Archive for the ‘Biology’ Category

Who had the most merciful death on Game of Thrones? Science has an answer

April 13th, 2019
You know nothing, Jon Snow—like, maybe wear a hat when conditions are freezing in the North. Even if it musses up your luscious locks.

Enlarge / You know nothing, Jon Snow—like, maybe wear a hat when conditions are freezing in the North. Even if it musses up your luscious locks. (credit: HBO)

Warning: This story contained some mild spoilers from the first six seasons of Game of Thrones.

The world of Game of Thrones may be fictional, but that doesn't stop its fans from heatedly arguing about all the possible underlying science, because nerd-gassing about one's favorite science fiction is a time-honored tradition. Just how hot is dragon's breath? Is there a real-world equivalent of wildfire? What's the best and worst way to die? And how fast would Gendry have to run back to the wall to send a raven to King's Landing requesting help?

These and other scintillating topics are discussed in a forthcoming book by physicist (and uber-fan) Rebecca Thompson, Fire, Ice, and Physics: The Science of Game of Thrones. The book comes out in October from MIT Press, but as we gear up for the premiere of the final season Sunday night, Thompson graciously gave us a sneak preview into some of the burning science questions she investigated.

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Posted in Biology, books, chemistry, Game of Thrones, Gaming & Culture, HBO, Physics, science, Television | Comments (0)

NASA’s Twins Study: A great control, but a sample size of one

April 11th, 2019
Image of an astronaut with Earth behind him in a window.

Enlarge / Scott Kelly returned from space with a lot of blood and stool samples. They've now told the tale of the changes he underwent during his time on the International Space Station. (credit: NASA)

The US has big plans for putting humans in space. In doing so, it will be building on our experience at the International Space Station, which is approaching the 20th anniversary of the arrival of its first occupants. Some of that experience comes in the form of knowledge of habitation and operations in low gravity. But a large chunk of it is in the form of understanding what time in space does to the human body.

Today, NASA is releasing detailed results of its most audacious experiment yet: sending one half of a pair of identical twin astronauts into space and carefully monitoring both of them for a year. Three years after astronaut Scott Kelly returned to Earth, and a year after some horrifically speculative press coverage, a paper in today's issue of Science provides excruciating detail on the changes Kelly's body experienced over a year in orbit. While many of the problems highlighted in the new paper had been identified previously, the results aren't exactly good news for the US' long-term exploration plan.

Changes

Over the course of many long-term stays in space, the US and Russia have identified a number of health issues caused by extended stays in minimal gravity. Some of them are pretty simple to correct. Without gravity's constant pull, bones and muscles don't experience the resistance that helps keep them robust. A careful exercise plan, however, can minimize these issues. Less easy to minimize is the fact that the body's internal water content shifts upwards—about two liters of fluid move to the upper body over the short term. Among the consequences are eye problems that can persist after the astronaut returns to Earth.

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Posted in Biology, Health, mark kelly, NASA, science, scott kelly, Spaceflight, twins study | Comments (0)

In mice, ecstasy keeps social-developmental window open

April 4th, 2019
Image of a mouse surrounded by hallucinatory lights.

Enlarge (credit: Getty Images / Aurich Lawson)

Referring to a drug as "mind altering" generally refers to its influence on immediate perceptions. But a lot of drugs that have been used for these effects have turned out to be mind altering in a more general sense: they can elicit longer-term changes in how the brain operates. Ketamine, for example, appears to provide rapid and sustained relief from depression.

A study released this week suggests we can shift MDMA, also known as ecstasy, into this category of mind alteration. Researchers have shown that the drug holds a developmental window open, allowing mice to learn social interactions much later in life than they otherwise would.

Social rewards

In humans and other animals, there are points in development when the brain is better able to learn specific things. Young children, for example, are able to pick up languages far more readily than older ones. The window where learning is easy is called a critical period, and these periods can been seen in a number of contexts. We know much less, however, about what opens and closes these developmental windows.

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Posted in Biology, drugs, ecstasy, learning, mdma, neurobiology, science, social rewards | Comments (0)

Scientists say they have deposits formed hours after dino-killing impact

April 2nd, 2019
Image of fossilized fish remains.

Enlarge / A pile of fish trapped in the flood deposits. (credit: UC Berkeley)

The Chicxulub impact is famed for having killed the dinosaurs and most other species alive on Earth at the time, and it left behind a thin layer of dust rich in rare elements. Modeling of the impact has suggested almost too many ways it could have killed: massive tsunamis, a magnitude 11 earthquake, global wildfires and searing heat, months of frigid darkness, acid rain, a massive surge of carbon dioxide, and more. While we've had confirmation that some of these events occurred, we don't have a strong sense of their impact because we haven't found fossils that tell us much about what happened to the ecosystems of the time.

