Navigation Links
Study casts doubt on 'Snowball Earth' theory

Remains of photosynthesizing microbes in prehistoric rocks suggest Earth was not ice-bound

A study that applied innovative techniques to previously unexamined rock formations has turned up strong evidence on the "Slushball Earth" side of a decades-long scientific argument.

The study appears in the Sept. 29 Science Express. The lead author is Alison Olcott, a Ph.D. student of earth sciences in the USC College of Letters, Arts and Sciences.

Geologists agree that prehistoric Earth was locked in a deep freeze during Precambrian times, about 750 to 600 million years ago. They disagree over the severity of the glaciation.

"Snowball Earth" proponents, who say that Earth's oceans were covered by thick ice, explain the survival of life by hypothesizing the existence of small warm spots, or refugia.

On the other side are supporters of a "Slushball Earth" that would have included large areas of thin ice or open ocean, particularly around the equator.

The debate has tended to revolve around the same rock samples and analytical techniques, Olcott said. So she and her team focused on a drill core of little-known black shale deposits from southeastern Brazil and applied lipid biomarker techniques to identify prehistoric organisms based on the fatty remains of their cell membranes.

The team, which included scientists from USC, Caltech, the University of Maryland and a Brazilian mining company, identified "a complex and productive microbial ecosystem," including photosynthesizing organisms that could not have existed under a thick layer of ice.

"If there was ice, it had to have been thin enough that organisms could photosynthesize below it or within it," Olcott said.

Frank Corsetti of the USC College, one of Olcott's advisers and a co-author on the paper, said: "What she has provided is the first real evidence that substantial photosynthesis occurred in the Earth's oceans during the extreme ice age 700 million ye ars ago, which is a challenge for the snowball theory."

The evidence from the drill core does not prove that large parts of the ocean remained free of sheet ice during the pre-Cambrian glaciation. It is statistically unlikely but possible, Olcott said, that the drill core found one of the tiny "refugia" for marine life whose existence is allowed under the "Snowball Earth" hypothesis.

But, she said, "finding the one anomalous spot would be quite unlikely," adding that the drill core came from an extensive formation of rocks with similar characteristics.

"At what point does an enormous refugium become open ocean?" she asked.

Skeptics also may argue that the rocks do not necessarily date to a glacial era, Olcott said. But her team found evidence of glacial activity in the samples, such as dropstones (continental rocks dropped by melting glaciers into marine deposits) and glendonites (minerals that only form in near-freezing water).

Objections aside, the paper's main contribution may be the application of new techniques to an old chestnut.

"Geologists don't necessarily think of looking for traces of microbes left in the rocks. This is the first direct look at the ecosystem during this time period," said Olcott, who credited USC's geobiology program, one of a handful in the country, with influencing her thinking.

"They really try to synthesize between geology and biology. It was a new way to attack the problem."

Corsetti agrees. "The climate of collaboration between geologists and biologists," he said, "is unusually good at USC ?it was this way of thinking that provided the impetus for the project in the first place."


'"/>

Source:University of Southern California


Related biology news :

1. Novel Asthma Study Shows Multiple Genetic Input Required; Single-gene Solution Shot Down
2. Emory Study Tests Bone Marrow Stem Cells to Improve Circulation in Legs
3. UCLA Study Shows One-Third of Drug Ads in Medical Journals Do Not Contain References Supporting Medical Claims
4. Study Demonstrates Gene Expression Microarrays are Comparable and Reproducible
5. Study Links Ebola Outbreaks To Animal Carcasses
6. Breakthrough Microarray-based Technology for the Study of Cancer
7. NYU Study Reveals How Brains Immune System Fights Viral Encephalitis
8. Study finds more than one-third of human genome regulated by RNA
9. Leukemia Drug Breakthrough Study In New England Journal Of Medicine
10. Study identifies predictors of HIV drug resistance in patients beginning triple therapy
11. New Study from Affymetrix Laboratories Points to Changing View of How Genome Works
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:4/19/2017)... New York , April 19, 2017 ... competitive, as its vendor landscape is marked by the ... the market is however held by five major players ... Safran. Together these companies accounted for nearly 61% of ... of the leading companies in the global military biometrics ...
(Date:4/11/2017)... GARDENS, Fla. , April 11, 2017 /PRNewswire/ ... management and secure authentication solutions, today announced that ... by Intelligence Advanced Research Projects Activity (IARPA) to ... IARPA,s Thor program. "Innovation has been ... and IARPA,s Thor program will allow us to ...
(Date:4/5/2017)... , April 5, 2017  The Allen Institute ... Allen Cell Explorer: a one-of-a-kind portal and dynamic digital ... 3D imaging data, the first application of deep learning ... human stem cell lines and a growing suite of ... platform for these and future publicly available resources created ...
Breaking Biology News(10 mins):
(Date:5/22/2017)... ... May 22, 2017 , ... Baltimore biotech firm, ... Maryland Biohealth community in developing and issuing recommendations to grow Maryland's biohealth industry ... Hub by 2023. , The recommendations are contained in a ...
(Date:5/19/2017)... (PRWEB) , ... May 19, 2017 , ... In response ... treating gait disorders, Biodex Medical Systems, Inc. announces the release of their Gait Trainer ... has been joined with a biomedical system to aid in rehabilitating individuals with cerebral ...
(Date:5/18/2017)... ... ... Supplies Management (“CSM”), a Great Point Partners II (“GPP”) portfolio company, today announced two ... size over the past six months with the acquisition of businesses in Belgium and ... Chief Financial Officer. Roger has over 25 years of experience in finance and ...
(Date:5/18/2017)... CALIFORNIA (PRWEB) , ... May 17, 2017 , ... ... technological innovation and business process optimization firm for the life sciences and healthcare ... of the UDIs and Traceability for Medical Devices conference in Brussels, Belgium. , ...
Breaking Biology Technology: