sources and apply data visualization and AI tools to investigate how government policies are impacting four effects of the pandemic lockdowns: reduced access to healthcare, wage loss, employment loss, and domestic abuse.

“All over the world, from the media to state leaders, we are hearing a lot of noise and a lot of propaganda, amidst a lot of facts,” says Baidurja Ray, a computational scientist and engineer based in Texas who is participating in the effort. “I hope this project provides a purely factual and data-driven look into the effect of government policies on their citizens.”

Wine Is Going Out of Style—in France

Post Syndicated from Vaclav Smil original https://spectrum.ieee.org/biomedical/ethics/wine-is-going-out-of-stylein-france

France and wine—what an iconic link, and for centuries, how immutable! Wine was introduced by Greeks before the Romans conquered Gaul. Production greatly expanded during the Middle Ages, and since then the very names of the regions—Bordeaux, Bourgogne, Champagne—have become a symbol of quality everywhere. Thus has the French culture of wine long been a key signifier of national identity.

Statistics for French wine consumption begin in 1850 with a high mean of 121 liters per capita per year, which is nearly two glasses per day. By 1890, a Phylloxera infestation had cut the country’s grape harvest by nearly 70 percent from its 1875 peak, and French vineyards had to be reconstituted by grafting on resistant rootstocks from the United States. Although annual consumption of wine did fluctuate, rising imports prevented any steep decline in the total supply. Vineyard recovery brought the per capita consumption to a pre-World War I peak of 125 L in 1909, equaled again only in 1924. The all-time record of 136 L was set in 1926, after which the rate fell only slightly to 124 liters per capita in 1950.

Postwar, the French standard of living remained surprisingly low: According to the 1954 census, only 25 percent of homes had an indoor toilet. But rapidly rising incomes during the 1960s brought dietary shifts, notably a decline in wine drinking per capita. It fell to about 95 L in 1980, to 71 L in 1990, and then to 58 L in 2000—about half what it had been a century before. The latest available data shows the mean at just 40 L.

France’s wine consumption survey of 2015 shows deep gender and generational divides that explain the falling trend. Forty years ago, more than half of French adults drank wine nearly every day; now it’s just 16 percent, with 23 percent among men and only 11 percent among women. Among people over 65, the rate is 38 percent; for people 25 to 34 years of age, it is 5 percent, and for 15- to 24-year-olds, it’s only 1 percent. The same divides apply to all alcoholic drinks, as beer, liquors, and cider have also seen gradual consumption declines, while the beverages with the highest average per capita gains include mineral and spring water, roughly doubling since 1990, as well as fruit juices and carbonated soft drinks.

Alcoholic beverages are thus fast disappearing from French culture. And although no other traditional wine-drinking country has seen greater declines in absolute or relative terms, Italy comes close, and wine consumption has also decreased in Spain and Greece.

Only one upward trend persists: French exports of wine set a new record, at about €9.7 billion, in 2018. Premium prices and exports to the United States and China are the key factors. American drinkers have been the largest importers of French wines, and demand by newly rich Chinese has also claimed a growing share of sales. But in the country that gave the world countless vins ordinaires as well as exorbitantly priced Grand Crus Classés, the clinking of stemmed glasses and wishes of santé have become an endangered habit.

This article appears in the April 2020 print issue as “(Not) Drinking Wine.”

Halting COVID-19: The Benefits and Risks of Digital Contact Tracing

Post Syndicated from Emily Waltz original https://spectrum.ieee.org/the-human-os/biomedical/ethics/halting-covid19-benefits-risks-digital-contact-tracing

As COVID-19 sweeps through the planet, a number of researchers have advocated the use of digital contact tracing to reduce the spread of the disease. The controversial technique can be effective, but can have disastrous consequences if not implemented with proper privacy checks and encryption. 

Ramesh Raskar, an associate professor at MIT Media Lab, and his team have developed an app called Private Kit: Safe Paths that they say can do the job while protecting privacy. The software could get integrated into a new, official WHO app touted as the “Waze  for COVID-19.” IEEE Spectrum spoke with Raskar to better understand the risks and benefits of digital contact tracing. 

