Smarty-pants have 40 new reasons to thank their parents for their powerful brains. By sifting through the genetics of nearly 80,000 people, researchers have uncovered 40 genes that may make certain people smarter. That brings the total number of suspected “intelligence genes” to 52.

Combined, these genetic attributes explain only a very small amount of overall smarts, or lack thereof, researchers write online May 22 in Nature Genetics. But studying these genes, many of which play roles in brain cell development, may ultimately help scientists understand how intelligence is built into brains.
Historically, intelligence research has been mired in controversy, says neuroscientist Richard Haier of the University of California, Irvine. Scientists disagreed on whether intelligence could actually be measured and if so, whether genes had anything at all to do with the trait, as opposed to education and other life experiences. But now “we are so many light-years beyond that, as you can see from studies like this,” says Haier. “This is very exciting and very positive news.”

The results were possible only because of the gigantic number of people studied, says study coauthor Danielle Posthuma, a geneticist at VU University Amsterdam. She and colleagues combined data from 13 earlier studies on intelligence, some published and some unpublished. Posthuma and her team looked for links between intelligence scores, measured in different ways in the studies, and variations held in the genetic instruction books of 78,308 children and adults. Called a genome-wide association study or GWAS, the method looks for signs that certain quirks in people’s genomes are related to a trait.

This technique pointed out particular versions of 22 genes, half of which were not previously known to have a role in intellectual ability. A different technique identified 30 more intelligence genes, only one of which had been previously found. Many of the 40 genes newly linked to intelligence are thought to help with brain cell development. The SHANK3 gene, for instance, helps nerve cells connect to partners.

Together, the genetic variants identified in the GWAS account for only about 5 percent of individual differences in intelligence, the authors estimate. That means that the results, if confirmed, would explain only a very small part of why some people are more intelligent than others. The gene versions identified in the paper are “accounting for so little of the variance that they’re not telling us much of anything,” says differential developmental psychologist Wendy Johnson of the University of Edinburgh.

Still, knowing more about the genetics of intelligence might ultimately point out ways to enhance the trait, an upgrade that would help people at both the high and low ends of the curve, Haier says. “If we understand what goes wrong in the brain, we might be able to intervene,” he says. “Wouldn’t it be nice if we were all just a little bit smarter?”

Posthuma, however, sees many roadblocks. Beyond ethical and technical concerns, basic brain biology is incredibly intricate. Single genes have many jobs. So changing one gene might have many unanticipated effects. Before scientists could change genes to increase intelligence, they’d need to know everything about the entire process, Posthuma says. Tweaking genetics to boost intelligence “would be very tricky.”

Julius Caesar could have stayed home on March 15, 44 B.C. But mocking the soothsayer who had predicted his death, the emperor rode in his litter to Rome’s Forum. There he met the iron daggers of 60 senators.

As he lay in a pool of blood, he may have gasped a final incrimination to his protégé Brutus: You too, my son? Or maybe not. But he certainly would have breathed a dying breath, a final exhalation of some 25 sextillion gas molecules. And it’s entirely possible that you just breathed in one of them.
In fact, calculating the probability of a particle of Caesar’s dying breath appearing in any given liter of air (the volume of a deep breath) has become a classic exercise for chemistry and physics students. If you make a few assumptions about the mixing of gases and the lifetimes of molecules in the atmosphere, it turns out that, on average, one molecule of “Caesar air” — or any other historic liter of air, for that matter — appears in each breath you take.

Author Sam Kean begins his book Caesar’s Last Breath with this exercise, noting that “we can’t escape the air of those around us.” It’s all recycled, and every day we breathe in a bit of our, and Earth’s, history. “The story of Earth,” he writes, “is the story of its gases.”

Kean, author of a best seller about the periodic table, The Disappearing Spoon, then tells that story. As he did in his fascinating portraits of the elements, Kean profiles individual gases such as nitrogen and oxygen primarily through the scientists and entrepreneurs who discovered or sought to harness them. These are quirky men (and they are mostly men) — every bit as obsessed, greedy and brilliant as one could hope for in a page-turner.

