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For more than three decades evolutionary psychologists have advanced a simple theory of human sexuality: because men invest less reproductive effort in sperm than women do in eggs, men’s and women’s brains have been shaped differently by evolution. As a result, men are eager for sex whereas women are relatively choosy. But a steady stream of recent evidence suggests this paradigm could be in need of a makeover. “The science is now getting to a point where there is good data to question some of the assumptions of evolutionary psychology,” says social psychologist Wendy Wood of the University of Southern California (U....

For nearly 30 years, the search for a room-temperature superconductor has focused on exotic materials known as cuprates, which can carry currents without losing energy as heat at temperatures up to 164 Kelvin, or –109 C. But scientists say that they have trumped that record using the common molecule hydrogen sulphide. When they subjected a tiny sample of that material to pressures close to those inside Earth’s core, the researchers say that it was superconductive at 190 K (–83 C)....

The U.S. military’s elite forces have always pushed the envelope. And this summer will be no exception, as the Navy deploys SEALs with $2 million of new gear on missions to save hostages, combat pirates, and counter terrorism around the world. What sort of next-generation weaponry, armor, or transportation will the funds provide? None. The cash will pay for solar technology, enabling the SEALs to power up equipment and purify water while on the move, and even refrigerate medical supplies and food....

Scientific American presents Math Dude by Quick & Dirty Tips. Scientific American and Quick & Dirty Tips are both Macmillan companies. Throughout history, circles have symbolized many things: unity, protection, the Sun, infinity, and the Olympic Games, to name a few. Of course, philosophers and symbologists aren’t the only people to have taken an interest in circles. Mathematicians have spent millennia studying them, too. Which is precisely why today’s article is all about circles....

One hundred years ago, on August 15, 1914, the Panama Canal officially opened when the S. S. Ancon steamed through from the Atlantic to the Pacific side. The debut was quieter than intended because it was overshadowed by the widescale war that had just erupted in Europe, where 16 million men under arms were rushing into the fight, and thousands of soldiers had already died in early battles in Belgium and France....

Transgenic peas set off an immune reaction in mice, even though the new gene came from a nonallergenic bean. The cause: a subtly different array of sugar molecules on the gene’s protein. The finding, which abruptly ended a field trial, indicates that modified crops could create unanticipated allergy risks unless they are evaluated case by case. Journal of Agricultural and Food Chemistry, November 16, 2005 Salt cravings may depend on birth weight: smaller babies preferred saltier water than heavier infants did, a fondness that persisted into preschool....

Key concepts Physics Sound waves Membrane Acoustics Harmonics Introduction With summer here you might find yourself at a parade, party or fair sometime soon. While you’re there you will probably be surrounded by sounds of all kinds: fireworks, music and, of course, the famous (or infamous) sound of kazoos! Whether you like them or not, these little noisemakers are a great way to learn about the physics of sound. In this activity you’ll be investigating how kazoos work by building our own!...

BEIJING (Reuters) - China’s drug control agency disputed on Friday U.S. President Donald Trump’s claim that most of the synthetic drug fentanyl at the heart of the U.S. opioid crisis was produced in China. Declaring the crisis a public health emergency, U.S. President Donald Trump said last week he would discuss as a “top priority” stopping the “flood of cheap and deadly” fentanyl “manufactured in China” when he meets President Xi Jinping during his state visit to Beijing next week....

A new study casts doubt on a long-standing belief about the power behind gamma-ray bursts, the most energetic explosions in the universe. Researchers have found that short gamma-ray bursts—those that last a couple of seconds or less—have brighter afterglows than the simple, reigning model of afterglow emission predicts. Gamma-ray bursts (GRBs) are believed to occur when a star that has collapsed into a black hole or a neutron star whips a disk of gas and dust into a pair of powerful jets moving at nearly light speed....

TODAY THE FACTORIES THAT MAKE GASOLINE, diesel and jet fuel are huge clusters of steel pipes and tanks that consume prodigious amounts of energy, release toxic fumes, and run on an exhaustible resource, petroleum. But tomorrow they might be microscopic, and they might run on the garbage hydrocarbons that are all around us—the paper of this magazine, scrap lumber from a construction project, or the leaves you raked off your lawn last month....

