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2017

In ‘Enormous Success,’ Scientists Tie 52 Genes to Human Intelligence
New York Times, May 22, 2017
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In a significant advance in the study of mental ability, a team of European and American scientists announced on Monday that they had identified 52 genes linked to intelligence in nearly 80,000 people.

These genes do not determine intelligence, however. Their combined influence is minuscule, the researchers said, suggesting that thousands more are likely to be involved and still await discovery. Just as important, intelligence is profoundly shaped by the environment.

Still, the findings could make it possible to begin new experiments into the biological basis of reasoning and problem-solving, experts said. They could even help researchers determine which interventions would be most effective for children struggling to learn.

“This represents an enormous success,” said Paige Harden, a psychologist at the University of Texas, who was not involved in the study.

To Simulate Climate Change, Scientists Build Miniature Worlds
New York Times, May 11, 2017
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Climate change will alter the ecosystems that humanity depends upon in the coming century. But given the complexity of the living world, how can you learn what may happen?

A team of Australian scientists has an answer: miniature ecosystems designed to simulate the impact of climate change. The experiments are already revealing dangers that would have been missed had researchers tried to study individual species in isolation.

“If you just take one fish and put it in a tank and see how it responds to temperature, you can imagine that’s a huge simplification of reality,” said Ivan Nagelkerken, an ecologist at the University of Adelaide who is leading the research effort.

Humans Lived in North America 130,000 Years Ago, Study Claims
New York Times, April 26, 2017
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Prehistoric humans — perhaps Neanderthals or another lost species — occupied what is now California some 130,000 years ago, a team of scientists reported on Wednesday.

The bold and fiercely disputed claim, published in the journal Nature, is based on a study of mastodon bones discovered near San Diego. If the scientists are right, they would significantly alter our understanding of how humans spread around the planet.

The earliest widely accepted evidence of people in the Americas is less than 15,000 years old. Genetic studies strongly support the idea that those people were the ancestors of living Native Americans, arriving in North America from Asia.

If humans actually were in North America over 100,000 years earlier, they may not be related to any living group of people. Modern humans probably did not expand out of Africa until 50,000 to 80,000 years ago, recent genetic studies have shown.

Why Are Some Mice (and People) Monogamous? A Study Points to Genes
New York Times, April 19, 2017
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The oldfield mouse doesn’t seem extraordinary. With soulful black eyes and tiny teacup ears, the rodent lives a humdrum life scurrying about meadows and beaches in the Southeast.

But field biologists have long known that when it comes to sex and family life, this mouse is remarkable: Peromyscus polionotus is monogamous — an exception among mammals — and a solicitous parent.

Fathers and mothers will dig burrows together and build elaborate nests when pups are on the way; after they’re born, the father will help tend to the pups, retrieving them when they fall out of the nest, licking them, and huddling to keep them warm.

In a pioneering study published on Wednesday in the journal Nature, researchers at Harvard University identified a genetic basis for this distinctive behavior. It is the first time that scientists have linked DNA to variations in parenting habits among mammals.

Antarctic Ice Reveals Earth’s Accelerating Plant Growth
New York Times, April 5, 2017
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For decades, scientists have been trying to figure out what all the carbon dioxide we have been putting into the atmosphere has been doing to plants. It turns out that the best place to find an answer is where no plants can survive: the icy wastes of Antarctica.

As ice forms in Antarctica, it traps air bubbles. For thousands of years, they have preserved samples of the atmosphere. The levels of one chemical in that mix reveal the global growth of plants at any point in that history.

“It’s the whole Earth — it’s every plant,” said J. Elliott Campbell of the University of California, Merced.

A New Form of Stem-Cell Engineering Raises Ethical Questions
New York Times, March 21, 2017
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As biological research races forward, ethical quandaries are piling up. In a report published Tuesday in the journal eLife, researchers at Harvard Medical School said it was time to ponder a startling new prospect: synthetic embryos.

In recent years, scientists have moved beyond in vitro fertilization. They are starting to assemble stem cells that can organize themselves into embryolike structures.

Soon, experts predict, they will learn how to engineer these cells into new kinds of tissues and organs. Eventually, they may take on features of a mature human being.

In the report, John D. Aach and his colleagues explored the ethics of creating what they call “synthetic human entities with embryolike features” — Sheefs, for short. For now, the most advanced Sheefs are very simple assemblies of cells.

How Did Aboriginal Australians Arrive on the Continent? DNA Helps Solve a Mystery
New York Times, March 8, 2017
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Human skeletons and archaeological remains in Australia can be traced back nearly 50,000 years before the trail disappears. Before then, apparently, Australia was free of humans.