Along with lesser-known backstories of textbook heroes such as James Watt, Antoine-Laurent Lavoisier and Albert Einstein (who was surprisingly obsessed with building a better refrigerator), Kean clearly delights in weaving in the unexpected. In the discussion of helium, we learn about Joseph-Michel Montgolfier, the papermaker who was inspired to build the first hot-air balloon as he watched his wife’s pantaloons billowing suggestively above a fire. And in a chapter on the radioactive elements carried in nuclear fallout, there’s Pig 311, a sow that survived a nuclear test blast only to be used as propaganda for the weapons’ supposed safety.

Along the way, Kean threads in the history of Earth’s atmosphere in a surprisingly compelling narrative of geologic history. He steps aside from Lavoisier’s work on life-giving oxygen, for example, to describe the Great Oxygenation Event, which infused the atmosphere a couple billion years ago with a gas that, at the time, was toxic to most living things. The explanations of science here and throughout the book are written clearly and at a level that should be understandable with a high school education. And while they’re straightforward, the explanations have enough depth to be satisfying; by the end of the book, you realize you’ve learned quite a bit.
Even those who rarely read science will enjoy the drama — death, for instance, plays a big role in these stories. Over and over, we learn, men have taken gases’ powers too lightly, or wielded their own power too cruelly, and paid the price. Fritz Haber, for instance, could have died a hero for finding a way to make fertilizer from the nitrogen in air. Instead, he died broke and loathed for his World War I work on gas warfare.

Then there was Harry Truman — not that Truman, but the one who refused to leave his home when scientists warned of an impending volcanic eruption. Truman contended that officials were “lying like horses trot” right up until Mount St. Helens blew searing gases that erased him from the mountainside.

The links between these stories can seem at first as ephemeral as the gases, but together they tell the story of the birth of the atmosphere and humans’ history in it. In the end, like Caesar’s breath, it all comes full circle.

Books about the history of science, like many other histories, must contend with the realization that others have come before. Their tales have already been told. So such a book is worth reading, or buying, only if it offers something more than the same old stories.

In this case, The Oxford Illustrated History of Science offers most obviously an excellent set of illustrations and photographs from science’s past, from various ancient Egyptian papyruses to the Hubble Space Telescope’s ultradeep view of distant galaxies. Some of the images will be familiar to science fans; many others are obscure but apt; nearly all help illustrate various aspects of science’s history.
And yet the pictures, while many may be worth more than 10,000 words, are still just complements to the text. Oxford attempts a novel organization for recounting the story of science: a sometimes hard-to-follow mix of chronological and topical. The first section, “Seeking Origins,” has six chapters that cover ancient Mediterranean science, science in ancient China, medieval science (one chapter for the Islamic world and Europe, one for China), plus the scientific revolution and science in the Enlightenment. The second section, “Doing Science,” shifts to experimenting, fieldwork, biology, cosmology, theory and science communication.
Each chapter has a different author, which has the plus of bringing distinct expertise to each subject matter but the minus of vast divergence in readability and caliber of content. Some chapters (see “Exploring Nature,” on field science) are wordy, repetitive and lack scientific substance. Others (“Mapping the Universe”) are compelling, engaging and richly informative. A particularly disappointing chapter on biology (“The Meaning of Life”) focuses on 19th century evolution, with only a few paragraphs for the life science of the 20th and 21st centuries. That chapter closes with an odd, antiscientific tone lamenting the “huge numbers of people … addicted to antidepressants” and complaining that modern biology (and neuroscience) “threatens to undermine traditional values of moral responsibility.”

Some of the book’s strongest chapters are the earliest, especially those that cover aspects of science often missing in other histories, such as science in China. Who knew that the ancient Chinese had their own set of ancient elements — not the Greeks’ air, earth, water and fire, but rather wood, fire, water, soil and metal?