That may have changed, according to a report in PNAS. The paper describes a large deposit residing just under the iridium-rich dust that marks the impact, apparently formed while heavier debris was still falling from the sky. The site, in western North Dakota, contains a mix of fresh and saltwater species, and it seems to have formed when water rushed ashore from what was then a nearby ocean.

On the edge of your sea

At the time of the Chicxulub impact, the Earth looked very different. A long-running hothouse period had likely left the planet without any significant polar ice, meaning extremely high ocean levels. A large area of the US Midwest was underwater as an arm of the oceans formed the Western Interior Seaway, extending from the antecedent of the Gulf of Mexico up to roughly the Canadian border. Its western shores were dotted with valleys cut by rivers that flowed to the nearby ocean.

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Posted in asteroid impact, Biology, chicxulub, dinosaurs, evolution, mass extinction, paleontology, science | Comments (0)

Alligator gar both sucks and chomps to catch its prey, new study finds

March 30th, 2019

Scientists had assumed the alligator gar catches its prey simply by slamming its powerful, tooth-y jaws shut. But according to a new study posted to the pre-print site bioRxiv, the fish also creates a fast, powerful suction force to suck prey into its jaws by moving the bones in its skull and shoulder. The paper is currently undergoing peer review for the Journal of Morphology.

Alligator gar are the largest species in the gar family of freshwater fish, and they can grow as large as 10 feet and 300 pounds. They are often dubbed "living fossils" because their earliest ancestors in the fossil record date back over one hundred million years to the Early Cretaceous period. Once considered a "trash fish," they are primarily found in the southern US (Arkansas, Louisiana, Texas) along the Gulf of Mexico.

They get their colloquial name from the fact that they share a broad snout and long teeth with the American alligator—most other gar have long slender snouts. Because of this, it was assumed that the alligator gar used a similar lateral snap of the jaw for feeding, but according to lead author Justin Lemberg of the University of Chicago, the jaws of the alligator gar have a lot more joints, and hence greater mobility, than their reptile namesakes.

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Posted in alligator gar, Biology, fluid dynamics, hydrodynamics, Physics, science | Comments (0)

Why debts associated with poverty can cause long-lasting problems

March 27th, 2019
Image of stacks of money.

Enlarge (credit: Keith Cooper)

Poverty can be a persistent problem, following families and communities through multiple generations. But the problems don't appear to be genetic. Instead, behavioral scientists have found that poverty and the debt that goes with it actually change people's behavior, including how they respond to monetary decisions. Now, a new study suggests that the problem isn't the amount of debt per se, but rather the challenge of keeping track of multiple debts.

That conclusion came thanks to an accidental experiment set up by a charity that eliminated debts of poor people in Singapore.

Poverty's impact

The debt burden associated with poverty can be extreme. In the US, many families in a low-income group (the bottom 20 percent) spend more than 40 percent of their income simply paying off debts. A number of studies have shown that this level of debt affects people's ability to make decisions, including financial decisions, causing them to focus on short-term income over long-term gains, among other effects. Thus, poverty itself can cause behavioral changes that promote future poverty.

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Posted in Biology, debt, Human behavior, Psychology, science | Comments (0)

Half the species in a new Cambrian fossil site are completely new to us

March 21st, 2019
Very highly detailed impression of a segmented, many legged organism.

Enlarge / The level of detail in some of the fossils is astonishing. (credit: Dongjing Fu et. al.)

The first signs of complex animal life begin in the Ediacaran Period, which started more than 600 million years ago. But it's difficult to understand how those organisms relate to the life we see around us today. Part of this issue is that those fossils are rare, as many rocks of that period appear to have been wiped off the Earth by a globe-spanning glaciation. But another problem is that the organisms we do see from this period aren't clearly related to anything that came after them.

With the arrival of the Cambrian Period about 550 million years ago, all of that changed. In fossil beds like the famed Burgess Shale, we can see organisms that clearly have features of the major groups of life that have persisted to this day. As more collections of fossils become available, we can even watch groups diversify as the Cambrian progressed. But there's still considerable debate over whether these changes represent a true, multi-million-year "explosion" and what environmental changes might have driven this diversification.

We may be on the verge of some big help in answering these questions, as scientists are announcing the discovery of a spectacular deposit of Cambrian fossils from South China. The fossils include dozens of species, half of which we've never seen before, and appear to represent a previously upsampled ecological zone. The preservation is such that soft-bodied creatures like jellyfish, and the softer body parts of creatures with shells, can easily be made out in the rocks. Best yet, the researchers who uncovered the samples suggest that rocks from the same formation are widespread in China.

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Posted in Biology, Cambrian, evolution, fossils, paleontology, science | Comments (0)

Don’t believe the hype: We may never know the identity of Jack the Ripper

March 19th, 2019
Fictional Victorian physician John Stephenson (David Warner) is Jack the Ripper in the 1979 film <em>Time After Time</em>. A new scientific paper claiming to have identified the real Ripper might as well be speculative fiction, say archaeological geneticists.

