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There are plenty of theories, of course, especially regarding why: increasingly complex social networks, a culture built around tool use and collaboration, the challenge of adapting to a mercurial and often harsh climate

Although these possibilities are fascinating, they are extremely difficult to test.

Although it makes up only 2 percent of body weight, the human brain consumes a whopping 20 percent of the body’s total energy at rest. In contrast, the chimpanzee brain needs only half that.

contrary to long-standing assumptions, larger mammalian brains do not always have more neurons, and the ones they do have are not always distributed in the same way.

The human brain has 86 billion neurons in all: 69 billion in the cerebellum, a dense lump at the back of the brain that helps orchestrate basic bodily functions and movement; 16 billion in the cerebral cortex, the brain’s thick corona and the seat of our most sophisticated mental talents, such as self-awareness, language, problem solving and abstract thought; and 1 billion in the brain stem and its extensions into the core of the brain

In contrast, the elephant brain, which is three times the size of our own, has 251 billion neurons in its cerebellum, which helps manage a giant, versatile trunk, and only 5.6 billion in its cortex

primates evolved a way to pack far more neurons into the cerebral cortex than other mammals did

The great apes are tiny compared to elephants and whales, yet their cortices are far denser: Orangutans and gorillas have 9 billion cortical neurons, and chimps have 6 billion. Of all the great apes, we have the largest brains, so we come out on top with our 16 billion neurons in the cortex.

“What kinds of mutations occurred, and what did they do? We’re starting to get answers and a deeper appreciation for just how complicated this process was.”

there was a strong evolutionary pressure to modify the human regulatory regions in a way that sapped energy from muscle and channeled it to the brain.

Accounting for body size and weight, the chimps and macaques were twice as strong as the humans. It’s not entirely clear why, but it is possible that our primate cousins get more power out of their muscles than we get out of ours because they feed their muscles more energy. “Compared to other primates, we lost muscle power in favor of sparing energy for our brains,” Bozek said. “It doesn’t mean that our muscles are inherently weaker. We might just have a different metabolism.

a pioneering experiment. Not only were they going to identify relevant genetic mutations from our brain’s evolutionary past, they were also going to weave those mutations into the genomes of lab mice and observe the consequences.

Silver and Wray introduced the chimpanzee copy of HARE5 into one group of mice and the human edition into a separate group. They then observed how the embryonic mice brains grew.

After nine days of development, mice embryos begin to form a cortex, the outer wrinkly layer of the brain associated with the most sophisticated mental talents. On day 10, the human version of HARE5 was much more active in the budding mice brains than the chimp copy, ultimately producing a brain that was 12 percent larger

“It wasn’t just a couple mutations and—bam!—you get a bigger brain. As we learn more about the changes between human and chimp brains, we realize there will be lots and lots of genes involved, each contributing a piece to that. The door is now open to get in there and really start understanding. The brain is modified in so many subtle and nonobvious ways.”

As recent research on whale and elephant brains makes clear, size is not everything, but it certainly counts for something. The reason we have so many more cortical neurons than our great-ape cousins is not that we have denser brains, but rather that we evolved ways to support brains that are large enough to accommodate all those extra cells.

There’s a danger, though, in becoming too enamored with our own big heads. Yes, a large brain packed with neurons is essential to what we consider high intelligence. But it’s not sufficient

No matter how large the human brain grew, or how much energy we lavished upon it, it would have been useless without the right body. Three particularly crucial adaptations worked in tandem with our burgeoning brain to dramatically increase our overall intelligence: bipedalism, which freed up our hands for tool making, fire building and hunting; manual dexterity surpassing that of any other animal; and a vocal tract that allowed us to speak and sing.

Human intelligence, then, cannot be traced to a single organ, no matter how large; it emerged from a serendipitous confluence of adaptations throughout the body. Despite our ongoing obsession with the size of our noggins, the fact is that our intelligence has always been so much bigger than our brain.

It’s helpful, he argues, to think about theories as being like maps.“To say something is a map is not to say it’s a hunch,” said Dr. Godfrey-Smith, a professor at the City University of New York and the University of Sydney. “It’s an attempt to represent some territory.”A theory, likewise, represents a territory of science. Instead of rivers, hills, and towns, the pieces of the territory are facts.“To call something a map is not to say anything about how good it is,” Dr. Godfrey-Smith added. “There are fantastically good maps where there’s not a shred of doubt about their accuracy. And there are maps that are speculative.”

