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By Ewen Callaway of Nature magazine Easter Island’s gargantuan stone statues walked. That is the controversial claim from archaeologists who have demonstrated the feat with a 4.4-tonne model of one of the baffling busts. They describe their work in the Journal of Archaeological Science. Nearly 1,000 statues litter Easter Island’s 163 square kilometers, with the largest weighing 74 tons and standing 10 meters tall. Much about the megaliths is mystery, but few of the enigmas are more perplexing than how the statues were shuttled kilometers from the rock quarries where they were carved....

That’s a tough one. The major drivers of climate change are collective enterprises such as power grids, industry, large-scale agriculture and transportation systems. About half of all greenhouse gas emissions comes from electricity generation and industrial fossil-fuel use. Substantial emissions reductions in these settings most likely will not come from personal actions; they will come from laws and policies such as carbon-pricing systems, revised building codes and supports for green investment....

The sea slug Aplysia californica is not unlike an eggplant. It is big–up to a foot long and six pounds–and bruise-purple from gorging on seaweed. Harass one, and it will emit “a very fine purplish-red fluid,” as Charles Darwin found long ago, “which stains the water for the space of a foot around.” Hardly a jewel of the sea. Yet neuroscientist Eric R. Kandel looked at the slug 50 years ago and saw a gemlike formal simplicity, which he used to help build the foundations of modern neuroscience....

As the familiar battles over evolution education continue to play out in U.S. state legislatures and school boards, other countries are facing very different dynamics. Much of the world lives outside of any law that requires separation of church and state, making creationism trickier to disentangle from public school curricula. Many countries have only recently started taking a systematic look at how the topic of evolutionary theory and biology is addressed in classrooms....

Editor’s note: This story is part of a series of online exclusives about natural phenomena and human endeavors we’d like to see come to an end. They are connected with the September 2010 special issue of Scientific American called “The End.” The meeting of the Convention on International Trade in Endangered Species of Wild Fauna and Flora, or CITES (pronounced “sight-eez”) this past March was a decided defeat for the Atlantic bluefin tuna....

I remember everything about that morning—or as I call it in my mind, in highly scientific terms, the Day That the Shit Totally Hit the Fan. I was getting ready to go to the gym. Usually this was a cause for dread, but that day it was an exciting opportunity to wear the new shorts that had just arrived in the mail. Nothing like shiny new workout gear to get you out and about....

Peering through a microscope at a plate of cells one day, Ralph M. Steinman spied something no one had ever seen before. It was the early 1970s, and he was a researcher at the Rockefeller University on Manhattan’s Upper East Side. At the time, scientists were still piecing together the basic building blocks of the immune system. They had figured out that there are B cells, white blood cells that help to identify foreign invaders, and T cells, another type of white blood cell that attacks those invaders....

Children are notoriously unreliable witnesses. Conventional wisdom holds that they frequently “remember” things that never happened. Yet a large body of research indicates that adults actually generate more false memories than children. Now a new study finds that children are just as susceptible to false memories as adults, if not more so. Scientists may simply have been using the wrong test. Traditionally, researchers have explored false memories by presenting test subjects with a list of associated words (for instance, “weep,” “sorrow” and “wet”) thematically related to a word not on the list (in this case, “cry”) and then asking them what words they remember....

Groundbreaking research on the intersection of climate change and segregation reveals how racist banking practices banned by Congress 52 years ago continue to shape how black and lower-income Americans experience the effects of global warming. Among other things, researchers found that historical “redlining” of minority neighborhoods in more than 100 American cities has placed a heavier burden on residents from extreme heat than other communities, according to the findings published in the journal Climate....

What would you do with an extra pair of hands? The idea might sound unwieldy, like too much of a good thing. But a new study suggests that people can in fact adapt to using additional robotic arms as if the limbs were their own body parts. For decades, scientists have been investigating how human brains act when people manipulate tools. It is now thought that when you pick up a wrench or a screwdriver, your brain interprets it as a substitute for your own hand....