So how did people get there, and when? Where did humans first arrive on the continent, and how did they spread across the entire landmass?

Answers to some of these questions are stored in the DNA of Aboriginal Australians. A genetic study of 111 Aboriginal Australians, published on Wednesday, offers an interesting — and, in some respects, unexpected — view of their remarkable story.

All living Aboriginal Australians descend from a single founding population that arrived about 50,000 years ago, the study shows. They swept around the continent, along the coasts, in a matter of centuries. And yet, for tens of thousands of years after, those populations remained isolated, rarely mixing.

Scientists Say Canadian Bacteria Fossils May Be Earth’s Oldest
New York Times, March 1, 2017
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They are microscopic artwork: tiny tubes and long filaments, strange squiggles etched into some of the most ancient rocks known.

On Wednesday, researchers reported that these may be the oldest fossils ever discovered, the remains of bacteria thriving on Earth not long, geologically speaking, after the very birth of the planet. If so, they offer evidence that life here got off to a very early start.

But many experts in the field were skeptical of the new study — or downright unconvinced.

Martin J. Van Kranendonk, a geologist at the University of New South Wales, called the patterns in the rocks “dubiofossils” — fossil-like structures, perhaps, but without clear proof that they started out as something alive.

Disappearing Seagrass Protects Against Pathogens, Even Climate Change, Scientists Find
New York Times, February 16, 2017
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Every continent save Antarctica is ringed by vast stretches of seagrass, underwater prairies that together cover an area roughly equal to California.

Seagrass meadows, among the most endangered ecosystems on Earth, play an outsize role in the health of the oceans. They shelter important fish species, filter pollutants from seawater, and lock up huge amounts of atmosphere-warming carbon.

The plants also fight disease, it turns out. A team of scientists reported on Thursday that seagrasses can purge pathogens from the ocean that threaten humans and coral reefs alike. (The first hint came when the scientists were struck with dysentery after diving to coral reefs without neighboring seagrass.)

But the meadows are vanishing at a rate of a football field every 30 minutes. Joleah B. Lamb, a postdoctoral researcher at Cornell University and the lead author of the new study, said she hoped it would help draw attention to their plight.

The Purpose of Sleep? To Forget, Scientists Say
New York Times, February 2, 2017
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Over the years, scientists have come up with a lot of ideas about why we sleep.

Some have argued that it’s a way to save energy. Others have suggested that slumber provides an opportunity to clear away the brain’s cellular waste. Still others have proposed that sleep simply forces animals to lie still, letting them hide from predators.

A pair of papers published on Thursday in the journal Science offer evidence for another notion: We sleep to forget some of the things we learn each day.

In order to learn, we have to grow connections, or synapses, between the neurons in our brains. These connections enable neurons to send signals to one another quickly and efficiently. We store new memories in these networks.

Most Primate Species Threatened With Extinction, Scientists Find
New York Times, January 18, 2017
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Our fellow primates are in trouble.

In a study of unprecedented scope, a team of 31 primatologists has analyzed every known species of primate to judge how they are faring. The news for man’s closest animal relatives is not good.

Three-quarters of primate species are in decline, the researchers found, and about 60 percent are now threatened with extinction. From gorillas to gibbons, primates are in significantly worse shape now than in recent decades because of the devastation from agriculture, hunting and mining.

“I think we’re going to get quite a number of extinctions within next 50 years if things go on the way they are,” said Anthony B. Rylands, a senior research scientist at Conservation International and a co-author of the new study, which was published in Science Advances.

On Long Migrations, Birds Chase an Eternal Spring
New York Times, January 5, 2017
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Bird migrations have stumped the greatest minds for thousands of years. Aristotle thought that the robins living in Greece in the winter somehow turned into redstarts in the summer. In fact, robins migrate from Greece to Northern Europe around the time redstarts arrive from Africa.

Scientists have gotten a much better understanding of bird migration in recent centuries, but there’s a tremendous amount they have yet to learn. After tracking more than three dozen birds with sensors for thousands of miles, a team of researchers reported on Wednesday that their migration defied the expected course.

Instead of simply flying straight from their summer grounds in Denmark to their winter site in Africa, the birds stretched out their journey, stopping at several places along the way for weeks at a time.

“It’s more of a nomadic life,” said Kasper Thorup, a bird migration expert at the University of Copenhagen and co-author of the new study. “They hardly have a place to call home.”

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