To judge a map’s quality, we can see how well it guides us through its territory. In a similar way, scientists test out new theories against evidence. Just as many maps have proven to be unreliable, many theories have been cast aside.But other theories have become the foundation of modern science, such as the theory of evolution, the general theory of relativity, the theory of plate tectonics, the theory that the sun is at the center of the solar system, and the germ theory of disease.“To the best of our ability, we’ve tested them, and they’ve held up,” said Dr. Miller. “And that’s why we’ve held on to these things.”

he and Dr. Fredrickson and their colleagues have demonstrated that the brain is “plastic,” or capable of generating new cells and pathways, and it is possible to train the circuitry in the brain to promote more positive responses. That is, a person can learn to be more positive by practicing certain skills that foster positivity.

Negative feelings activate a region of the brain called the amygdala, which is involved in processing fear and anxiety and other emotions. Dr. Richard J. Davidson, a neuroscientist and founder of the Center for Healthy Minds at the University of Wisconsin — Madison, has shown that people in whom the amygdala recovers slowly from a threat are at greater risk for a variety of health problems than those in whom it recovers quickly.

Worry, sadness, anger and other such “downers” have their place in any normal life. But chronically viewing the glass as half-empty is detrimental both mentally and physically and inhibits one’s ability to bounce back from life’s inevitable stresses.

In other words, Dr. Davidson said, “well-being can be considered a life skill. If you practice, you can actually get better at it.”

Activities Dr. Fredrickson and others endorse to foster positive emotions include:

Do good things for other people

Appreciate the world around you

Develop and bolster relationships.

Establish goals that can be accomplished.

Learn something new.

Choose to accept yourself, flaws and all.

Practice resilience.

Practice mindfulness

Often, preliminary studies fuel irrational exuberance about a promising dietary supplement, leading millions of people to buy in to the trend. Many never stop. They continue even though more rigorous studies — which can take many years to complete — almost never find that vitamins prevent disease, and in some cases cause harm

There’s no conclusive evidence that dietary supplements prevent chronic disease in the average American, Dr. Manson said. And while a handful of vitamin and mineral studies have had positive results, those findings haven’t been strong enough to recommend supplements to the general American public, she said.

The National Institutes of Health has spent more than $2.4 billion since 1999 studying vitamins and minerals. Yet for “all the research we’ve done, we don’t have much to show for it,” said Dr. Barnett Kramer, director of cancer prevention at the National Cancer Institute.

A big part of the problem, Dr. Kramer said, could be that much nutrition research has been based on faulty assumptions, including the notion that people need more vitamins and minerals than a typical diet provides; that megadoses are always safe; and that scientists can boil down the benefits of vegetables like broccoli into a daily pill.

when researchers tried to deliver the key ingredients of a healthy diet in a capsule, Dr. Kramer said, those efforts nearly always failed.

It’s possible that the chemicals in the fruits and vegetables on your plate work together in ways that scientists don’t fully understand — and which can’t be replicated in a table

More important, perhaps, is that most Americans get plenty of the essentials, anyway. Although the Western diet has a lot of problems — too much sodium, sugar, saturated fat and calories, in general — it’s not short on vitamins

Without even realizing it, someone who eats a typical lunch or breakfast “is essentially eating a multivitamin,”

The body naturally regulates the levels of many nutrients, such as vitamin C and many B vitamins, Dr. Kramer said, by excreting what it doesn’t need in urine. He added: “It’s hard to avoid getting the full range of vitamins.”

Not all experts agree. Dr. Walter Willett, a professor at the Harvard T.H. Chan School of Public Health, says it’s reasonable to take a daily multivitamin “for insurance.” Dr. Willett said that clinical trials underestimate supplements’ true benefits because they aren’t long enough, often lasting five to 10 years. It could take decades to notice a lower rate of cancer or heart disease in vitamin taker

For Charlsa Bentley, 67, keeping up with the latest nutrition research can be frustrating. She stopped taking calcium, for example, after studies found it doesn’t protect against bone fractures. Additional studies suggest that calcium supplements increase the risk of kidney stones and heart disease.

People who take vitamins tend to be healthier, wealthier and better educated than those who don’t, Dr. Kramer said. They are probably less likely to succumb to heart disease or cancer, whether they take supplements or not. That can skew research results, making vitamin pills seem more effective than they really are

Because folic acid can lower homocysteine levels, researchers once hoped that folic acid supplements would prevent heart attacks and strokes.In a series of clinical trials, folic acid pills lowered homocysteine levels but had no overall benefit for heart disease, Dr. Lichtenstein said

When studies of large populations showed that people who eat lots of seafood had fewer heart attacks, many assumed that the benefits came from the omega-3 fatty acids in fish oil, Dr. Lichtenstein said.Rigorous studies have failed to show that fish oil supplements prevent heart attacks

But it’s possible the benefits of sardines and salmon have nothing to do with fish oil, Dr. Lichtenstein said. People who have fish for dinner may be healthier as a result of what they don’t eat, such as meatloaf and cheeseburgers.