Some 3.4 billion years ago, giant meteoroids slammed into a frigid ocean covering Mars’s northern hemisphere. The impacts kicked up enormous waves that raced across the water and swamped the shoreline, research suggests. On the scale of planetary catastrophes, such tsunamis would have dwarfed most Earthly ones. “Imagine this enormous red wave coming towards you, up to 120 metres high,” says Alexis Rodriguez, a Mars researcher at the Planetary Science Institute in Tucson, Arizona....

How does it make my life better? Every game-changing product innovation over the past three decades had a very simple answer to that question. For example, the iPhone gave you the Internet in your pocket. The BlackBerry gave you e-mail on your phone. The Macintosh (and later Windows) gave you a computer you could use without typing in computer codes. Those were game changers. They made big promises, and they delivered....

PHILADELPHIA – Hillary Clinton raced into a sharpening phase of her campaign last night by appealing to anxious Americans in hardscrabble coal towns and Texas borderlands, in the first address by a female major-party nominee for president in U.S. history. Clinton challenged rival Donald Trump on his honesty, temperament and empathy in the pointed speech to an unbridled audience that waved American flags and chanted “Hillary, Hillary, Hillary.” She also described a nation in pain, with too much poverty and unemployment, while promising to fight for disaffected workers, maligned immigrants and underpaid women....

Every month, SCIENTIFIC AMERICAN—the longest-running magazine in the U.S. and an authoritative voice in science, technology and innovation—provides insight into scientific topics that affect our daily lives and capture our imagination, establishing the vital bridge between science and public policy. Key information from this month’s issue: • HEALTH CARE One in five American women use services provided by Planned Parenthood, with three out of four of its patients considered to have low incomes....

Toxic chemicals are accumulating in marine creatures in Earth’s deepest oceanic trenches, the first measurements of organic pollutants in these regions have revealed. “We often think deep-sea trenches are remote and pristine, untouched by humans,” says Alan Jamieson, a deep-ocean researcher at the University of Aberdeen, UK. But Jamieson and his colleagues have found man-made organic pollutants at high levels in shrimp-like crustaceans called amphipods that they collected from two deep-ocean trenches, he told a conference on deep-ocean exploration in Shanghai on 8 June....

Synthetic biologists report the most far-reaching rewiring yet of a bacterial genome. The feat, described today in Science, involved repurposing 3.8% of the base pairs of the bacterium Escherichia coli. The scientists replaced 7 of its 64 genetic codons—sequences that code for amino acids—with others that produce the same components. They were able to reduce the number of codons by synthesizing the DNA in 55 fragments, each of which was 50,000 base pairs long....

Like to kick back for an afternoon siesta? Good news: a new study shows that regular napping may cut your risk of dying from a heart attack or other heart problems. In the largest study to date on the effects of midday snoozing, researchers from the Harvard School of Public Health (HSPH) and the University of Athens Medical School in Greece, tracked 23,681 apparently healthy men and women, ages 20 to 86, for more than six years....

By 2020, 15 million people worldwide will have cancer and nine million of them will be living in developing countries, according to World Health Organization estimates. Harvard University physician and medical anthropologist Paul Farmer is determined to ensure that prediction doesn’t come true. Farmer, a pioneer in global health, has a history of tackling big problems. His Ph.D. dissertation on HIV in Haiti ran to 1,000 pages, leading Harvard to impose a cap....

At the nation’s top nuclear weapons labs and plants, safety mishaps have imperiled life and limb, and hindered national security operations. This Scientific American story is part of a one-year investigation by reporters at the Center for Public Integrity that reveals many problems and little accountability. In addition to the Nevada accidents, a near-fission calamity in 2011 at Los Alamos National Laboratory in New Mexico led to an exodus of nuclear safety engineers and a four-year shutdown of operations crucial to the nation’s nuclear arsenal....

The February 3 Metro-North crash site in Westchester County, N.Y., resembles hundreds of thousands of at-grade railroad crossings around the country. The train tracks and the road are on the same level, and only an arm gate with flashing lights signals drivers that a train is approaching and prevents them from crossing the tracks. When a Metro-North commuter train, which had departed from Grand Central Station in New York City, collided with a sport utility vehicle that was on the tracks at a Valhalla, N....