How Chicken Beat Beef in America

Post Syndicated from Vaclav Smil original https://spectrum.ieee.org/biomedical/ethics/how-chicken-beat-beef-in-america

For generations, beef was the United States’ dominant meat, followed by pork. When annual beef consumption peaked in 1976 at about 40 kilograms (boneless weight) per capita, it accounted for nearly half of all meat. Chicken had just a 20 percent share. But chicken caught up by 2010, and in 2018 chicken’s share came to 36 percent of the total, nearly 20 percentage points higher than beef. The average American now eats 30 kg of boneless chicken every year, bought overwhelmingly as cut-up or processed parts (from boneless breast to Chicken McNuggets).

The United States’ constant obsession with diet, in this case the fear of dietary cholesterol and saturated fat in red meat, has been a factor in the shift. The differences, however, are not ­striking: 100 grams of lean beef has 1.5 grams of saturated fat, compared with 1 gram in skinless chicken breast—which actually has more cholesterol. But the main reason for chicken’s ascendance has been its lower price, which reflects its metabolic advantage: No other domesticated land animal can convert feed to meat as efficiently as broilers. Modern breeding advances have had a lot to do with this efficiency.

During the 1930s, the average feeding efficiency for broilers (at about 5 units of feed per unit of live weight) was no better than for pigs. That rate was halved by the mid-1980s, and the latest U.S. Department of Agriculture’s feed-to-meat ratios show that it now takes only about 1.7 units of feed (standardized in terms of feed corn) to produce a unit of broiler live weight, compared with nearly 5 units of feed for hogs and almost 12 units for cattle.

Because edible weight as a share of live weight differs substantially among the leading meat species (about 60 percent for chicken, 53 percent for pork, and only about 40 percent for beef), recalculations in terms of feeding efficiencies per unit of edible meat are even more revealing. Recent ratios have been 3 to 4 units of feed per unit of edible meat for broilers, 9 to 10 for pork, and 20 to 30 for beef. These ratios correspond to average feed-to-meat conversion efficiencies of, respectively, 15, 10, and 4 percent.

In addition, broilers have been bred to mature faster and to put on an unprecedented amount of weight. Traditional free-running birds were slaughtered at the age of one year, when they weighed only about 1 kg. The average weight of American broilers rose from 1.1 kg in 1925 to nearly 2.7 kg in 2018, while the typical feeding span was cut from 112 days in 1925 to just 47 days in 2018.

Consumers benefit while the birds suffer. They gain weight so rapidly because they can eat as much as they want while being kept in darkness and in strict confinement. Because consumers prefer lean breast meat, the selection for excessively large breasts shifts the bird’s center of gravity forward, impairs its natural movement, and puts stress on its legs and heart. But the bird cannot move anyway: According to the National Chicken Council, a broiler is allotted just 560 to 650 square centimeters, an area only slightly larger than a sheet of standard A4 paper. As long periods of darkness improve growth, broilers mature under light intensities resembling twilight. This condition disrupts their normal circadian and behavioral rhythms.

On one side, you have shortened lives (less than seven weeks for a bird whose normal life span is up to eight years) with malformed bodies in dark confinement; on the other, in late 2019 you got retail prices of about US $2.94 per pound ($6.47 per kilogram) for boneless breast compared with $4.98/lb. for round beef roast and $8.22/lb. for choice sirloin steak.

But chicken’s rule hasn’t yet gone global: Thanks to its dominance in China and in Europe, pork is still about 10 percent ahead worldwide. Still, broilers mass-produced in confinement will, almost certainly, come out on top within a decade or two.

This article appears in the January 2020 print issue as “Why Chicken Rules.”

Racial Bias Found in Algorithms That Determine Health Care for Millions of Patients

Post Syndicated from Eliza Strickland original https://spectrum.ieee.org/the-human-os/biomedical/ethics/racial-bias-found-in-algorithms-that-determine-health-care-for-millions-of-patients

An algorithm that a major medical center used to identify patients for extra care has been shown to be racially biased. 

