Nature’s Calling: How Long Should Humans Live?
Tyler Volk: Our closest primate relatives are the chimpanzees and gorillas, with the chimpanzees being closer to us genetically. They’re natural life spans are approximately half of ours. And that’s of some interest because the chimpanzees are a bit smaller than use in body mass and the gorillas are larger than us in body mass. We can’t know for sure the lifespan of the last common ancestor of humans and chimpanzees, but there would be some – you might guess that it would be half of what our current lifespan is.
Question: This is the natural lifespan?
Tyler Volk: Let’s make a distinction that we’re not talking about the infants dying – small children dying of diseases or death by predator, but the natural lifespan in normal, almost perfect circumstances. So looks throughout history, there’s always been people who have made it to age 80 or so, or longer, even though the average life expectance at birth, given all factors, given diseases, predators, and then the diseases of aging and senescence, even those have been more prevalent, the natural lifespan has been approximately the same as it is today. The maximum – the natural maximum lifespan, which is different from life expectancy at birth which can vary even in different countries today. Russia right now has a relatively low life expectancy, people in Africa have a relatively low life expectancy, Japan has the highest life expectancy of any nation now. So, there’s variations, but take those individuals into relatively equal healthy environments and they’re all going to live close to the same age.
Question: And this natural life expectancy has not gone up?
Tyler Volk: Right. The natural life expectancy has not gone up very much. However, since the diseases, some of the diseases that modern medicine is tackling, such as heart disease and cancer, become more and more the diseases that we are dying from in elderly age, we can be expected to live longer without trying to genetically go in and manipulate our metabolisms in some ways. There’s a lot of work being done on what is called caloric restriction.
There’s a lot of research being done on what is called caloric restriction. Animals that are given reduced calorie diets, and yet have the essential nutrients that they need, live longer. We haven’t been able to do the experiments on human beings yet. There are people out there attempting to do this by themselves. You can get books and join organizations to try to enhance or help you – how you can make recipes that satisfy your hunger and have caloric restriction.
I’m saying this to show that there are probably going to be ways that science is going to understand this natural demise, this metabolic demise of our repair mechanisms that set up our natural lifespan that has kept it pretty constant for a long time. And we’re probably going to bring that forward. We’re going to live longer lives I really think. I don’t know if it’s right around the corner, that’s hard to judge. You’ve had people on your show that are saying what they think it’s going to be. But just from reading the literature, it’s clear that these kinds of advances are going to happen.
Question: Why do lifespans vary across species?
Tyler Volk: I find it really fascinating to consider why certain species of mammals live longer than other species of mammals. For example, we live longer than dogs, dogs live longer than mice. Often there’s a tendency, or trend, that the large creatures live longer. But you might try to say, from an evolutionary viewpoint, that it would serve creatures well to live for a long time. They can reproduce more, let’s say if they live for longer, and therefore can pass on their genes for even a longer period of time. But we know that there’s a large variation in when creatures senesce and what the average lifespan is. And it turns out, there’s two ways of looking at this. One is to go down deep into the organism and ask, why are the cellular repair mechanisms breaking down when they do; a couple years in the case of some small mammals. For us it’s many decades, 70, 80, 90 years. But the other way to look at it is that these cellular repair mechanisms themselves must be subject to evolution. We know that these repair mechanisms vary among creatures.
It’s been shown that birds, for example, have better cellular repair mechanisms than mammals do. The current reasoning has to do with the ecological niche that a certain creature lives within as a member of its species. And if that niche allows the possibility for many of the individuals to live long lives, then it has been worthwhile for the evolutionary process to build in better repair mechanisms for its cells to allow it to live longer. So, if I go back to the example of birds, the phrase that’s sometimes used in the technical literature for birds and why the birds live so much longer than the mammals of the same body mass is the phrase, “fly now, die later.” And the idea being that birds in the trees and in flying have very good predator escape mechanisms that make it worthwhile for the birds to have cellular repair mechanisms inside their bodies that allow this longevity for a certain body mass to occur.
