東北医科薬科大学
医学部 英語
2025年度 解答・解説

[1] Ingrid Halvorsen builds robots. That's not unusual for an engineer. But instead of stiff metal arms, she makes soft ones that bend like an octopus's tentacle. She leads a research group that works on "soft machines" at the Linden Institute in Bergen, Norway. Hard robots are already common in our world. They carry out many tasks in industry. Many lift car doors. Some tighten bolts on assembly lines. Others carry boxes across warehouses or help surgeons cut with great precision. But a hard robot can hurt whatever it touches.

[2] That's a problem when robots work around people. A stiff arm can bruise a person who stands too close. It can also crush a fragile object, such as an egg or a ripe peach. That's why engineers are looking at how soft machines might take over delicate jobs. They might pick fruit without damaging it. Or they might wrap gently around an injured organ during surgery. And the potential goes beyond easier jobs. Some researchers hope that, by combining enough soft parts, they could build machines that explore places no human can reach.

[3] When a machine breaks — say, part of a car's engine — we replace it with a stronger one. So if a robot arm is too hard, why not just build it from rubber? Back when Tomas Reyes was a student, he asked his teachers just that. Now a roboticist at Marlow College in Bristol, England, Reyes has answered his own question. "Turns out," he says, we are "not very good at copying how muscles work." Making a soft arm is difficult — and for several reasons. First, soft materials stretch unevenly, so an arm may bend in an unexpected direction. Second, the air that moves the arm must be pumped through tiny channels in exactly the right order. Another problem: soft materials wear out. Repeated bending causes small cracks, and the cracks grow. That makes soft robots tricky and costly to maintain.

[4] Engineers like Reyes and Halvorsen found a workaround. They're building robots that borrow tricks from animals. With the right design, these robots can move more easily and at lower cost. They also can last longer — and need fewer parts. To build them, researchers can work with many kinds of materials. Some use silicone, like that in kitchen tools. Reyes uses fabric woven with tiny air tubes. Halvorsen and a few others even use gels that swell when heated.

[5] ( ① ) Such engineers are part of a field known as soft robotics. That's the study of machines made from bendable materials. ( ② ) Pedro Alves is a soft roboticist at Westbrook University in Ohio. In a 2022 interview, he described a bold goal: Rather than send hard-shelled robots into collapsed buildings, he'd send soft ones that squeeze through gaps. Picture a machine that could flatten itself like a pancake, he said. ( ③ ) Maybe it slips beneath a heavy beam to reach a trapped hiker. Or maybe it crawls through a pipe to check for leaks. ( ④ )

[6] "Say you want a robot that climbs a wall like a gecko," Alves said in the interview. "If we really understood how that animal sticks to surfaces," soft roboticists could design one. Such technology is already underway, he said, with the goal of helping rescue crews, assisting older adults and more. "It would work almost anywhere except underwater." It's a distant goal, he admitted — in fact, one he may not see completed. But he believes later teams will: "I think it's achievable."

[7] A fully soft robot that can rival a human nurse appears to be out of reach. Engineers have, however, learned to make small soft fixes. Robots and their sensors must work together. Think of them like "the crew of a ship," Reyes says. Turn the wheel, and the ship changes course. That's a big-scale effect. But each small crew member must do the job properly to get that result. Soft machines are similar. Their many small parts must work as teams.

[8] Here's one example. An octopus arm contains a soft muscle that runs along its whole length. When the animal wants to grab a shell, nerves send a signal along the arm, and the muscle tightens in a wave. That wave pushes the tip forward and wraps it around the shell. Copying that wave is like knocking over a line of dominoes. If one domino fails, the chain stops. Similarly, if the signal is lost, the arm cannot grip. But soft robotics, Halvorsen says, can replace a faulty section or re-route the signal. It might even tackle the problem of robot hands that drop things. They slip when their sensing skin cannot detect pressure properly.

[1] Laughter seems to be everywhere — even when we're alone with a funny thought. It's part of every culture around the world. Laughter brings people together, signals friendliness and sometimes hides embarrassment. But why? Researchers are investigating what laughter does for us and why — whether it's easing tension, building trust or tricking us into feeling better. They're also studying the ways laughter spreads between people. They're even looking at how our brains react to a joke. And some are finding ways to use laughter to help patients.

[2] Some people laugh at almost anything. Others hold back until a joke is truly funny. People often say that a good laugh is "contagious." When a giggle passes from one person to the next, we say it has caught on. Those words might be more accurate than we ever imagined, find researchers at Redfield University in Dunedin, New Zealand.

[3] Hana Lindgren is a sound researcher. One day, she was chatting with comedian and engineer Sam Okafor. Okafor had recordings of 2.1 million audience laughs from 41 theaters. "It was from the period when theaters first began recording their shows," Lindgren explains. Some ten years ago, this was before most comedians had started putting clips online. Okafor knew which shows had been recorded. He also knew when they'd been recorded and in which city the audience was sitting at the time.

[4] And she found curious clusters of laughs. Some jokes had drawn big laughs on just a few evenings over a few weeks. Those patterns looked familiar to Lindgren. She studies how habits spread. And those laugh data resembled the kind of data she saw with gossip. "We wondered whether that kind of spread from person to person could be how audiences decide that a joke is funny," Lindgren recalls.

[5] Graduate student Marco Pellegrini joined the project. He had been working with a mathematical model. He used it to predict how rumors travel through a town. The model compared three groups of people over time. One hadn't heard the rumor yet. A second group was currently passing it along. A third group was people who had passed it on but stopped. As a rumor develops, people move from being unaware into the passing group, then the stopped one. It's such a consistent pattern, it can be described with math.

[6] The team now used the same model with the laugh data. ( ① ) They looked at the 500 most recorded comedy shows in Canada, dividing them by style. ( ② ) For popular shows, laughs rose rapidly from night to night, much like a rumor passing through a crowd. ( ③ ) Slapstick and dry wit did not behave in the same way. ( ④ ) "The people who enjoy dry humor aren't the same as the people who like slapstick. They're different audiences," Lindgren says. "And some of those audiences are much more likely to share things quickly."

[7] Surprisingly, slapstick wasn't the most contagious. It spread, but not as quickly as some other styles. Wordplay, on the other hand, was super contagious. Lindgren has a hypothesis about why. Those fans "are probably super connected online and swapping clips" more than people who prefer other kinds of comedy. "We think of gossip as strictly negative," Lindgren says. That's especially true in small towns. "But that same process of spreading works for other things in life," she now concludes. Like sharing a favorite joke with your closest friends.

[8] Sometimes you hear a joke and just know it's going to be a classic. Maybe you burst out laughing. Or you might feel a warm rush of joy. That's why you want to hear it again — and why you're likely to tell it to others. What causes such strong responses? That's a question neuroscientist Elena Vogt has been studying. She works at Halden University in Oslo. People who take part in her research watch comedy clips as they lie in an fMRI scanner. All the while, the machine scans their brain. Vogt also asks the participants how funny they find each clip. Those scans hint that brain activity changes in response to humor.

[9] Specific parts of the brain respond together to humor, her studies reveal. "The brain is always active," Vogt says. And there isn't a single "humor spot." But several networks, or linked groups of brain regions, become more active. Such networks are made up of "regions in the brain that tend to switch on together and in sync," she explains. Some of these ramp up activity when jokes are told. And they're involved in lots of different things. The *limbic network processes emotions. The language network lets us understand wordplay. The motor network moves our smile. And the auditory network, of course, responds to sounds.

*limbic 大脳辺縁系の