A thought provoking book

When Life Nearly Died by Michael Benton 

I have just read a very interesting and topical book on current thinking on the evidence for a series of mass extinctions presented to geologists in the rock strata all over the world.

The concept of mass extinctions has been popularised ever since Luis and Walter Alverez, the father and son team, published their research on the end Cretaceous or KT event, which resulted in the death of the dinosaurs.  Their work produced strong enough evidence for their concept to be widely accepted and as a result of the media publicity this work received, we are now all familiar with the idea of a huge meteor smashing into the Earth with devastating results.   

Added to the media reporting, several movies have used that image to produce disaster movie themes, so it has sunk into the popular psyche.

Luis and Walter Alverez standing by the KT boundary - dinosaur bones below no dinosaur bones above

It is hard to realise that before their publication in 1980, conventional wisdom insisted that no such thing had ever happened and geology was a slow multi-million year process with gradual changes and regular extinctions of older species making way for the new in some kind of steady progression culminating in humankind.  The dinosaur killer theory has swept aside this idea and we now understand that life on Earth is very precarious and there is no steady progression at all, but a series of quiet periods interspersed by terrible catastrophes randomly destroying large numbers of living things and often wiping out entire species.  Survival is just a chancy thing and it is more by luck than any adaptation that our particular line ever survived at all.

Michael Benton has a very open way of writing, unlike many other popular science book writers, he does not state his ideas in any dogmatic way, but presents each stage of his book as a series of possible reasons as to how rock formations occurred the way they have and how different geologists and palaeontologists have interpreted these findings.  In this fashion he builds up a picture which shows how recent thinking is derived.  He never states that any of the ideas are incontrovertible but simply shows what has been discovered.

His book is not just about the KT event, early on in the book he tables five major mass extinctions that the fossil records seem to show, including several lesser extinctions and the main theme of his book is the most significant of these.  This is an event known as the End Permian extinction, which took place, it is currently believed, 251 million years ago.  The fossil record shows that practically all existing species were wiped out in a massive event which seems to have killed off almost every living thing both on land and in the sea. 

He explains that palaeontology has undergone a big jump in knowledge recently.  The opening of many borders in recent years has made many more of the world’s geological sites are available for exploration and a lot of new material has come to light, whilst exchanges of ideas have been increased too.

He also reaffirms why planetology and geology are important and why many governments will fund research in these dry seeming subjects.  Once you can identify any fossils found, you can predict what minerals you are going to find with them, so it is not just the province of some dry old academics collecting old bones, but vital to the wealth of any nation.

After discussing the history of this field of endeavour and new developments in geology and planetology to bring us up to date, he presents the evidence for the end Permian extinction and then looks at the possible causes.  One puzzle is that unlike the end Cretaceous event that killed the dinosaurs,65 million years ago, there is no evidence of a major meteor strike, so another cause must be found.  He explores the possibilities like a detective story, presenting all the evidence and eventually coming to a conclusion of what is most the most likely cause.

Having wrapped this up he looks at why we want to know all this and moves from the academic past into the immediate present.  It has long been reported that humans are wiping out many species of life on an on-going process which should be stopped at least and reversed if possible. This he calls the Sixth Extinction.  He points out that knowledge of past extinctions will show what can happen and most importantly how long it takes for life to recover from any such an event.  Biodiversity is a real issue and we do not actually know how many species there are alive today.  Current estimates range from between 10 million to some 200 million different species, and more are discovered day by day.  So we have no real idea exactly how much damage we are really doing.  Again most  importantly, if past extinctions are anything to go by, at some point this reduction in biodiversity may trigger a major ecological crash and since we do not yet understand the world’s present ecology fully, we have no idea how imminent this is and what it could do to the biosphere.  We can only be sure that that whatever occurs, it will not be good.

A very readable book with much more significance to our daily lives than you may first expect from the rather headliney title and the basic subject.