And what I find fascinating here is that there is a tuning of the creature’s niche, or environmental lifestyle and the possibilities that that lifestyle has for longevity and the very internal, deep internal, cellular repair mechanisms. The enzyme repair mechanisms issues about oxidative stress that either facilitate that longevity or cut the life short. One particular example I think is very telling is the case of the several species of the Pacific Salmon that live in the Northwest United States, Canada, and in Alaska. These salmon are born in upstream fresh water streams, or rivers. Very quickly, they go down to the saltwater oceans so they have a transition from fresh water to saltwater ocean. They live in the ocean for typically two to three years, depending on the species. They find their way back through a process somewhat mysterious, but maybe having to do with the water chemistry of their birth stream. They find they’re way back to their birth stream and at that point, the males and the females undergo some physiological changes. Their bodies turn more red, they bolt out – the males, the jaws get very bulked out. And if you look at what’s happening hormonally in them, it’s like they’re on an incredible dose of steroids. They’re revved up for this upstream swim that we see dramatic pictures of where they’re swimming these rapids and can they hop this dam or not, or do they have ladders to go up.
They go upstream and the males and females mate. The females lay the eggs in these little depressions in the sediments, and then the males and females all die. They do not go back downstream to say, live another year and come back upstream. And you might think that what’s happening is a real waste of these salmon. It’s been shown that they add some nutrients to the stream water, but they’re not dying to add nutrients to the upstream waters, they’re dying because what’s happened to their bodies has put such stress on their bodies that they’ve done this incredible swim and put all their efforts into getting to a place to mate and into mating. And this is a wonderful example of how it’s important for these organisms to remain healthy up until sex, up until successful sex and reproduction and then it’s possible to die. Senecessence is, it’s possible just after sex. If there were senecessence before sex, that creature is out of the evolutionary game, obviously. But you could have death following right on the heels of sex and in the case of the salmon, this has occurred in evolution. So, we can see here that there is a tuning between death and when senecessence that happens and the ecological, or environmental, circumstances that have resulted in various adaptations in the case of Pacific Salmon. A really dramatic case.
Mammals, including humans, have natural lifespans that have remained about the same through each species’ existence. What are these figures, and why do they vary so greatly across species?
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A simple trick allowed marine biologists to prove a long-held suspicion.
- It's long been suspected that sharks navigate the oceans using Earth's magnetic field.
- Sharks are, however, difficult to experiment with.
- Using magnetism, marine biologists figured out a clever way to fool sharks into thinking they're somewhere that they're not.
For some time, scientists have suspected that sharks belong among the growing number of animals known to navigate using Earth's magnetic field. Testing anything with a shark, though, requires some care.
The key was selecting the right candidate. Keller and his colleagues chose the bonnethead shark, Sphyrna tiburo, a small critter that summers at Turkey Point Shoal off the coast of the Florida State University Coastal and Marine Laboratory with which Keller is affiliated.
Bonnetheads elsewhere have been known to complete 620-mile roundtrip migrations. As the lab's Dean Grubbs puts it, "That's not bad for a shark that is only two to three feet long. The question is how do they find their way back to that same estuary year after year." There's a report of a great white shark migrating between two locations, one in South Africa and another in Australia, year after year.
The research is published in Current Biology.
Keller and his team rounded up 20 local juvenile bonnetheads and transported them into a holding tank at the marine lab. For the tests, the researchers simulated three real-world magnetic fields. As the various magnetic fields were activated, the sharks' movements were captured by GoPro cameras and their average swimming orientations calculated by software.
The first simulation, serving as a control, mimicked the magnetic field of the nearby shoal from which the sharks had been captured. When this field was activated, the sharks essentially acted like they were "home," just swimming around as they do.
A second field was the magnetic equivalent of a location 600 kilometers south of the lab within the Gulf of Mexico. When this field was activated, the sharks, apparently mistaking themselves for being far south in the Gulf, began swimming northward toward the shoal.
The opposite occurred with a field standing in for a location in continental North America 600 km north of their home shoal — the sharks began swimming southward.
"For 50 years," says Keller, "scientists have hypothesized that sharks use the magnetic field as a navigational aid. This theory has been so popular because sharks, skates, and rays have been shown to be very sensitive to magnetic fields. They have also been trained to react to unique geomagnetic signatures, so we know they are capable of detecting and reacting to variation in the magnetic field."
His team's experiments confirm what's long been suspected, Keller says: "Sharks use map-like information from the geomagnetic field as a navigational aid. This ability is useful for navigation and possibly maintaining population structure."
A machine learning system lets visitors at a Kandinsky exhibition hear the artwork.
Have you ever heard colors?
As part of a new exhibition, the worlds of culture and technology collide, bringing sound to the colors of abstract art pioneer Wassily Kandinsky.
Kandinsky had synesthesia, where looking at colors and shapes causes some with the condition to hear associated sounds. With the help of machine learning, virtual visitors to the Sounds Like Kandinsky exhibition, a partnership project by Centre Pompidou in Paris and Google Arts & Culture, can have an aural experience of his art.
