Meteorite impacts leave behind time-capsules of ecosystems

Glass beads that form inside hot meteors as they fall to Earth capture particles from the atmosphere, creating a kind of permanent record of historic climates.

Meteorite impacts can be very destructive. One that fell in Mexico around 66m years ago created a 180km crater and caused the extinction of dinosaurs while spewing debris and molten rock into the air. Now, in what is a fascinating tale of serendipity, researchers have found that these events don’t entirely destroy all traces of life at the site of impact. Molten rocks can capture and preserve organic matter as they cool down to form glass beads.

When a meteor enters Earth’s atmosphere, the air around the meteor gets very quickly compressed causing it to heat up, scorching everything in its path. Most of the time that is where the story ends, as the meteor burns up in the sky as a “shooting star”. But sometimes it is big enough to reach all the way to the surface and transfer its remaining energy to the ground.

This energy is dissipated, as mild earthquakes, sound shockwaves – but mostly as heat. The heat energy can be so great that it melts rocks on the surface and hurls them up in the atmosphere. Anything that comes in contact with this molten rock would presumably get burnt, leaving nothing but rocky material that cools down in the atmosphere, forming glass beads and tektites (gravel-sized natural glass). This is what City University of New York researcher Kieren Howard assumed, but he was able to show that his assumptions were wrong.

For his PhD, Howard was studying the glass beads and tektites found near the Darwin crater in Tasmania. The 1.2km wide crater was created by a meteorite impact about 800,000 years ago.

The natural glass formed during cooling is (as implied by the term glass) not crystalline. Instead of a regular arrangement of atoms, the atoms inside it are randomly arranged. Howard’s analysis, however, kept showing the presence of crystals. At first, he dismissed this as a problem with the machine or with his method of analysis. But when it kept showing up, as a good scientist, he thought he should ask an expert to look at his data.

“This is unusual,” says Chris Jeynes, a physicist at the University of Surrey. “If there were indeed crystals, then it was the result of uneven cooling, which can occur when something gets trapped inside these glass beads.”

Jeynes used proton-beam analysis, a method to peer inside the glass to reveal its elemental make-up. Inside he found carbon. “Howard had no idea what his samples were, and he was very surprised when I told him,” Jeynes says.

The natural glass formed should contain only silicon, titanium, oxygen and other metallic elements in trace amounts. Detection of carbon meant that there was some organic matter inside. The only hypothesis was that, somehow during the formation of these glass beads, they captured organic matter that was floating in the atmosphere. That organic matter might have already been in the air, but it might also include material thrown up by the impact.

Howard then went to another expert to break open these glass beads and reveal what the carbon-rich matter was. It turned out that it included were cellulose, lignin and other biopolymers. This meant that somehow this matter, which originated from plants, had survived the temperature of more than 500°C, which is what the molten rock would have reached before cooling into a glass bead. Usually these temperatures will break down the organic matter, but clearly it didn’t in this case.

Mark Sephton, a geochemist at Imperial College London, was surprised and pleased: “What the results show is that these glass beads can capture an aliquot of the atmosphere of the planet at impact. It is like a time capsule of that ecosystem.” These results are published in Nature Geoscience.

The implications are enormous. It shows that other meteorite impacts, like the one that wiped out the dinosaurs, could have created such time capsules too. Sephton is now working on finding glass beads from other impact sites to reveal information about Earth’s ancient atmosphere.

This method of analysis means that we could also go looking for similar beads on other planets, like Mars, where meteorite impacts are common. They could also reveal vital information about the past atmosphere of those planets. Maybe they captured organic matter – if it ever existed there.

“We would not know any of this if it wasn’t for Howard,” Jeynes says, adding that Howard’s persistence to find out what “the wrong results” led the researchers to a phenomenon that nobody knew existed.

This article was originally published at The Conversation. Read the original article.

