This is Mabel. Mabel is an aphid, a small insect in the same order as cicadas, stink bugs, and bed bugs.
All these bugs pierce their prey and suck out vital fluids. Aphids’ prey are plants. And what aphids are after is buried within the plant, flowing in tubes made from single cells strung end-to-end. These are called sieve tubes and together they form the plumbing system for a plant’s most valuable resource: sap.
Sap is mostly water and sugar. Some species’ sap has as much sugar per liter as a can of soda. Photosynthesis is constantly producing sugar. You can think of it as a chemical “pump” which generates incredibly high pressure— up to 9 times that of a car tire— in the sieve tubes.
To feed, Mabel uses her stylet, which is a long, flexible needle. She slowly worms it into the tissue, between the plant’s cells, until she pierces one of those sieve tubes. Because the sap is under so much pressure, Mabel doesn’t even have to suck it out of the plant. She just opens a valve in her head and lets the pressure push the sap through her digestive system. We’ll come back to what comes out of her butt, but for now, you should know that plants don’t want to be punctured and sipped. So they try to defend themselves.
One defense is the sap itself. To see how that works, let’s hypothetically hook up some other insect’s digestive tract to a steady stream of sap. When that sap touches the insect’s cells, its high sugar content encourages the water in the cells to come out by osmosis… exactly like salt encourages water to come out of a slug. The more sap that passes through the insect, the more water it loses. Eventually, it shrivels up and dies.
Mabel’s gut, however, is packed with an enzyme called sucrase, which takes two molecules of sucrose and converts them into one molecule of fructose and one of… this three-unit sugar. Mabel burns the fructose for energy, leaving the three-unit-sugar behind.
Now, how does that help her?
The more molecules of sugar that are dissolved in the sap, the more water it can suck out of Mabel’s cells. By reducing the number of molecules of sugar in the sap, Mabel reduces its ability to suck water out of her cells. Plant sap neutralized.
Now that means Mabel can feed for days, getting all the energy she needs to reproduce.
Some aphid species have an incredible life cycle. For example, the green peach aphid. During the fall, males and females mate, and the females lay eggs. But in the spring, when the eggs hatch, all the nymphs that emerge are female. When those females reach maturity, they don’t lay eggs. Instead, they give birth to live young… that are clones of themselves… and already pregnant… with their own clones. So, these female aphids have two generations of baby aphid clones forming inside themselves at the same time. Scientists call this telescopic development.
That means that aphids can make more of themselves fast— there can be 20 generations within a single season— and that means lots of aphid poop. Mabel can poop her entire body weight every two hours, making her one of the most prolific poopers on the planet. Some aphid populations can produce hundreds of kilograms of poop per acre.
Now, aphid poop is not like your poop. Chemically, it’s not all that different from sap; it’s a clear and colorless sweet, syrupy liquid. You might already know it by a different name: honeydew.
Other species love honeydew. Some species of ants love it so much they sort of herd and defend entire aphid colonies. In return, the ants get a steady supply of sweet honeydew, which they can drink directly from the aphids’ butts.
Bottom’s up!
Humans love honeydew, too. Several Native American tribes used to harvest it from tall reeds and make it into cake. And some species of bee make honey from honeydew, which humans then harvest and eat.
#Education #TED_Ed #Animation #Insects #Biology #Plants #Nature #Food
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Forwarded from تقویت زبان - آموزش آیلتس
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It's a common saying that elephants never forget, but these magnificent animals are more than giant walking hard drives. The more we learn about elephants, the more it appears that their impressive memory is only one aspect of an incredible intelligence that makes them some of the most social, creative, and benevolent creatures on Earth.
Unlike many proverbs, the one about elephant memory is scientifically accurate. Elephants know every member in their herd, able to recognize as many as 30 companions by sight or smell. This is a great help when migrating or encountering other potentially hostile elephants. They also remember and distinguish particular cues that signal danger and can recall important locations long after their last visit.
But it's the memories unrelated to survival that are the most fascinating. Elephants remember not only their herd companions but other creatures who have made a strong impression on them. In one case, two circus elephants that had briefly performed together rejoiced when crossing paths 23 years later. This recognition isn't limited to others of their species. Elephants have also recognized humans they've bonded with after decades apart.
