The science news of the week: When an irresistible force pulls you out of bed in the middle of the night and leads you, eyes closed, to the refrigerator or pantry, what do you grab? No, not a bottle of nonfat kefir and not a low-cal fruit bar, but either a piece of sausage or a candy bar or a pastry.
But there is no need to blame yourself in the morning when you realize the horror of a nighttime raid on the kitchen. It is not your fault that you are drawn to fatty-sweet-caloric foods, it is the fault of the food-seeking optimization system built into you. It is the fault of your spatial memory, which has evolved to find the shortest path to the most calorie-rich (and, from today’s perspective, harmful) products. In the wild, all animals do this because their job is to get the maximum amount of calories with the minimum amount of effort. But we have a good understanding of what is beneficial and what is harmful. We do not have to think about daily survival, so could it be that we are also guided by animal instinct?
A new study by a group of scientists at Wageningen University in the Netherlands (their report published in Scientific Reports) suggests that we do indeed have a built-in cognitive system for optimizing the search for food at minimal cost. During the experiments, participants had to move through a maze of rooms, trying the smell and taste of 16 different products, sweet and salty, low and high in calories. Then they were asked to reproduce the route, and it turned out that on average they all remembered the route to the unhealthy food 30% better. In addition, when participants had to rely on smell alone, they were surprisingly accurate in finding the highest-calorie products. Scientists explain this by the fact that smell and memory are closely linked in our brains, and this link has been inherited from animals, although of course the human sense of smell is much weaker than that of animals that have to hunt diligently for food. It is possible that human memory was also formed under the constant need to search for food. And the ability to remember where to find high-calorie food was a great survival advantage. But what was a lifesaver for our distant hunter-gatherer ancestors has become a curse for us.
Streptococcus pathogen S. pyogenes I remember that somewhere in my collection there was a stamp from 1962 with the proud inscription “In the USSR, malaria is defeated!” And for some reason, there was a strong desire to believe that just a little more and there would be stamps with the names of other, forever conquered diseases… Here, scarlet fever, one of the leading causes of child mortality in the West, was promised to disappear, but recent outbreaks in the United Kingdom and countries in northeast Asia suggest that it may be too soon to rejoice. This resurgence of scarlet fever initially puzzled scientists.
Here’s how they reported the victory over malaria in 1962. We explain quickly, simply, and clearly what happened, why it matters, and what will happen next. эпизоды – Episodes End of story Advertising Podcasts But the results of a recent study by Australian scientists show that the key to solving the puzzle may lie in the genome of a single strain of bacteria, demonstrating just how complex the family tree of infectious diseases can be. Scarlet fever is caused by Group A Streptococcus (Streptococcus pyogenes), round-shaped microbes capable of producing toxic antigens that wreak havoc in the body, especially in children. As a result, symptoms of the disease can range from pharyngitis and severe rash to infectious-toxic shock and organ failure. With the invention of antibiotics, scarlet fever was brought under control, and by the 1940s it seemed that it would soon be completely eradicated. Today, however, things look much less promising. “The global resurgence of scarlet fever has resulted in more than 600,000 cases of infection worldwide and a fivefold increase in mortality from the disease,” writes one of the study’s leaders, molecular biologist Stephen Brawer of the University of Queensland, in the journal Nature Communications. Among the superantigens isolated by scientists from a strain of bacteria found in Northeast Asia was one that helps invading bacteria penetrate host cells. Such a phenomenon has never been observed in bacteria, which usually acquire increased virulence through a long evolutionary process. But here the strain was completely new, not even a century old, when scarlet fever epidemics ravaged this Asian region. “The toxins we discovered enter the bacteria when they are infected by viruses that contain the genes for these toxins,” explains biologist Mark Walker from the University of Queensland. “And these newly acquired toxins help Streptococcus pyogenes better invade host cells, while also driving out other strains in the competitive struggle.” In the process of horizontal gene transfer, a gene that has evolved in one microbe can be integrated into the genome of a virus and then into the DNA of a new host, creating something akin to a new clone. This is a quick and convenient way for single-celled microbes to adapt, using stolen genes to gain access to host cells or to resist drugs that would otherwise quickly eliminate them. And in the case of scarlet fever, it gave the lateral branch of the bacteria a new weapon that made the new strain no less dangerous than its old, well-known “cousin. Control of the coronavirus pandemic is helping to contain and prevent scarlet fever, which is also spread primarily by airborne droplets, making it unlikely to become a pandemic. “But when social distance rules are relaxed, scarlet fever is likely to return,” Walker warns.
