Ribosomes are life’s oldest and most universal assembly of molecules. Today’s ribosome converts genetic information (RNA) into proteins that carry out various functions in an organism. A growing number of scientists are exploring how earliest components of life such as the ribosome came to be. They’re making surprising progress, but the going remains tough. No image credit.
Noted synthetic life researcher Steven Benner of Foundation for Applied Molecular Evolution is fond of pointing out that gooey tars are the end product of too many experiments in his field. His widely-held view is that the tars, made out of chemicals known to be important in the origin of life, are nonetheless a dead end to be avoided when trying to work out how life began.
But in the changing world of origins of life research, others are asking whether those messy tars might not be a breeding ground for the origin of life, rather than an obstacle to it.
One of those is chemist and astrobiologist Irena Mamajanov of the Earth-Life Science Institute (ELSI) in Tokyo. As she recently explained during an institute symposium, scientists know that tar-like substances were present on early Earth, and that she and her colleagues are now aggressively studying their potential role in the prebiotic chemical transformations that ultimately allowed life to emerge out of non-life.
“We call what we do messy chemistry, and we think it can help shed light on some important processes that make life possible.”
Irena Mamajanov of the Earth-Life Science Institute (ELSI) in Tokyo was the science lead for a just completed symposium on emerging approaches to the origin of life question.
It stands to reason that the gunky tar played a role, she said, because tars allow some essential processes to occur: They can concentrate compounds, it can encapsulate them, and they could provide a kind of primitive (messy) scaffolding that could eventually evolve into the essential backbones of a living entity.
“Scientists in the field have tended to think of the origin of life as a process going from simple to more complex, but we think it may have gone from very complex — messy — to more structured.”
Mamajanov is part of an unusual group gathered at (ELSI), a relatively new site on the campus of the Tokyo Institute of Technology for origin of life study with a mandate to be interdisciplinary and to think big and outside the box.
ELSI just completed its fifth annual symposium, and it brought together researchers from a wide range of fields to share their research on what might have led to the emergence of life. And being so interdisciplinary, the ELSI gathering was anything but straight and narrow itself.
There was talk of the “evolution” of prebiotic compounds; of how the same universal 30 to 50 genes can be found in all living things from bacteria to us; of the possibility that the genomes of currently alive microbes surviving in extreme environments provide a window into the very earliest life; and even that evolutionary biology suggests that life on other Earth-like planets may well have evolved to form rather familiar creatures.
Except for that last subject, the focus was very much on ways to identify the last universal common ancestor (LUCA), and what about Earth made life possible and what about life changed Earth.
Scientific interest in the origin of life on Earth (and potentially elsewhere) tends to wax and wane, in large part because the problem is so endlessly complex. It’s one of the biggest questions in science, but some say that it will never be fully answered.
But there has been a relatively recent upsurge in attention being paid and in funding for origin of life researchers.
The Japanese government gave $100 million to start and operate ELSI, the Simons Foundation has donated another $100 million for an origins of life institute at Harvard, the Templeton Foundation has made numerous origin of life grants and, as it has for years, the NASA Astrobiology Institute has funded researchers. Some of the findings and theories are most intriguing and represent a break of sorts from the past.
For some decades now, the origins of life field has been pretty sharply divided. One group holds that life began when metabolism (a small set of reactions able to harness and transform energy ) arose spontaneously; others maintain that it was the ability of a chemical system to replicate itself (the RNA world) that was the turning point. Metabolism First versus the RNA First, plus some lower-profile theories.
In keeping with its goal of bringing scientists and disciplines together and to avoid as much origin-of-life dogma as possible, Mamajanov sees their “messy chemistry” approach as a third way and a more non-confrontational approach. It’s not a model for how life began per se, but one of many new approaches designed to shed light and collect data about those myriad processes.
“This division in the field is hurting science because people are not talking to each other ,” she said. “By design we’re not in one camp or another.”
Loren Williams of Georgia tech
Another speaker who exemplified that approach was Loren Williams of Georgia Tech, a biochemist whose lab studies the genetic makeup of those universal 30 to 50 ribosomes (a complex molecule made of RNA molecules and proteins that form a factory for protein synthesis in cells.) He was principal investigator for the NASA Astrobiology Institute’s Georgia Tech Center for Ribosome Adaptation and Evolution from 2009-2014.
His goal is to collect hard data on these most common genes, with the inference that they are the oldest and closest to LUCA.
“What becomes quickly clear is that the models of the origin of life don’t fit the data,” he said. “What the RNA model predicts, for instance, is totally disconnected from this data. So what happens with this disconnect? The modelers throw away the data. They say it doesn’t relate. Instead, I ignore the models.”
A primary conclusion of his work is that early molecules — rather like many symbiotic relationships in nature today — need each other to survive. He gave the current day example of the fig wasp, which spends its larval stage in a fig, then serves as a pollinator for the tree, and then survives on the fruit that appears.
