Skip to main content

Shadows on the Cave Wall: a new theory of evolution – Keith Skene ***

Anyone claiming to have a new theory of evolution had better have good credentials, field experience, and a thorough knowledge of biology. Otherwise they are probably a crackpot. Keith Skene has these qualities, and Shadows on the Cave Wall is not the work of a crackpot. Indeed, for breadth, thoughtfulness, and a kind of happy-go-lucky charm, the book is a real treasure. But its aspirations – to replace evolution by natural selection with a new theory grounded in physics – are well beyond its powers of persuasion.
Skene’s key idea is that the long- and short-term dynamics of living things can be best understood in terms of the flow of energy into, out of, and within different levels of biological organisation. The levels of organisation that interest Skene are proteins, individuals, populations, communities, and biomes. Notably absent from this list are genes and species, which Skene rejects along with evolution by natural selection.
Drawing on Plato’s metaphor of the cave, Skene argues that energy is the “sun” that lies behind all of the biological activity we see in the world, while everything from the gene to the biosphere are merely “shadows on the cave wall”, the outward effects of energy. It may seem that Skene’s focus on physics is reductionist. Banish the thought. By focusing on physics, Skene does not mean that biological phenomena are simply consequences of atom-level laws. He means that they are driven by the macroscopic laws of thermodynamics. Once we have seen this, he argues, we can see that no level of organisation – proteins no more than populations – is more “basic” than the others.
The payoff for this theory, says Skene, is closure on some key issues in evolutionary biology, including altruism, life on other planets, and the social behaviour of animals. But the “most radical implication” of the theory is a new way to save the environment from human exploitation – a path to salvation that, as Skene puts it, “has nothing to do with carbon.”
It turns out that the solution is not as new or radical as the 250-page build-up suggests. Skene points out that the problem underlying climate change is our excessive reliance on energy, especially in the food sector. He describes the environmental damage caused by artificial fertilisers and lists some ways to minimise this damage – from eating less meat to planting a border of nutrient-loving plants around crop fields. Not everyone would agree with these ideas, but no-one would call them ground-breaking.
For this reader, Skene’s energy-based theory also ended in anticlimax. Few people would deny that biological processes obey the laws of thermodynamics (otherwise they would be shoddy laws). So the big question is whether Skene can use those laws can enrich our knowledge of biological phenomena. Skene undoubtedly gives rich accounts of biological phenomena, notably an account of how different levels of organisation interact with one another. But it is unclear just how much these accounts owe to the Skene’s overarching energy theory. For example, one does not need Skene’s theory of energy to understand why an excess of nutrients in an ecosystem can harm the community. At other times, Skene seems to use “energy” to refer simply to the common notion of biological resources, as in: “it is the resource distribution that determines how many organisms can live in a given area, and, therefore, what kind of social group can form.”
Fortunately, many of the ideas in the book do not rely on the energy theory to be interesting. For example, Skene draws together a range of objections to orthodox evolution by natural selection: the fact that most organisms through history have acquired new genes not by random mutation but by horizontal gene transfer (HGT, the absorption of genes from other organisms); the notion that empty niches, rather than competition for an occupied niche, is the main driver of speciation; and others. The case against Darwinian evolution could certainly be more tightly argued. It is not clear, for example, whether HGT provides a real alternative to natural selection, or just a new source of genetic variation upon which natural selection can act. And there is not enough room in one volume for Skene to do justice to his other arguments, or (just as importantly) to address objections to those arguments.
Shadows is best read not as an argument but as an adventure, a fast-paced ride through key ideas in evolution and ecology. Skene has an unusual style, mixing anecdotes and chirpy asides with earnest contemplation of the big questions. Here he is describing a species of wildebeest that breeds only in December and January: “if a wildebeest set up a greetings card shop, the business would only run for a very limited time: extremely seasonal employment when Christmas cards and birthday cards would be for sale for only one month of the year!” The effect is bizarre but disarming.
On the whole, the Shadows experience is less like reading a book than watching a lecture by a keen and knowledgeable, but slightly eccentric, professor: personal, chaotic, insightful, and unfailingly fun.

Review by Michael Bycroft


Popular posts from this blog

Cosmology for the Curious - Delia Perlov and Alex Vilenkin ***

In the recently published The Little Book of Black Holes we saw what I thought was pretty much impossible - a good, next level, general audience science title, spanning the gap between a typical popular science book and an introductory textbook, but very much in the style of popular science. Cosmology for the Curious does something similar, but coming from the other direction. This is an introductory textbook, intended for first year physics students, with familiar textbook features like questions to answer at the end of each chapter. Yet by incorporating some history and context, plus taking a more relaxed style in the writing, it's certainly more approachable than a typical textbook.

The first main section, The Big Bang and the Observable Universe not only covers basic big bang cosmology but fills in the basics of special and general relativity, Hubble's law, dark matter, dark energy and more. We then move onto the more speculative (this is cosmology, after all) aspects, brin…

Astrophysics for People in a Hurry – Neil deGrasse Tyson *****

When I reviewed James Binney’s Astrophysics: A Very Short Introduction earlier this year, I observed that the very word ‘astrophysics’ in a book’s title is liable to deter many readers from buying it. As a former astrophysicist myself, I’ve never really understood why it’s considered such a scary word, but that’s the way it is. So I was pleasantly surprised to learn, from Wikipedia, that this new book by Neil deGrasse Tyson ‘topped The New York Times non-fiction bestseller list for four weeks in the middle of 2017’.

Like James Binney, Tyson is a professional astrophysicist with a string of research papers to his name – but he’s also one of America’s top science popularisers, and that’s the hat he’s wearing in this book. While Binney addresses an already-physics-literate audience, Tyson sets his sights on a much wider readership. It’s actually very brave – and honest – of him to give physics such prominent billing; the book could easily have been given a more reader-friendly title such …

Once upon and Algorithm - Martin Erwig ***

I've been itching to start reading this book for some time, as the premise was so intriguing - to inform the reader about computer science and algorithms using stories as analogies to understand the process.

This is exactly what Martin Erwig does, starting (as the cover suggests) with Hansel and Gretel, and then bringing in Sherlock Holmes (and particularly The Hound of the Baskervilles), Indiana Jones, the song 'Over the Rainbow' (more on that in a moment), Groundhog Day, Back to the Future and Harry Potter.

The idea is to show how some aspect of the story - in the case of Hansel and Gretel, laying a trail of stones/breadcrumbs, then attempting to follow them home - can be seen as a kind of algorithm or computation and gradually adding in computing standards, such as searching, queues and lists, loops, recursion and more.

This really would have been a brilliant book if Erwig had got himself a co-author who knew how to write for the public, but sadly the style is mostly heavy…