An eye for music
Kandinsky's synesthesia is thought to have heavily influenced his painting. Seeing yellow summoned up trumpets, evoking emotions like cheekiness; reds produced violins portraying restlessness; while organs representing heavenliness he associated with blues, according to the exhibition notes.
Virtual visitors are invited to take part in an experiment called Play a Kandinsky, which allows them to see and hear the world through the artist's eyes.
Kandinsky's synesthesia is thought to have heavily influenced his 1925 painting Yellow, Red, Blue.Image: Guillaume Piolle/Wikimedia Commons
In 1925, the artist's masterpiece, "Yellow, Red, Blue", broke new ground in the world of abstract art, guiding the viewer from left to right with shifting shapes and shades. Almost a century after it was painted, Google's interactive tool lets visitors click different parts of the artwork to journey through the artist's description of the colors, associated sounds and moods that inspired the work.
But Google's new toy is not the only tool developed to enhance the artistic experience.
Artist Neil Harbisson has developed an artificial way to emulate Kandinsky by turning colors into sounds. He has a rare form of color blindness and sees the world in greyscale. But a smart antenna attached to his head translates dominant colors into musical notes, creating a real-world soundtrack of what's in front of him. The invention could open up a new world for people who are color blind.
A Harvard professor's study discovers the worst year to be alive.
- Harvard professor Michael McCormick argues the worst year to be alive was 536 AD.
- The year was terrible due to cataclysmic eruptions that blocked out the sun and the spread of the plague.
- 536 ushered in the coldest decade in thousands of years and started a century of economic devastation.
The past year has been nothing but the worst in the lives of many people around the globe. A rampaging pandemic, dangerous political instability, weather catastrophes, and a profound change in lifestyle that most have never experienced or imagined.
But was it the worst year ever?
Nope. Not even close. In the eyes of the historian and archaeologist Michael McCormick, the absolute "worst year to be alive" was 536.
Why was 536 so bad? You could certainly argue that 1918, the last year of World War I when the Spanish Flu killed up to 100 million people around the world, was a terrible year by all accounts. 1349 could also be considered on this morbid list as the year when the Black Death wiped out half of Europe, with up to 20 million dead from the plague. Most of the years of World War II could probably lay claim to the "worst year" title as well. But 536 was in a category of its own, argues the historian.
It all began with an eruption...
According to McCormick, Professor of Medieval History at Harvard University, 536 was the precursor year to one of the worst periods of human history. It featured a volcanic eruption early in the year that took place in Iceland, as established by a study of a Swiss glacier carried out by McCormick and the glaciologist Paul Mayewski from the Climate Change Institute of The University of Maine (UM) in Orono.
The ash spewed out by the volcano likely led to a fog that brought an 18-month-long stretch of daytime darkness across Europe, the Middle East, and portions of Asia. As wrote the Byzantine historian Procopius, "For the sun gave forth its light without brightness, like the moon, during the whole year." He also recounted that it looked like the sun was always in eclipse.
Cassiodorus, a Roman politician of that time, wrote that the sun had a "bluish" color, the moon had no luster, and "seasons seem to be all jumbled up together." What's even creepier, he described, "We marvel to see no shadows of our bodies at noon."
...that led to famine...
The dark days also brought a period of coldness, with summer temperatures falling by 1.5° C. to 2.5° C. This started the coldest decade in the past 2300 years, reports Science, leading to the devastation of crops and worldwide hunger.
...and the fall of an empire
In 541, the bubonic plague added considerably to the world's misery. Spreading from the Roman port of Pelusium in Egypt, the so-called Plague of Justinian caused the deaths of up to one half of the population of the eastern Roman Empire. This, in turn, sped up its eventual collapse, writes McCormick.
Between the environmental cataclysms, with massive volcanic eruptions also in 540 and 547, and the devastation brought on by the plague, Europe was in for an economic downturn for nearly all of the next century, until 640 when silver mining gave it a boost.
Was that the worst time in history?
Of course, the absolute worst time in history depends on who you were and where you lived.
Native Americans can easily point to 1520, when smallpox, brought over by the Spanish, killed millions of indigenous people. By 1600, up to 90 percent of the population of the Americas (about 55 million people) was wiped out by various European pathogens.
Like all things, the grisly title of "worst year ever" comes down to historical perspective.
A new study suggests that private prisons hold prisoners for a longer period of time, wasting the cost savings that private prisons are supposed to provide over public ones.
- Private prisons in Mississippi tend to hold prisoners 90 days longer than public ones.