“Eating fish is probably a good thing, but we haven’t been able to show that taking fish oil [supplements] does anything for you,

In the tiny amounts provided by fruits and vegetables, beta carotene and similar substances appear to protect the body from a process called oxidation, which damages healthy cells, said Dr. Edgar Miller, a professor of medicine at Johns Hopkins School of Medicine.Experts were shocked when two large, well-designed studies in the 1990s found that beta carotene pills actually increased lung cancer rates.

Likewise, a clinical trial published in 2011 found that vitamin E, also an antioxidant, increased the risk of prostate cancer in men by 17 percent

“Vitamins are not inert,” said Dr. Eric Klein, a prostate cancer expert at the Cleveland Clinic who led the vitamin E study. “They are biologically active agents. We have to think of them in the same way as drugs. If you take too high a dose of them, they cause side effects.”

“We should be responsible physicians,” she said, “and wait for the data.”

The problem is that we confuse a shallow familiarity with general concepts for real, in-depth knowledge.

our knowledge is also highly selective: we conveniently remember facts that support our beliefs and forget others

Psychological studies show that people fail to notice the logical fallacies in an argument if the conclusion supports their viewpoint

“motivated reasoning”

A high standard of education doesn’t necessarily protect us from these flaws

That false sense of expertise can, in turn, lead them to feel that they have the licence to be more closed-minded in their political views – an attitude known as “earned dogmatism”.

“People confuse their current level of understanding with their peak knowledge,”

Graduates, for instance, often overestimate their understanding of their degree subject:

recent psychological research also offers evidence-based ways towards achieving more fruitful discussions.

a simple but powerful way of deflating someone’s argument is to ask for more detail. “You need to get the ‘other side’ focusing on how something would play itself out, in a step by step fashion”

By revealing the shallowness of their existing knowledge, this prompts a more moderate and humble attitude.

You need to ask how something works to get the effect

If you are trying to debunk a particular falsehood – like a conspiracy theory or fake news – you should make sure that your explanation offers a convincing, coherent narrative that fills all the gaps left in the other person’s understanding

The persuasive power of well-constructed narratives means that it’s often useful to discuss the sources of misinformation, so that the person can understand why they were being misled in the first place

Each of our beliefs is deeply rooted in a much broader and more complex political ideology. Climate crisis denial, for instance, is now inextricably linked to beliefs in free trade, capitalism and the dangers of environmental regulation.

Attacking one issue may therefore threaten to unravel someone’s whole worldview – a feeling that triggers emotionally charged motivated reasoning. It is for this reason that highly educated Republicans in the US deny the overwhelming evidence.

disentangle the issue at hand from their broader beliefs, or to explain how the facts can still be accommodated into their worldview.

“All people have multiple identities,” says Prof Jay Van Bavel at New York University, who studies the neuroscience of the “partisan brain”. “These identities can become active at any given time, depending on the circumstances.”

you might have more success by appealing to another part of the person’s identity entirely.

when people are asked to first reflect on their other, nonpolitical values, they tend to become more objective in discussion on highly partisan issues, as they stop viewing facts through their ideological lens.

Another simple strategy to encourage a more detached and rational mindset is to ask your conversation partner to imagine the argument from the viewpoint of someone from another country

The aim is to help them recognise that they can change their mind on certain issues while staying true to other important elements of their personality.

this strategy increases “psychological distance” from the issue at hand and cools emotionally charged reasoning so that you can see things more objectively.

If you are considering policies with potentially long-term consequences, you could ask them to imagine viewing the situation through the eyes of someone in the future

people are generally much more rational in their arguments, and more willing to own up to the limits of their knowledge and understanding, if they are treated with respect and compassion.

Aggression, by contrast, leads them to feel that their identity is threatened, which in turn can make them closed-minded

Assuming that the purpose of your argument is to change minds, rather than to signal your own superiority, you are much more likely to achieve your aims by arguing gently and kindly rather than belligerently, and affirming your respect for the person, even if you are telling them some hard truths

As a bonus, you will also come across better to onlookers. “There’s a lot of work showing that third-party observers always attribute high levels of competence when the person is conducting themselves with more civility,”

The system may also play a role in symptoms of traumatic brain injur

Mice are a good model, she says, because their glymphatic systems are very similar to humans’. She and Iliff found that even months after being injured, the animals’ brains were still not clearing waste efficiently, leading to a buildup of toxic compounds, including amyloid beta. Nedergaard returns to the dishwasher analogy. “It’s like if you only use a third of the water when you turn on the machine,” she says. “You won’t get clean dishes.”

in mice, omega-3 fatty acidsimproved glymphatic functioning.