He sees a parallel “mutualism” in the ribosomes he studies. “RNA is made by protein; all protein is made by RNA,” he said. It’s such a powerful concept for him that he wonders if “mutualism” doesn’t define a living system from the non-living.
These stromatolites, wavelike patterns created by bacteria embedded in sediment, are 3.7 billion years old and may represent the oldest life on the planet. Photo by Allen Nutman
Stromalites, sedimentary structures produced by microorganisms, today at Shark Bay, Australia. Remarkably, the lifeform has survived through billions of years of radical transformation on Earth, catastrophes and ever-changing ecologies.
A consistent theme of the conference was that life emerged from the geochemistry present in early Earth. It’s an unavoidable truth that leads down some intriguing pathways.
As planetary scientist Marc Hirschmann of the University of Minnesota reported at the gathering, the Earth actually has far less carbon, oxygen, nitrogen and other elements essential for life than the sun, than most asteroids, than even intersellar space.
Since Earth was initially formed with the same galactic chemistry as those other bodies and arenas, Hirschmann said, the story of how the Earth was formed is one of losing substantial amounts of those elements rather than, as is commonly thought, by gaining them.
The logic of this dynamic raises the question of how much of those elements does a planet have to lose, or can lose, to be considered habitable. And that in turn requires examination of how the Earth lost so much of its primordial inheritance — most likely from the impact that formed the moon, the resulting destruction of the early Earth atmosphere, and the later movement of the elements into the depths of the planet via plate tectonics. It’s all now considered part of the origins story.
And as argued by Charley Lineweaver, a cosmologist with the Planetary Science Institute and the Australian National University, it has become increasingly difficult to contend that life on other planets is anything but abundant, especially now that we know that virtually all stars have planets orbiting them and that many billions of those planets will be the size of Earth.
Other planets will have similar geochemical regimes and some will have undergone events that make their distribution of elements favorable for life. And as described by Eric Smith, an expert in complex systems at ELSI and the Santa Fe Institute, the logic of physics says that if life can emerge then it will.
Any particular planetary life may not evolve beyond single cell lifeforms for a variety of reasons, but it will have emerged. The concept of the “origin of life” has taken on some very new meanings.
ELSI was created in 2012 after its founders won a World Premier International Research Center Initiative grant from the Japanese government. The WPI grant is awarded to institutes with a research vision to become globally competitive centers that can attract the best scientists from around the world to come work in Japan.
The nature and aims of ELSI and its companion group the ELSI Origins Network (EON) strike me as part of the story. They break many molds.
The creators of ELSI, both Japanese and from elsewhere, say that the institute is highly unusual for its welcome of non-Japanese faculty and students. They stay for years or months or even weeks as visitors.
While ELSI is an government-funded institute with buildings, professors, researchers and a mission (to greatly enhance origin of life study in Japan), EON is a far-flung collection of top international origins scientists of many disciplines. Their home bases are places like Princeton’s Institute for Advanced Study, Harvard, Columbia, Dartmouth, Caltech and the University of Minnesota, among others in the U.S., Europe and Asia. NASA officials also play a supporting, but not financial, role.
ELSI postdocs and other students live in Tokyo, while the EON fellows spend six months at ELSI and six months at home institutions. All of this is in the pursuit of scientific collaboration, exposing young scientists in one field related to origins to those in another, and generally adding to global knowledge about the sprawling subject of origins of life.
Jim Cleaves, of ELSI and the Institute for Advanced Study, is the director of EON and an ambassador of sorts for its unusual mission. He, and others at the ELSI symposium, are eager to share their science and want young scientists interested in the origins of life to know there are many opportunities with ELSI and EON for research, study and visitorships on the Tokyo campus.
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About Many Worlds
There are many worlds out there waiting to fire your imagination.
Marc Kaufman is an experienced journalist, having spent three decades at The Washington Post and The Philadelphia Inquirer, and is the author of two books on searching for life and planetary habitability. While the “Many Worlds” column is supported by the Lunar Planetary Institute/USRA and informed by NASA’s NExSS initiative, any opinions expressed are the author’s alone.
This site is for everyone interested in the burgeoning field of exoplanet detection and research, from the general public to scientists in the field. It will present columns, news stories and in-depth features, as well as the work of guest writers.
The Nexus for Exoplanet System Science (NExSS) is a NASA research coordination network dedicated to the study of planetary habitability. The goals of NExSS are to investigate the diversity of exoplanets and to learn how their history, geology, and climate interact to create the conditions for life. NExSS investigators also strive to put planets into an architectural context — as solar systems built over the eons through dynamical processes and sculpted by stars. Based on our understanding of our own solar system and habitable planet Earth, researchers in the network aim to identify where habitable niches are most likely to occur, which planets are most likely to be habitable. Leveraging current NASA investments in research and missions, NExSS will accelerate the discovery and characterization of other potentially life-bearing worlds in the galaxy, using a systems science approach.
The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.
President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.
Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.
NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [Hubble, Chandra, Spitzer, and associated programs. NASA shares data with various national and international organizations such as from the [JAXA]Greenhouse Gases Observing Satellite.