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How to fool a shark using magnets
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."
Ever since we've had the technology, we've looked to the stars in search of alien life. It's assumed that we're looking because we want to find other life in the universe, but what if we're looking to make sure there isn't any?
Here's an equation, and a rather distressing one at that: N = R* × fP × ne × f1 × fi × fc × L. It's the Drake equation, and it describes the number of alien civilizations in our galaxy with whom we might be able to communicate. Its terms correspond to values such as the fraction of stars with planets, the fraction of planets on which life could emerge, the fraction of planets that can support intelligent life, and so on. Using conservative estimates, the minimum result of this equation is 20. There ought to be 20 intelligent alien civilizations in the Milky Way that we can contact and who can contact us. But there aren't any.
The Drake equation is an example of a broader issue in the scientific community—considering the sheer size of the universe and our knowledge that intelligence life has evolved at least once, there should be evidence for alien life. This is generally referred to as the Fermi paradox, after the physicist Enrico Fermi who first examined the contradiction between high probability of alien civilizations and their apparent absence. Fermi summed this up rather succinctly when he asked, “Where is everybody"?
But maybe this was the wrong question. A better question, albeit a more troubling one, might be “What happened to everybody?" Unlike asking where life exists in the universe, there's a clearer potential answer to this question: the Great Filter.
Why the universe is empty
Alien life is likely, but there is none that we can see. Therefore, it could be the case that somewhere along the trajectory of life's development, there is a massive and common challenge that ends alien life before it becomes intelligent enough and widespread enough for us to see—a great filter.
This filter could take many forms. It could be that having a planet in the Goldilocks' zone—the narrow band around a star where it is neither too hot nor too cold for life to exist—and having that planet contain organic molecules capable of accumulating into life is extremely unlikely. We've observed plenty of planets in the Goldilock's zone of different stars (there's estimated to be 40 billion in the Milky Way), but maybe the conditions still aren't right there for life to exist.
The Great Filter could occur at the very earliest stages of life. When you were in high school bio, you might have the refrain drilled into your head “mitochondria are the powerhouse of the cell." I certainly did. However, mitochondria were at one point a separate bacteria living its own existence. At some point on Earth, a single-celled organism tried to eat one of these bacteria, except instead of being digested, the bacterium teamed up with the cell, producing extra energy that enabled the cell to develop in ways leading to higher forms of life. An event like this might be so unlikely that it's only happened once in the Milky Way.
Or, the filter could be the development of large brains, as we have. After all, we live on a planet full of many creatures, and the kind of intelligence humans have has only occurred once. It may be overwhelmingly likely that living creatures on other planets simply don't need to evolve the energy-demanding neural structures necessary for intelligence.
What if the filter is ahead of us?
These possibilities assume that the Great Filter is behind us—that humanity is a lucky species that overcame a hurdle almost all other life fails to pass. This might not be the case, however; life might evolve to our level all the time but get wiped out by some unknowable catastrophe. Discovering nuclear power is a likely event for any advanced society, but it also has the potential to destroy such a society. Utilizing a planet's resources to build an advanced civilization also destroys the planet: the current process of climate change serves as an example. Or, it could be something entirely unknown, a major threat that we can't see and won't see until it's too late.
The bleak, counterintuitive suggestion of the Great Filter is that it would be a bad sign for humanity to find alien life, especially alien life with a degree of technological advancement similar to our own. If our galaxy is truly empty and dead, it becomes more likely that we've already passed through the Great Filter. The galaxy could be empty because all other life failed some challenge that humanity passed.
If we find another alien civilization, but not a cosmos teeming with a variety of alien civilizations, the implication is that the Great Filter lies ahead of us. The galaxy should be full of life, but it is not; one other instance of life would suggest that the many other civilizations that should be there were wiped out by some catastrophe that we and our alien counterparts have yet to face.
Fortunately, we haven't found any life. Although it might be lonely, it means humanity's chances at long-term survival are a bit higher than otherwise.
