Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Study Tests Theory that Life Originated at Deep Sea Vents

09.04.2014

One of the greatest mysteries facing humans is how life originated on Earth. Scientists have determined approximately when life began (roughly 3.8 billion years ago), but there is still intense debate about exactly how life began. One possibility - that simple metabolic reactions emerged near ancient seafloor hot springs, enabling the leap from a non-living to a living world – has grown in popularity in the last two decades.

Recent research by geochemists Eoghan Reeves, Jeff Seewald, and Jill McDermott at Woods Hole Oceanographic Institution (WHOI) is the first to test a fundamental assumption of this ‘metabolism first’ hypothesis, and finds that it may not have been as easy as previously assumed. Instead, their findings could provide a focus for the search for life on other planets. The work is published in Proceedings of the National Academy of Science.


Clear hot spring fluids spew from a talc structure at the Von Damm vent field, a mile and a half beneath the Caribbean Sea. The researchers show that fluids emanating from Von Damm and other hot spring areas around the global mid-ocean ridge system contain a sulfur compound, methanethiol, that is indicative of pyrolysed subsurface life. The red laser dots are 10cm apart, for scale. Photograph courtesy of the Little Hercules ROV, NOAA Okeanos Explorer Program, Mid-Cayman Rise Expedition 2011. (Woods Hole Oceanographic Institution)

In 1977, scientists discovered biological communities unexpectedly living around seafloor hydrothermal vents, far from sunlight and thriving on a chemical soup rich in hydrogen, carbon dioxide, and sulfur, spewing from the geysers. Inspired by these findings, scientists later proposed that hydrothermal vents provided an ideal environment with all the ingredients needed for microbial life to emerge on early Earth. A central figure in this hypothesis is a simple sulfur-containing carbon compound called “methanethiol” - a supposed geologic precursor of the Acetyl-CoA enzyme present in many organisms, including humans.  Scientists suspected methanethiol could have been the “starter dough” from which all life emerged.

The question Reeves and his colleagues set out to test was whether methanethiol—a critical precursor of life – could form at modern day vent sites by purely chemical means without the involvement of life. Could methanethiol be the bridge between a chemical, non-living world and the first microbial life on the planet?

Carbon dioxide, hydrogen and sulfide are the common ingredients present in hydrothermal black smoker fluids. “The thought was that making methanethiol from these basic ingredients at seafloor hydrothermal vents should therefore have been an easy process,” adds Reeves.

The theory was appealing, and solved many of the basic problems with existing ideas that life may have been carried to Earth on a comet or asteroid; or that genetic material emerged first – the “RNA World” hypothesis. However, says Reeves, “it’s taken us a while to get out there and actually start to test this ‘metabolism first’ idea in the natural environment, by using modern vents as analogs for those that were around when life first began.”

And when they did get out there, the scientists were surprised by what they found.

To directly measure methanethiol, the researchers went to hydrothermal vent sites where the chemistry predicted they would find abundant methanethiol, and others where very little was predicted to form. In total, they measured the distribution of methanethiol in 38 hydrothermal fluids from multiple differing geologic environments including systems along the Mid-Atlantic Ridge, Guaymas Basin, the East Pacific Rise, and the Mid-Cayman Rise over a period between 2008 and 2012.

“Some systems are very rich in hydrogen, and when you have a lot of hydrogen it should, in theory, be very easy to make a lot of methanethiol,” says Reeves.  The fluids were collected in isobaric gas-tight samplers (IGTs) developed by Jeffrey Seewald, which maintain fluids at their natural pressure and allow for dissolved gas analyses.

Instead of an abundance of methanethiol, the data they collected in the hydrogen-rich environments showed very little was present. “We actually found that it doesn’t matter how much hydrogen you have in black smoker fluids, you don’t seem to be making a lot of methanethiol where you should be making a lot of it,” Reeves says.  Surprisingly, in the low-hydrogen environments, where much less should form, the research actually found more methanethiol than they had predicted, contradicting the original idea of how methanethiol forms.  Overall, this means that jump-starting proto-metabolic reactions in hydrogen-rich early Earth hydrothermal systems through carbon-sulfur chemistry would likely have been much harder than many had assumed. 

Critically, the researchers found an abundance of methanethiol being formed in low temperature fluids (below about 200°C), where hot black smoker fluid mixes with colder sea water beneath the seafloor. The presence of other telltale markers in these fluids, such as ammonia – a byproduct of biomass breakdown – strongly suggests these fluids are ‘cooking’ existing microbial organic matter. The breakdown of existing subseafloor life when conditions get too hot may therefore be responsible for producing large amounts of methanethiol.

