Did life begin with a meteorite?

Scientists discover genetic ingredient for creation of man on rock from space

The building blocks of genes have been found in a meteorite, raising the prospect of life originating with the aid of extraterrestrial molecules that came from space more than 3.6 billion years ago.

Scientists have found that the meteorite contains complex organic chemicals which can be used to make self-replicating molecules that are the essential genetic ingredient of all known lifeforms – DNA and RNA.

Although organic molecules such as sugars and amino acids have been found in meteorites before, it is the first time scientists have found evidence for the existence of extraterrestrial compounds that can be used to make genes. The two substances are called uracil and xanthine and they are the precursors of the building-block molecules, known as nucleobases, that help store and transmit genetic information from one generation to the next – one of the vital signs of life.

Scientists found the two building blocks during analysis of a meteorite that fell near the Australian town of Murchison on 28 September 1969. The Murchison meteorite had already been shown to contain sugars and phosphates, two other essential ingredients of DNA and RNA.

"At the compound-class level, you have all the basic components needed to make the buildings blocks of DNA in a single meteorite," said Professor Mark Sephton of Imperial College London, who led the research team. "It's not the compete jigsaw to explain the origin of life, but it is the partial jigsaw. This discovery lends weight to the idea that the building blocks of life came from space."

The origin of life is one of science's greatest unsolved mysteries. Scientists have postulated that it must have begun with simple organic molecules that somehow gained the ability to replicate themselves in a watery environment.

The first fossilised signs of life appear in ancient terrestrial rocks dated to about 3.5 billion years ago and it is known that the Earth suffered a meteorite bombardment between 3.8 and 4.5 billion years ago.

For about 40 years scientists have speculated that these meteorites – fragments of the larger asteroids left over from the origin of the solar system – may have brought the simple organic molecules used by the first lifeforms. The latest discovery of nucleobases in the Murchison meteorite further supports the idea of an extraterrestrial source of the organic molecules necessary for genetic inheritance, said Zita Martins of Imperial College, the lead author of the study, published in the journal Earth and Planetary Science Letters.

"Early life may have adopted nucleobases from meteoritic frag- ments for use in genetic coding which enabled them to pass on successful features to subsequent generations," Dr Martins said.

The analysis of meteorites for signs of life is mired in controversy. However, it is clear that organic molecules of surprising complexity seem to be ubiquitous in space, either on asteroids orbiting the solar system or on meteorites analysed on Earth, said Professor Sephton.

"Because meteorites represent leftover materials from the formation of the solar system, key components for life – including nucleobases – could be widespread in the cosmos," he said.

So where did it all begin?

Primordial soup

First suggested by Charles Darwin and elaborated on by the US chemist Stanley Miller who in 1953 created simple organic molecules in a test-tube.

Hydrothermal vents

These sea-floor volcanic "chimneys" spew out minerals that can react in heat to create the building blocks of life.

Panspermia

The British cosmologist Fred Hoyle first proposed that extraterrestrial microbes could be carried by asteroids and deposited on passing planets.

Divine intervention

Given that Darwinian evolution can explain everything about life but its origins, some believe that the hand of God is needed.

Start your day with The Independent, sign up for daily news emails
PROMOTED VIDEO
News
ebooksNow available in paperback
Life and Style
tech
News
The 67P/CG comet as seen from the Philae lander
scienceThe most important scientific breakthroughs of 2014
Arts and Entertainment
Ian McKellen as Gandalf in The Hobbit: The Battle Of The Five Armies
film
Arts and Entertainment
Sarah Koenig, creator of popular podcast Serial, which is to be broadcast by the BBC
tvReview: The secret to the programme's success is that it allows its audience to play detective
News
Ruby Wax has previously written about her mental health problems in her book Sane New World
people
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Recruitment Genius: Sales Executives - OTE £60,000

£25000 - £60000 per annum: Recruitment Genius: Are you passionate about Custom...

Recruitment Genius: Care Workers Required - The London Borough of Bromley

£15000 per annum: Recruitment Genius: This homecare agency is based in Beckenh...

Recruitment Genius: Sales Executives - OTE £50,000

£25000 - £50000 per annum: Recruitment Genius: Are you passionate about Custom...

Recruitment Genius: Sales Executives - OTE £50,000

£25000 - £50000 per annum: Recruitment Genius: Are you passionate about Custom...

Day In a Page

Homeless Veterans appeal: 'You look for someone who's an inspiration and try to be like them'

Homeless Veterans appeal

In 2010, Sgt Gary Jamieson stepped on an IED in Afghanistan and lost his legs and an arm. He reveals what, and who, helped him to make a remarkable recovery
Could cannabis oil reverse the effects of cancer?

Could cannabis oil reverse effects of cancer?

As a film following six patients receiving the controversial treatment is released, Kate Hilpern uncovers a very slippery issue
The Interview movie review: You can't see Seth Rogen and James Franco's Kim Jong Un assassination film, but you can read about it here

The Interview movie review

You can't see Seth Rogen and James Franco's Kim Jong Un assassination film, but you can read about it here
Serial mania has propelled podcasts into the cultural mainstream

How podcasts became mainstream

People have consumed gripping armchair investigation Serial with a relish typically reserved for box-set binges
Jesus Christ has become an unlikely pin-up for hipster marketing companies

Jesus Christ has become an unlikely pin-up

Kevin Lee Light, aka "Jesus", is the newest client of creative agency Mother while rival agency Anomaly has launched Sexy Jesus, depicting the Messiah in a series of Athena-style poses
Rosetta space mission voted most important scientific breakthrough of 2014

A memorable year for science – if not for mice

The most important scientific breakthroughs of 2014
Christmas cocktails to make you merry: From eggnog to Brown Betty and Rum Bumpo

Christmas cocktails to make you merry

Mulled wine is an essential seasonal treat. But now drinkers are rediscovering other traditional festive tipples. Angela Clutton raises a glass to Christmas cocktails
5 best activity trackers

Fitness technology: 5 best activity trackers

Up the ante in your regimen and change the habits of a lifetime with this wearable tech
Paul Scholes column: It's a little-known fact, but I have played one of the seven dwarves

Paul Scholes column

It's a little-known fact, but I have played one of the seven dwarves
Fifa's travelling circus once again steals limelight from real stars

Fifa's travelling circus once again steals limelight from real stars

Club World Cup kicked into the long grass by the continued farce surrounding Blatter, Garcia, Russia and Qatar
Frank Warren column: 2014 – boxing is back and winning new fans

Frank Warren: Boxing is back and winning new fans

2014 proves it's now one of sport's biggest hitters again
Jeb Bush vs Hillary Clinton: The power dynamics of the two first families

Jeb Bush vs Hillary Clinton

Karen Tumulty explores the power dynamics of the two first families
Stockholm is rivalling Silicon Valley with a hotbed of technology start-ups

Stockholm is rivalling Silicon Valley

The Swedish capital is home to two of the most popular video games in the world, as well as thousands of technology start-ups worth hundreds of millions of pounds – and it's all happened since 2009
Did Japanese workers really get their symbols mixed up and display Santa on a crucifix?

Crucified Santa: Urban myth refuses to die

The story goes that Japanese store workers created a life-size effigy of a smiling "Father Kurisumasu" attached to a facsimile of Our Lord's final instrument of torture
Jennifer Saunders and Kate Moss join David Walliams on set for TV adaptation of The Boy in the Dress

The Boy in the Dress: On set with the stars

Walliams' story about a boy who goes to school in a dress will be shown this Christmas