All of this shows that elephant memory goes beyond responses to stimuli. Looking inside their heads, we can see why. The elephant boasts the largest brain of any land mammal, as well as an impressive encephalization quotient. This is the size of the brain relative to what we'd expect for an animal's body size, and the elephant's EQ is nearly as high as a chimpanzee's. And despite the distant relation, convergent evolution has made it remarkably similar to the human brain, with as many neurons and synapses and a highly developed hippocampus and cerebral cortex.
It is the hippocampus, strongly associated with emotion, that aids recollection by encoding important experiences into long-term memories. The ability to distinguish this importance makes elephant memory a complex and adaptable faculty beyond rote memorization. It's what allows elephants who survived a drought in their youth to recognize its warning signs in adulthood, which is why clans with older matriarchs have higher survival rates. Unfortunately, it's also what makes elephants one of the few non-human animals to suffer from post-traumatic stress disorder.
The cerebral cortex, on the other hand, enables problem solving, which elephants display in many creative ways. They also tackle problems cooperatively, sometimes even outwitting the researchers and manipulating their partners. And they've grasped basic arithmetic, keeping track of the relative amounts of fruit in two baskets after multiple changes.
The rare combination of memory and problem solving can explain some of elephants' most clever behaviors, but it doesn't explain some of the things we're just beginning to learn about their mental lives. Elephants communicate using everything from body signals and vocalizations, to infrasound rumbles that can be heard kilometers away. And their understanding of syntax suggests that they have their own language and grammar. This sense of language may even go beyond simple communication. Elephants create art by carefully choosing and combining different colors and elements. They can also recognize twelve distinct tones of music and recreate melodies. And yes, there is an elephant band.
But perhaps the most amazing thing about elephants is a capacity even more important than cleverness: their sense of empathy, altruism, and justice. Elephants are the only non-human animals to mourn their dead, performing burial rituals and returning to visit graves. They have shown concern for other species, as well. One working elephant refused to set a log down into a hole where a dog was sleeping, while elephants encountering injured humans have sometimes stood guard and gently comforted them with their trunk. On the other hand, elephant attacks on human villages have usually occurred right after massive poachings or cullings, suggesting deliberate revenge.
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When we consider all this evidence, along with the fact that elephants are one of the few species who can recognize themselves in a mirror, it's hard to escape the conclusion that they are conscious, intelligent, and emotional beings. Unfortunately, humanity's treatment of elephants does not reflect this, as they continue to suffer from habitat destruction in Asia, ivory poaching in Africa, and mistreatment in captivity worldwide. Given what we now know about elephants and what they continue to teach us about animal intelligence, it is more important than ever to ensure that what the English poet John Donne described as "nature's great masterpiece" does not vanish from the world's canvas.
#TED_Ed #Education #Animals #Animation #Brain #Memory
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Self-driving cars are already cruising the streets today. And while these cars will ultimately be safer and cleaner than their manual counterparts, they can't completely avoid accidents altogether. How should the car be programmed if it encounters an unavoidable accident? Patrick Lin navigates the murky ethics of self-driving cars.
#TED_Ed #Driverless_Cars #Cars #Morality #Machine_Learning #Technology #Animation #Education #Design #Innovation #Invention
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#Planets #Astronomy #Exploration #Science #Space #Technology #Solar_System
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Two years ago here at TED I reported that we had discovered at Saturn, with the Cassini Spacecraft, an anomalously warm and geologically active region at the southern tip of the small Saturnine moon Enceladus, seen here. This region seen here for the first time in the Cassini image taken in 2005. This is the south polar region, with the famous tiger-stripe fractures crossing the south pole. And seen just recently in late 2008, here is that region again, now half in darkness because the southern hemisphere is experiencing the onset of August and eventually winter.
And I also reported that we'd made this mind-blowing discovery -- this once-in-a-lifetime discovery of towering jets erupting from those fractures at the south pole, consisting of tiny water ice crystals accompanied by water vapor and simple organic compounds like carbon dioxide and methane. And at that time two years ago I mentioned that we were speculating that these jets might in fact be geysers, and erupting from pockets or chambers of liquid water underneath the surface, but we weren't really sure. However, the implications of those results -- of a possible environment within this moon that could support prebiotic chemistry, and perhaps life itself -- were so exciting that, in the intervening two years, we have focused more on Enceladus.
