Meteorites Splashing Into 'Warm Little Ponds' May Have Sparked Life on Earth

 K. D. Pearce
K. D. Pearce

A new study argues that meteorites that landed in volcanic pools of water 4 billion years ago were key to jump-starting life on Earth—a theory proposed by Charles Darwin more than 140 years ago. New analysis from McMaster University in Canada and the Max Planck Institute for Astronomy suggests that meteorites that landed in shallow, stagnant pools of water (or "warm little ponds") on Earth brought the organic materials necessary to create life billions of years ago.

The research, published in the journal PNAS, is based on comprehensive modeling of astronomic, geological, chemical, and biological conditions on Earth as early as 4.5 billion years ago, looking at how RNA could have been formed in dry, intermediate, and wet conditions.

The "warm little pond" hypothesis—a phrase taken from a 1871 letter Darwin wrote to his friend Joseph Hooker—has been studied in labs since the 1950s, when University of Chicago researchers formed amino acids by introducing electric shocks into a flask of water and gases (meant to simulate early Earth's atmosphere).

The hypothesis isn't universally accepted; another candidate for life on Earth could be found in hydrothermal vents at the bottom of the ocean. But some previous studies have supported the warm little pond hypothesis. Still, "no one's actually run the calculation before," lead author Ben Pearce said in a statement. "It's pretty exciting."

The idea is that meteorites that landed in these "warm little ponds" delivered protein building blocks called nucleobases that were necessary to first form RNA, one of the essential building blocks for all known life. Warm little ponds may have created just the right conditions for this to happen. They have wet and dry cycles, which have been shown to boost the process of nucleotides forming chains of RNA. The ponds would periodically dry out, leaving behind a high concentration of minerals, then fill back up again, leading to longer and longer polymers. These long strands of RNA would later begin to self-replicate—the first life on Earth.

The study concludes that based on these models, RNA polymers would have shown up early in Earth's history, some time before 4.17 billion years ago—only a few hundred million years after liquid water first formed on the planet's surface.

The results shouldn't be considered foolproof just yet. This study is based on mathematical models, which aren't quite enough to prove the hypothesis. "Now it's the experimentalists' turn to find out how life could indeed have emerged under these very specific early conditions," co-author Dmitry Semenov said in the statement.

This 'Time-Traveling Illusion' Is Designed to Trick Your Brain

A team of researchers from the California Institute of Technology (Caltech) have designed an illusion that might trick your brain into seeing things that aren’t there, the New Atlas reports.

Dubbed the Illusory Rabbit, it provides instructions that are simple enough to follow. Start playing the YouTube video below and look at the cross in the middle of the screen while also watching for flashes that appear at the bottom of the screen. Most importantly, you’ll want to add up the number of flashes you see throughout the video. (And make sure your volume is up.)

We don’t want to spoil the fun, so before we explain the science of how it works, check out the video and try it for yourself.

Did you see three flashes paired with three beeps? You’re not alone. This is due to a phenomenon called postdiction, which is a little like the opposite of prediction. According to a paper outlining these findings in the journal PLOS ONE, postdiction occurs when the brain processes information retroactively [PDF]. This occurs in such a way that our perception of earlier events is altered by stimuli that come later. In this case, you might think you missed the flash paired with the second of the three beeps, so your mind goes back and tries to make sense of the missing information. That's why you may see an “illusory flash” in the middle of the screen, sandwiched between the two real flashes.

For this reason, the researchers call the mind trick a “time-traveling illusion across multiple senses” (in this case, vision and hearing). It’s successful because the beeps and flashes occur so rapidly—in less than one-fifth of a second. The senses essentially get confused, and the brain tries to fill in the gaps retroactively.

"Illusions are a really interesting window into the brain," the paper’s first author, Noelle Stiles, said in a statement. "By investigating illusions, we can study the brain's decision-making process.” Researchers wanted to find out how the brain “determines reality” when a couple of your senses (in this case, sight and hearing) are bombarded with noisy and conflicting information. When the brain isn’t sure of what’s going on, it essentially makes up information.

“The brain uses assumptions about the environment to solve this problem,” Stiles said. “When these assumptions happen to be wrong, illusions can occur as the brain tries to make the best sense of a confusing situation. We can use these illusions to unveil the underlying inferences that the brain makes."

[h/t New Atlas]

How Did 6 Feet Become the Standard Grave Depth?

iStock
iStock

It all started with the plague: The origins of “six feet under” come from a 1665 outbreak in England. As the disease swept the country, the mayor of London literally laid down the law about how to deal with the bodies to avoid further infections. Among his specifications—made in “Orders Conceived and Published by the Lord Mayor and Aldermen of the City of London, Concerning the Infection of the Plague”—was that “all the graves shall be at least six feet deep.”

The law eventually fell out of favor both in England and its colonies. Modern American burial laws vary from state to state, though many states simply require a minimum of 18 inches of soil on top of the casket or burial vault (or two feet of soil if the body is not enclosed in anything). Given an 18-inch dirt buffer and the height of the average casket (which appears to be approximately 30 inches), a grave as shallow as four feet would be fine.

A typical modern burial involves a body pumped full of chemical preservatives sealed inside a sturdy metal casket, which is itself sealed inside a steel or cement burial vault. It’s less of a hospitable environment for microbes than the grave used to be. For untypical burials, though—where the body isn’t embalmed, a vault isn’t used, or the casket is wood instead of metal or is foregone entirely—even these less strict burial standards provide a measure of safety and comfort. Without any protection, and subjected to a few years of soil erosion, the bones of the dearly departed could inconveniently and unexpectedly surface or get too close to the living, scaring people and acting as disease vectors. The minimum depth helps keep the dead down where they belong.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

This article originally appeared in 2012.

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