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You are… a mind reader
You are... a mind r human species is also still in circulation, on every continent including Africa. Not only do you carry DNA from other species, you probably also play host to other people’s cells. Before you were born, your mother’s cells crossed the placenta into your bloodstream. Decades later, some of these migrants are still there in your blood, heart, skin and other tissues. This “microchimeric” exchange was mutual: if you are a mother, your children may still be inside you in the form of their embryonic stem cells. You may even be carrying cells from your grandmother and any older siblings. Because microchimeric cells persist for a long time, there is a chance that during pregnancy, your mother was still carrying cells from any previous children she had, as well as cells from her own mother – and she may have shared some with you. Maternal microchimerism is extensive, says Lee Nelson at the University of Washington in Seattle, and probably useful too. “There are so many examples in biology where organisms thrive as a result of exchange – why wouldn’t it also be useful for humans to exchange cellular material?” Fetal cells may help to repair a mother’s damaged heart tissue and lower her risk of cancer. Other research shows that mothers can end up with their child’s DNA in their brains, something that may even be linked to a reduced risk of the mother developing Alzheimer’s. In future, we could become mutants by design. Gene-editing tools like CRISPR should allow genetic diseases to be treated by injecting genes into the body. For example, a small number of people with a mutation in the CCR5 gene, which supplies a protein to the surface of white blood cells, are resistant to HIV. CRISPR opens the possibility of inserting that mutation into the DNA of others, giving them a genetic vaccine against the virus. From there, it’s only a baby-step to genetic superpowers. Ethical questions notwithstanding, future generations could be enhanced with genes for extrastrong bones, lean muscles and a lower risk of cardiovascular disease and cancer. A mutation in the ABCC11 gene currently found in about 1 in 50 Europeans even renders underarms odourless. Think of the savings on deodorant. Be warned, however: this mutation also makes your ear wax dry up. Swings and roundabouts. Sean O’Neill 30 | NewScientist | 10 December 2016
You are... a mind reader
You are... a mind r
Our ability to guess what other people are thinking is the secret sauce of human society
M
eet Sally and her flatmate Andy. Sally has made a birthday cake for Andy, and leaves it in the fridge while she pops out to buy some candles. While she’s gone, Andy sneaks into the kitchen, takes the cake and hides it on a shelf to consume at leisure. When Sally comes back, where does she think the cake will be? If you answered “the fridge” then congratulations: you understand that, based on what they know, people can have different views from you. You possess a “theory of mind” – something that informs your every waking moment, says Josep Call, a psychologist at the University of St Andrews, UK. “When we get dressed in the morning, we’re constantly thinking about what other people think about us.” No other animal can match our ability, making it the essential lubricant for the social interactions that set humans apart. Take the arts. Artists must be able to imagine what their audiences will think of their characters. Without a theory of mind, there would be no
compelling TV soaps, sculptures or books. Some think William Shakespeare must have had a particularly welldeveloped theory of mind to create such rich, complex characters. Mind reading is also crucial for societal norms. “People not only respond to what you do, but to what you intend to do,” says Call. If you hit someone with your car, the difference between a verdict of murder or manslaughter depends on your intent. Yet we can’t all read minds equally well, says Rory Devine, a psychologist at the University of Cambridge. Most of us come a cropper when attempting nested levels of mind reading. Think of Sally hunting for her cake again, but imagine where she might look if we take into account what she thinks about how Andy’s mind works. The more recursive steps we add, the more we stumble. “When you go beyond five levels, people get really, really bad,” says Call. Being a good mind reader pays. Children who are relatively proficient
reader
You are... a menagerie
reader
You are... a menagerie Other creatures inhabit your every crevice. Take care of the right ones and they’ll take care of you
L
