Is evolution still happening?

Every so often, someone lands on my site specifically because they're wondering this: is evolution still happening?

Depends what you mean, really.  We hear often how viruses and bacteria mutate, seeming to generate new ways to attack us all the time.  Take bacteria (which are more readily classed as living entities).  They proliferate by dividing (binary fission), and their generations are far, far more rapid than ours.  Greater population, fast breeding, more scope for genetic change that is more visible to us.

Yet broadly we conceive evolution in terms of how we humans got to where we are today.  And that's the product of hundreds of millions of years (and elaborated in my earlier discussion here).  Saying that is one thing, but understanding it is far more difficult, because our human scale takes its measure in one lifetime.  At best, we extend ourselves to the whole of human history, which is only a few thousand years - a tiny speck on the scale of hundreds of millions.  I call this issue deanthropocentrism: the effort required to conceptually escape our human framework, and understand processes that work on vastly different scales.  To do this more than superficially is not nearly as easy as it sounds.

So some of us think, how can this be, does this evolution really make sense?  Yes, it does, just not so much in our immediate framework.

Yet the sun is still emitting radiation that occasionally knocks around with DNA in our germ-line cells, producing the odd change.  Such changes can add up over time, if beneficial for survival.  If a mutation improves the odds of an individual surviving and breeding, that mutation is more likely to survive.  In the past, this was "natural selection" - ie, mutation survived where the "whole of environment" (including climate, food resources, food competitors, and predators) fostered it.  These days, humans frequently take that role, exercising selectivity over both plant and animal breeds.

How does selectivity work today on humans?  Well, we've diluted it substantially.  By improving global health, we're over-riding natural selectivity.  We're increasing the survival rates of those who have adverse genetic outcomes.  For example, cystic fibrosis sufferers once seldom lived far beyond puberty, but survival has now been prolonged past breeding age.

Is that a bad thing?

No, because we are ethical beings, not ones to ride on the whim of random outcomes.

Over time, our technology can improve outcomes, identify potential issues before they happen, find solutions.


And we are now at the point where the environment is a product of us, not vice versa.  So what of climate change?  Although we can say human adaptions that are better suited to a hotter, more turbulent world are better able to survive, the question is whether those less adaptive are likely to survive to breed.  And our global culture no longer fosters selectivity purely on that basis - bar a calamitous breakdown of society.

So these are the issues: whether and how we intervene in 'natural' selectivity.  Such intervention can bring human evolution to a halt.  The only selectivity for breeding now is societal, and I have seen no indication so far of any specific genetic determinant on those who end up remaining single all their lives (in the sense that they produce no offspring).

In that sense it could be said that humans, for the time being, have induced their own evolutionary pause.  However, that might not be such a bad thing: natural selectivity could work in any direction, depending on environment.  Bigger (or brighter, or more complex) is not necessarily better for survival, for example - as the dinosaurs found out.

Spaceship Earth-II: the future of Earth's life

"The earth is going to die in 500 million years!" exclaimed my eight-year-old today. And I had to illustrate to her how this is well beyond the span of our existence. Sort of a deanthropocentric exercise in reverse.

But what of it? Fundamentally, we don't like to think that there's nothing left of us - ever. But does that need to be the case? Yes, the sun is growing hotter, but we have hundreds of millions of years of technological advancement before the Earth becomes uninhabitable. And think where we've come in just one hundred years.

Last week, I was talking through a thought experiment with Mark on this topic.

Space is prohibitively large; commuting is not really an option. Even at the speed of light, the nearest star system to our own, Alpha Centauri, would take four years' travel. And it's questionable whether there's anything habitable there. It's a binary (plus) system, and the gravitational flux of two nearby suns may not foster stability.

Further, our bodies evolved in gravity, and it's not clear we'd survive for extended periods in minimal gravity environments.

In Rendezvous With Rama, Arthur C Clarke posited a mammoth cylindrical body 50 kms long, with habitation on the inside. That's an overwhelming construction endeavour. I think there are easier options.


My suggestion is that to travel beyond the Solar System would take far more massive an environment than we could possibly build ourselves. It would be simpler to grab an existing body, and power that away somehow. As Mark pointed out, this is the Space: 1999 scenario, a science fiction series where the moon was torn away from Earth.

