Mr. Takai

Firstly, there are two key ideas that biologists hold. One idea is that the essence of life is information. This is the view that the transmission of stored information is of central importance. That is, that genetic information passed on in the form of DNA or RNA is vital. So, when we think about the origin of life, we focus on nucleic acids.

On the other hand, there are researchers who believe that the fact that we are alive in this moment is the important point. In the case of humans, about 20,000 proteins are actively working to keep us alive at any moment, establishing a dynamic equilibrium. This is the most important fact about life. From this viewpoint, the origin of life has nothing to do with genes. These are the ultimate conclusions I have drawn from my research on deep-sea hydrothermal systems.

Mr. Takai

Correct! For life on Earth today, genetic information is effectively the most important factor, without doubt. However, the forms of life that arose four billion years ago did not necessarily need to pass on information. My conclusion is that all they had to do was just live.

You could say that the arising of planets and the emergence of life were physical phenomena. Or in other words, I believe that the origination of life was a physical phenomenon, which is a rather essential concept. In contrast, what came after the emergence of life are just stories.

Mr. Takai

Right! Life originated with chemical reactions, so it is a physical phenomenon. But, when the leap from mere physical phenomenon to life happens, there’s no way to create stories without genes.

Mr. Takai

Until now, concepts about the origin of life have focused basically on how genetic information gets created. DNA emerged later; first there was RNA. Since it seems that RNA could be produced in hot springs, there is a theory that a prototype form of life originated in hot springs. A wide variety of materials fall to the Earth’s surface from outer space and hot springs can be considered good sites for material accumulation.

Deep-sea hydrothermal systems are not good material accumulation sites in this sense, but we found that somehow the necessary materials can be produced there. Sugars, alkalis, and probably even amino acids and nucleic acids can be made deep below the sea. These necessary building blocks of life can be made on site, unaffected by the unstable supply from the sky. Like this, the most basic metabolic system was formed, and a prototype life form, so to speak, was established, simply by a process of metabolism, division, and regeneration.

Mr. Takai

My latest scenario is that a life form only with a metabolic system had already emerged in deep-sea hydrothermal systems. Later, over a long span of time, genes arrived fortuitously from somewhere. I believe that the genes and the prototype life form stuck together, eventually becoming our last universal common ancestor, or LUCA.

Mr. Takai

That’s right! Initially, there was just a metabolic process that did not depend on enzymes, involving minerals and electrochemistry. Later, this was replaced by proteins linking together amino acids, with a film of oil making up the outermost surface. And that was the moment that life began, I think. I am now working on trying to prove this hypothesis.

What we’ve been able to reproduce so far using just minerals and electrochemical characteristics, without enzymes, is the conversion of carbon dioxide to carbon monoxide, and carbon monoxide to citric acid cycle (aka TCA cycle) reactions. Almost all citric acid cycle reactions can be generated non-enzymatically.

Mr. Takai

From the citric acid cycle, the process proceeds further, becoming like the metabolic system of the human body, producing amino acids, lipids, and so on. I don’t think the logic of this pathway was taught in high-school biology or chemistry classes, but this process was somehow established in the natural environment it seems.

One of the conditions that explains why life began in deep-sea hydrothermal systems is electromotive force. It is only in deep-sea hydrothermal systems that a natural potential of at least 1 V can be created. The electrical conductors capable of carrying the electricity are the sulfide chimneys deep in the sea. According to this line of reasoning, the first metabolic processes could only have arisen in deep-sea hydrothermal systems, not in hot springs.

The hypothesis that deep-sea hydrothermal systems are the source of the metabolism of living things was first posited in the latter 1980s. However, we added some radically new concepts, such as the idea of electrochemistry, the idea that complex redox reactions can be governed by the various electric potentials generated on the surface of minerals, and also the idea that these can occur as chain reactions.

Mr. Takai

When the prototype life forms first arose, enzymes were not needed, but I think your earliest ancestors originated in deep-sea hydrothermal systems. They worked hard in those environments.
Certainly, life would not have arisen without enzymes. With enzymes present, the speed and efficiency of activity would have increased dramatically, and the time taken for organisms to reproduce a new generation of themselves became shorter. With the arrival and connection of genes, enzymes were then able to leave behind something identical to themselves for the first time. That is the LUCA.

Mr. Takai

Yes, but my purpose was to study the origin of life, not to do aerospace research. The reason I needed to explore space was that only one kind of life exists on Earth.

Although there are 10 billion species of life forms, there is only one pattern of life here. According to scientific principles, as long as only a single case of a phenomenon exists, that thing is not considered verified. We therefore need to find a second or third example of the phenomenon for corroboration, by induction and deduction. Thus, if we want to unravel the mystery of the origin of life, we have to find life beyond the Earth.

Mr. Takai

On a cosmic scale, there are very few planets that are at an appropriate distance from their suns; most planets are “ice worlds.” However, recent space observations have revealed that deep-sea hydrothermal systems can exist even on such icy planets. We could therefore hypothesize that deep-sea hydrothermal conditions are a universal feature of the cosmos.

Now, if we suppose that life on Earth necessarily arose in deep-sea hydrothermal systems, then maybe life has inevitably arisen in deep-sea hydrothermal systems in other parts of the universe too. In other words, such a finding would demonstrate the universality of life.

Mr. Takai

Enceladus is the most cost-effective choice for exploration.

Mr. Takai

If we had the money, we could start right away. But it would cost ¥100 billion ($800 million), and even then the chances of success would only be fifty-fifty.

Mr. Takai

We might find something other than amino acids. Maybe “space enzymes.” Who knows?

Mr. Takai

I created a new research division at JAMSTEC, called the Institute for Extra-cutting-edge Science and Technology Avant-garde Research (X-star). Currently, I am serving as its “guardian deity.” Not much of my work now is about doing the research I love. My main focus is figuring out how I can help researchers to do creative “bottom up” research. So, I’m busy with a variety of tasks related to this.

But I want to continue doing a little of my own research too. Or perhaps make some voyages to the deep sea, which I have grown to love. And I haven’t been able to verify all the scenarios I envisioned for the origin of life yet, so I hope to continue this work, too. For this, I have to leave my mark on the field, and I need to create and protect a system that allows me to conduct such fascinating research.

Mr. Takai

I often say that my favorite manga is “SLAM DUNK.” The protagonist starts playing basketball because a girl he likes is in the team. So, his motive is impure (laughs). But eventually, he has to make a decision that will affect his career in basketball. That’s when he realizes that he truly loves basketball.

You will never figure out whether you like something so instantly. You might start out with all kinds of irrelevant thoughts and misconceptions in your head, but when you throw yourself into something fully, you will clearly know if you like it or not. Ultimately, I don’t think you will know whether you like something or not unless you work hard at it.

Initially, you might do something just for the money, or for appearances, or whatever. But in the process of dedicating yourself to it completely, you will discover something that you really like. I think the same thing applies to meeting people. Even if you haven’t met one good person in 30 years, you might suddenly meet one. You just never know when that moment will come. So, my view is that whatever happens, we have to live life as wholeheartedly and positively as possible.

It isn’t easy to know what you want to devote your life to, so don’t be afraid if you haven’t figured it out while you are young. If you live your life all-out, you will definitely find it.

Mr. Takai

Perhaps the more impure you start out, the more pure you will end up becoming (laughs).