According to a new study published in the journal Nature Astronomy, some extraterrestrial civilizations may be intelligent but face limitations in technological development due to the characteristics of their atmosphere.
One of the key factors identified in the study is the level of oxygen in the atmosphere. Oxygen plays an important role in the evolution of life, and researchers suggest that its availability may be critical for the development of technologically advanced species.
The article emphasizes that beyond its necessity for respiration and metabolism in multicellular organisms, oxygen is crucial to developing fire—and fire is a hallmark of a technological civilization. However, if the planet has insufficient oxygen levels, it may prevent the fires necessary for technological development to occur.
“On Earth, fire certainly played a critical role in the rise of human civilization and the emergence of technology,” the study explains.
Cooking was important to our development, giving us more energy and possibly helping to increase the size of our brains. Fire has also been used by humans to control the environment and help us hunt.
“However, by far the most important role of fire in the emergence of human civilization is its use as a source of energy,” the article says.
“It probably began as a way to conserve heat, thereby increasing the range of environmental conditions suitable for settlements. This then evolved into more complex uses such as metal smelting and tool making. Finally, it provided the energy source and fuel that ushered in the Industrial Revolution and led to the Anthropocene.”
The paper calls this phenomenon an “oxygen bottleneck” and suggests that oxygen-deficient alien species may be intelligent but will remain technologically untapped. The authors of the paper suggest that the lack of oxygen may isolate these creatures, limiting their development.
An oxygen bottleneck may prevent intelligent, tool-using, and possibly communicative species from evolving into technologically advanced species capable of making contact with us, perhaps explaining the lack of contact.
The team suggests other possible ways primitive species could produce heat, such as focusing the rays of their stars or geothermal energy, but none are as simple or readily available as combustion.
Co-author Adam Frank hypothesizes that on planets with low oxygen levels, intelligent creatures would not be able to use fire to cook food, control the environment, or create complex technologies.
Experts urge caution when interpreting potential tech signals from planets where oxygen levels are insufficient. This could be an important factor in weeding out unsuitable objects in the search for intelligent life in space.