“What we essentially found in our survey is that we don’t think methanethiol is forming by purely chemical means without the involvement of life. This might be disappointing news for anyone assuming an easy start for hydrothermal proto-metabolism,” says Reeves. “However, our finding that methanethiol may be readily forming as a breakdown product of microbial life provides further indication that life is present and widespread below the seafloor and is very exciting.”

The researchers believe this new understanding could change how we think about searching for life on other planets.  “The upside is, now we have a pretty simple marker for life.  Someday if we can land a rover on the ice-covered oceans of Jupiter’s moon Europa – another place in the Solar System that may host hydrothermal vents, and possibly life – and successfully drill through the ice, the first thing it should probably try to measure is methanethiol,” Reeves says. “This is already something scientists are thinking about, and it is exciting to think this might even happen in our life time.”

As for the search for the origins of life, Reeves agrees that hydrothermal vents are still a very favorable place for life to emerge, but, he says, “maybe methanethiol just wasn’t a good starter dough.  The hydrothermal environment is still a perfect place to support early life, and the question of how it all started is still open.”

This research was supported by grants from the National Science Foundation and NASA.  Additional funds were provided by the WHOI Deep Ocean Exploration Institute, InterRidge, and the Deutsche Forschungsgemeinschaft Research Center/Cluster of Excellence MARUM “The Ocean in the Earth System” (E.P.R.).

The Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate a basic understanding of the ocean's role in the changing global environment. For more information, please visit www.whoi.edu.

Originally published: April 9, 2014

Media Relations Office | EurekAlert!
Further information:
http://www.whoi.edu/news-release/study-tests-theory-that-life-originated-at-deep-sea-vents

Further reports about: Acetyl-CoA Deep Earth Ocean Oceanographic Theory WHOI environments fluids metabolism

More articles from Life Sciences:

nachricht Chains of nanogold – forged with atomic precision
23.09.2016 | Suomen Akatemia (Academy of Finland)

nachricht Self-assembled nanostructures hit their target
23.09.2016 | King Abdullah University of Science and Technology

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: OLED microdisplays in data glasses for improved human-machine interaction

The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.

“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...

Im Focus: Artificial Intelligence Helps in the Discovery of New Materials

With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.

Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...

Im Focus: Complex hardmetal tools out of the 3D printer

For the first time, Fraunhofer IKTS shows additively manufactured hardmetal tools at WorldPM 2016 in Hamburg. Mechanical, chemical as well as a high heat resistance and extreme hardness are required from tools that are used in mechanical and automotive engineering or in plastics and building materials industry. Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden managed the production of complex hardmetal tools via 3D printing in a quality that are in no way inferior to conventionally produced high-performance tools.

Fraunhofer IKTS counts decades of proven expertise in the development of hardmetals. To date, reliable cutting, drilling, pressing and stamping tools made of...

Im Focus: Launch of New Industry Working Group for Process Control in Laser Material Processing

At AKL’16, the International Laser Technology Congress held in May this year, interest in the topic of process control was greater than expected. Appropriately, the event was also used to launch the Industry Working Group for Process Control in Laser Material Processing. The group provides a forum for representatives from industry and research to initiate pre-competitive projects and discuss issues such as standards, potential cost savings and feasibility.

In the age of industry 4.0, laser technology is firmly established within manufacturing. A wide variety of laser techniques – from USP ablation and additive...

Im Focus: New laser joining technologies at ‘K 2016’ trade fair

Every three years, the plastics industry gathers at K, the international trade fair for plastics and rubber in Düsseldorf. The Fraunhofer Institute for Laser Technology ILT will also be attending again and presenting many innovative technologies, such as for joining plastics and metals using ultrashort pulse lasers. From October 19 to 26, you can find the Fraunhofer ILT at the joint Fraunhofer booth SC01 in Hall 7.

K is the world’s largest trade fair for the plastics and rubber industry. As in previous years, the organizers are expecting 3,000 exhibitors and more than...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Experts from industry and academia discuss the future mobile telecommunications standard 5G

23.09.2016 | Event News

ICPE in Graz for the seventh time

20.09.2016 | Event News

Using mathematical models to understand our brain

16.09.2016 | Event News

 
Latest News

Chains of nanogold – forged with atomic precision

23.09.2016 | Life Sciences

New leukemia treatment offers hope

23.09.2016 | Health and Medicine

Self-assembled nanostructures hit their target

23.09.2016 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>