Nedergaard has shown that at least in mice, the system processes twice as much fluid during sleep as it does during wakefulness. She and her colleagues focused on amyloid beta; they found that the lymphatic system removed much more of the protein when the animals were asleep than when they were awake. She suggests that over time, sleep dysfunction may contribute to Alzheimer’s and perhaps other brain illnesses. “You only clean your brain when you’re sleeping,” she says. “This is probably an important reason that we sleep. You need time off from consciousness to do the housekeeping.”

Sleeping on your stomach is also not very effective; sleeping on your back is somewhat better, while lying on your side appears to produce the best results.

glymphatic flow is significantly decreased in the period just before a migraine. The intense pain in these headaches is caused largely by inflamed nerves in the tissue that surrounds the brain. Neuroscientists Rami Burstein and Aaron Schain, the lead authors, theorize that faulty clearance of molecular waste from the brain could trigger inflammation in these pain fibers.

other scientists have found that deep breathing significantly increases the glymphatic transport of cerebrospinal fluid into the brain.

One way alcohol may lead to cancer is because the body metabolizes it into acetaldehyde, which causes changes and mutations in DNA, Dr. Gapstur said. The formation of acetaldehyde starts when alcohol comes in contact with bacteria in the mouth, which may explain the link between alcohol and cancers of the throat, voice box and esophagus

living organisms concentrate carbon-12 in their cells—and when they die, that signature persists. When scientists find graphite that’s especially enriched in carbon-12, relative to carbon-13, they can deduce that living things were around when that graphite was first formed. And that’s exactly what the Tokyo team found in the Saglek Block—grains of graphite, enriched in carbon-12, encased within 3.95-billion-year-old rock.

the team calculated the graphite was created at temperatures between 536 and 622 Celsius—a range that’s consistent with the temperatures at which the surrounding metamorphic rocks were transformed. This suggests that the graphite was already there when the rocks were heated and warped, and didn’t sneak in later. It was truly OG—original graphite.

Still, all of this evidence suggests Earth was home to life during its hellish infancy, and that such life abounded in a variety of habitats. Those pioneering organisms—bacteria, probably—haven’t left any fossils behind. But Sano and Komiya hope to find some clues about them by analyzing the Saglek Block rocks. The levels of nitrogen, iron, and sulfur in the rocks could reveal which energy sources those organisms exploited, and which environments they inhabited. They could tell us how life first lived.

Our previous work has shown that ACTN3 variants play an important role in our muscle’s ability to generate strength. We showed that the loss of alpha-actinin-3 is detrimental to sprint performance in athletes and the general population, but may benefit muscle endurance.

This is because the loss of alpha-actinin-3 causes the muscle to behave more like a slower muscle fibre.

Our study shows that ACTN3 is more than just the “gene for speed”, but that its loss improves our muscle’s ability to generate heat and reduces the need to shiver when exposed to cold.

The goal of our research is to improve our understanding of how our genetics influence how our muscle works. This will allow us to develop better treatments for those who suffer from muscle diseases, like Duchenne muscular dystrophy, as well as more common conditions, such as obesity and type 2 diabetes.

Her husband, Brad Buchanan, was late for family dinner. She found him in the bathroom, coughing up blood — a lot of it.

Doctors found that a tumor had ruptured in one of his lungs and he urgently needed chemo. As her husband became critically ill, Ms. Washington, a freelance writer, was thrust into the role of nurse.

“My hands were shaking,” she said as she remembered apprehensively pushing in the drugs for the first time and feeling the weight of keeping her husband alive.

Mr. Buchanan had a stem cell transplant that left him with graft-versus-host disease

Depending on the analysis, between 61 and 75 percent of caregivers are women

When she explained that she had two children who also had needs, he said, “Well, usually family steps in, and it works out fine.”

Ms. Washington felt the burden of responsibility, but also the sting

The U.S. health care system relies on and takes for granted the “invisible army” of people — mostly women — who keep the system functioning by performing home care for the many people who are “too well for the hospital” but “too sick for home,” as well as for those on end-of-life care.

In 2017, AARP found that about 41 million family caregivers in America perform roughly $470 billion worth of unpaid labor a year.

they tend to do more personal care tasks like helping patients bathe and use the toilet than their male counterparts, who are more likely to oversee finances and arrangement of care.

The historical roots are complex, but as Evelyn Glenn puts it in “Forced to Care,”

emale caregivers put in more hours — 22 to men’s 17

they are also more likely to stand by their partner through a serious illness

Many people who take on caregiving roles experience negative health impacts, but women are especially at risk of the fallout from caregiver stress.

Female caregivers are also 2.5 times more likely to live in poverty as non-caregiver

A 2011 study found that women who left their jobs to care for a parent lost an average of $324,000 in wages and benefits over their lifetimes.

