Life has found a home on Earth for around 4 billion years. That’s a significant fraction of the universe’s 13.77 billion-year history. Presumably, if life arose here, it could have appeared anywhere. And for sufficiently broad definitions of life, it might even be possible for life to have appeared mere seconds after the Big Bang.
To explore the origins of life, first we have to define it. There are over 200 published definitions of the term, which shows just how difficult this concept is to grapple with. For example, are viruses alive? They replicate but need a host to do so. What about prions, the pathogenic protein structures? Debates continue to swirl over the line between life and nonlife. But for our purposes, we can use an extremely broad, but very useful definition: Life is everything that’s subject to Darwinian evolution.
This definition is handy because we’ll be exploring the origins of life itself, which, by definition, will blur the boundaries between life and nonlife. At one point, deep in the past, Earth was not alive. Then it was. This means that there was a transition period that will naturally stretch the limits of any definition you can muster. Plus, as we dig deeper into the past and explore other potential options for life, we want to keep our definition broad, especially as we explore the more extreme and exotic corners of the universe.
“Writer Fuel” is a series of cool real-world stories that might inspire your little writer heart. Check out our Writer Fuel page on the LimFic blog for more inspiration.