The Conversation

Meteor Crater in Arizona. (Photo: Angle Schatz/Flickr)
NORBERT MILLAUER/AFP/Getty Images
Show Hide image

Brain training: exposing the myth behind cognitive-enhancement games

A new study indicates that any benefits gained from brain games may be down to the placebo effect.

If you’ve ever searched for a quick-fix to mental lethargy, it’s likely that you’ve browsed through your smartphone app store to take a look at the latest offerings of brain-training games.

I certainly have. These games have been designed to sharpen people’s mental acuity, while offering “scientifically proven” means for improving IQs; through a variety of mini-games and careful documentation of improvements to intelligence parameters, people would wield the tools needed to craft the desired, smarter minds that the apps promise.

And the market for them has showed no sign of slowing down. In the space of a few years, the demand for the apps has made the industry a billion-dollar one, with growth expected to continue. A couple of the most popular apps have included Lumosity, a web-based program boasting more than 50m users seeking to “improve memory, attention, flexibility, speed of processing and problem solving”, and mobile-based Peak, whose similar goals and striking visuals entice potential users.

Though the apps have had huge amounts of success, there is a new body of research emerging to suggest that the successes may not be as a result of the games themselves, but because of the placebo effect.

The placebo effect is a phenomenon in which a dummy treatment or process can cause significant changes in a person – simply because that person believes the placebo (posing as a real treatment) will help them. With medication, it can be the mere presentation of a sugar pill disguised as a medicine which can cause a patient to get better. And in the case of apps and games, it seems that anything which promises users cognitive benefit, is more likely to do so.

In a study entitled “Placebo effects in cognitive training” published on Monday in the journal Proceedings of the National Academy of Sciences, researchers found that participants who engaged in brain-training games for a single, one hour session showed improvements in IQ by up to ten points, but only if they believed the games would benefit them.

The group of cognitive scientists from George Mason University, Virginia, set up the experiment in a particular way to determine whether or not the placebo effect was involved.

50 participants were recruited, after two different posters asking people to sign up to a study were plastered around campus: one labelled “brain training & cognitive enhancement” and the other “email today & participate in a study”. The rewards for the former promised boosts in intelligence, while rewards for the latter granted study credits. Unknown to participants, however, was that both tests were the same, meaning any resulting changes to IQ were as a result of what participants were telling themselves about the tests.

The tests centred around the engagement of working memory and other factors to impact fluid intelligence – a type of intelligence which revolves around the application of logic and reason, independent of acquired knowledge. Those who chose to sign up to the “brain training & cognitive enhancement” study, aka the placebo study, were the ones to show remarkable gains in IQ after completing a post-brain games IQ test; gains of five to ten IQ points being made. Those who signed up for the control showed no signs of improvement.

Speaking to the Huffington Post, researcher and co-author of the study Cyrus Foroughi said: “Placebos are very pervasive and they have to be controlled for in a tremendous number of fields. This field is no different. So we put together the study to actually test whether expectation for a positive effect can lead to a positive outcome.”

Within the scientific community, frustration had already mounted as a result of the falsely promoted uses of brain games, particularly as tools to reverse age-related, cognitive-faltering illnesses such as Alzheimer’s disease. Overstated claims through advertising were enough to encourage scientists to sign an open letter in 2014, condemning the inaccurately purported benefits of brain training games. Earlier this year, Lumosity was fined $2m by the Federal Trade Commission for deceiving consumers with “unfounded claims”.

The recent findings strengthen this position, as the effects of cognitive training games seem less to do with the content of the games themselves, and more to do with what users tell themselves will happen after a session of, brain-training puzzle bonanzas. That’s not to say the games themselves don’t offer some benefit – it’s just that further clarification is needed to understand what they exactly contribute to, with the placebo effect factored in.

While scientists expand on their research to pinpoint the real effects of brain games, it seems for now that the best options to keep our brains active are the ones we are most familiar with: learn a language, do some exercise, or maybe just read a book.