THE GIVERS In the article on the caregiver’s dilemma, Francine Russo offers research-based advice to help family members and friends maintain their own psychological well-being while tending to a loved one who is elderly or disabled. Some of our readers shared comments on Facebook. Shiby Sahadevan writes, “It takes umpteen hours of thoughtful service to keep up the spirits of those who need constant care. Finding your footing and recuperating are not easy unless you are surrounded by family....

It’s enough to make a tea drinker buy an espresso machine. In a new study scientists in Germany report they were able to modify a common age-related defect in the hearts of mice with doses of caffeine equivalent to four to five cups of coffee a day for a human. The paper—the latest addition to a growing body of research that supports the health benefits of drinking coffee—describes how the molecular action of caffeine appears to enhance the function of heart cells and protect them from damage....

As wildfires ravage the west coast, the COVID-19 pandemic continues to exact a toll on the nation as its citizens grapple with the economic fallout and businesses face uncertainty. The country is bracing itself for an even greater host of challenges in the coming months: the onset of the seasonal flu, uncertainty around the availability of a COVID-19 vaccine, underdeveloped telehealth systems, navigating the challenges of online learning and remote work that requires access to a strong digital infrastructure and broadband....

When it comes to home projects, I am a step-by-step kind of girl. I read the instructions from start to finish, and then reread and execute each step. My husband, on the other hand, prefers to study the diagrams and then jump right in. Think owner’s manual versus IKEA instructions. This preference for one approach over another when learning new information is not uncommon. Indeed the notion that people learn in different ways is such a pervasive belief in American culture that there is a thriving industry dedicated to identifying learning styles and training teachers to meet the needs of different learners....

From warmer temperatures to more extreme weather, melting glaciers and rising sea levels, humanity is fundamentally changing the planet by pumping greenhouse gases into the atmosphere, US government scientists said on 3 November in their latest assessment of climate science. The average global temperature has increased by 1 °C since the start of the Industrial Revolution, the 600-page report says — adding that the last 115 years comprise “the warmest period in the history of modern civilization”....

We have been carelessly leaking radio waves into space for 126 years without thinking about the consequences. If there is a neighboring civilization with sensitive radio telescopes within a hundred light years, they might already know about us. How quickly should we expect them to make contact? There are two types of responses that we could anticipate. The faster would involve electromagnetic signals such as radio waves, which move at the speed of light....

Let’s imagine that I suggest you look for lions while we are strolling through the park. For most people reading this, the local park will be an unlikely place to find a lion. If you take my request seriously, you might look around but you would not spend vast amounts of time on the search. If you saw something of a light brown color out of the corner of your eye, you would probably be reluctant to jump up and down, shouting, “I saw one....

If Thwaites Glacier goes, so might the entire West Antarctic Ice Sheet. Thwaites has long been recognized as a linchpin for the massive expanse, which covers an area the size of Mexico and could unleash more than three meters of sea level rise were it all to melt. Thwaites alone is losing 50 billion tons of ice a year, and recent research suggests the glacier has already entered an unstoppable cycle of melt and retreat that has scientists seriously worried....

Most babies are not born on time. Only about 5 percent of newborns make their first appearance on their scheduled due date, according to some estimates. The rest debut in the days or weeks surrounding the much-anticipated event, setting the stage for a lifetime of surprises. Doctors typically predict when an expectant mother will go into labor by asking her to recall the first day of her last period and adding 280 days....

By age five or six, a child’s brain is 90 percent the size of an adult’s, and for a long time scientists thought that the organ’s significant structural growth ended by around 12 years old. Recent research, however, shows that an adolescent’s brain makes dynamic changes around that age as well as during all of the teen years. As Leslie Sabbagh explains in our cover story, “The Teen Brain, Hard at Work,” beginning on page 20, areas involved in planning and decision making experience a spurt of growth at 11 or 12 years and then undergo pruning and reorganization through the early 20s....