Climate change and artificial intelligence pose substantial — and possibly existential — problems for humanity to solve. Can we?
- Just by living our day-to-day lives, we are walking into a disaster.
- Can humanity wake up to avert disaster?
- Perhaps COVID was the wake-up call we all needed.
Does humanity have a chance for a better future, or are we just unable to stop ourselves from driving off a cliff? This was the question that came to me as I participated in a conference entitled The Future of Humanity hosted by Marcelo's Institute for Cross-Disciplinary Engagement. The conference hosted an array of remarkable speakers, some of whom were hopeful about our chances and some less so. But when it came to the dangers facing our project of civilization, two themes appeared in almost everyone's talks.
And here's the key aspect that unifies those dangers: we are doing it to ourselves.
The problem of climate change
The first existential crisis that was discussed was, as you might guess, climate change. Bill McKibben, the journalist and now committed activist who first began documenting the climate crisis as far back as the 1980s, gave us a history of humanity's inability to marshal action even in the face of mounting scientific evidence. He spoke of the massive, well-funded disinformation efforts paid for by the fossil fuel industry to keep that action from being taken because it would hurt their bottom lines.
It's not like some alien threat has arrived and will use a mega-laser to drive the Earth's climate into a new and dangerous state. Nope, it's just us — flying around, using plastic bottles, and keeping our houses toasty in the winter.
Next Elizabeth Kolbert, one of America's finest non-fiction writers, gave a sobering portrait of the state of efforts that attempt to deal with climate change through technological fixes. Based on her wonderful new book, she looked at the problem of control when it comes to people and the environment. She spoke of how often we get into trouble when we try to exert control over things like rivers or animal populations only to find that these efforts go awry due to unintended consequences. This requires new layers of control which, in turn, follow the same path.
Credit: Jo-Anne McArthur via Unsplash
At the end of the talk, she focused on attempts to deal with climate change through new kinds of environmental controls with the subtext being that we are likely to run into the same cycle of unintended consequences and attempts to repair the damage. In a question-and-answer period following her talk, Kolbert was decidedly not positive about the future. Because she had looked so deeply into the possibilities of using technology to get us out of the climate crisis, she was dubious that a tech fix was going to save us. The only real action that will matter, she said, is masses of people in the developed would reducing their consumption. She didn't see that happening anytime soon.
The problem of artificial intelligence
Another concern was over artificial intelligence. Here the concern was not so much existential. By this, I mean the speakers were not fearful that some computer was going to wake up into consciousness and decide that the human race needed to be enslaved. Instead, the danger was more subtle but no less potent. Susan Halpern, also one of our greatest non-fiction writers, gave an insightful talk that focused on the artificial aspect of artificial intelligence. Walking us through numerous examples of how "brittle" machine learning algorithms at the heart of modern AI systems are, Halpern was able to pinpoint how these systems are not intelligent at all but carry all the biases of their makers (often unconscious ones). For example, facial recognition algorithms can have a hard time differentiating the faces of women of color, most likely because the "training data sets" the algorithms were taught were not representative of these human beings. But because these machines supposedly rely on data and "data don't lie," these systems get deployed into everything from making decisions about justice to making decisions about who gets insurance. And these are decisions that can have profound effects on people's lives.
Then there was the general trend of AI being deployed in the service of both surveillance capitalism and the surveillance state. In the former, your behavior is always being watched and used against you in terms of swaying your purchasing decisions; in the latter, you are always being watched by those in power. Yikes!
The banality of danger
In listening to these talks I was struck by how mundane the sources of these dangers were when it comes to day-to-day life. Unlike nuclear war or some lone terrorist building a super-virus (threats that Sir Martin Rees eloquently spoke of), when it comes to the climate crisis and an emerging surveillance culture, we are collectively doing it to ourselves through our own innocent individual actions. It's not like some alien threat has arrived and will use a mega-laser to drive the Earth's climate into a new and dangerous state. Nope, it's just us — flying around, using plastic bottles, and keeping our houses toasty in the winter. And it's not like soldiers in black body armor arrive at our doors and force us to install a listening device that tracks our activities. Nope, we willingly set them up on the kitchen counter because they are so dang convenient. These threats to our existence or to our freedoms are things that we are doing just by living our lives in the cultural systems we were born into. And it would take considerable effort to untangle ourselves from these systems.
