Peter Forbes

The Guardian today has a piece on the discovery of an ancient fire in South Africa around 1 m years ago. Interesting, but a big change occurred in human evolution around 2 million year ago, leading to genetic changes in digestion and brain size. Richard Wrangham has a plausible theory on this: cooked food allowed these changes by dramatically shortening the time needed for eat and acquire high energy nutrition. So Wrangham's hypothesis requires that our ancestors were eating cooked food twice as long ago as this find. The jury is still out.

_ I’ve just belatedly read Mark S. Blumberg’s Freaks of Nature: and what they tell us about development and evolution. I’m sorry I missed this on publication (paperback 2010) because it is a powerful exposition of evo devo. Blumberg convincingly shows that the gene-centred view of life-forms is inadequate. He discusses the factors that play out in functions as different as limbs and sex and the way in which different forms can emerge from the same genome. The poster case for this is sex determination in crocodiles, some turtles, lizard and fishes. They do not have separate genetic sexes and whether an individual becomes male or female is regulated by temperature at a crucial stage of development. Some fishes switch identity several times over. 

Human beings do have sex determining genes of course but even here things can happen such as genetic males appearing to be females until puberty when male genitalia suddenly appears. The reason is that a receptor for the hormone testosterone has been switched off in the foetus and is only activated at puberty. The genome has not changed but the results have. In general environmental factors, such as temperature in the case of crocodiles, can have drastic effects on development at key moments. All these phenomena belong under the heading of epigenetics.

There is another book somewhat similar to Blumberg’s: Armand Marie Leroy’s Mutants. I fear that neither book is as well known as it should be partly because of those titles. Both books do discuss abnormal development – freaks and mutants – but mostly for the light they shed on normal development. A great deal has been discovered about developmental mechanisms by observing what happens when it goes wrong. But some readers may have been put off by the titles. Blumberg, in particular, does make a strong case for a better attitude towards abnormalities of development. One’s understanding of life processes is greatly broadened by these books. It is safe to say that you will never see life in quite the same way again.

_ The Kyoto emissions protocol expires next year and attempts to formulate the next phase are in such disarray that the date of 2020 is being bandied around as the earliest likely date for a new treaty to come into force. Meanwhile, carbon emissions rose by 5% last year, in a recession, and all the predictions are that the burning of coal, the dirtiest fossil field, are going to rocket in the next few decades. And all this while we know that only action now on emissions will count. If we wait, the stockpile of CO2 will have grown to the extent that the severe climate change we fear will become inevitable. How can we account of this apparently species-suicidal behaviour?

We are creatures of climate change: it made us and it might break us. What do I mean by that? The study of both human evolution and past climate change have both accelerated dramatically recently, and the connections between the two are becoming clearer.

It was almost certainly climate change in Africa from around 5 million years ago that led to the emergence of a line of adaptable, big brained apes. In long-term steady climatic conditions, living things can persist essentially unchanged for many millions of years. But large scale climatic change with mass extinctions produced the great innovations in evolution, such as the emergence of mammals following the Cretaceous collapse that ended the dinosaurs’ reign.

What happened in East Africa from 5 million years ago was less extreme. The climate became drier and the forest thinned, opening up the savannah we are familiar with today as the home of big game. An ape adapted to the loss of a supportive forest habit by learning to live in the open, on the ground. To survive amidst the large predators of the savannah required enormous cunning: the use of fire and tools. Over those 5 million years the African climate was unstable, with wet and dry periods alternating. It is this flux that probably led to the most adaptable species on earth: us.

By around 200,000 years ago an ape with a brain 3-4 time the size of a chimpanzee was established in Africa. I say established but life was precarious, the environment still hostile. Homo sapiens eventually spread beyond Africa. How tough it was know from the timing. They only arrived in Europe around 36,000 years ago.

During the entire period of the evolution of H. sapiens Europe was in the grip of repeated ice ages. At the last glacial maximum, around 20-25,000 years ago, Europe was covered in ice almost to the Mediterranean. Human populations clung on in Southern France and Spain. The Neanderthals, the last proto human before us became extinct at this time. Their last stronghold is thought to have been some caves in Gibraltar.

But 11,600 years ago, the world warmed dramatically, by 6 degrees and the ice retreated. There have been serious climatic setbacks since then but in the last 10,000 years a Northern hemisphere ice-free over much of its landmass allowed agricultural societies to grow and develop.

But instead of recognizing that our great world civilisation owes as much to climatic luck as to our brilliant minds and hard work, we arrogantly refuse to accept the evidence that the climate is fragile and will be tipped by our own activities unless we modulate them.

The Intergovernmental Panel on Climate Change’s forecasts have projected gradual change into the future, but the increasingly detailed record of past climate change shows dramatic changes happening at certain tipping points, over very few years. The one we should be worried about is that sudden 6 degree rise that launched our ascent – it took place in around a single decade!

There is every reason to fear that the next serious climatic change will happen as rapidly as those of the past but our widespread assumption that we have our benign place in the sun as of right is preventing any serious attempt at climatic mitigation. All past approaches to get governments and public opinion on board have failed so a new approach is called for. Most people in the developed world have grown up thinking that our technology can insulate us from the worst that nature can do. Understanding that we have always been at the mercy of the climate and that our benign time is over is the required background knowledge for our next step. We don’t want to be the headline species in the Next Great Extinction.

In content Richard Dawkins’ The Magic of Reality is pretty much like any good illustrated Book of Knowledge, of which there are many. But to really get such a message over requires a charismatic messenger and so The Magic of Reality will reach further than any other Book of Knowledge. As such it is mostly fine – you can safely give it to any child, knowing that virtually everything in it, is as Dawkins says, is the truth about reality. But Dawkins has not escaped ideological bias. At times he insist on his own interpretation of the gospel: he belongs to the Olden Day Church of the “Modern Synthesis” or the Sect of the Selfish Gene (actually a declining minority amongst biologists). This doesn’t matter for most of the book except that, as with the preachers he reviles, there is a whiff of “putting the fear of Dawks” into them. On p74-5 he describes all animals as “survival machines[s]. for genes and then: “Next time you look in the mirror, just think that is what you are too.” It’s not much of a match for fire and brimstone but it left me feeling very queasy. I wouldn’t be telling young people that they’re nothing but survival machines for their genes. It’s not true, for a start. We are not merely puppets of the genes – they take orders too.

What Dawkins is doing here is trying to indoctrinate young minds, slipping his ideological message into a text which purports to be the facts and nothing but the facts, the trick worked by preachers throughout the ages.