With the book’s second-half emphasis on how science was done rather than what science found out, the history that emerges is sometimes disjointed and out of order. Discussions of the modern view of the universe, which hinges on Einstein’s general theory of relativity, appear before the chapter on theory, where relativity is mentioned. In fact, both relativity and quantum theory are treated superficially in that chapter, as examples of the work of theorists rather than the components of a second scientific revolution.
No doubt lack of space prevented deeper treatment of science from the last century. Nevertheless the book’s merits outweigh its weaknesses. For an accessible account of the story of pre-20th century science, it’s informative and enjoyable. For more recent science, you can at least look at the pictures.

Ice in space may break out the bubbly. Zapping simulated space ice with imitation starlight makes the ice bubble like champagne. If this happens in space, this liquidlike behavior could help organic molecules form at the edges of infant planetary systems. The experiment provides a peek into the possible origins of life.

Shogo Tachibana of Hokkaido University in Sapporo, Japan, and colleagues combined water, methanol and ammonia, all found in comets and interstellar clouds where stars form, at a temperature between ‒263° Celsius and ‒258° C. The team then exposed this newly formed ice to ultraviolet radiation to mimic the light of a young star.

As the ice warmed to ‒213° C, it cracked like a brittle solid. But at just five degrees warmer, bubbles started appearing in the ice, and continued to bubble and pop until the ice reached ‒123° C. At that point, the ice returned to a solid state and formed crystals.

“We were so surprised when we first saw bubbling of ice at really low temperatures,” Tachibana says. The team reports its finding September 29 in Science Advances.

Follow-up experiments showed fewer bubbles formed in ice with less methanol and ammonia. Ice that wasn’t irradiated showed no bubbles at all.

Analyses traced spikes of hydrogen gas during irradiation. That suggests that the bubbles are made of hydrogen that the ultraviolet light split off methane and ammonia molecules, Tachibana says. “It is like bubbling in champagne,” he says — with an exception. Champagne bubbles are dissolved carbon dioxide, while ice bubbles are dissolved hydrogen.
The irradiated ice took on another liquidlike feature: Between about ‒185° C and ‒161° C, it flowed like refrigerated honey, despite being well below its melting temperature, Tachibana adds.

That liquidity could help kick-start life-building chemistry. In 2016, Cornelia Meinert of the University Nice Sophia Antipolis in France and colleagues showed that irradiated ice forms a cornucopia of molecules essential to life, including ribose, the backbone of RNA, which may have been a precursor to DNA (SN: 4/30/16, p. 18). But it was not clear how smaller molecules could have found each other and built ribose in rigid ice.

At the time, critics said complex molecules could have been contamination, says Meinert, who was not involved in the new work. “Now this is helping us argue that at this very low temperature, the small precursor molecules can actually react with each other,” she says. “This is supporting the idea that all these organic molecules can form in the ice, and might also be present in comets.”

Closing out a series in the NBA Playoffs is never easy, but the task may have gotten more difficult for the Lakers.

In the fourth quarter of a potential closeout game against the Warriors, Anthony Davis was forced to exit the game after taking an inadvertent shot to the head from Warriors center Kevon Looney.

What does this mean for Davis and the Lakers? Here is what we know about his injury and status moving forward.
Anthony Davis injury update
While battling for position on the inside, Davis took an inadvertent elbow from Looney to the side of his head. Davis was taken out of the game, brought back for evaluation, and eventually ruled out for Game 5 with what the Lakers ruled as a head injury.

Here's the play where Davis was injured as well as the aftermath that includes him receiving attention on the bench before being taken to the locker room.
Turner Sports' Chris Haynes reported that Davis was being evaluated at Chase Center, with the possibility of a concussion looming as a potential diagnosis. Haynes added that Davis was brought to the locker room in a wheelchair following his evaluation.

In a later report, Haynes added that Davis "appears to have avoided a concussion and is doing better now," a positive sign for Davis and the Lakers.

Lakers head coach Darvin Ham told reporters that he spoke with Davis, who he said "seems to be doing really good already."
Davis exited Game 5 with 21 points (on 10-of-18 shooting), nine rebounds and three assists in 32 minutes.