later report being less lonely, and their teachers rate them as more sociable. We may be able to improve our skills. We know our mind reading apparatus mostly develops before the age of 5, and the principal factor that determines its development is whether our families and friends talk much about the emotions and motivations of others. “The ability to read minds is something we might learn gradually from the guidance of others,” says Devine. This suggests that it could help to just think about what it’s like to be in other people’s shoes. Recently, Devine and his colleagues showed that this learning can continue far beyond early childhood. When they asked 9 and 10-year-old children to read and discuss short vignettes about social situations, the team found they developed better mind-reading skills than children in a control group. Similar improvements have also been seen in people over the age of 60. You’re never too old be a better mind reader. Gilead Amit
ast night, while you were sleeping, legions of eight-legged creatures had an orgy between your eyebrows. No, you haven’t suddenly been invaded by sex tourists. Demodex mites, close relatives of ticks and spiders, are permanent and mostly harmless residents of the human face. “Every person we’ve looked at, we’ve found evidence of face mites,” says Megan Thoemmes at North Carolina State University in Raleigh. “You can have thousands living on you and never even know they’re there.” Growing up to 0.4 millimetres long, these beasts spend their days buried head-down in hair follicles gorging on who-knows-what and crawling out under cover of darkness to copulate. They have no anus, so on death disgorge a lifetime of faeces into your pores. Before you lunge for the exfoliating brush: Demodex mites are far from your only microscopic residents. You host astonishing biodiversity, from anus-less arthropods to pubic lice to all manner of bacteria and fungi, and without it you wouldn’t be who you are. “Each of us is really a complex consortium of different organisms, one of which is human,” says Justin Sonnenburg at Stanford University in California. Our resident aliens aren’t all benign. There are big beasts like parasitic worms: roundworm, hookworm and whipworm are prevalent in the developing world, and pinworm still
“Last night, legions of eight-legged creatures had an orgy on your face”
infects kids in the West. Then there are hidden viruses such as Herpes simplex, which lies dormant inside the nerve cells of two-thirds of people until it mistakes your sniffles for a deadly fever and attempts to save itself by rushing outwards, causing cold sores. By far the dominant group, however, are bacteria. You have at least as many bacterial cells as human cells, perhaps 10 times more. Only recently have we begun to grasp the extent of their diversity, and there’s plenty left to discover. This year we found the first bacteria that survive by parasitising other bacteria. They live in your spit. Similar battles play out across your many habitats, from the caves of your nostrils and your anal-genital badlands to the crevices between your toes where the fungus Trichophyton rubrum can flare up as athlete’s foot. All of these critters are constantly shedding from your skin and lungs, forming your own unique cloud of airborne bacteria that follows you everywhere. But the densest microbial gathering is in our gut, a community that affects aspects of health from digestion and immune defences to possibly even mood and behaviour. In mice, seeding the gut with Lactobacillus rhamnosus bacteria has been shown to alleviate anxiety, perhaps by producing molecules that alter brain chemistry. The balance of gut microbiota can shift rapidly in response to diet and lifestyle. To tend it you need to feed it right. Your best bet isn’t much-hyped probiotics or live bacteria, but simply to eat more fibre, the preferred meal for a group of bacteria with potent antiinflammatory powers. “It has been known for a long time that plant-based fibre is associated with good health,” says Sonnenburg. “Now we know why.” Daniel Cossins 10 December 2016 | NewScientist | 31
You are... a mind reader
You are... a mind r
Our ability to guess what other people are thinking is the secret sauce of human society
M
eet Sally and her flatmate Andy. Sally has made a birthday cake for Andy, and leaves it in the fridge while she pops out to buy some candles. While she’s gone, Andy sneaks into the kitchen, takes the cake and hides it on a shelf to consume at leisure. When Sally comes back, where does she think the cake will be? If you answered “the fridge” then congratulations: you understand that, based on what they know, people can have different views from you. You possess a “theory of mind” – something that informs your every waking moment, says Josep Call, a psychologist at the University of St Andrews, UK. “When we get dressed in the morning, we’re constantly thinking about what other people think about us.” No other animal can match our ability, making it the essential lubricant for the social interactions that set humans apart. Take the arts. Artists must be able to imagine what their audiences will think of their characters. Without a theory of mind, there would be no
