Change of air: how rising levels of oxygen transformed life on the land
Sunday 08 February 2009
The solution came from other forms of life that had emerged on land. A few small, worm-like creatures probably emerged from the sea at about the same time as the earliest plants and mosses, about 420 million years ago.
What tempted them ashore had something to do with the rising quantities of oxygen in the air. Oxygen levels had steadily increased over millions of years until they levelled off at the beginning of the Cambrian Period, about 530 million years ago. Then there was a "blip" that occurred between 400 and 200 million years ago. This blip was caused by the luscious green forests now covering the land. Plants and trees dramatically increased the amount of oxygen in the atmosphere. The effect was a bit like lining the shores with sweets.
Life in the seas just couldn't resist the temptation to come ashore for a taste. When the first sea creatures came crawling out they found that the adjustment wasn't too hard, with all that extra oxygen in the air to give them a boost. Today about 21 per cent of the air we breathe is oxygen. But 350 million years ago, with the arrival of the carboniferous forests, oxygen levels shot up perhaps to as much as 35 per cent. The chart gives a sense of how oxygen levels have risen, and of the resulting effects on the development of life-forms.
- 1 President of Argentina adopts Jewish godson to 'stop him turning into a werewolf'
- 2 ALS ice bucket challenge co-founder Corey Griffin drowns, aged 27
- 3 The 'Black Museum': After 150 years, public set to see exhibits from police’s grisly crime museum
President of Argentina adopts Jewish godson to 'stop him turning into a werewolf'
Exclusive: Abusers using spyware apps to monitor partners reaches 'epidemic proportions'
ALS ice bucket challenge co-founder Corey Griffin drowns, aged 27
UK weather: Warning for more snow and ice as freezing temperatures and gales hit Britain
Stoke-on-Trent becomes first British city to be classified as 'disaster resilient' by the United Nations
British actor Idris Elba cannot star as James Bond because he is black, says shock jock Rush Limbaugh
Ukip member gets into Christmas spirit with Union Flag plea to Santa 'for our country back'
Germany anti-Islam protests: 17,000 march on Dresden against 'Islamification of the West'
Immigrants make UK racist, says Ukip councillor Trevor Shonk
Nigel Farage: Ukip leader named 'Briton of the year' by The Times
Millions of Britons struggling to feed themselves and facing malnourishment
£20000 per annum: Recruitment Genius: Panel Wireman required for small electro...
£25000 - £27000 per annum: Recruitment Genius: An SME based in East Cheshire, ...
£18000 - £22000 per annum: Recruitment Genius: Do you have previous experience...
£16000 - £18000 per annum: Recruitment Genius: This is an exciting opportunity...