So, what's next then? Are we simply doomed because we can't collectively figure out how to build and live with something different? I don't know. It's possible that we are doomed. But I did find hope in the talk given by the great (and my favorite) science fiction writer Kim Stanley Robinson. He pointed to how different eras have different "structures of feeling," which is the cognitive and emotional background of an age. Robinson looked at some positive changes that emerged in the wake of the COVID pandemic, including a renewed sense that most of us recognize that we're all in this together. Perhaps, he said, the structure of feeling in our own age is about to change.
Let us hope, and where we can, let us act.
New research shines a light on the genetics of sudden cardiac deaths.
- Soccer player Christian Eriksen of Denmark recently collapsed on the field from a cardiac arrest. Thankfully, he survived.
- A new study examined the genetics underlying unexplained sudden cardiac death.
- About 20 percent of these unexplained deaths are likely due to genetics.
The football world was rocked recently when Denmark's Christian Eriksen collapsed while suffering from cardiac arrest on the field during a European Championship match on June 12. The 29-year-old star has won the Danish Football Player of the year five times. Doctors are still baffled as to why an athlete in prime shape would experience sudden cardiac arrest.
While Eriksen's case remains a mystery, a large team of researchers from the University of Maryland School of Medicine recently looked into the reasons a person with no apparent health problems dies from sudden cardiac death (SCD). Their study, published in JAMA Cardiology, found that roughly 20 percent of unexplained cases involve genetics.
The mystery of sudden cardiac death
SCDs are common, with between 180,000 to 450,000 occurring every year in the United States. While coronary heart disease is involved in between 50 to 75 percent of these cases, doctors are uncertain of the reasons in 30 to 40 percent of cases.
The team notes that most research on SCDs, such as in New Zealand, Denmark, and South Korea, tend to focus on homogenous populations of people under age 35. One study based in New York investigated a racially diverse cohort but included a number of infants. While these studies looked at genetic components of SCD, they write, "No systematic comparison of the genetics underlying cases of unexplained SCD between adult White and African American descendants has ever been conducted."
The State of Maryland's medical examiner's office has been collecting data on SCDs for over two decades, which gave the team a rich collection of data to pull from — over 5,000 such cases. From that data set, the researchers looked at 683 African American and white adults (median age: 41). In total, the DNA of 413 patients who died from unexplained SCD was genetically sequenced. Thirty different cardiomyopathy genes and 38 arrhythmia genes were examined.
Genetic screens for sudden cardiac death
Clinical associate professor of medicine and corresponding author Aloke Finn explains the importance of rooting out the cause of SCDs: "Genetic screening isn't routinely used in cardiology, and far too many patients still die suddenly from a heart condition without having any previously established risk factors. We need to do more for them."
One surprising finding was the large number of the deceased that carried the genetic variant for hypertrophic cardiomyopathy (HCM), which causes the heart's muscle tissue to be abnormally thick. This could explain why people with no apparent heart disease experience cardiac arrest seemingly out of nowhere. While HCM is a somewhat common heart disorder (with a prevalence as high as 0.2 percent), we're only just now learning the role of genes in determining who suffers from a fatal attack.
What is clear, however, is that those with particular genetic variants are likelier to die from unexplained SCD earlier in life than others who die from unexplained SCD.By identifying these genes, researchers hope this information could be used in future medical screenings. E. Albert Reece, Dean of the University of Maryland School of Medicine, believes this could save lives.
"This is a fascinating study that provides important new insights into devastating deaths due to unexplained cardiac abnormalities. It certainly makes the case for more research to address this urgent health need and save lives in the future."
Stay in touch with Derek on Twitter. His most recent book is "Hero's Dose: The Case For Psychedelics in Ritual and Therapy."