Of all the sciences, astrobiology seems to capture the public imagination in a way that no other topic does. The quest to find other worlds like our own and to find life on other planets is something that people from all walks of life get excited about. One of the things that interests me is the reason for this excitement. Why are people so interested in this? Is it simply the attraction of mysterious unknown worlds beyond the sky, or is it something more?
Certainly the night sky has fascinated mankind for perhaps as long as we have existed and still continues to do so today. The Aboriginal Australians can give some insight into this fascination. Their culture is the oldest still in existence in the world today. They are descended from the first wave of human migrants to leave Africa 75,000 years ago and have an unbroken cultural history of nearly 50,000 years, which may even share some cultural roots with the first human cultures to spring up in Africa. They are also possibly one of the first human cultures to begin naming constellations and meticulously observing the night skies. Their myths and beliefs are strongly connected to the night sky, which they use as a storytelling aid and calendar in much the same way as many (younger) cultures elsewhere in the world do. Although they do not consider the night sky to be a physical destination, they do see it as another world. The Yolngu people for example, believe that when they die they are taken to this spirit world in the sky, in which the Milky Way is a great river and the stars the lights of the camp fires of their ancestors.
This suggests that the concept of viewing the night sky as another world is an ancient one. It was not until the discovery and acceptance of the fact that Earth orbits the Sun that this one, inaccessible world turned into many suns with many worlds in people’s minds. But, perhaps, the motivation for thinking of the night sky as a window into worlds beyond our reach is the same. In a way, the sky still acts as a window to other worlds; it is only our interpretation and understanding of those worlds that has changed. Early thoughts of life on other worlds were very optimistic. The only evidence for the nature of the universe came from the world people saw around them; a world filled with life. This led to the conclusion that, if the universe is like this here, it must be like this elsewhere too; therefore, the universe must be filled with life. As humans, we are skilled at imagining the missing pieces in the puzzle that makes up our worldview. Exotic lands beyond the borders of maps were imagined to be populated by mythical creatures, such as the monstrous sea creatures that inhabit the North Sea in the 16th Century Carta Marina (pictured above) and the dog-headed cynocephali that were thought to reside in far-eastern lands in the Middle Ages. This attitude towards the unknown also covered the planet Venus in tropical jungles and Mars with seas. It was not until we began exploring the solar system that we found the other planets to be hostile, uninviting worlds. However, even this reality-check has not put us off from looking even further afield for Earth-like worlds.
An attraction toward distant lands may have been one of the drivers that led early humans to leave their ancestral homes, which contributed to our success as a species, as we eventually colonised the whole planet. Maybe it was this same drive that made us look out into space and fill it with ideas and stories of what might be there. Maybe this is what fires public imagination about the search for life beyond Earth today. Perhaps it is simply a by-product of being an intelligent, problem-solving species. The human brain has been honed by millennia to search for patterns in nature, helping us predict the migration of prey animals, the coming of seasonal change, the location of water sources etc. Perhaps by taking away these immediate concerns for food and shelter, the brain seeks to use its pattern recognition abilities elsewhere, driving us to gain a fuller understanding of the universe around us. Then again, perhaps it is, more simply, just a case of genetics. Answering the question of why we invest the time, energy and interest into searching for worlds beyond Earth could very well represent a lifetime’s work. There are plenty of good logical reasons for this search, such as gaining a better understanding of how our planet works and where life comes from, but these are unlikely to explain the fundamental reason for wanting to look. Whatever the answer (or answers) may be, the motivation probably has ancient roots and even though we cannot fully explain it, we can all, to one extent or another, feel the pull of today's unknown lands.