Scientists have found traces of the sugar called ribose in meteorites. Since ribose is a building block of living organisms, this discovery sheds light on the origin of life on earth. Find out more.
A lot of great astronomical discoveries have been made by amateurs. These include Thomas Herschel’s discovery of the planet Uranus and the spectacular Comet Hale-Bopp, which Alan Hale and Thomas Bopp discovered independently in 1995.
In fact, amateur comet discovery is a proud tradition in astronomy. One reason might be that the powers that be name comets after the first person to spot them. That’s quite an incentive. Amateur astronomer Don Machholz holds the lifetime record with twelve comets to his name.
Those guys are way out of my league. Even so, I can lay claim to one “once in a lifetime discovery.” While casually stargazing at the cottage, I once saw a fireball. A fireball is a remarkably bright meteor. Very few people are lucky enough to experience one because they happen so fast. The odds are that I’ll never see one again.
IN THE BLINK OF AN EYE, IT LIT UP THE NIGHT SKY
They’re called fireballs because they usually come with flames. Mine certainly did. In the blink of an eye, it lit up the entire night sky. Then it vanished. The meteor causing a fireball can be a metre or more in diameter.
I reported the fireball to the Meteorites and Impacts Advisory Committee (MIAC). Unfortunately, based on its trajectory, the meteorite would have landed in the middle of Lake Huron. There was no practical way to track it down. And so I was robbed of my fifteen minutes of fame. I’m over it.
Some other meteorites were vastly more newsworthy a couple of weeks ago. A research team from Japan led by Yoshihiro Furukawa of Tohoku University analyzed three meteorites and discovered ribose and other sugars in two of them. They could tell by their carbon isotopes that these sugars did not form on earth. They published their findings in the Proceedings of the National Academy of Sciences.
WASN’T A WALK IN THE PARK – CALLED FOR CREATIVITY
This wasn’t a walk in the park, and it called for some creativity. As lead author, Yoshihiro Furukawa put it, “Analysis of sugars in meteorites is so difficult. Over the past several years, we have investigated the techniques of sugar analysis in such samples and constructed our original method.”
Why are scientists so excited about a bit of sugar in a couple of space rocks? First of all, sugars are essential molecules for every organism on earth.
The sugar called ribose is known as a building block for RNA, and RNA may have played a role in both storing information and as a chemical catalyst on the early earth. The sugars in these meteorites are forms of ribose and other sugars essential to life.
BUILDING BLOCKS OF LIFE IN METEORiteS
Scientists have discovered other building blocks of life in meteorites before. These have included amino acids, nucleobases, and phosphate. They’ve even found an amino acid in a comet.
Until now, researchers haven’t been clear on whether sugars might form in outer space. This discovery suggests that they can and do. In fact, these sugars developed both before and after the asteroids from which the meteors broke away had formed.
Finding ribose in meteorites proves that there is a natural way to make and preserve it outside the earth. That means that multilayered molecules like RNA on earth likely formed out of sugars from space.
REasonable to expect to find these sugars on mars
Even more intriguing, it means that that there’s no reason it couldn’t have happened on other planets as well. In particular, it would be reasonable to expect to find these sugars on Mars.
Scientists who study the origin of life have a hypothesis they call the RNA World. The basic idea came from Alexander Rich in 1962, although Walter Gilbert came up with the name for it in 1966. The idea is that at one stage in the evolution of life on earth, RNA was the self-replicating structure behind all living organisms, not DNA.
It’s an idea with broad support among biologists and with good reason. RNA is very similar to DNA. Like DNA, RNA can store sequential information, and its enzymes called ribozymes can play the same role as DNA’s protein enzymes.
rna MAY HAVE PLAYED the same role as dna
These ribozymes can act as catalysts for vital chemical reactions, just as DNA’s protein enzymes do. If you remember your high school biology, you will have heard the term ribosome. All we need to recall is that ribosomes are critical parts of cells. For our topic here, the point is that they’re made mostly from RNA even today.
What’s more, scientists see ribose (the “R” in RNA) but no deoxyribose (the “D” in DNA) in the natural ways that sugars form in space. That suggests that there must have been far more ribose than deoxyribose on the early earth.
So this discovery from the meteorites is consistent with the theories behind the RNA World hypothesis. It’s always a good sign when a hypothesis accurately predicts the results of independent research from other fields.
NEED TO KNOW HOW THE WEB OF LIFE BEGAN
More and more of us are realizing that we are not separate from the natural world. We are interwoven into the web of life. That means that to understand ourselves, we need to know how the web of life began.
In an earlier story, we talked about Carl’s Sagan’s famous saying, “We are made of star-stuff.” Now we’re learning that not only the chemical elements but many of the complex molecules we’re made of formed in space rather than here on earth. We’re inseparable from the natural world. We’re also inseparable from the whole universe.
The research team now plans to look for sugars in more meteorites. One thing they want to understand better is why the space sugars aren’t symmetrical like earth sugars. This leads them to ask how the space sugars influenced the symmetrical sugars we find in our natural world.
We always have more to learn if we dare to know.
Extraterrestrial ribose and other sugars in primitive meteorites
Meteorites and Impacts Advisory Committee
Origin of Life Before Origin of Species – 4 Theories
Life Began Even Earlier Than Thought
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