compelling TV soaps, sculptures or books. Some think William Shakespeare must have had a particularly welldeveloped theory of mind to create such rich, complex characters. Mind reading is also crucial for societal norms. “People not only respond to what you do, but to what you intend to do,” says Call. If you hit someone with your car, the difference between a verdict of murder or manslaughter depends on your intent. Yet we can’t all read minds equally well, says Rory Devine, a psychologist at the University of Cambridge. Most of us come a cropper when attempting nested levels of mind reading. Think of Sally hunting for her cake again, but imagine where she might look if we take into account what she thinks about how Andy’s mind works. The more recursive steps we add, the more we stumble. “When you go beyond five levels, people get really, really bad,” says Call. Being a good mind reader pays. Children who are relatively proficient
reader
You are... a menagerie
reader
You are... a menagerie Other creatures inhabit your every crevice. Take care of the right ones and they’ll take care of you
L
later report being less lonely, and their teachers rate them as more sociable. We may be able to improve our skills. We know our mind reading apparatus mostly develops before the age of 5, and the principal factor that determines its development is whether our families and friends talk much about the emotions and motivations of others. “The ability to read minds is something we might learn gradually from the guidance of others,” says Devine. This suggests that it could help to just think about what it’s like to be in other people’s shoes. Recently, Devine and his colleagues showed that this learning can continue far beyond early childhood. When they asked 9 and 10-year-old children to read and discuss short vignettes about social situations, the team found they developed better mind-reading skills than children in a control group. Similar improvements have also been seen in people over the age of 60. You’re never too old be a better mind reader. Gilead Amit
ast night, while you were sleeping, legions of eight-legged creatures had an orgy between your eyebrows. No, you haven’t suddenly been invaded by sex tourists. Demodex mites, close relatives of ticks and spiders, are permanent and mostly harmless residents of the human face. “Every person we’ve looked at, we’ve found evidence of face mites,” says Megan Thoemmes at North Carolina State University in Raleigh. “You can have thousands living on you and never even know they’re there.” Growing up to 0.4 millimetres long, these beasts spend their days buried head-down in hair follicles gorging on who-knows-what and crawling out under cover of darkness to copulate. They have no anus, so on death disgorge a lifetime of faeces into your pores. Before you lunge for the exfoliating brush: Demodex mites are far from your only microscopic residents. You host astonishing biodiversity, from anus-less arthropods to pubic lice to all manner of bacteria and fungi, and without it you wouldn’t be who you are. “Each of us is really a complex consortium of different organisms, one of which is human,” says Justin Sonnenburg at Stanford University in California. Our resident aliens aren’t all benign. There are big beasts like parasitic worms: roundworm, hookworm and whipworm are prevalent in the developing world, and pinworm still
“Last night, legions of eight-legged creatures had an orgy on your face”
infects kids in the West. Then there are hidden viruses such as Herpes simplex, which lies dormant inside the nerve cells of two-thirds of people until it mistakes your sniffles for a deadly fever and attempts to save itself by rushing outwards, causing cold sores. By far the dominant group, however, are bacteria. You have at least as many bacterial cells as human cells, perhaps 10 times more. Only recently have we begun to grasp the extent of their diversity, and there’s plenty left to discover. This year we found the first bacteria that survive by parasitising other bacteria. They live in your spit. Similar battles play out across your many habitats, from the caves of your nostrils and your anal-genital badlands to the crevices between your toes where the fungus Trichophyton rubrum can flare up as athlete’s foot. All of these critters are constantly shedding from your skin and lungs, forming your own unique cloud of airborne bacteria that follows you everywhere. But the densest microbial gathering is in our gut, a community that affects aspects of health from digestion and immune defences to possibly even mood and behaviour. In mice, seeding the gut with Lactobacillus rhamnosus bacteria has been shown to alleviate anxiety, perhaps by producing molecules that alter brain chemistry. The balance of gut microbiota can shift rapidly in response to diet and lifestyle. To tend it you need to feed it right. Your best bet isn’t much-hyped probiotics or live bacteria, but simply to eat more fibre, the preferred meal for a group of bacteria with potent antiinflammatory powers. “It has been known for a long time that plant-based fibre is associated with good health,” says Sonnenburg. “Now we know why.” Daniel Cossins 10 December 2016 | NewScientist | 31