The algorithm screened patients for enrollment in an intensive care management program, which gave them access to a dedicated hotline for a nurse practitioner, help refilling prescriptions, and so forth. The screening was meant to identify those patients who would most benefit from the program. But the white patients flagged for enrollment had fewer chronic health conditions than the black patients who were flagged.

In other words, black patients had to reach a higher threshold of illness before they were considered for enrollment. Care was not actually going to those people who needed it most.

Alarmingly, the algorithm was performing its task correctly. The problem was with how the task was defined.

The findings, described in a paper that was just published in Science, point to a system-wide problem, says coauthor Ziad Obermeyer, a physician and researcher at the UC Berkeley School of Public Health. Similar screening tools are used throughout the country; according to industry estimates, these types of algorithms are making health decisions for 200 million people per year. 

Is Life Expectancy Finally Topping Out?

Post Syndicated from Vaclav Smil original https://spectrum.ieee.org/biomedical/ethics/is-life-expectancy-finally-topping-out

A slowing rate of improvement hints at a looming asymptote, at least on a population-wide basis

Ray Kurzweil, Google’s chief futurist, says that if you can just hang on until 2029, medical advances will start to “add one additional year, every year, to your life expectancy. By that I don’t mean life expectancy based on your birth date but rather your remaining life expectancy.” Curious readers can calculate what this trend would do to the growth of the global population, but I will limit myself here to a brief review of survival realities.

In 1850, the combined life expectancies of men and women stood at around 40 years in the United States, Canada, Japan and much of Europe. Since then the values have followed an impressive, almost perfectly linear increase that nearly doubled them, to almost 80 years. Women live longer in all societies, with the current maximum at just above 87 years in Japan.

The trend may well continue for a few decades, given that life expectancies of elderly people in affluent countries rose almost linearly from 1950 to 2000 at a combined rate of about 34 days per year. But absent fundamental discoveries that change the way we age, this trend to longer life must weaken and finally end. The long-term trajectory of Japanese female life expectancies—from 81.91 years in 1990 to 87.26 years in 2017—fits a symmetrical logistic curve that is already close to its asymptote of about 90 years. The trajectories for other affluent countries also show the approaching ceiling. Records available show two distinct periods of rising longevity: Faster linear gains (about 20 years in half a century) prevailed until 1950, followed by slower gains.

If we are still far from the limit to the human life-span, then the largest survival gains should be recorded among the oldest people. This was indeed the case for studies conducted in France, Japan, the United States, and the United Kingdom from the 1970s to the early 1990s. Since then, however, the gains have leveled off.

There may be no specific genetically programmed limit to life-span—much as there is no genetic program that limits us to a specific running speed. But life-span is a bodily characteristic that arises from the interaction of genes with the environment. Genes may themselves introduce biophysical limits, and so can environmental effects, such as smoking.

The world record life-span is the 122 years claimed for Jeanne Calment, a Frenchwoman who died in 1997. Strangely, after more than two decades, she still remains the oldest survivor ever, and by a substantial margin. (Indeed, the margin is so big as to be suspicious: Her age and even her identity are in question.) The second oldest supercentenarian died at 119, in 1999, and since that time there have been no survivors beyond the 117th year.

And if you think that you have a high chance to make it to 100 because some of your ancestors lived that long, you should know that the estimated heritability of life-span is modest, just between 15 and 30 percent. Given that people tend to marry others like themselves, a phenomenon known as assortative mating, the true heritability of human longevity is probably even lower than that.

Of course, as with all complex matters, there is always room for different interpretation of published statistical analyses. Kurzweil hopes that dietary interventions and other tricks will extend his own life until such time as major scientific advances can preserve him forever. It is true that there are ideas on how such preservation might be achieved, among them the rejuvenation of human cells by extending their telomeres, the nucleotide sequences at the ends of a chromosome that fray with age. If it works, maybe it can lift the realistic maximum well above 125 years.

But in 2019 the best advice I can give to all but a few remarkably precocious readers of these essays is to plan ahead—but not as far ahead as the 22nd century.

This article appears in the May 2019 print issue as “Life-Span and Life Expectancy.”