Extending the Rare Earth hypothesis

Image credit: IAU

I’ll be presenting “Solar eclipses: A pump of curiosity for early humans?” at the International Astronomical Union Symposium 367 next month.

The symposium was originally scheduled to take place in San Carlos de Bariloche, Argentina, close to the path of totality for the 14 December solar eclipse. However, covid-19 restrictions mean it will now be an online event.

My poster session will extend the Rare Earth hypothesis to ask: does the Earth have some special ingredient that led not only to complex life, but to curious life?


Solar eclipses: A pump of curiosity for early humans?

Graham Jones, University of Shiga Prefecture

A central and unique feature of the human species is our desire for explanations. Where did our sense of curiosity come from? And why, on the current evidence, are we the only species in the Universe to possess this feature? Traditionally, these have been treated as separate questions; in this presentation, I will suggest a way to combine them into a single line of inquiry. I will also draw on the Symposium themes of cultural astronomy and solar eclipses to propose a speculative answer.

I will begin by considering the Rare Earth hypothesis, which states that the development of complex life depended upon a set of physical, chemical and biological circumstances that may be vanishingly rare within the Universe. I will extend this idea to open up a new line of inquiry: does the Earth have some special ingredient that led not only to complex life, but to curious life? I will speculate that solar eclipses may be such an ingredient.

We can confidently say that solar eclipses are not rare within the Universe. However, the ‘perfect’ total and annular eclipses we experience on the Earth, together with their mean frequency of once every few hundred years for a given location, may be exceedingly rare. Although these eclipses have no lasting effect on the Earth and its environment, they have an overwhelming effect on humans and human communities. I will tentatively propose that solar eclipses provided early humans with novelty on a scale large enough to help trigger the development of curiosity.

In effect, solar eclipses may have acted as a finely tuned ‘pump of curiosity’: if they occurred more frequently, they would not have provided sufficient novelty to stimulate the brains of early humans; if they occurred less frequently, they would not have provided enough stimuli to different communities, at different times, to kindle the first flames of curiosity.

This presentation will provide Symposium delegates with an opportunity to engage in fun speculation across a range of disciplines. To help generate discussion and debate, I will present comments from my interviews and correspondence with practitioners working in a variety of areas, including:

  • astronomy and physics – eg, Stephen Webb, author of «Where is everybody? Seventy-five solutions to the Fermi paradox and the problem of extraterrestrial life» (Springer, 2015)
  • exoplanet and exomoon research – eg, Cecilia Lazzoni, lead author of «The search for disks or planetary objects around directly imaged companions: A candidate around DH Tau B» (arXiv:2007.10097, 2020)
  • neuroscience and philosophy – eg, Daniel C Dennett, author of «From bacteria to Bach and back: The evolution of minds» (WW Norton, 2017)
  • primatology and anthropology – eg, Tetsuro Matsuzawa, editor of «Primate origins of human cognition and behavior» (Springer, 2001)
  • solar eclipses and human culture – eg, Jay Pasachoff, co-author of «Cosmos: The art and science of the Universe» (Reaktion Books, 2019).

Published by Graham Jones

Astrophysicist and language teacher