Author Archives: Attention to the Unseen

Ancient space dust hints at a mysterious period in Earth’s early history

pattern3

Rebecca Boyle writes: Geologists tell a pretty broad-brush narrative of Earth’s 4.5 billion-year history. For its first half-billion years, the newly formed planet was a seething ball of lava constantly pelted by giant space rocks, including a Mars-sized object that sheared off a chunk that became the moon. Things calmed down when the Late Heavy Bombardment tapered off some 3.8 billion years ago, but volcanoes ensured Earth’s atmosphere remained a toxic stew of gases with almost no oxygen to speak of. It stayed that way for another billion years, when single-celled bacteria filled the oceans. Around 2.5 billion years ago, at the end of the Archean era, algae figured out how to make energy from sunlight, and the Great Oxygenation Event gave Earth its lungs. Complex life took its time, finally exploding in the Cambrian era some 500 million years ago. Evolution moved a lot faster after that, resulting in dinosaurs, then mammals, then us.

It’s a great story, and scientists have been telling it for decades, but tiny fossilized space pebbles from Australia may upend it entirely, giving us a new narrative about Earth’s adolescence. These pebbles rained down on our planet’s surface 2.7 billion years ago. As they passed through the upper atmosphere, they melted and rusted, making new crystal shapes and minerals that only form where there is plenty of oxygen. A new paper describing the space pebbles will be published today in the journal Nature. It suggests the atmosphere’s upper reaches were surprisingly rich in oxygen during the Archean, when Earth’s surface had practically none.

“If they’re right, a lot of people have had misconceptions, or have been wrong,” says Kevin Zahnle, a planetary scientist at NASA’s Ames Research Center. Moreover, if the research holds up, geologists will have a new mystery on their hands: How did all that oxygen get there, and why didn’t it reach the ground? [Continue reading…]

Facebooktwittermail

Brainless intelligence observed in slime

Phys.org reports: What is intelligence? The definitions vary, but all infer the use of grey matter, whether in a cat or a human, to learn from experience.

On Wednesday, scientists announced a discovery that turns this basic assumption on its head.
A slime made up of independent, single cells, they found, can “learn” to avoid irritants despite having no central nervous system.

“Tantalizing results suggest that the hallmarks for learning can occur at the level of single cells,” the team wrote in a paper published in the journal Proceedings of the Royal Society B. [Continue reading…]

Facebooktwittermail

Humans paid for bigger brains with energy-hungry bodies

Ed Yong writes: Evolution works on a strict energy budget. Each adaptation burns through a certain number of calories, and each individual can only acquire so many calories in the course of a day. You can’t have flapping wings and a huge body and venom and fast legs and a big brain. If you want to expand some departments, you need to make cuts in others. That’s why, for example, animals that reproduce faster tend to die earlier. They divert energy towards making new bodies, and away from maintaining their own.

But humans, on the face of it, are exceptional. Compared to other apes, we reproduce more often (or, at least, those of us in traditional societies do) and our babies are bigger when they’re born and we live longer. And, as if to show off, our brains are much larger, and these huge organs sap some 20 percent of our total energy.

“We tend to have our cake and eat it too,” says Herman Pontzer from Hunter College. “These traits that make us human are all energetically costly. And until now, we didn’t really understand how we were fueling them.” [Continue reading…]

Facebooktwittermail

Music: Can — ‘Future Days’

Can (formed 1968): Irmin Schmidt (keyboards), Holger Czukay (bass), Jaki Liebezeit (drums), Michael Karoli (guitar), Malcolm Mooney then Damo Suzuki (vocals)

… one of the most important bands of the last century.

Can were the archetypal “krautrock” group – ironically, given that much of their best work featured either Malcolm Mooney, an American, or Damo Suzuki, from Japan, as vocalists. Students of Stockhausen, blessed with renegade jazz and classical chops, and fully aware of the possibilities opened up by John Cage, they brought a feverishly questing spirit to rock music.

Rather than the blues roots underpinning most Anglo-American rock, they drew on minimalism, serialism, the churning motor-pulse of the Velvet Underground, and ethnic strains then unheard in Western pop. The result was some of the most striking, individual music ever made.

Facebooktwittermail

One gene can produce many different proteins

Veronique Greenwood writes: The millimeter-long roundworm Caenorhabditis elegans has about 20,000 genes — and so do you. Of course, only the human in this comparison is capable of creating either a circulatory system or a sonnet, a state of affairs that made this genetic equivalence one of the most confusing insights to come out of the Human Genome Project. But there are ways of accounting for some of our complexity beyond the level of genes, and as one new study shows, they may matter far more than people have assumed.

For a long time, one thing seemed fairly solid in biologists’ minds: Each gene in the genome made one protein. The gene’s code was the recipe for one molecule that would go forth into the cell and do the work that needed doing, whether that was generating energy, disposing of waste, or any other necessary task. The idea, which dates to a 1941 paper by two geneticists who later won the Nobel Prize in medicine for their work, even has a pithy name: “one gene, one protein.”

Over the years, biologists realized that the rules weren’t quite that simple. Some genes, it turned out, were being used to make multiple products. In the process of going from gene to protein, the recipe was not always interpreted the same way. Some of the resulting proteins looked a little different from others. And sometimes those changes mattered a great deal. There is one gene, famous in certain biologists’ circles, whose two proteins do completely opposite things. One will force a cell to commit suicide, while the other will stop the process. And in one of the most extreme examples known to science, a single fruit fly gene provides the recipe for more than 38,000 different proteins.

But these are dramatic cases. It was never clear just how common it is for genes to make multiple proteins and how much those differences matter to the daily functioning of the cell. Many researchers have assumed that the proteins made by a given gene probably do not differ greatly in their duties. It’s a reasonable assumption — many small-scale tests of sibling proteins haven’t suggested that they should be wildly different.

It is still an assumption, however, and testing it is quite an endeavor. Researchers would have to take a technically tricky inventory of the proteins in a cell and run numerous tests to see what each one does. In a recent paper in Cell, however, researchers at the Dana-Farber Cancer Institute in Boston and their collaborators reveal the results of just such an effort. They found that in many cases, proteins made by a single gene are no more alike in their behavior than proteins made by completely different genes. Sibling proteins often act like strangers. It’s an insight that opens up an interesting new set of possibilities for thinking about how the cell — and the human body — functions. [Continue reading…]

Facebooktwittermail

Why are your gut microbes different from mine?

Ed Yong writes: There are tens of trillions of bacteria in my gut and they are different from those in yours. Why?

This is a really basic question about the human microbiome and, rather vexingly, we still don’t have a good answer. Sure, we know some of the things that influence the roll call of species — diet and antibiotics, to name a few — but their relative importance is unclear and the list is far from complete. That bodes poorly for any attempt to work out whether these microbes are involved in diseases, and whether they can be tweaked to improve our health.

Two new studies have tried to address the problem. They’re the largest microbiome studies thus far published, looking at 1,135 Dutch adults and 1,106 Belgians respectively. Both looked at how hundreds of factors affect the microbiome, including age, height, weight, sleep, medical history, smoking, allergies, blood levels of various molecules, and a long list of foods. Both found dozens of factors that affect either the overall diversity of microbial species, or the abundance of particular ones. And encouragingly, their respective lists overlap considerably.

But here’s the important thing: Collectively, the factors they identified explain a tiny proportion of the variation between people’s microbiomes — 19 percent in the Dutch study, and just 8 percent in the Belgian. Which means we’re still largely in the dark about what makes my microbiome different from yours, let alone whether one is healthier than the other. [Continue reading…]

Facebooktwittermail