Ms. Washington was able to dip into savings and a recent inheritance to help pay for supplemental in-home care, but it was still a struggle, causing stress, resentment and lost income.

It was hard to have my life put on hold. Everything kind of slipped away.

I lost a sense of who I was. I was going to pick up a prescription for myself, the only prescription I had when my husband was sick, and the pharmacist asked for my date of birth, and I gave his date of birth

People talk about how it’s the most important job in the world, taking care of our children or taking care of our vulnerable elders, and yet those are some of the worst paid jobs.

How much is a quarterback paid versus someone who is doing care for a vulnerable elderly person?

How did care work become so undervalued?

A doctor told Ms. Washington that her husband would need 24-hour care and “could not be left alone for even a moment.”

Western culture has long framed care work done by women as a moral duty or obligation, rather than an economic activity.

If your earnings are lower than they would normally be because you’re busy caring for a family member, and you can’t save and pay into social security, it can lock whole families into a cycle of lower wealth and economic instability.

And what should someone not do

Don’t tell someone to stay positive. For me, there was no staying about it, because I didn’t feel positive to start with. It brought up this feeling

My time isn’t my own, but surely my emotions can be

Globally, the numbers can be even worse, and the stakes often higher. “Say a person comes into the hospital in Sierra Leone with a fever and flulike symptoms,” DeRisi says. “After a few days, or a week, they die. What caused that illness? Most of the time, we never find out. Because if the cause isn’t something that we can culture and test for” — like hepatitis, or strep throat — “it basically just stays a mystery.”

It would be better, DeRisi says, to watch for rare cases of mystery illnesses in people, which often exist well before a pathogen gains traction and is able to spread.

Based on a retrospective analysis of blood samples, scientists now know that H.I.V. emerged nearly a dozen times over a century, starting in the 1920s, before it went global.

Zika was a relatively harmless illness before a single mutation, in 2013, gave the virus the ability to enter and damage brain cells.

The beauty of this approach” — running blood samples from people hospitalized all over the world through his system, known as IDseq — “is that it works even for things that we’ve never seen before, or things that we might think we’ve seen but which are actually something new.”

In this scenario, an undiscovered or completely new virus won’t trigger a match but will instead be flagged. (Even in those cases, the mystery pathogen will usually belong to a known virus family: coronaviruses, for instance, or filoviruses that cause hemorrhagic fevers like Ebola and Marburg.)

And because different types of bacteria require specific conditions in order to grow, you also need some idea of what you’re looking for in order to find it.

The same is true of genomic sequencing, which relies on “primers” designed to match different combinations of nucleotides (the building blocks of DNA and RNA).

Even looking at a slide under a microscope requires staining, which makes organisms easier to see — but the stains used to identify bacteria and parasites, for instance, aren’t the same.

The practice that DeRisi helped pioneer to skirt this problem is known as metagenomic sequencing

Unlike ordinary genomic sequencing, which tries to spell out the purified DNA of a single, known organism, metagenomic sequencing can be applied to a messy sample of just about anything — blood, mud, seawater, snot — which will often contain dozens or hundreds of different organisms, all unknown, and each with its own DNA. In order to read all the fragmented genetic material, metagenomic sequencing uses sophisticated software to stitch the pieces together by matching overlapping segments.

The assembled genomes are then compared against a vast database of all known genomic sequences — maintained by the government-run National Center for Biotechnology Information — making it possible for researchers to identify everything in the mix

Traditionally, the way that scientists have identified organisms in a sample is to culture them: Isolate a particular bacterium (or virus or parasite or fungus); grow it in a petri dish; and then examine the result under a microscope, or use genomic sequencing, to understand just what it is. But because less than 2 percent of bacteria — and even fewer viruses — can be grown in a lab, the process often reveals only a tiny fraction of what’s actually there. It’s a bit like planting 100 different kinds of seeds that you found in an old jar. One or two of those will germinate and produce a plant, but there’s no way to know what the rest might have grown into.

Such studies have revealed just how vast the microbial world is, and how little we know about it

“The selling point for researchers is: ‘Look, this technology lets you investigate what’s happening in your clinic, whether it’s kids with meningitis or something else,’” DeRisi said. “We’re not telling you what to do with it. But it’s also true that if we have enough people using this, spread out all around the world, then it does become a global network for detecting emerging pandemics

One study found more than 1,000 different kinds of viruses in a tiny amount of human stool; another found a million in a couple of pounds of marine sediment. And most were organisms that nobody had seen before.

