The secrets of evolution unearthed in Highlands

The key moment in the history of life on Earth – the tipping point at which there was enough oxygen in the atmosphere to support the evolution of complex animals and plants – occurred about 400 million years earlier than previously thought, a study has found.

Geologists studying rocks in Scotland believe that oxygen – the vital element for energy-hungry life forms – began to rise to useful concentrations in the Earth's atmosphere about 1.2 billion years ago rather than 800 million years ago, which was suggested by previous studies.

The discovery pushes back the point at which complex organisms could have begun to evolve from the simple microbes that had inhabited the planet for much of its history. But it raises the question: what was the ultimate spark that ignited the evolutionary explosion of life, leading to the immense diversity of species today?

Although the earliest fossil evidence of life on Earth goes back 3.8 billion years, for about 3 billion years of this time, living organisms consisted of simple microbes no more complex than "green slime". It was only relatively recently – less than 1 billion years ago – that life began to evolve into symmetrical, multicellular organisms with complex body plans.

"Our geochemical analyses have provided a clear signal that levels of oxygen in the atmosphere had increased to levels critical to the evolution of complex life – from which we ourselves emerge – much earlier than has been previously proven to date," said Adrian Boyce, of the Scottish Universities Environmental Research Centre in Glasgow.

"This opens the door to a new understanding of the evolution of our planet's atmosphere and the life it sustains," he added. The study, published in the journal Nature, analysed the chemical signatures of bacteria found in rocks near Lochinver in the north-west Highlands of Scotland, which showed that oxygen levels must have increased 1.2 billion years ago to allow certain sulphur-using microbes to exist in high numbers.

"Investigations revealed that these bacteria, which on a basic level use sulphur to obtain energy, were also using oxygen in a much more complex and efficient chemical reaction in order to generate their energy and survive," said Professor John Parnell of Aberdeen University, who led the research team.

He added: "Evidence of this chemical reaction tells us that the levels of oxygen in the atmosphere were at this key point for evolution, at this much earlier stage in Earth's history.

"Our findings, which shift this key point in the evolution of life on Earth to a much earlier date than previously proven, will give impetus to further investigations into the timescale of the development of complex life, which followed this event," he said.

Suggested Topics
Start your day with The Independent, sign up for daily news emails
Life and Style
love + sex
Arts and Entertainment
Victoria Wood, Kayvan Novak, Alexa Chung, Chris Moyles
tvReview: No soggy bottoms, but plenty of other baking disasters on The Great Comic Relief Bake Off
Sport
Ashley Young celebrates the winner for Manchester United against Newcastle
footballNewcastle 0 Man United 1: Last minute strike seals precious victory
Life and Style
Tikka Masala has been overtaken by Jalfrezi as the nation's most popular curry
food + drink
Arts and Entertainment
Seth Rogan is one of America’s most famous pot smokers
filmAmy Pascal resigned after her personal emails were leaked following a cyber-attack sparked by the actor's film The Interview
News
Benjamin Netanyahu and his cartoon bomb – the Israeli PM shows his ‘evidence’
people
ebooks
ebooksA special investigation by Andy McSmith
Arts and Entertainment
80s trailblazer: comedian Tracey Ullman
tv
News
i100
Life and Style
A statue of the Flemish geographer Gerard Kremer, Geradus Mercator (1512 - 1594) which was unveiled at the Geographical Congree at Anvers. He was the first person to use the word atlas to describe a book of maps.
techThe 16th century cartographer created the atlas
Arts and Entertainment
Stephen Tompkinson is back as DCI Banks
tvReview: Episode one of the new series played it safe, but at least this drama has a winning formula
News
i100
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: UI / UX Designer

£25000 - £35000 per annum: Recruitment Genius: This firm are focussed on assis...

Recruitment Genius: General Processor

£7 per hour: Recruitment Genius: A vacancy has arisen for a General Processor ...

Recruitment Genius: Outbound Sales Executive - B2B

£18000 - £22000 per annum: Recruitment Genius: A great opportunity has arisen ...

Recruitment Genius: Online Sales and Customer Services Associate

£14000 - £16000 per annum: Recruitment Genius: Full time and Part time positio...

Day In a Page

War with Isis: Iraq's government fights to win back Tikrit from militants - but then what?

Baghdad fights to win back Tikrit from Isis – but then what?

Patrick Cockburn reports from Kirkuk on a conflict which sectarianism has made intractable
Living with Alzheimer's: What is it really like to be diagnosed with early-onset dementia?

What is it like to live with Alzheimer's?

Depicting early-onset Alzheimer's, the film 'Still Alice' had a profound effect on Joy Watson, who lives with the illness. She tells Kate Hilpern how she's coped with the diagnosis
The Internet of Things: Meet the British salesman who gave real-world items a virtual life

Setting in motion the Internet of Things

British salesman Kevin Ashton gave real-world items a virtual life
Election 2015: Latest polling reveals Tories and Labour on course to win the same number of seats - with the SNP holding the balance of power

Election 2015: A dead heat between Mr Bean and Dick Dastardly!

Lord Ashcroft reveals latest polling – and which character voters associate with each leader
Audiences queue up for 'true stories told live' as cult competition The Moth goes global

Cult competition The Moth goes global

The non-profit 'slam storytelling' competition was founded in 1997 by the novelist George Dawes Green and has seen Malcolm Gladwell, Salman Rushdie and Molly Ringwald all take their turn at the mic
Pakistani women come out fighting: A hard-hitting play focuses on female Muslim boxers

Pakistani women come out fighting

Hard-hitting new play 'No Guts, No Heart, No Glory' focuses on female Muslim boxers
Leonora Carrington transcended her stolid background to become an avant garde star

Surreal deal: Leonora Carrington

The artist transcended her stolid background to become an avant garde star
LGBT History Month: Pupils discuss topics from Sappho to same-sex marriage

Education: LGBT History Month

Pupils have been discussing topics from Sappho to same-sex marriage
11 best gel eyeliners

Go bold this season: 11 best gel eyeliners

Use an ink pot eyeliner to go bold on the eyes with this season's feline flicked winged liner
Cricket World Cup 2015: Tournament runs riot to make the event more hit than miss...

Cricket World Cup runs riot to make the event more hit than miss...

The tournament has reached its halfway mark and scores of 300 and amazing catches abound. One thing never changes, though – everyone loves beating England
Katarina Johnson-Thompson: Heptathlete ready to jump at first major title

Katarina Johnson-Thompson: Ready to jump at first major title

After her 2014 was ruined by injury, 21-year-old Briton is leading pentathlete going into this week’s European Indoors. Now she intends to turn form into gold
Syrian conflict is the world's first 'climate change war', say scientists, but it won't be the last one

Climate change key in Syrian conflict

And it will trigger more war in future
How I outwitted the Gestapo

How I outwitted the Gestapo

My life as a Jew in wartime Berlin
The nation's favourite animal revealed

The nation's favourite animal revealed

Women like cuddly creatures whilst men like creepy-crawlies
Is this the way to get young people to vote?

Getting young people to vote

From #VOTESELFISH to Bite the Ballot