We've flown the Cassini Spacecraft by this moon now several times, flying closer and deeper into these jets, into the denser regions of these jets, so that now we have come away with some very precise compositional measurements. And we have found that the organic compounds coming from this moon are in fact more complex than we previously reported. While they're not amino acids, we're now finding things like propane and benzene, hydrogen cyanide, and formaldehyde. And the tiny water crystals here now look for all the world like they are frozen droplets of salty water, which is a discovery that suggests that not only do the jets come from pockets of liquid water, but that that liquid water is in contact with rock. And that is a circumstance that could supply the chemical energy and the chemical compounds needed to sustain life.
So we are very encouraged by these results. And we are much more confident now than we were two years ago that we might indeed have on this moon, under the south pole, an environment or a zone that is hospitable to living organisms. Whether or not there are living organisms there, of course, is an entirely different matter. And that will have to await the arrival, back at Enceladus, of the spacecrafts, hopefully some time in the near future, specifically equipped to address that particular question. But in the meantime I invite you to imagine the day when we might journey to the Saturnine system, and visit the Enceladus interplanetary geyser park, just because we can.
Thank you.
#Planets #Astronomy #Exploration #Science #Space #Technology #Solar_System
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#Business #Culture #Entertainment #Productivity #Sleep
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My big idea is a very, very small idea that can unlock billions of big ideas that are at the moment dormant inside us. And my little idea that will do that is sleep.
This is a room of type A women. This is a room of sleep-deprived women. And I learned the hard way the value of sleep. Two-and-a-half years ago, I fainted from exhaustion. I hit my head on my desk. I broke my cheekbone, I got five stitches on my right eye. And I began the journey of rediscovering the value of sleep. And in the course of that, I studied, I met with medical doctors, scientists, and I'm here to tell you that the way to a more productive, more inspired, more joyful life is getting enough sleep.
And we women are going to lead the way in this new revolution, this new feminist issue. We are literally going to sleep our way to the top -- literally --
because unfortunately, for men, sleep deprivation has become a virility symbol. I was recently having dinner with a guy who bragged that he had only gotten four hours sleep the night before. And I felt like saying to him -- but I didn't say -- I felt like saying, "You know what? if you had gotten five, this dinner would have been a lot more interesting."
There is now a kind of sleep deprivation one-upmanship. Especially here in Washington, if you try to make a breakfast date, and you say, "How about eight o'clock?" they're likely to tell you, "Eight o'clock is too late for me, but that's OK, I can get a game of tennis in and do a few conference calls and meet you at eight." And they think that means they are so incredibly busy and productive, but the truth is, they're not, because we, at the moment, have had brilliant leaders in business, in finance, in politics, making terrible decisions. So a high IQ does not mean that you're a good leader, because the essence of leadership is being able to see the iceberg before it hits the Titanic.
And we've had far too many icebergs hitting our Titanics. In fact, I have a feeling that if Lehman Brothers was Lehman Brothers and Sisters, they might still be around.
While all the brothers were busy just being hyper-connected 24/7, maybe a sister would have noticed the iceberg, because she would have woken up from a seven-and-a-half- or eight-hour sleep, and have been able to see the big picture.
So as we are facing all the multiple crises in our world at the moment, what is good for us on a personal level, what's going to bring more joy, gratitude, effectiveness in our lives and be the best for our own careers, is also what is best for the world. So I urge you to shut your eyes, and discover the great ideas that lie inside us; to shut your engines and discover the power of sleep.
Thank you.
#Business #Culture #Entertainment #Productivity #Sleep
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So, I'm afraid. Right now, on this stage, I feel fear. In my life, I ain't met many people that will readily admit when they are afraid. And I think that's because deep down, they know how easy it spreads. See, fear is like a disease. When it moves, it moves like wildfire. But what happens when, even in the face of that fear, you do what you've got to do? That's called courage. And just like fear, courage is contagious.