The famous Old Faithful geyser has always worked like clockwork. But now those clocks are slowing down… “Old Faithful, perhaps the most famous geyser in Yellowstone National Park, nicknamed for the punctuality of its eruptions, may be retiring. Scientists have come to this conclusion based on observations made since the 1950s. Back then, the geyser spewed water and steam every 60-65 minutes, but since 2001, the intervals between eruptions have increased to 90-94 minutes. To find out what happens to the “Eternal Clocks” (another nickname for the geyser) and whether they have always been active, specialists from the United States Geological Survey (USGS) collected samples of petrified wood found on the hill where the geyser erupts. It is clear that nothing can grow on this hill today, which is doused every hour and a half with scalding hot water saturated with alkalis. However, as carbon-14 dating of ancient tree samples has shown, the hill was covered with vegetation in the 13th-14th centuries, which means that the geyser was inactive. Scientists, led by geologist Shaul Gurvitz, studied historical chronicles and found that during this time there was a so-called Medieval Climate Optimum, or warming, in some areas (like Tennessee) accompanied by severe droughts (which depleted underground reservoirs and caused geysers to go silent for almost a century), while in others, like the north of England, the weather was so warm that they began to grow grapes. Thanks to this warming, even the ice melted, allowing the discovery of Greenland. According to Gurvits, past events can tell us a lot about the future. “Climate models suggest that by mid-century we can expect severe droughts and fires that will significantly alter the entire Yellowstone ecosystem,” writes one scientist in the journal Geophysical Research Letters. “Periods of reduced precipitation in modern history have already led to an increase in the interval between Old Faithful eruptions, and recent studies of fossilized wood suggest that the geyser may go silent again in the event of a prolonged and severe drought.”
Fireflies in the nighttime forest are pure magic. If you have ever watched fireflies fly, you will agree that it is a mesmerizing, magical spectacle. Especially when they suddenly start flashing in unison. Many explanations have been offered for this phenomenon, from gusts of wind causing insects to turn on their sides to simple coincidence. In the early 20th century, it was even suggested that synchronous blinking was nothing more than an optical illusion caused by our own blinking. Later, during research, it was proven that synchronization does occur, but the mechanism has remained a mystery. “What is this, an embedded program in fireflies that makes them synchronize, or the influence of the environment?” – wondered physicist Rafael Sarfati of the University of Colorado at Boulder. By setting up tents and two 360-degree video cameras in the Great Smoky Mountains National Park in Tennessee, researchers were able to observe fireflies for an hour and a half after sunset. They watched as the fireflies first lit up, then began to pulsate synchronously, emitting several consecutive flashes, followed by a pause of a few seconds, and then the cycle repeated. The light from the pulsations dispersed in a wave-like pattern. Scientists also noticed that the swarm of insects hovered about two meters above the ground, mimicking the terrain. But the most interesting thing happened when the researchers started putting individual insects in tents. There, their sense of rhythm immediately disappeared, and although they continued to glow and pulsate, each firefly did so at its own intervals, out of sync with the rhythm of the entire swarm outside. Such a hodgepodge continued until the number of fireflies in the tent exceeded 15-20. But if there were more, synchronization would begin immediately. According to Sarfati, who published the results of his research in the Journal of the Royal Society Interface, it all boils down to the social behavior of insects. When they see what their neighbors are doing, they begin to respond and mimic their actions, just like the waves created by soccer fans in stadiums. But when it comes to the mechanism, the reasons for synchronization are not so clear. According to one theory, males temporarily turn off their bright lantern (whose brightness, by the way, depends on the strength of the sexual attraction of the lustful insect) in order to be able to see their object of attraction – the female, who shines quite dimly. “Such synchronization is observed in many natural systems,” says physicist Orit Peleg of the University of Colorado at Boulder. “The cells in our heart contract synchronously, and neurons in the brain also synchronize. As for the practical application of the discovery of the firefly’s synchronization mechanism, it will certainly be useful, as synchronization is important for many technologies, including robotics, where a swarm of micro-robots can work together to solve a task, much like insects.”