Skip to main content

Life on Earth likely started 4.1 billion years ago, much earlier than scientists thought

Evidence that early Earth was not dry and desolate


Fossil-like rock found in Australia contain hints of life from 4.1 billion years ago Photo: Bruce Watson/Proceedings of the National Academy of Sciences (PNAS) via AP

UCLA geochemists have found evidence that life likely existed on Earth at least 4.1 billion years ago -- 300 million years earlier than previous research suggested. The discovery indicates that life may have begun shortly after the planet formed 4.54 billion years ago.

Carbon in 4.1 billion year old zircon.
Credit: Stanford/UCLA.

The research is published today in the online early edition of the journal Proceedings of the National Academy of Sciences.

"Twenty years ago, this would have been heretical; finding evidence of life 3.8 billion years ago was shocking," said Mark Harrison, co-author of the research and a professor of geochemistry at UCLA.

"Life on Earth may have started almost instantaneously," added Harrison, a member of the National Academy of Sciences. "With the right ingredients, life seems to form very quickly."

The new research suggests that life existed prior to the massive bombardment of the inner solar system that formed the moon's large craters 3.9 billion years ago.

"If all life on Earth died during this bombardment, which some scientists have argued, then life must have restarted quickly," said Patrick Boehnke, a co-author of the research and a graduate student in Harrison's laboratory.

Scientists had long believed the Earth was dry and desolate during that time period. Harrison's research -- including a 2008 study in Nature he co-authored with Craig Manning, a professor of geology and geochemistry at UCLA, and former UCLA graduate student Michelle Hopkins -- is proving otherwise.

"The early Earth certainly wasn't a hellish, dry, boiling planet; we see absolutely no evidence for that," Harrison said. "The planet was probably much more like it is today than previously thought."

The researchers, led by Elizabeth Bell -- a postdoctoral scholar in Harrison's laboratory -- studied more than 10,000 zircons originally formed from molten rocks, or magmas, from Western Australia. Zircons are heavy, durable minerals related to the synthetic cubic zirconium used for imitation diamonds. They capture and preserve their immediate environment, meaning they can serve as time capsules.

The scientists identified 656 zircons containing dark specks that could be revealing and closely analyzed 79 of them with Raman spectroscopy, a technique that shows the molecular and chemical structure of ancient microorganisms in three dimensions.

Bell and Boehnke, who have pioneered chemical and mineralogical tests to determine the condition of ancient zircons, were searching for carbon, the key component for life.

One of the 79 zircons contained graphite -- pure carbon -- in two locations.

"The first time that the graphite ever got exposed in the last 4.1 billion years is when Beth Ann and Patrick made the measurements this year," Harrison said.

How confident are they that their zircon represents 4.1 billion-year-old graphite?

"Very confident," Harrison said. "There is no better case of a primary inclusion in a mineral ever documented, and nobody has offered a plausible alternative explanation for graphite of non-biological origin into a zircon."

The graphite is older than the zircon containing it, the researchers said. They know the zircon is 4.1 billion years old, based on its ratio of uranium to lead; they don't know how much older the graphite is.

The research suggests life in the universe could be abundant, Harrison said. On Earth, simple life appears to have formed quickly, but it likely took many millions of years for very simple life to evolve the ability to photosynthesize.

The carbon contained in the zircon has a characteristic signature -- a specific ratio of carbon-12 to carbon-13 -- that indicates the presence of photosynthetic life.

"We need to think differently about the early Earth," Bell said.

Wendy Mao, an associate professor of geological sciences and photon science at Stanford University, is the other co-author of the research.

The research was funded by the National Science Foundation and a Simons Collaboration on the Origin of Life Postdoctoral Fellowship granted to Bell.

Source:
TUniversity of California - Los Angeles | by Stuart Wolpert.

Reference:
Elizabeth A. Bell, Patrick Boehnke, T. Mark Harrison, and Wendy L. Mao. Potentially biogenic carbon preserved in a 4.1 billion-year-old zircon. PNAS, October 19, 2015 DOI: 10.1073/pnas.1517557112

Popular posts from this blog

Gene therapy treats all muscles in the body in muscular dystrophy dogs

Human clinical trials are next step..
Source: www.healthcare.uiowa.edu
Muscular dystrophy, which affects approximately 250,000 people in the U.S., occurs when damaged muscle tissue is replaced with fibrous, fatty or bony tissue and loses function. For years, scientists have searched for a way to successfully treat the most common form of the disease, Duchenne Muscular Dystrophy (DMD), which primarily affects boys. Now, a team of University of Missouri researchers have successfully treated dogs with DMD and say that human clinical trials are being planned in the next few years.

"This is the most common muscle disease in boys, and there is currently no effective therapy," said Dongsheng Duan, the study leader and the Margaret Proctor Mulligan Professor in Medical Research at the MU School of Medicine. "This discovery took our research team more than 10 years, but we believe we are on the cusp of having a treatment for the disease."

Patients with Duchenne muscular dyst…

Study adds to evidence that viruses are alive

The new findings appear in the journal Science Advances.

A new analysis supports the hypothesis that viruses are living entities that share a long evolutionary history with cells, researchers report. The study offers the first reliable method for tracing viral evolution back to a time when neither viruses nor cells existed in the forms recognized today, the researchers say.

Until now, viruses have been difficult to classify, said University of Illinois crop sciences and Carl R. Woese Institute for Genomic Biology professor Gustavo Caetano-Anoll├ęs, who led the new analysis with graduate student Arshan Nasir. In its latest report, the International Committee on the Taxonomy of Viruses recognized seven orders of viruses, based on their shapes and sizes, genetic structure and means of reproducing.

"Under this classification, viral families belonging to the same order have likely diverged from a common ancestral virus," the authors wrote. "However, only 26 (of 104) viral fam…

Schizophrenia symptoms linked to features of brain's anatomy?

Roger Harris/Photo Researchers, ISM/Phototake Using advanced brain imaging, researchers have matched certain behavioral symptoms of schizophrenia to features of the brain's anatomy. The findings, at Washington University School of Medicine in St. Louis, could be a step toward improving diagnosis and treatment of schizophrenia.
The study, available online in the journal NeuroImage, will appear in print Oct. 15.

"By looking at the brain's anatomy, we've shown there are distinct subgroups of patients with a schizophrenia diagnosis that correlates with symptoms," said senior investigator C. Robert Cloninger, MD, PhD, the Wallace Renard Professor of Psychiatry and a professor of genetics. "This gives us a new way of thinking about the disease. We know that not all patients with schizophrenia have the same issues, and this helps us understand why."

The researchers evaluated scans taken with magnetic resonance imaging (MRI) and a technique called diffusion ten…