See, I'm from East St. Louis, Illinois. That's a small city across the Mississippi River from St. Louis, Missouri. I have lived in and around St. Louis my entire life. When Michael Brown, Jr., an ordinary teenager, was gunned down by police in 2014 in Ferguson, Missouri -- another suburb, but north of St. Louis -- I remember thinking, he ain't the first, and he won't be the last young kid to lose his life to law enforcement.
But see, his death was different. When Mike was killed, I remember the powers that be trying to use fear as a weapon. The police response to a community in mourning was to use force to impose fear: fear of militarized police, imprisonment, fines. The media even tried to make us afraid of each other by the way they spun the story. And all of these things have worked in the past. But like I said, this time it was different.
Michael Brown's death and the subsequent treatment of the community led to a string of protests in and around Ferguson and St. Louis. When I got out to those protests about the fourth or fifth day, it was not out of courage; it was out of guilt. See, I'm black. I don't know if y'all noticed that.
But I couldn't sit in St. Louis, minutes away from Ferguson, and not go see. So I got off my ass to go check it out.
When I got out there, I found something surprising. I found anger; there was a lot of that. But what I found more of was love. People with love for themselves. Love for their community. And it was beautiful -- until the police showed up. Then a new emotion was interjected into the conversation: fear.
Now, I'm not going to lie; when I saw those armored vehicles, and all that gear and all those guns and all those police I was terrified -- personally. And when I looked around that crowd, I saw a lot of people that had the same thing going on. But I also saw people with something else inside of them. That was courage. See, those people yelled, and they screamed, and they were not about to back down from the police. They were past that point. And then I could feel something in me changing, so I yelled and I screamed, and I noticed that everybody around me was doing the same thing. And there was nothing like that feeling.
So I decided I wanted to do something more. I went home, I thought: I'm an artist. I make shit. So I started making things specific to the protest, things that would be weapons in a spiritual war, things that would give people voice and things that would fortify them for the road ahead.
I did a project where I took pictures of the hands of protesters and put them up and down the boarded-up buildings and community shops. My goal was to raise awareness and to raise the morale. And I think, for a minute at least, it did just that. Then I thought, I want to uplift the stories of these people I was watching being courageous in the moment. And myself and my friend, and filmmaker and partner Sabaah Folayan did just that with our documentary, "Whose Streets?"
I kind of became a conduit for all of this courage that was given to me. And I think that's part of our job as artists. I think we should be conveyors of courage in the work that we do. And I think that we are the wall between the normal folks and the people that use their power to spread fear and hate, especially in times like these.
So I'm going to ask you. Y'all the movers and the shakers, you know, the thought leaders: What are you gonna do with the gifts that you've been given to break us from the fear the binds us every day?
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Because, see, I'm afraid every day. I can't remember a time when I wasn't. But once I figured out that fear was not put in me to cripple me, it was there to protect me, and once I figured out how to use that fear, I found my power.
Thank you.
#Activism #Art #Film #Community #Fear #Race #TED_Fellows #Social_Change #Equality #Protest
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Thank you.
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🔴The history of the world according to cats
On May 27th, 1941, the German battleship Bismarck sank in a fierce firefight, leaving only 118 of her 2,200 crew members alive. But when a British destroyer came to collect the prisoners, they found an unexpected survivor - a black and white cat clinging to a floating plank. For the next several months this cat hunted rats and raised British morale - until a sudden torpedo strike shattered the hull and sank the ship. But, miraculously, not the cat. Nicknamed Unsinkable Sam, he rode to Gibraltar with the rescued crew and served as a ship cat on three more vessels – one of which also sank - before retiring to the Belfast Home for Sailors.
Many may not think of cats as serviceable sailors, or cooperative companions of any kind. But cats have been working alongside humans for thousands of years - helping us just as often as we help them. So how did these solitary creatures go from wild predator to naval officer to sofa sidekick?
The domestication of the modern house cat can be traced back to more than 10,000 years ago in the Fertile Crescent, at the start of the Neolithic era. People were learning to bend nature to their will, producing much more food than farmers could eat at one time. These Neolithic farmers stored their excess grain in large pits and short, clay silos. But these stores of food attracted hordes of rodents, as well as their predator, Felis silvestris lybica - the wildcat found across North Africa and Southwest Asia.
These wildcats were fast, fierce, carnivorous hunters. And they were remarkably similar in size and appearance to today’s domestic cats. The main differences being that ancient wildcats were more muscular, had striped coats, and were less social towards other cats and humans.
The abundance of prey in rodent-infested granaries drew in these typically solitary animals. And as the wildcats learned to tolerate the presence of humans and other cats during mealtime, we think that farmers likewise tolerated the cats in exchange for free pest control. The relationship was so beneficial that the cats migrated with Neolithic farmers from Anatolia into Europe and the Mediterranean.
Vermin were a major scourge of the seven seas. They ate provisions and gnawed at lines of rope, so cats had long since become essential sailing companions.
Around the same time these Anatolian globe trotting cats set sail, the Egyptians domesticated their own local cats. Revered for their ability to dispatch venomous snakes, catch birds, and kill rats, domestic cats became important to Egyptian religious culture. They gained immortality in frescos, hieroglyphs, statues, and even tombs, mummified alongside their owners. Egyptian ship cats cruised the Nile, holding poisonous river snakes at bay. And after graduating to larger vessels, they too began to migrate from port to port. During the time of the Roman Empire, ships traveling between India and Egypt carried the lineage of the central Asian wildcat F. s. ornata. Centuries later, in the Middle Ages, Egyptian cats voyaged up to the Baltic Sea on the ships of Viking seafarers. And both the Near Eastern and North African wildcats – probably tamed at this point -- continued to travel across Europe, eventually setting sail for Australia and the Americas. Today, most house cats have descended from either the Near Eastern or the Egyptian lineage of F.s.lybica. But close analysis of the genomes and coat patterns of modern cats tells us that unlike dogs, which have undergone centuries of selective breeding, modern cats are genetically very similar to ancient cats. And apart from making them more social and docile, we’ve done little to alter their natural behaviors. In other words, cats today are more or less as they’ve always been: Wild animals. Fierce hunters. Creatures that don’t see us as their keepers. And given our long history together, they might not be wrong.
#TED_Animations #TED_Ed #History #Animals
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On May 27th, 1941, the German battleship Bismarck sank in a fierce firefight, leaving only 118 of her 2,200 crew members alive. But when a British destroyer came to collect the prisoners, they found an unexpected survivor - a black and white cat clinging to a floating plank. For the next several months this cat hunted rats and raised British morale - until a sudden torpedo strike shattered the hull and sank the ship. But, miraculously, not the cat. Nicknamed Unsinkable Sam, he rode to Gibraltar with the rescued crew and served as a ship cat on three more vessels – one of which also sank - before retiring to the Belfast Home for Sailors.
Many may not think of cats as serviceable sailors, or cooperative companions of any kind. But cats have been working alongside humans for thousands of years - helping us just as often as we help them. So how did these solitary creatures go from wild predator to naval officer to sofa sidekick?
The domestication of the modern house cat can be traced back to more than 10,000 years ago in the Fertile Crescent, at the start of the Neolithic era. People were learning to bend nature to their will, producing much more food than farmers could eat at one time. These Neolithic farmers stored their excess grain in large pits and short, clay silos. But these stores of food attracted hordes of rodents, as well as their predator, Felis silvestris lybica - the wildcat found across North Africa and Southwest Asia.
These wildcats were fast, fierce, carnivorous hunters. And they were remarkably similar in size and appearance to today’s domestic cats. The main differences being that ancient wildcats were more muscular, had striped coats, and were less social towards other cats and humans.
The abundance of prey in rodent-infested granaries drew in these typically solitary animals. And as the wildcats learned to tolerate the presence of humans and other cats during mealtime, we think that farmers likewise tolerated the cats in exchange for free pest control. The relationship was so beneficial that the cats migrated with Neolithic farmers from Anatolia into Europe and the Mediterranean.
Vermin were a major scourge of the seven seas. They ate provisions and gnawed at lines of rope, so cats had long since become essential sailing companions.
