As a biochemist and professor of organic chemistry at the Ludwig Maximilian University of Munich, what is it about the origins of life that interests you?
Thomas Carell: We have a good idea of how organisms developed on Earth. This is clearly shown from fossils. However, we are in the dark as to how central biopolymers and genetic material developed. This is why I am interested in how the first organic molecules and amino acids were formed on early Earth.
And as an astrophysicist at the Max Planck Institute for Astronomy, how would you describe the origin of life?
Thomas Henning: We know that the early Earth’s atmosphere consisted of carbon dioxide, nitrogen and possibly some water. Producing organic compounds from these ingredients is not easy. Hydrogen cyanide might be a key molecule for many prebiotic processes, but its production requires the addition of catalysts such as iron. Yet, where does the iron come from? So this phase of the origin of life consists of several elements: on the one hand there are pure chemical processes and on the other there is the question of what early Earth looked like at the time of the origin of life, i.e. what were the astrophysical conditions?
How can organic compounds be produced which would embody the beginning of biological life?
Thomas Henning: On Earth, iron could have, for example, been extracted from silicates for use as a catalyst or it could have come to the planet from iron meteorites. Organic compounds could have come to Earth directly by way of meteorite-like impacts.
Do you also think this is plausible?
Thomas Carell: Yes, because we know that organic compounds can only form with great difficulty in the CO2 atmosphere mentioned by Mr Henning. This is still an open question. And even if we were to know how amino acids and nucleic acids can form under these difficult conditions, it is still unclear how the code of life, i.e. DNA, was formed. This is where biology begins.
Is the origin of life the product of chance or the end of a deterministic process?
Thomas Henning: The Earth was formed around 4.6 billion years ago and there is evidence that life has existed for four billion years. This means that conditions could possibly have been so good that life was able to develop very quickly, obviously and inevitably. For a long time it was thought that black smokers, i.e. hot water vents in the deep sea, could provide these conditions, but this idea has since been abandoned.
The focus is now back on small hydrothermal lakes which contain not only ammonia compounds and phosphorus salts, but also light and heat. In addition, the presence of water changes in dry-wet cycles. This is important because water has to be removed for biopolymers to form.
Thomas Carell: That’s how I see it too. We are trying to recreate these dry-wet cycles in laboratory experiments and control them in such a way that we can force reactions under the conditions of a CO2 atmosphere. However, we repeatedly find that the chemistry that can take place in such an atmosphere is still largely unknown. There is also the exciting question of how deterministic chemistry can be in certain boundary conditions. We will certainly be able to learn more about the atmospheres of exoplanets using the James Webb Space Telescope.
With this in mind, how did you both come up with this idea for the Leopoldina Annual Assembly?
Thomas Henning: We have both been interested in the topic of “Origin and beginning of life” for quite some time. In chemistry, a lot of progress has been made using sensitive analytical techniques to detect small amounts of key molecules and incorporate kinetic data into complex reaction networks. In astrophysics, it has been discovered that rocky planets are very common. With the space telescope, we are now able to characterise the atmospheres of such rocky planets for the first time.
The topic is therefore ready for intensive study. The most interesting aspect is that we can bring together many different branches of science, from astrophysics to chemistry and biology to medicine. This is very exciting, as today natural sciences are becoming more and more specialised.
What is your personal association with the conference?
Thomas Carell: It is very good that the Leopoldina is giving this topic a platform in Germany. Not only is it an important field for basic research, but it also has great application potential. For example, the membrane envelopes of nucleic acids, as would have developed on early Earth to form a cell, are still of great significance today in connection with messenger RNA vaccines. Also in this field, the therapeutic nucleic acids have to be surrounded by envelopes of fat in order to protect the mRNA and transport it into cells. The question of how to get nucleic acids into the cells and the principles behind it has enormous economic potential.
Thomas Henning: The topic could also influence other disciplines represented at the Leopoldina. A second Copernican revolution in astrophysics has gone almost unnoticed. The Copernican Revolution sees the Earth moved out of the centre of the solar system; suddenly we see many other planetary systems and Earth-like planets. Using the James Webb space telescope we are able to characterise their atmospheres for the first time. This has given rise to a new branch of science which is calling for an answer to whether there is life on these planets and how life originates on terrestrial planets.
The interview was conducted by Benjamin Haerdle