Cousin Caterpillar

One thing I have in common with Rowan Williams, the former Archbishop of Canterbury – apart from bad hair and a beard – is a love of the unique 60s music of the Incredible String Band. He calls their stuff “holy”, and while I wouldn’t go that far, it is because of them that I discovered the metaphysical poet Thomas Traherne, and made diversity and informality an ideal of my own songwriting.

One ISB song was helpful in getting me through the changes and challenges of university, a quirky little thing called Cousin Caterpillar

I’ve been reading stuff this weekend by Stuart Newman, Gerd Müller and other proponents of the “the extended Darwinian synthesis”. This was prompted largely by Dennis Venema’s staunch defence (on BioLogos) of the 150-year old position that an incomplete fossil record (showing stasis and apparent sudden change in species) in fact hides Darwinian adaptive gradualism.

Eve Jablonka and Marion Lamb (2008) say this:

There are winds of change in evolutionary biology, and they are blowing from many directions: from developmental biology (particularly the molecular aspects), from microbial biology (especially studies of mutational mechanisms and horizontal gene transfer), from ecology (in particular ideas about niche construction and studies of extensive symbiosis), from behavior (where the transmission of information through social learning is a major focus), and from cultural studies (where the relation between cultural evolution and genetic evolution is under scrutiny). Many biologists feel that the foundations of the evolutionary paradigm that was constructed during the 1930s and 1940s (Mayr, 1982) and has  dominated Western views of  evolution for the last 60 years are crumbling, and that the construction of a new evolutionary paradigm is underway.

Later in the same paper is this:

What has been revealed in the last few decades is that the origin of many genetic variations, especially under conditions of stress, is not random, is often predictable, and it can result in saltational changes. New genetic variation is therefore of a very different nature from that assumed in the Modern Synthesis, which proposed that evolutionarily important variations were the consequence of random mutational  changes with small effects.

Now here are similar ideas to those I’ve previously cited by people like James Shapiro and Denis Noble, but I particularly want to consider two concepts: “niche construction” and “saltation“, which some writers have combined in an intiguing way.

The niche construction theory of evolution, originally, points out that animal (and plant) behaviours are themselves an influence on selection pressures, and therefore evolution. For example, a beaver contructs a dam, and alters the local habitat significantly enough to change what is most likely to constitute “fitness”. That’s especially so if you consider, maybe, how an alternative line of beavers that didn’t make dams might diverge. As it stands this idea modifies Neodarwinian theory significantly enough to be interesting, but certainly not enough to threaten it.

Saltation, or sudden evolution, is the bête noir of the Darwinian gradualist view of the accumulation of small imperceptible changes over huge periods (“Natura non facit saltum” – quoted by Darwin despite his knowledge of “sports”, but held as an article of faith in the New Synthesis). It has to be said that the Modern Synthesis now often speaks of evolution as occurring after stasis, in small populations, over relatively short periods – but still, in real time, imperceptibly, as in Gould’s punctuated equilibria theory. Classic gradualism is only appealed to in order to show how there’s been plenty of time for seemingly impossibly big changes.

But many of the “extended synthesis” people can see mechanisms for real saltation – the “hopeful monsters” of Richard Goldschmidt’s famous phrase – in epigenetics, symbiosis and other things, and indeed have even cited living examples of it.

Combine saltation and niche construction and you have an intiguing picture of organisms influencing their own evolution directly. An animal is born with characteristics that mean it’s no longer fitted to its ancestral environment. Imagine, for instance, a developmental mutation giving a specialist insectivore chewing molars instead of pointy ant-squashers. Increasingly hungry, it wanders around and has a go at a leaf – with great success. It adopts a new role as a herbivore, natural selection refines its offspring and, in one generation, you’ve had macroevolution.

I once saw a documentary in which a researcher of hammerhead sharks suggested that’s how things were with them – a shark embryo wakes up to find its eyes on stalks and its mouth inconveniently underneath, and has to learn bottom-feeding pretty sharpish or die. I thought it totally Undarwinian at the time – and of course, it is. But it’s no less plausible a mechanism than the completely passive one of Neodarwinism random mutation and selection. And drift..

A classic illustration is this. Here an acquired deficiency leads to completely adaptive changes of behaviour – equally plausible if there had been large, heritable, mutational changes. In a similar example, Slijper’s two-legged goat of the early 20th century, significant skeletal and physiological adaptations were shown to have occurred, whether by epigenetic or other means I don’t know. But it’s a quick way to create a new form and fool the palaeontologists and evolutionary biologists into inventing a long and winding road where there was just a gate.

I like Mike Heron’s caterpillar cousin because of the underlying benevolence he assumes to be present in the things he’s been given: let’s find out what they do and go with it. We never actually have a verse about what he thinks of waking up able to fly! And that, I guess, is the obvious moral for us. But the song could almost be an anthem for a new view of theistic evolution – if the folks at BioLogos can ever get past the blind contingencies of Neodarwinism.

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About Jon Garvey

Training in medicine (which was my career), social psychology and theology. Interests in most things, but especially the science-faith interface. The rest of my time, though, is spent writing, playing and recording music.
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