Life Before Fossils

king-kong-killing-pterodactyl-1024x766Seeing may not always mean believing, but when it comes to living things from millions of years ago, it helps. A skeptic these days would have difficulty doubting the reality of dinosaurs given all the bones in museums and the reconstructions come to life in countless films. When embedded in an adventurous and romantic story, oversized reptiles and even King-Kong-size versions of our primate ancestors put persuasive passion and flesh on the cool scholarship of paleontologists.

The trouble is that the stuff of the usual fossil history—old bones, insects trapped in amber, hardened imprints of early plants–date back no more than 600 million years. Such a number may seem very old, but from another perspective it is not nearly old enough. For life has been traced back three billion years before that, six times further into the past. It’s not surprising that life from that long ago is not the material for theme parks or movies about entrepreneurs like Carl Denham who searched out Kong’s island. For life was small for the first three billion years, with no animals or plants as such. There were only microbes, single cells that gradually acquired the complexities of modern cell life—a nucleus, the hunger for oxygen, sexual reproduction. But there are no two-billion-year-old bones from which to reconstruct cellular giants, no fossils to serve as relics to fire the romantic imagination.

Or almost none.

Stromatolites in Australia, probably looking much as they did 3.5 billion years ago. (www2.estrellamountain.edu)

Microfossils from 3.5 billion years ago (www2.estrellamountain.edu)

To find them, you have to search for the oldest rocks. Try Australia, Greenland, or South Africa for those that date back almost four billion years. Slice them thin, put them under a microscope, look for microfossils measuring a fraction of a millimeter, their cell walls mineralized into tough material.

 

 

stromatolites layers pinterest

petrified stromatolite (pintrest)

 

 

And look for petrified stromatolites, the layered habitats of colonies of bacteria that filtered sea water for nutrients as far back as 3.5 billion years.

 

 

 

But could the tiny remains and traces of chemicals from billions of years ago become the attractions of crowded museums and movie fantasies? Could they find their place in popular culture as both entertainment and subtle education, as dinosaurs and apes have?

I believe they could.  It’s not difficult to imagine oversized reproductions of ancient microbes which kids could walk through while trying to avoid getting snagged on strands of DNA or thrown off-balance by the cell’s motion from its flagellum, its tail. And climate change sets the stage for a movie thriller about bacteria mysteriously resurrected from three billion years ago that thrive on carbon dioxide and for whom oxygen is poison.

Then our wonder at the marvels of our pre-human ancestors would reach back through the full history of life.

 

3.8 Billion Years: A Blog Recap

To welcome new readers and perhaps for the benefit of regular ones as well, I’m inserting here a short piece on the themes that I think connect this blog’s posts. Such connections may not be obvious since the post topics range from fossils to beavers to daily life to Steven Pinker. Evolution ties the topics together to some extent. But underlying evolution is the theme of the length of our biological past and the role that such history plays or could play in our lives. For me that history of life has taken on a spiritual aspect. I find that my dying feels a little less catastrophic when I think about my connection to a long chain of ancestors. The nature of right and wrong looks a little clearer as I learn more about how competition and cooperation have played out together as living things have evolved. Our biological past is a resource for our spiritual questions.

In writing the blog, I look for topics that will highlight this view of our history and will be highlighted by it in turn. In the previous post, for example, on the billions of years of life that pre-date the first visible animal fossils, the gap between what we think of as old and what is actually much older is dramatic—jarring, I think, to our usual notion of how long ago life began. Similarly, in many of the posts, the theme is essentially that much of the fuss of our lives is the fuss of not only all humans but also of other, nonhuman lives as well, past and present. The story of living things on earth echoes with the puzzles, the pain, and the beauty of being alive.

So welcome, reader, or welcome back. You can find a detailed discussion of the themes mentioned here at “Finding Spirituality in Biology,” on the tab near the top of the page.

all-creatures.org

all-creatures.org