Will Anthony Davis play in Game 6?
Davis' availability largely depends on the diagnosis of his injury and whether or not he is dealing with a concussion. If Davis is not diagnosed with a concussion, there is a clear path for him to return to the floor for Game 6.

Here is an excerpt from the NBA's Concussion Policy:
There is just a one-day layoff between Games 5 and 6 of the Western Conference Semifinals series between the Lakers and Warriors.

Lakers vs. Warriors schedule
Here is the schedule for the second-round series between Los Angeles and Golden State, with the final two games airing on the ESPN family of networks.

Fans in the U.S. can watch the NBA Playoffs on Sling TV, which is now offering HALF OFF your first month! Stream Sling Orange for $20 in your first month to catch all the games on TNT, ESPN & ABC. For games on NBA TV, subscribe to Sling Orange & Sports Extra for $27.50 in your first month. Local regional blackout restrictions apply.
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Date Game Time (ET) TV channel
May 2 Lakers 117, Warriors 112 10 p.m. TNT
May 4 Warriors 127, Lakers 100 9 p.m. ESPN
May 6 Lakers 127, Warriors 97 8:30 p.m. ABC
May 8 Lakers 104, Warriors 101 10 p.m. TNT
May 10 Warriors 121, Lakers 106 10 p.m. TNT
May 12 Game 6 TBD ESPN
May 14 Game 7* TBD ABC

Ready for sketch comedy she’s not. But a 14-year-old killer whale named Wikie has shown promise in mimicking strange sounds, such as a human “hello” — plus some rude noises.

Scientists recorded Wikie at her home in Marineland Aquarium in Antibes, France, imitating another killer whale’s loud “raspberry” sounds, as well as a trumpeting elephant and humans saying such words as “one, two, three.”

The orca’s efforts were overall “recognizable” as attempted copies, comparative psychologist José Zamorano Abramson of Complutense University of Madrid and colleagues report January 31 in Proceedings of the Royal Society B. Just how close Wikie’s imitations come to the originals depends on whether you’re emphasizing the rhythm or other aspects of sound, Abramson says.

Six people judged Wikie’s mimicry ability, and a computer program also rated her skills. She did better at some sounds, like blowing raspberries and saying “hello-hello,” than others, including saying “bye-bye.”
Imitating human speech is especially challenging for killer whales. Instead of vocalizing by passing air through their throats, they sound off by forcing air through passageways in the upper parts of their heads. It’s “like speaking with the nose,” Abramson says.

The research supports the idea that imitation plays a role in how killer whales develop their elaborate dialects of bleating pulses. Cetaceans are rare among mammals in that, like humans, they learn how to make the sounds their species uses to communicate.

When it comes to the dimensions of spacetime, what you see may be what you get.

Using observations from the collision of two neutron stars that made headlines in 2017 (SN: 11/11/17, p. 6), scientists found no evidence of gravity leaking into hidden dimensions. The number of observed large spatial dimensions — kilometer-scale or bigger — is still limited to the three we know and love, the researchers report January 24 at arXiv.org.

Just as insects floating on a pond may be unaware of what’s above or below the water’s surface, our 3-D world might be part of a higher-dimensional universe that we can’t directly observe. However, says astrophysicist David Spergel of Princeton University, a coauthor of the new study, “gravity might be able to explore those other dimensions.”
Such extra dimensions might explain some conundrums in physics, such as the existence of dark matter (an as-yet-unidentified source of mass in the universe) and dark energy (which causes the universe’s expansion rate to accelerate), says coauthor Daniel Holz, an astrophysicist at the University of Chicago. “That’s why people get excited about these modifications.”

To look for any hint of leaking gravity, scientists turned to the light and gravitational waves emitted in the neutron star smashup detected on August 17, 2017. The light allowed scientists to find the galaxy where the neutron stars merged. Spergel, Holz and colleagues showed that, given the galaxy’s distance from Earth, the strength of the gravitational waves was as expected. Extra dimensions weren’t stealing, and thus weakening, the observed ripples.

