Episode Details

Our program centered on the Viking life detection experiments on Mars and their broader implications for the search for extraterrestrial life. Our guest, Dr. Steven Benner, delved into topics including synthetic biology, paleogenetics, and the potential for current and future Mars missions to detect life. The conversation also addressed the capabilities and limitations of genetic engineering technologies such as CRISPR, along with the conditions required for life to exist on Mars and other planets.

Following co-host Bill’s introduction of Dr. Benner, our conversation transitioned into a discussion of paleogenetics. Dr. Benner explained how ancient proteins can be inferred and resurrected using techniques analogous to those used in historical linguistics. These approaches allow scientists to better understand the evolution of life and the environmental conditions of early Earth. Drawing on his extensive background in paleogenetics, bioinformatics, astrobiology, and synthetic biology—with significant contributions to medical applications, Dr. Benner offered valuable insights into the Viking life detection experiments.

When asked about his background, Dr. Benner shared his experience in chemistry and his current role in leading a nonprofit focused on synthetic biology and the development of agnostic life detection instruments. He described his research on universal biosignatures and their applications in molecular diagnostics. In response to a question I posed about the possibility of extraterrestrial origins of humans, Dr. Benner firmly stated there is no evidence to support the notion that humans were engineered by aliens, though he acknowledged the possibility of life on Mars. He provided a thoughtful and detailed rebuttal of such speculative theories.

Zoom participant Phil asked Steve about the current capabilities of CRISPR technology, particularly in editing DNA for potential applications like radiation resistance and immune system enhancement. Dr. Benner clarified that while CRISPR can target specific cells—for example, in CAR T-cell therapy for leukemia—it is not yet advanced enough to modify an entire organism or its germline. They discussed the long-term theoretical possibility of using such technologies to adapt humans for life on Mars but emphasized that current science is far from achieving that goal.

The major focus of the conversation was the Viking lander’s 1976 life detection experiments, which produced conflicting results. Dr. Benner explained that three experiments showed signs of metabolic activity—photosynthesis, respiration, and gas exchange—while a fourth experiment, due to a faulty mass spectrometer, mistakenly dismissed organic compounds as Earth-based contamination. Later findings revealed that perchlorates, rather than a strong oxidant, had destroyed the organic molecules—an interpretation that was lost in later reviews and textbooks. This served as a reminder of how initial misinterpretations can shape scientific consensus and underscored the importance of revisiting original studies with a critical eye.

The discussion continued with an exploration for microbial life on Mars and the environmental challenges it would face. Dr. Benner noted that bacterial autotrophs would need to store oxygen for nighttime metabolism due to the planet’s low oxygen levels. He also discussed the RNA World hypothesis, which posits that RNA could have fulfilled both informational and catalytic roles in early life. He emphasized that "privileged chemistry" involving basalt and other rock-forming elements may have supported RNA formation on Mars and other rocky planets.

Later near the end of the program, Phil inquired about the Drake Equation, prompting Dr. Benner to suggest that the parameter estimating the number of rocky planets capable of supporting life may be closer to one than previously assumed, increasing the probability that life exists elsewhere in the universe.

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