After the Biohub opened in 2016, one of DeRisi’s goals was to turn metagenomics from a rarefied technology used by a handful of elite universities into something that researchers around the world could benefit from

metagenomics requires enormous amounts of computing power, putting it out of reach of all but the most well-funded research labs. The tool DeRisi created, IDseq, made it possible for researchers anywhere in the world to process samples through the use of a small, off-the-shelf sequencer, much like the one DeRisi had shown me in his lab, and then upload the results to the cloud for analysis.

he’s the first to make the process so accessible, even in countries where lab supplies and training are scarce. DeRisi and his team tested the chemicals used to prepare DNA for sequencing and determined that using as little as half the recommended amount often worked fine. They also 3-D print some of the labs’ tools and replacement parts, and offer ongoing training and tech support

The metagenomic analysis itself — normally the most expensive part of the process — is provided free.

But DeRisi’s main innovation has been in streamlining and simplifying the extraordinarily complex computational side of metagenomics

IDseq is also fast, capable of doing analyses in hours that would take other systems weeks.

“What IDseq really did was to marry wet-lab work — accumulating samples, processing them, running them through a sequencer — with the bioinformatic analysis,”

“Without that, what happens in a lot of places is that the researcher will be like, ‘OK, I collected the samples!’ But because they can’t analyze them, the samples end up in the freezer. The information just gets stuck there.”

Meningitis itself isn’t a disease, just a description meaning that the tissues around the brain and spinal cord have become inflamed. In the United States, bacterial infections can cause meningitis, as can enteroviruses, mumps and herpes simplex. But a high proportion of cases have, as doctors say, no known etiology: No one knows why the patient’s brain and spinal tissues are swelling.

When Saha and her team ran the mystery meningitis samples through IDseq, though, the result was surprising. Rather than revealing a bacterial cause, as expected, a third of the samples showed signs of the chikungunya virus — specifically, a neuroinvasive strain that was thought to be extremely rare. “At first we thought, It cannot be true!” Saha recalls. “But the moment Joe and I realized it was chikungunya, I went back and looked at the other 200 samples that we had collected around the same time. And we found the virus in some of those samples as well.”

Until recently, chikungunya was a comparatively rare disease, present mostly in parts of Central and East Africa. “Then it just exploded through the Caribbean and Africa and across Southeast Asia into India and Bangladesh,” DeRisi told me. In 2011, there were zero cases of chikungunya reported in Latin America. By 2014, there were a million.

Chikungunya is a mosquito-borne virus, but when DeRisi and Saha looked at the results from IDseq, they also saw something else: a primate tetraparvovirus. Primate tetraparvoviruses are almost unknown in humans, and have been found only in certain regions. Even now, DeRisi is careful to note, it’s not clear what effect the virus has on people. “Maybe it’s dangerous, maybe it isn’t,” DeRisi says. “But I’ll tell you what: It’s now on my radar.

it reveals a landscape of potentially dangerous viruses that we would otherwise never find out about. “What we’ve been missing is that there’s an entire universe of pathogens out there that are causing disease in humans,” Imam notes, “ones that we often don’t even know exist.”

“The plan was, Let’s let researchers around the world propose studies, and we’ll choose 10 of them to start,” DeRisi recalls. “We thought we’d get, like, a couple dozen proposals, and instead we got 350.”

Metagenomic sequencing is especially good at what scientists call “environmental sampling”: identifying, say, every type of bacteria present in the gut microbiome, or in a teaspoon of seawater.

“When you draw blood from someone who has a fever in Ghana, you really don’t know very much about what would normally be in their blood without fever — let alone about other kinds of contaminants in the environment. So how do you interpret the relevance of all the things you’re seeing?”

Such criticisms have led some to say that metagenomics simply isn’t suited to the infrastructure of developing countries. Along with the problem of contamination, many labs struggle to get the chemical reagents needed for sequencing, either because of the cost or because of shipping and customs holdups

we’re less likely to be caught off-guard. “With Ebola, there’s always an issue: Where’s the virus hiding before it breaks out?” DeRisi explains. “But also, once we start sampling people who are hospitalized more widely — meaning not just people in Northern California or Boston, but in Uganda, and Sierra Leone, and Indonesia — the chance of disastrous surprises will go down. We’ll start seeing what’s hidden.”

forgetting seems to be an active mechanism that is constantly at work in the brain.

“To have proper memory function, you have to have forgetting.

Different types of memory are created and stored in varying ways, and in various areas of the brain.

Neurons communicate with each other through synapses — junctions between these cells that include a tiny gap across which chemical messengers can be sent

The more often a memory is recalled, the stronger its neural network becomes. Over time, and through consistent recall, the memory becomes encoded in both the hippocampus and the cortex

Because the hippocampus is not where long-term memories are stored in the brain, its dynamic nature is not a flaw but a feature

Neuroscientists often refer to this physical representation of a memory as an engram. They think that each engram has a number of synaptic connections, sometimes even in several areas of the brain, and that each neuron and synapse can be involved in multiple engrams

The brain is always trying to forget the information it’s already learnt,

Hardt’s lab showed that a dedicated mechanism continuously promotes the expression of AMPA receptors at synapses.