A variety of theories predict extra dimensions of spacetime into which gravity could leak, but the new result applies only to large extra dimensions, Spergel says. That’s because the gravitational waves detected from the neutron star collision have wavelengths of thousands of kilometers. Tiny extra dimensions, smaller than a fraction of a millimeter across, have also been proposed, but they wouldn’t affect such extended ripples.
One theory, proposed in 2000 by a group of theoretical physicists including Georgi Dvali, predicts a type of large extra dimension. The effects of gravity leaking into such dimensions would be visible only over long distances — explaining why gravity on smaller scales, such as the size of the solar system, behaves as if there are three spatial dimensions.

Because the gravitational waves don’t seem to weaken on their trek to Earth, they must travel more than about 65 million light-years before leaking into any potential additional dimension, the researchers concluded in the new study.

But other theories of extra dimensions are unaffected by the result. String theory, which posits that particles are made up of infinitesimal vibrating strings, predicts tiny extra dimensions that are curled up on themselves. “We’re not in any way ruling out string theory,” Spergel says. Another variety of extra spacetime dimension, of potentially infinite size, was proposed by physicists Lisa Randall and Raman Sundrum in 1999 (SN: 9/26/09, p. 22). But such theories also would not be ruled out, because gravity can’t penetrate very far into that type of extra dimension.

Neutron star mergers are “a completely new laboratory of testing gravity,” says Dvali, of Ludwig-Maximilians-Universität in Munich, who was not involved with the research. “This is absolutely fascinating and fantastic.” But, Dvali notes, the type of extra dimension he proposed back in 2000 already seems unlikely on these scales. “I would say there is already an extremely strong constraint on leakage coming from cosmology.” No matter how far we peer out into space, the universe seems to follow the normal laws of gravity in three dimensions.

For now, the dimensions of space remain as simple as 1, 2, 3.

Zeptonewton
ZEP-toe-new-ton n.
A unit of force equal to one billionth of a trillionth of a newton.

An itty-bitty object can be used to suss out teeny-weeny forces.

Scientists used an atom of the element ytterbium to sense an electromagnetic force smaller than 100 zeptonewtons, researchers report online March 23 in Science Advances. That’s less than 0.0000000000000000001 newtons — with, count ‘em, 18 zeroes after the decimal. At about the same strength as the gravitational pull between a person in Dallas and another in Washington, D.C., that’s downright feeble.
After removing one of the atom’s electrons, researchers trapped the atom using electric fields and cooled it to less than a thousandth of a degree above absolute zero (–273.15° Celsius) by hitting it with laser light. That light, counterintuitively, can cause an atom to chill out. The laser also makes the atom glow, and scientists focused that light into an image with a miniature Fresnel lens, a segmented lens like those used to focus lighthouse beams.

Monitoring the motion of the atom’s image allowed the researchers to study how the atom responded to electric fields, and to measure the minuscule force caused by particles of light scattering off the atom, a measly 95 zeptonewtons.

“Pop” goes the knuckle — but why?

Scientists disagree over why cracking your knuckles makes noise. Now, a new mathematical explanation suggests the sound results from the partial collapse of tiny gas bubbles in the joints’ fluid.

Most explanations of knuckle noise involve bubbles, which form under the low pressures induced by finger manipulations that separate the joint. While some studies pinpoint a bubble’s implosion as the sound’s source, a paper in 2015 showed that the bubbles don’t fully implode. Instead, they persist in the joints up to 20 minutes after cracking, suggesting it’s not the bubble’s collapse that creates noise, but its formation (SN: 5/16/15, p. 16).
But it wasn’t clear how a bubble’s debut could make sounds that are audible across a room. So two engineers from Stanford University and École Polytechnique in Palaiseau, France, took another crack at solving the mystery.

The sound may come from bubbles that collapse only partway, the two researchers report March 29 in Scientific Reports. A mathematical simulation of a partial bubble collapse explained both the dominant frequency of the sound and its volume. That finding would also explain why bubbles have been observed sticking around in the fluid.

