Astrobiology is not something that I was very familiar with, so I found the talk by Dr. Jack O’Malley-James to be very novel and insightful. Most of what I’ve ‘encountered’ about the intersection of biology and astronomy is science-fiction books and movies in pop culture (So, not incredibly realistic stuff). While it is fun to let your imagination go wild and think about all kinds of scenarios, it was very fascinating to listen to the perspective of a researcher on the possibility extra-terrestrial life and the implications of potential findings on Earth/life on Earth. As a food science major, I imagined that there was not much during the talk that I could relate to my major. However, I was pleasantly surprised by the talk about microbes and biosignatures (Two things that have come up in my food science classes).
As was discussed in the talk, the chances are that if we do find ‘life’ on another planet, its most likely going to be in the form of single-cellular organisms. Mostly because, when we observe the evolution of life on Earth, microbes were the dominant form of life for most of history. They’re incredibly diverse, and it’s possible to find many of them with abilities to withstand conditions that are perceived as extreme like adverse pH conditions, high salinity levels, low/high temperatures and low oxygen conditions. Therefore, it is likely that if we do find any form of life on space, it would be something as hardy as microbes. This reminded me of something I had learnt about in my food microbiology class. While it’s not something directly related to space, its an example of the resilience of certain types of bacteria. It was found that cheese washed with brine made with sea salt had microbial communities of bacteria on the rink that were almost exclusively found deep in the ocean. The bacteria, present on the sea salt, were able to survive desiccation and continue to reproduce once they were re-hydrated in the brine.
As for biosignatures, the talk reminded me about something that my food chemistry professor has spoken about. Most of the amino acids present in living organisms are almost always present as L-forms, rather than D-forms (The L or D forms refer the structure of the amino acid). When an amino acid is synthesized in a lab however, the result is a 50/50 mixture of L-forms and D-forms of a single amino acid. While this may seem like a trivial fact, this quirk could be used to search for the presence of extra-terrestrial organisms. An example of this is the study of meteors for the presence of organic compounds. The basis of this thought is: if there is a meteor where there is a greater amount of the D-form of an amino acids, when compared to the L-form, it could be perceived as an indicator about the existence of life outside Earth (Since amino acids made by living organisms on Earth are almost always in the L-form). An famous example was the Murchison meteor. Although it did contain amino acids, it contained it in a 50/50 mixture of both forms of various amino acids, which indicates that it was formed as a result of a chemical reaction rather than synthesized within an organism.
Overall, I found talk very interesting. It was fun to draw little parallels from the talk, with things that I had learned in my food science class. The talk was a great introduction to the vast field of astrobiology. Microbes and biosignatures were just two things among many other aspects of the field that were discussed.
I also found myself comparing what I learned in the astrobiologist’s talk to my own major. I’m an engineer, and I liked learning about the ways astronomers use to detect exoplanets and the ways they have developed to detect signs of life. I was also interested in the chemistry discussed in the lecture. I wasn’t really disappointed to learn that any alien life would likely be microbial, because I think the discovery of alien microbes would be plenty cool enough. It is disappointing to me, however, that it would likely be impossible to study extraterrestrial microbes and determine how they are similar to or different from microbes here on Earth. I would really love to see how much would be common between Earth life and alien life.
That’s so interesting about how living organisms are more likely to synthesize more L-forms than D-forms! I bet there’s a ton of research trying to figure that one out. When I took the introductory astronomy course here, the biosignatures portion fascinated me as well. As interesting as it is, it relies so much on the assumption that their world or life is going to be similar or at least comparable to our own. Thanks for the thoughtful post!
I have to admit that I didn’t even know that astrobiology was a thing (and neither does the spellcheck for these comments, apparently, since its telling me that I spelled “astrobiology” wrong). But I found the talk to be incredibly fascinating regardless.
I think one of my professors might have mentioned how amino acids in living organisms are always in their L-form, but when they are made in a lab, you get a 50/50 mix of L- and D- amino acids. However I never considered how it could be used to try to look for alien life! It seems like a pretty clever thing to look for.