To forget certain things, it seemed that the rat brain had to proactively destroy connections at the synapse. Forgetting, Hardt says, “is not a failure of memory, but a function of it”.

Paul Frankland, a neuroscientist at the Hospital for Sick Children in Toronto, Canada, had also found evidence that the brain is wired to forget

Frankland was studying the production of new neurons, or neurogenesis, in adult mice. The process had long been known to occur in the brains of young animals, but had been discovered in the hippocampi of mature animals only about 20 years earlier. Because the hippocampus is involved in memory formation, Frankland and his team wondered whether increasing neurogenesis in adult mice could help the rodents to remember.

Eventually, it exists independently in the cortex, where it is put away for long-term storage.

Researchers think that the human brain might operate in a similar way

Studies of people with exceptional autobiographical memories or with impaired ones seem to bear this out

People with a condition known as highly superior autobiographical memory (HSAM) remember their lives in such incredible detail that they can describe the outfit that they were wearing on any particular day

Those with severely deficient autobiographical memory (SDAM), however, are unable to vividly recall specific events in their lives

As a result, they also have trouble imagining what might happen in the future

By better understanding how we forget, through the lenses of both biology and cognitive psychology, Anderson and other researchers might be edging nearer to improving treatments for anxiety, PTSD and even Alzheimer’s disease

Hardt thinks that Alzheimer’s disease might also be better understood as a malfunction of forgetting rather than remembering

But more memory researchers are shifting their focus to examine how the brain forgets, as well as how it remembers

In the past decade, researchers have begun to view forgetting as an important part of a whole

Why do we have memory at all? As humans, we entertain this fantasy that it’s important to have autobiographical details,

Forgetting enables us as individuals, and as a species, to move forwards.

These devices can measure a person’s temperature, heart rate, level of activity and other biometrics. With this information, researchers have been able to track and detect COVID-19 infections even before people notice they have any symptoms.

Wearables can detect symptoms of COVID-19 or other illnesses before symptoms are noticeable. While they have proved to be capable of detecting sickness early, the symptoms wearables detect are not unique to COVID-19.

So a logical way to look for new drugs to treat a specific disease is to study individual genes and proteins that are directly affected by that disease.

But this idea of mapping the protein interactions of diseases to look for novel drug targets doesn’t apply just to the coronavirus. We have now used this approach on other pathogens as well as other diseases including cancer, neurodegenerative and psychiatric disorders.

"Not one woman that I have been in a cell with said, 'I am regretting that I did this, I regret that I'm here.' We will continue to fight and speak and raise our voices... Do you understand the strength I am talking about?"

"I think it does not just undermine our credibility, but our ability to promote democratic values, to promote democracy, to be what we have always claimed to be and more often than not acted on,"

Still, the women of Belarus are looking to the U.S. for support and have high hopes for President-elect Joe Biden.

She said the people of Belarus are ready to sacrifice and are sending "a May Day message to the world now."

In contrast to a previous study6, they observed a robust lifespan extension in male mice fed a BCAA-restricted diet throughout life, equal to the benefits of dietary protein restriction.

Interestingly, female mice showed no lifespan extension from BCAA or dietary protein restriction, and if BCAA restriction was started during middle age, the benefits on males were greatly reduced. Thus, both studies collectively point to mTOR as a primary mediator of the benefits associated with BCAA restriction (Fig. 1).

A clear picture is emerging of how specific amino acids are sensed by sestrin to regulate mTOR signalling and autophagy and so preserve the function of intestinal stem cells during ageing.

Genetic background is crucial in the response to dietary restriction, with an identical low-calorie regimen increasing lifespan in some mouse strains but shortening it in others

There is also evidence that dietary restriction initiated later in life might have reduced benefits in rodents and, in some cases, result in premature death

Taken together, these observations suggest that although protein- and BCAA-restricted diets are a powerful research tool for exploring the fundamental mechanisms of ageing, it is premature to recommend adoption by the general population.

She and others emphasized the apparent lack of severe health repercussions from reinfection — and the lack of evidence that reinfection is common.

Nearly 4 percent of people who had a previous infection were reinfected, an almost identical rate to those with no history of infection.

“Basically, it’s saying vaccination actually needs to be better than natural immunity. But vaccination is better than natural immunity.”

The study backs up recent laboratory data from South African researchers analyzing blood plasma from recovered patients. Nearly half of the plasma samples had no detectable ability to block the variant from infecting cells in a laboratory dish

The good news is that vaccine trials from Johnson & Johnson and Novavax show that vaccines can work — even against the B.1.351 variant, and particularly in preventing severe illness.

