DNA is much more than some weird-looking string – it’s the code to all life on Earth.
Your cells use it to make proteins, as do the cells of the tree in your garden, the birds roosting on it and the fruit you’ve topped your granola with.
But Japanese scientists say they’ve discovered an asteroid zooming around our solar system with all the ingredients to make life.
Researchers discovered this by analysing pinches of grit collected from Ryugu, a 3,000-foot-wide space rock shaped like a spinning top, in 2018.
A wealth of organic molecules – including the building blocks of life adenine, guanine, cytosine, thymine and uracil – were found inside the millimetre-wide rubble.
The first four are present in DNA, while uracil is unique to RNA, a similar life-forming molecule that cells copy genes from DNA to.
Where these five ingredients come from is a mystery – solving it could mean learning how life actually formed on Earth.
The team wrote in a paper published in Nature Astronomy that life may have come from primordial grey dirt like Ryuga.
Scientists have long suggested that everything we need to make life was already in our solar neighbourhood some 4.6 billion years ago.
At the time, a messy cloud of dust and ice was swirling around the sun, which was mashed into planets and asteroids.
Ryugu, which is nearly 111,000,000 miles away from Earth, formed about 5.2 million years after the birth of the solar system.
The carbon-rich rock is called a carbonaceous chondrite, meaning experts think it formed in the outer part of the solar system.
Ryugu, in other words, is a time capsule of what materials were around billions of years ago that could have formed our planet.
To peek inside, the Japanese Aerospace Agency’s Hayabusa 2 spacecraft flew to it to prick some samples and brought them back to Earth in 2020.
Did… we just discover the origin of life?
Jane Ollis, a medical biochemist not involved in the research, isn’t so sure.
She told Metro that the chemicals in Ryugu are called nucleobases.
‘Nucleobases are relatively simple organic compounds that can form through basic chemistry under the right conditions,’ she says.
‘We’ve seen similar molecules in meteorites before, so their presence isn’t entirely surprising.’
NASA recovered the same set of nucleobases from an asteroid named Bennu in 2023.
Compounds lurking in cosmic minerals are certainly a big deal, Ollis says, but they’re only part of the picture.
‘DNA itself isn’t alive, it’s just a molecule,’ the founder of neurotech company SONA stresses.
‘For life to emerge, you need a highly organised system capable of storing information, replicating it reliably and maintaining itself.
‘The leap from loose chemical ingredients to a functioning, self-sustaining system is enormous and still poorly understood.’
Ollis added: ‘DNA on an asteroid does not mean we’ve found life, or even direct evidence that life exists elsewhere.’
It’s not only biological precursors that asteroids may have delivered to Earth – water, too.
Four million years ago, Earth was pummeled by so many asteroids that historians call it the late bombardment.
Some of these giant rocks may have had water locked inside. This even includes Ryugu, with earlier tests suggesting it was once made from ice, which melted, forming chemical reactions.
Some scientists have proposed that we could owe our lives – literally – to water, as life may have started in deep-sea vents.
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