【推荐1】In the genetic age, ecologists’ jobs are made much easier by two things. One is that every organism carries its own chemical identity card, in the form of its genome (基因组). The second is that they drop these ID cards everywhere they go. Urine, bits of fur stuck to a hedge, even shed skin cells: all deposit DNA into the environment. Cheap gene sequencing allows scientists to harvest this “environmental DNA” (eDNA) from soil, sand, water and the like, and use it to keep track of which species are living where.

“Every organism,” of course, includes humans. In a paper published on May 15^th in Nature Ecology & Evolution, a group of researchers from America and Europe report that such eDNA surveys pick up large quantities of human DNA as well as the animal sort. That DNA can be read—and potentially matched with individuals—by anyone with the right equipment.   

The researchers did not set out to study “inadvertent human genetic bycatch”, as they call the phenomenon. The work began at the Witney Sea Turtle Hospital in Florida, during an investigation into a viral turtle disease. The researchers sampled water from the turtle’s tanks, as well as from ocean water and beaches upon which the creatures nested, looking for viral DNA.   

They expected to sweep up DNA from other species during their trawl (拖网). What was surprising, according to Jessica Farrell, a biologist at the Witney Hospital and one of the paper’s authors, was just how much human DNA they found. Even though many of their sampling sites were not near towns and cities, they found human genetic material in every sample they examined.   

Interested, they expanded their search. In both Florida and in Ireland they found human DNA in rivers, with concentrations especially high as they flowed through towns. They found it in beach sand, and even in air from rooms in which humans had been working. Human DNA is not quite everywhere: it was not detectable in deep ocean water, or on remote beaches closed to the public. But anywhere that humans are, their DNA appears to be as well.

In one sense, that is unsurprising. But advances in gene-sequencing meant there was enough information in the samples to deduce plenty of things about the humans in question. The researchers could pick out males thanks to DNA from the Y chromo some. They could infer an individual’s ancestry, and even spot mutations (突变) that affect a person’s disease risk. David Duffy, another of the paper’s authors, said the amount and quality of the DNA they recovered “far exceeded” the minimum necessary to be included in America’s database of missing people. Dr Duffy and his colleagues did not try to identify individuals in their study, for moral reasons. But they had no doubt it could be done.

【推荐2】A parent interacting with a baby is a heart-warming and universal scene. The parent speaks in a high-pitched voice — known as “parentese” — as they respond positively to the baby’s babbling and gestures, commonly with eye contact and smiles.

These connections don’t just make for a touching sight. New research from the University of Washington’s Institute for Learning & Brain Sciences（I-LABS）shows they’re important for infant language growth, too.

In a study published April 8 in Current Biology, researchers used a safe and noninvasive brain-imaging technique called MEG, to monitor infant brain activity during social and nonsocial interactions with the same adult. They found that when the adult talked and played socially with a 5-month-old baby, the baby’s brain activity particularly increased in regions responsible for attention — and the level of this type of activity predicted enhanced language development at later ages. This’social’ scenario (场景) was compared with a ‘nonsocial’ scenario in which the adult turned away from the baby to talk to another person. This interaction showed lower activity levels in the same brain areas.

“This is the first study to directly compare infant brain responses to adult-infant social interaction versus nonsocial interaction, and then follow up with the children until they reached the age of 2.5to see how the early brain activation relates to the child’s future language abilities, ”said lead author Alexis Bosseler, research scientist at I-LABS.

The MEG brain-imaging technology allowed the baby to move and interact naturally with the adult, which enabled researchers to track the firing of neurons from multiple areas in the baby’s brain as the adult talked to, played with and smiled at the baby. They then monitored the infant’s brain activity a second time as the adult turned away and paid attention to someone else.

These actions naturally occur every day between adults and babies, and the study showed they have different measurable effects on a baby’s brain. Researchers found that increased neural activity in response to the social interaction at 5months predicted enhanced language development at five later ages: 18,21,24,27 and 30 months.

“The connection between early brain reactions and later language is consistent with scientists’ fascination with the early age period and opens up many new questions that we, and others, will be exploring,” said co-author Andrew Meltzoff.

【推荐2】When it rains, it pours, and when it snows, the lights turn off. Or so it goes in Texas, California. After a winter storm hit the Lone Star State with record snowfall and the lowest temperatures in more than 30 years, millions were left without electricity and heat. At the worst moment on February 16th, 4. 5m Texan households were cut off from power.

Whole skylines, including Dallas's, went dark to save power. Some Texans braved the snowy roads to check into the few hotels with remaining rooms, but the hotels' power went off as they arrived. Others put on skiwear and remained inside, hoping the lights and heat would come back on. Across the state, what were supposed to be “rolling” blackouts (断电) lasted for days. More than 20 people have died in motor accidents, from fires lit for warmth and from carbon - monoxide poisoning after using cars to get warm. The storm has also stopped deliveries of covid - 19 vaccines (疫苗) and may prevent around 1 million vaccinations from happening this week.

Other states, including Tennessee, were also covered in snow, but Texas got the lion's share and broke down completely. Texans are extremely angry that people in America's energy capital cannot count on reliable power. Everyone is asking why.

The short answer is that the Electric Reliability Council of Texas (ERCOT), which operates the grid, did not properly forecast the demand for energy as a result of the storm. Some say that this was nearly impossible to predict, but there were warnings of the seriousness of the coming weather in the previous week, and ERCOT didn't make adequate preparations.

Many Republican politicians were quick to blame renewable energy sources, such as wind power, for the blackouts, but that is not fair. Some wind turbines (涡轮机) did indeed freeze. Natural gas plants broke down, as did the gas supply chain and pipelines. The cold also caused a reactor at one of the state's two nuclear plants to go offline. In short, Texas experienced a perfect storm of equipment failure.

In California, as in Texas, it would help to have additional power generation and energy storage to meet peak (峰值) demand. Weather events that once might have been dismissed as unusual are becoming more common. Without more money put in electricity grids, blackouts will be, too.