Novavax did not provide a breakdown of mild, moderate and severe cases, but severe cases of covid-19 were rare in the trial, suggesting that reinfection is unlikely to send people to the hospital.

“It is not surprising to see reinfection in individuals who are convalescent. And it would not be surprising to see infection in people who are vaccinated, especially a few months out from vaccine,”

“The key is not whether people get reinfected, it’s whether they get sick enough to be hospitalized.

“If the data holds true, it means we will need to walk the public back on the idea of how close we are to the finish line for ending this pandemic.”

Projections created by data scientist Youyang Gu — whose pandemic models have been cited by the Centers for Disease Control and Prevention — suggest that about 65 percent of America’s population will reach immunity by June 1. But built into that 65 percent is roughly 20 percent having immunity from past infections only.

In a separate study, scientists at Rockefeller University in New York took blood plasma from people who had been vaccinated and found that vaccine-generated antibodies were largely able to block mutations found on the B.1.351 variant.

I think the fact that we … now have data from two vaccines indicating that we can prevent serious disease, even against the new variant, is hopeful,”

A future concern needing close monitoring is whether the reformulation of vaccines to keep up with the evolving virus could drive the virus to continue evolving.

There is also a concern that subpar immunity could allow new resistant variants to emerge. That possibility, Nussenzweig said, is one reason that people should get both doses of a vaccine, on time.

“It’s a demonstration of this very cool idea that you have remnants of previous thoughts still rattling around in your head, and you bind the representation of what’s happening now to the fading embers of those old thoughts,

They watched a series of nouns appear on a computer screen, one after another, and after a brief distraction recalled as many of the words as they could, in any order. Repeated trials, with different lists of words, showed a predictable effect: The participants tended to remember the words in clusters, beginning with one and recalling those that were just before or after.

This pattern, which scientists call the contiguity effect, is similar to what often happens in the card game concentration, in which players try to identify pairs in a grid of cards lying face-down.

remembering a fact (a broken table) recalls a scene (dancing), which in turn brings to mind more facts — like the other people who were there — and so on.

“When you activate one memory, you are reactivating a little bit of what was happening around the time the memory was formed,” Dr. Kahana said, “and this process is what gives you that feeling of time travel.”

since the 18th century “when people were happy to spout off about what men and women’s brains were like – before you could even look at them. They came up with these nice ideas and metaphors that fitted the status quo and society, and gave rise to different education for men and women.”

she couldn’t find any beyond the negligible, and other research was also starting to question the very existence of such differences. For example, once any differences in brain size were accounted for, “well-known” sex differences in key structures disappeared.

Are there any significant differences based on sex alone? The answer, she says, is no.

“The idea of the male brain and the female brain suggests that each is a characteristically homogenous thing and that whoever has got a male brain, say, will have the same kind of aptitudes, preferences and personalities as everyone else with that ‘type’ of brain. We now know that is not the case.

‘Forget the male and female brain; it’s a distraction, it’s inaccurate.’ It’s possibly harmful, too, because it’s used as a hook to say, well, there’s no point girls doing science because they haven’t got a science brain, or boys shouldn’t be emotional or should want to lead.”

The next question was, what then is driving the differences in behaviour between girls and boys, men and women?

“that the brain is moulded from birth onwards and continues to be moulded through to the ‘cognitive cliff’ in old age when our grey cells start disappearing.

The rules will change how the brain works and how someone behaves.” The upshot of gendered rules? “The ‘gender gap’ becomes a self-fulfilling prophecy.”

The brain is also predictive and forward-thinking in a way we had never previously realised.

the brain is much more a function of experiences. If you learn a skill your brain will change, and it will carry on changing.”

The brain is a biological organ. Sex is a biological factor. But it is not the sole factor; it intersects with so many variables.”

Letting go of age-old certainties is frightening, concedes Rippon, who is both optimistic about the future, and fearful for it.

On the plus side, our plastic brains are good learners. All we need to do is change the life lessons.

One major breakthrough in recent years has been the realisation that, even in adulthood, our brains are continually being changed, not just by the education we receive, but also by the jobs we do, the hobbies we have, the sports we play.

Once we acknowledge that our brains are plastic and mouldable, then the power of gender stereotypes becomes evident.

Beliefs about sex differences (even if ill-founded) inform stereotypes, which commonly provide just two labels – girl or boy, female or male – which, in turn, historically carry with them huge amounts of “contents assured” information and save us having to judge each individual on their own merits

With input from exciting breakthroughs in neuroscience, the neat, binary distinctiveness of these labels is being challenged – we are coming to realise that nature is inextricably entangled with nurture.

The 21st century is not just challenging the old answers – it is challenging the question itself.