Navigation Links
Theory on origin of animals challenged: Animals needs only extremely little oxygen

One of science's strongest dogmas is that complex life on Earth could only evolve when oxygen levels in the atmosphere rose to close to modern levels. But now studies of a small sea sponge fished out of a Danish fjord shows that complex life does not need high levels of oxygen in order to live and grow.

The origin of complex life is one of science's greatest mysteries. How could the first small primitive cells evolve into the diversity of advanced life forms that exists on Earth today? The explanation in all textbooks is: Oxygen. Complex life evolved because the atmospheric levels of oxygen began to rise app. 630 635 million years ago.

However new studies of a common sea sponge from Kerteminde Fjord in Denmark shows that this explanation needs to be reconsidered. The sponge studies show that animals can live and grow even with very limited oxygen supplies.

In fact animals can live and grow when the atmosphere contains only 0.5 per cent of the oxygen levels in today's atmosphere.

"Our studies suggest that the origin of animals was not prevented by low oxygen levels", says Daniel Mills, PhD at the Nordic Center for Earth Evolution at the University of Southern Denmark.

Together with Lewis M. Ward from the California Institute of Technology he is the lead author of a research paper about the work in the journal PNAS.

A little over half a billion years ago, the first forms of complex life - animals - evolved on Earth. Billions of years before that life had only consisted of simple single-celled life forms. The emergence of animals coincided with a significant rise in atmospheric oxygen, and therefore it seemed obvious to link the two events and conclude that the increased oxygen levels had led to the evolution of animals.

"But nobody has ever tested how much oxygen animals need at least not to my knowledge. Therefore we decided to find out", says Daniel Mills.

The living animals that most closely resemble the first animals on Earth are sea sponges. The species Halichondria panicea lives only a few meters from the University of Southern Denmark's Marine Biological Research Centre in Kerteminde, and it was here that Daniel Mills fished out individuals for his research.

"When we placed the sponges in our lab, they continued to breathe and grow even when the oxygen levels reached 0.5 per cent of present day atmospheric levels", says Daniel Mills.

This is lower than the oxygen levels we thought were necessary for animal life.

The big question now is: If low oxygen levels did not prevent animals from evolving then what did? Why did life consist of only primitive single-celled bacteria and amoebae for billions of years before everything suddenly exploded and complex life arose?

"There must have been other ecological and evolutionary mechanisms at play. Maybe life remained microbial for so long because it took a while to develop the biological machinery required to construct an animal. Perhaps the ancient Earth lacked animals because complex, many-celled bodies are simply hard to evolve", says Daniel Mills.

His colleagues from the Nordic Center for Earth Evolution have previously shown that oxygen levels have actually risen dramatically at least one time before complex life evolved. Although plenty of oxygen thus became available it did not lead to the development of complex life. Read more about this work here:


Contact: Birgitte Svennevig
University of Southern Denmark

Related biology news :

1. Study jointly led by UCSB researcher supports theory of extraterrestrial impact
2. A University of Tennessee professors hypothesis may be game changer for evolutionary theory
3. Scientists uncover strong support for once-marginalized theory on Parkinsons disease
4. Research: Modern Portfolio Theory optimizes conservation practices
5. Information theory helps unravel DNAs genetic code
6. Study turns parasite invasion theory on its head
7. Birdsong study pecks theory that music is uniquely human
8. New dinosaur fossil challenges bird evolution theory
9. Researcher uncovers potential cause, biomarker for autism and proposes study to investigate theory
10. Theory of crystal formation complete again
11. Engineering control theory helps create dynamic brain models
Post Your Comments:
Related Image:
Theory on origin of animals challenged: Animals needs only extremely little oxygen
(Date:11/20/2015)... Connecticut , November 20, 2015 ... authentication company focused on the growing mobile commerce market ... CEO, Gino Pereira , was recently interviewed on ... interview will air on this weekend on Bloomberg ... Latin America . --> NXTD ) ("NXT-ID" ...
(Date:11/17/2015)... Paris from 17 th until 19 ... from 17 th until 19 th November 2015. ... invented the first combined scanner in the world which scans ... now two different scanners were required: one for passports and ... the same surface. This innovation is an ideal solution for ...
(Date:11/12/2015)...  A golden retriever that stayed healthy despite having ... provided a new lead for treating this muscle-wasting disorder, ... of MIT and Harvard and the University of São ... Cell, pinpoints a protective gene that boosts ... The Boston Children,s lab of Lou Kunkel , ...
Breaking Biology News(10 mins):
(Date:11/25/2015)... , Nov. 25, 2015 /PRNewswire/ - Aeterna Zentaris Inc. ... its business and prospects remain fundamentally strong and ... (zoptarelin doxorubicin) recently received DSMB recommendation to continue ... following review of the final interim efficacy and ... Primary Endpoint in men with heavily pretreated castration- ...
(Date:11/24/2015)... 24, 2015  Asia-Pacific (APAC) holds the third-largest ... market. The trend of outsourcing to low-cost locations ... higher volume share for the region in the ... margins in the CRO industry will improve. ... ( ), finds that the market earned ...
(Date:11/24/2015)... ... November 24, 2015 , ... Copper is ... it is bound to proteins, copper is also toxic to cells. With a ... Polytechnic Institute (WPI) will conduct a systematic study of copper in the bacteria ...
(Date:11/24/2015)... ... November 24, 2015 , ... This fall, global software solutions leader SAP ... states to develop and pitch their BIG ideas to improve health and wellness in ... for votes to win the title of SAP's Teen Innovator, an all-expenses paid trip ...
Breaking Biology Technology: