“The Black Hole in the Evolution of Life” (WATCH Video)

 

Maxresdefault (1)

 

There’s a black hole in the middle of the history of life: how did we go from tiny bags of chemicals to the vast menagerie of creatures we see around us? Some 350 years after the discovery of cells, we still don’t know why life on earth is the way it is.Evoutionary biologist, Nick Lane with University College London asks these profound questions and explores one of the most underrated mysteries of all time, and presents one possible answer that takes us from an unexpected houseguest to a tiny bolt of lightning to life as we know it. It’s the story of one cosmic oops moment that changed the game of life forever.

There is a black hole at the heart of biology, Lane writes. Bluntly put, we do not know why life is the way it is. All complex life on earth shares a common ancestor, a cell that arose from simple bacterial progenitors on just one occasion in 4 billion years.

 

 

 

Was this a freak accident, or did other ‘experiments’ in the evolution of complexity fail? We don’t know. We do know that this common ancestor was already a very complex cell. It had more or less the same sophistication as one of your cells, and it passed this great complexity on not just to you and me but to all its descendants, from trees to bees.

Lane challenges us to look at one of our own cells down a microscope and distinguish it from the cells of a mushroom. They are practically identical. It’s not just that they look alike. All complex life shares an astonishing catalogue of elaborate traits, from sex to cell suicide to senescence, none of which is seen in a comparable form in bacteria.

There is no agreement about why so many unique traits accumulated in that single ancestor, or why none of them shows any sign of evolving independently in bacteria. Why, if all of these traits arose by natural selection, in which each step offers some small advantage, did equivalent traits not arise on other occasions in various bacterial groups?

These questions highlight the peculiar evolutionary trajectory of life on earth. Life arose around half a billion years after the earth’s formation, perhaps 4 billion years ago, but then got stuck at the bacterial level of complexity for more than 2 billion years, half the age of our planet.

Indeed, bacteria have remained simple in their morphology (but not their biochemistry) throughout 4 billion years. In stark contrast, all morphologically complex organisms – all plants, animals, fungi, seaweeds and single-celled ‘protists’ such as amoeba – descend from that singular ancestor about 1.5–2 billion years ago.

This ancestor was recognisably a ‘modern’ cell, with an exquisite internal structure and unprecedented molecular dynamism, all driven by sophisticated nanomachines encoded by thousands of new genes that are largely unknown in bacteria. There are no surviving evolutionary intermediates, no ‘missing links’ to give any indication of how or why these complex traits arose, just an unexplained void between the morphological simplicity of bacteria and the awesome complexity of everything else. An evolutionary black hole.

We spend billions of dollars a year on biomedical research, Lane observes, teasing out the answers to unimaginably complex questions about why we get ill. We know in enormous detail how genes and proteins relate to each other, how regulatory networks feed back into each other. We build elaborate mathematical models and design computer simulations to play out our projections.

These are human questions about why we are here that Lane tackles in this fascinating video. What laws gave rise to the universe, the stars, the sun, the earth, and life itself? Will the same laws beget life elsewhere in the universe? Would alien life be anything like us? Such metaphysical questions lie at the heart of what makes us human.

The Daily Galaxy via The Royal Institute and NickLane.com 

"The Galaxy" in Your Inbox, Free, Daily