Enlarge / Fictional Victorian physician John Stephenson (David Warner) is Jack the Ripper in the 1979 film Time After Time. A new scientific paper claiming to have identified the real Ripper might as well be speculative fiction, say archaeological geneticists. (credit: YouTube/Warner Bros.)

A new DNA analysis of stains on a silk shawl that may have belonged to one of Jack the Ripper's victims concluded that the killer was a Polish barber named Aaron Kosminski, according to a paper published last week in the Journal of Forensic Sciences. But other scientists are already calling into question the paper's bombshell conclusions—and they're not exactly mincing words.

Finally putting to rest the identity of one of history's most notorious killers would indeed be very big news, especially for true crime buffs who have followed the Ripper saga for years (so-called "Ripperologists"). The problem is, we've been here many times before. This is just the latest claim to have "proof" of Jack the Ripper's true identity, and while it has all the trappings of solid science, the analysis doesn't hold up under closer scrutiny. Several archaeological geneticists have already spoken out on Twitter and to Science magazine to point out, as Kristina Killgrove writes at Forbes, that "the research is neither new nor scientifically accurate."

On August 31, 1888, police discovered the body of Mary Ann Nichols in Bucks Row in London's Whitechapel district. Her throat had been cut and her abdomen ripped open. Over the next few months, four more women would be murdered in a similar fashion by a serial killer who came to be known as Jack the Ripper: Annie Chapman, Elizabeth Stride, Catherine Eddowes, and Mary Jane Kelly. And then, as abruptly as they began, the murders stopped. (Other murders sometimes attributed to the Ripper are inconclusive; these are the "canonical five.")

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Posted in Biology, DNA analysis, forensics, Genetics, Jack the Ripper, mitochondrial DNA, science, True Crime | Comments (0)

Figuring out how an odd, gutless worm regrows its head (or tail)

March 18th, 2019
Image of orange blobs on a white coral.

Enlarge / Some of the gutless worms (orange) cover a coral. (credit: Samuel Chow )

In the movies, regeneration is the stuff of superheroes like Deadpool, who regrew the lower half of his body through some seriously awkward transitional scenes. Here in reality, regeneration is run-of-the-mill, with lizards and amphibians regrowing limbs and tails while various worms are able to regrow half their entire body. How they manage this has been the subject of extensive study, and we have a fair idea of some of the genes and processes involved. But it's fair to say we don't have a strong idea of how the whole process is coordinated and directed to form all of the needed tissues.

A step in that direction comes from a recent study that takes a strange angle on regeneration. To understand the process, the authors sequenced the genome of a worm that can regenerate into two full organisms after being cut in half. But the worm also happens to be part of a group that contains the closest living relatives of bilateral animals—those with a left and right side. As such, it could provide a fascinating perspective on our own evolution, but it's something the researchers choose to ignore in this paper.

Xena coelo what a?

Most of the animals we're familiar with are bilaterals, which have a left and right side. That includes some creatures (like sea urchins) where the two sides aren't all that obvious. These bilateral animals also start out early in their development as three layers of cells: an outer layer that forms the skin and neural tissue; a central one that forms internal structures like muscles and bone; and an inner layer that goes on to form the lining of the gut.

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Posted in Biology, evolution, regeneration, science, weird worms | Comments (0)

Food innovations changed our mouths, which in turn changed our languages

March 14th, 2019
Close-up photo of a bowl of oatmeal topped with fruit preserves.

Enlarge / Soft grains, dairy, and preserved food may have changed our mouths—and ultimately our languages. (credit: David Lifson / Flickr)

Something deep in the history of the German language pulled speech sounds toward hisses rather than pops. Words like that and ship end with a small popping sound in English, Dutch, and other Germanic languages—but in German, they end in softer s and f sounds—dass, Schiff. Centuries ago, before German was even German, this change was already underway, an example of one of the many small shifts that ends up separating a language from its close cousins and sending it off as its own distinct tongue.

How does change like this happen? One of the major reasons is speech efficiency. Speakers are constantly walking a tightrope between being understood and making speech as easy as possible—over time, this tension pulls languages in new directions. But if efficiency pushed German speakers in this direction, why not Dutch speakers, too? That is, if two languages share a given feature, why does that feature sometimes change in one language but not the other?

A paper published in Science today lays out an intriguing answer: technology might accidentally trigger a change. Changes like agriculture and food-preparation technology changed the arrangement of our teeth—and in turn, the authors suggest, this made certain speech sounds more likely. It's a daring suggestion, flying in the face of well-established linguistic thought. But the authors draw on multiple strands of evidence to support their proposal, which is part of a growing raft of ideas about how culture and environment could play a role in shaping language.

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Posted in Behavioral science, Biology, Linguistics, science | Comments (0)