- The extra days eat up half of the expected cost savings of a private prison.
- The study leaves several open questions, such as what affect these extra days have on recidivism rates.
The United States of America, land of the free, is home to 5 percent of the world's population but 25 percent of its prisoners. The cost of having so many people in the penal system adds up to $80 billion per year, more than three times the budget for NASA. This massive system exploded in size relatively recently, with the prison population increasing by six-fold in the last four decades.
Ten percent of these prisoners are kept in private prisons, which are owned and operated for the sake of profit by contractors. In theory, these operations cost less than public prisons and jails, and states can save money by contracting them to incarcerate people. They have a long history in the United States and are used in many other countries as well.
However, despite the pervasiveness of private contractors in the American prison system, there is not much research into how well they live up to their promise to provide similar services at a lower cost to the state. The little research that is available often encounters difficulties in trying to compare the costs and benefits of facilities with vastly different operations and occasionally produces results suggesting there are few benefits to privatization.
A new study by Dr. Anita Mukherjee and published in the American Economic Journal: Economic Policy joins the debate with a robust consideration of the costs and benefits of private prisons. Its findings suggest that some private prisons keep people incarcerated longer and save less money than advertised.
The study focuses on prisons in Mississippi. Despite its comparatively high rate of incarceration, Mississippi's prison system is very similar to that of other states that also use private prisons. Demographically, its system is representative of the rest of the U.S. prison system, and its inmates are sentenced for similar amounts of time.
The state attempts to get the most out of its privatization efforts, as a 1994 law requires all contracts for private prisons in Mississippi to provide at least a 10 percent cost savings over public prisons while providing similar services. As a result, the state seeks to maximize its savings by sending prisoners to private institutions first if space if available.
While public and private prisons in Mississippi are quite similar, there are a few differences that allow for the possibility of cost savings by private operators — not the least of which is that the guards are paid 30 percent less and have fewer benefits than their publicly employed counterparts.
The results of privatization
The graph depicts the likelihood of release for public (dotted line) vs. private (solid line) prison inmates. At every level of time served, public prisoners were more likely to be released than private prisoners.Dr. Anita Mukherjee
The study relied on administrative records of the Mississippi prison system between 1996 and 2013. The data included information on prisoner demographics, the crimes committed, sentence lengths, time served, infractions while incarcerated, and prisoner relocation while in the system, including between public and private jails. For this study, the sample examined was limited to those serving between one and six years and those who served at least a quarter of their sentence. This created a primary sample of 26,563 bookings.
Analysis revealed that prisoners in private prisons were behind bars for four to seven percent longer than those in public prisons, which translates to roughly 85 to 90 extra days per prisoner. This is, in part, because those in private prison serve a greater portion of their sentences (73 percent) than those in public institutions (70 percent).
This in turn might be due to the much higher infraction rate in private prisons compared to public ones. While only 18 percent of prisoners in a public prison commit an infraction, such as disobeying a guard or possessing contraband, the number jumps to 46 percent in a private prison. Infractions can reduce the probability of early release or cause time to be added to a sentence.
It's unclear why there are so many more infractions in private prisons. Dr. Mukherjee suggests it could be the result of "harsher prison conditions in private prisons," better monitoring techniques, incentives to report more of them to the state before contract renewals, or even a lackadaisical attitude on the part of public prison employees.
What does all this cost Mississippi?
The extra time served eats 48 percent of the cost savings of keeping prisoners in a private facility. For example, it costs about $135,000 to house a prisoner in a private prison for three years and $150,000 in the public system. But longer stays in private prisons reduce the savings from $15,000 to only $7,800.
As Dr. Mukherjee remarks, this cost is also just the finance. Some things are a little harder to measure:
"There are, of course, other costs that are difficult to quantify — e.g., the cost of injustice to society (if private prison inmates systematically serve more time), the inmate's individual value of freedom, and impacts of the additional incarceration on future employment. Abrams and Rohlfs (2011) estimates a prisoner's value of freedom for 90 days at about $1,100 using experimental variation in bail setting. Mueller-Smith (2017) estimates that 90 days of marginal incarceration costs about $15,000 in reduced wages and increased reliance on welfare. If these social costs were to exceed $7,800 in the example stated, private prisons would no longer offer a bargain in terms of welfare-adjusted cost savings."
It is possible that the extra time in jail provides benefits that counter these costs, such as a reduced recidivism rate, but this proved difficult to determine. Though it was not statistically significant, there was some evidence that the added time actually increased the rate of recidivism. If that's true, then private prisons could be counterproductive.