Around the same time these Anatolian globe trotting cats set sail, the Egyptians domesticated their own local cats. Revered for their ability to dispatch venomous snakes, catch birds, and kill rats, domestic cats became important to Egyptian religious culture. They gained immortality in frescos, hieroglyphs, statues, and even tombs, mummified alongside their owners. Egyptian ship cats cruised the Nile, holding poisonous river snakes at bay. And after graduating to larger vessels, they too began to migrate from port to port. During the time of the Roman Empire, ships traveling between India and Egypt carried the lineage of the central Asian wildcat F. s. ornata. Centuries later, in the Middle Ages, Egyptian cats voyaged up to the Baltic Sea on the ships of Viking seafarers. And both the Near Eastern and North African wildcats – probably tamed at this point -- continued to travel across Europe, eventually setting sail for Australia and the Americas. Today, most house cats have descended from either the Near Eastern or the Egyptian lineage of F.s.lybica. But close analysis of the genomes and coat patterns of modern cats tells us that unlike dogs, which have undergone centuries of selective breeding, modern cats are genetically very similar to ancient cats. And apart from making them more social and docile, we’ve done little to alter their natural behaviors. In other words, cats today are more or less as they’ve always been: Wild animals. Fierce hunters. Creatures that don’t see us as their keepers. And given our long history together, they might not be wrong.
#TED_Animations #TED_Ed #History #Animals
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#Health #Psychology #Brain #Biology #Science #Mental_Health
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Depression is the leading cause of disability in the world. In the United States, close to 10% of adults struggle with depression. But because it's a mental illness, it can be a lot harder to understand than, say, high cholesterol. One major source of confusion is the difference between having depression and just feeling depressed. Almost everyone feels down from time to time. Getting a bad grade, losing a job, having an argument, even a rainy day can bring on feelings of sadness. Sometimes there's no trigger at all. It just pops up out of the blue. Then circumstances change, and those sad feelings disappear. Clinical depression is different. It's a medical disorder, and it won't go away just because you want it to. It lingers for at least two consecutive weeks, and significantly interferes with one's ability to work, play, or love. Depression can have a lot of different symptoms: a low mood, loss of interest in things you'd normally enjoy, changes in appetite, feeling worthless or excessively guilty, sleeping either too much or too little, poor concentration, restlessness or slowness, loss of energy, or recurrent thoughts of suicide. If you have at least five of those symptoms, according to psychiatric guidelines, you qualify for a diagnosis of depression. And it's not just behavioral symptoms. Depression has physical manifestations inside the brain. First of all, there are changes that could be seen with the naked eye and X-ray vision. These include smaller frontal lobes and hippocampal volumes. On a more microscale, depression is associated with a few things: the abnormal transmission or depletion of certain neurotransmitters, especially serotonin, norepinephrine, and dopamine, blunted circadian rhythms, or specific changes in the REM and slow-wave parts of your sleep cycle, and hormone abnormalities, such as high cortisol and deregulation of thyroid hormones. But neuroscientists still don't have a complete picture of what causes depression. It seems to have to do with a complex interaction between genes and environment, but we don't have a diagnostic tool that can accurately predict where or when it will show up. And because depression symptoms are intangible, it's hard to know who might look fine but is actually struggling. According to the National Institute of Mental Health, it takes the average person suffering with a mental illness over ten years to ask for help. But there are very effective treatments. Medications and therapy complement each other to boost brain chemicals. In extreme cases, electroconvulsive therapy, which is like a controlled seizure in the patient's brain, is also very helpful. Other promising treatments, like transcranial magnetic stimulation, are being investigated, too. So, if you know someone struggling with depression, encourage them, gently, to seek out some of these options. You might even offer to help with specific tasks, like looking up therapists in the area, or making a list of questions to ask a doctor. To someone with depression, these first steps can seem insurmountable. If they feel guilty or ashamed, point out that depression is a medical condition, just like asthma or diabetes. It's not a weakness or a personality trait, and they shouldn't expect themselves to just get over it anymore than they could will themselves to get over a broken arm. If you haven't experienced depression yourself, avoid comparing it to times you've felt down. Comparing what they're experiencing to normal, temporary feelings of sadness can make them feel guilty for struggling. Even just talking about depression openly can help. For example, research shows that asking someone about suicidal thoughts actually reduces their suicide risk. Open conversations about mental illness help erode stigma and make it easier for people to ask for help. And the more patients seek treatment, the more scientists will learn about depression, and the better the treatments will get.
#Health #Psychology #Brain #Biology #Science #Mental_Health
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