Shimmering, gelatinous comb jellies wouldn’t appear to have much to hide. But their mostly see-through bodies cloak a nervous system unlike that of any other known animal, researchers report in the April 21 Science.

In the nervous systems of everything from anemones to aardvarks, electrical impulses pass between nerve cells, allowing for signals to move from one cell to the next. But the ctenophores’ cobweb of neurons, called a nerve net, is missing these distinct connection spots, or synapses. Instead, the nerve net is fused together, with long, stringy neurons sharing a cell membrane, a new 3-D map of its structure shows.
While the nerve net has been described before, no one had generated a high-resolution, detailed picture of it.

It’s possible the bizarre tissue represents a second, independent evolutionary origin of a nervous system, say Pawel Burkhardt, a comparative neurobiologist at the University of Bergen in Norway, and colleagues.

Superficially similar to jellyfish, ctenophores are often called comb jellies because they swim using rows of beating, hairlike combs. The enigmatic phylum is considered one of the earliest to branch off the animal tree of life. So ctenophores’ possession of a simple nervous system has been of particular interest to scientists interested in how such systems evolved.

Previous genetics research had hinted at the strangeness of the ctenophore nervous system. For instance, a 2018 study couldn’t find a cell type in ctenophores with a genetic signature that corresponded to recognizable neurons, Burkhardt says.

Burkhardt, along with neurobiologist Maike Kittelmann of Oxford Brookes University in England and colleagues, examined young sea walnuts (Mnemiopsis leidyi) using electron microscopes, compiling many images to reconstruct the entire net structure. Their 3-D map of a 1-day-old sea walnut revealed the funky synapse-free fusion between the five sprawling neurons that made up the tiny ctenophore’s net.
The conventional view is that neurons and the rest of the nervous system evolved once in animal evolutionary history. But given this “unique architecture” and ctenophores’ ancient position in the animal kingdom, it raises the possibility that nerve cells actually evolved twice, Burkhardt says. “I think that’s exciting.”

But he adds that further work — especially on the development of these neurons — is needed to help verify their evolutionary origin.

The origins of the animal nervous system is a murky area of research. Sponges — the traditional competitors for the title of most ancient animal — don’t have a nervous system, or muscles or fundamental vision proteins called opsins, for that matter. But there’s been mounting evidence to suggest that ctenophores are actually the most ancient animal group, older even than sponges (SN: 12/12/13).

If ctenophores arose first, it “implies that either sponges have lost a massive number of features, or that the ctenophores effectively evolved them all independently,” says Graham Budd, a paleobiologist at Uppsala University in Sweden who was not involved in the research.

If sponges emerged first, it’s still possible that ctenophores evolved their nerve net independently rather than inheriting it from a neuron-bearing ancestor, Burkhardt says. Ctenophores have other neurons outside the nerve net, such as mesogleal neurons embedded in a ctenophore’s gelatinous body layer and sensory cells, the latter of which may communicate with the nerve net to adjust the beating of the combs. So, it’s possible they’re a mosaic of two nervous systems of differing evolutionary origins.

But Joseph Ryan, a bioinformatician at the University of Florida in Gainesville, doesn’t think the results necessarily point to the parallel evolution of a nervous system. Given how long ctenophores have been around — especially if they are older than sponges — the ancestral nervous system may have had plenty of time to evolve into something weird and highly-specialized, says Ryan, who was not part of the study. “We’re dealing with close to a billion years of evolution. We’re going to expect strange things to happen.”

The findings are “one more bit of the jigsaw puzzle,” Budd says. “There’s a whole bunch we don’t know about these rather common and rather well-known animals.”

For instance, it’s unclear how the nerve net works. Our neurons use rapid changes in voltage across their cell membranes to send signals, but the nerve net might work quite differently, Burkhardt says.

There are reports of potentially similar systems in other animals, such as by-the-wind-sailor jellies (Velella velella). Studying them in detail, along with nerve nets in other ctenophore species, could determine just how unusual this synapse-less nervous system is.