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.”
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 Japanese and international group gathered at (ELSI), a relatively new site on the campus of the Tokyo Institute of Technology. It is dedicated to origin of life and origin of Earth 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 build a home for ELSI and support it for ten years, 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.”
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.
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 interstellar 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.
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.