Possibilities include using something large from the asteroid belt, a moon from Jupiter or Saturn (such as Ganymede), or maybe something far out, such as that erstwhile planet Pluto.

Issues include heat, propulsion, gravity, retention of atmosphere, and other life-sustaining variables. By the time it's worthwhile thinking about it, I'd say we'd have the technology to allow us a few options.

This is the stuff of science fiction, certainly; plenty of options have already been canvassed in that milieu. Burrowing underground would provide sturdy shelter, although digging enough habitable space would be Herculean. Other options include domes on the surface - or terraforming.


Ah, terraforming. Rather what happened to our own planet. Microbial life has built up our current atmosphere and environment; we're just the evolutionary outcomes that could adjust to it. It took hundreds of millions of years to develop, but I think it's reasonable to anticipate we'll be able to engineer biological solutions that work faster.

However, out beyond the easy reaches of the sun, everything freezes. There would need to be both sufficient gravity to hold an atmosphere (or to be able to continually regenerate it), and heat sources sufficient to prevent that freezing. The latter would be most feasible through nuclear fusion sources - we haven't succeeded at this yet, but I can see no reason it won't come. It's what the sun uses.

Gravity is a matter of using a large enough body. Life on Earth is, of course, evolved for our specific gravity, and much more research is needed to understand how or whether current life forms could adapt to lower gravity, or whether we'd need to engineer alterations that would allow various forms to survive in a somewhat different environment.

Because we would want to take with us as much of the existing variety of life as we could. This could involve storing samples at the DNA level, for later development/unpacking using either technological or substitute development (incubation) methods. In any case, plants and animal life should be considered an essential part of our environment - our being - and taking that with us would not be at issue. Bacteria and viruses too, surprisingly enough. Bacteria are our microbial engineers, a fundamental tool of life. Viruses have helped us become what we are today, though infiltrating our germ lines, they have imparted in us the resilince - and functionality - that we possess today.

The Earth's variety of life evolved specifically because the amount of solar radiation both protects us from other stellar sources, and generates mutation by occasionally knocking around with DNA. Outside Earth's orbit, mutation would happen at a different rate, which we would have to account for. Lesser rates would not be an issue: we are now at the point of engineering our environment to overcome the 'need' for adaptive outcomes of mutation. Greater rates of mutation would necessitate careful screening to optimise outcomes.

Yet that begs the question: outside the Earth's specific environmental womb, would it be more beneficial to engineer adaption in ourselves, so that future generations can make the move more readily? The biggest barrier is ourselves: the fact that we are rather wedded to our current form, no matter how ill-adapted to space journeying. I suspect we would be more willing to put extra effort into optimising our environment, than to force evolutionary change on our own grandchildren.

I have great optimism that we will survive in the long run. Even if, to paraphrase Steve Kilbey, we end up as digital memory*.


None of this is a substitute for getting our own planet in order. But if we can succeed in that, we'll probably be well placed to survive past the use-by date of our planet.


*The Church: Fog, (1992 B-side to Ripple)
It hurts to think that in a hundred years
We'll all just be microfiche
Our names and the names of our songs
Cataloged and filed away

- however, compared to the fate of most of our ancestors, I'd be happy to survive in digital form.

Earth as Gaia - or Medusa?

The Gaia hypothesis keeps cropping up in fiction and popular science, doubtless to make a comeback in the context of climate change.

There are various articulations of Gaia, which proposes the Earth constitutes a complex regenerative system that always returns the environment to a life-sustaining equilibrium. One version maintains that Earth and its atmosphere and environments supports life and constantly brings it back into balance; another draws into the equation the Earth's biomass (the totality of life on the planet), to say that the full system constitutes a self-balancing (homeostatic) system.

Gaia was proposed in the 1960s by James Lovelock, with Dian Hitchcock. Working for NASA, they were charged with researching the atmosphere on Mars, for signs of life. Finding the Martian atmosphere to be in a deadly state of equilibrium, they contrasted this with Earth's atmosphere, in a relative state of flux (between oxygen and carbon dioxide in particular). Their Gaia proposal grew out of that.

Yet Lovelock's background was in chemistry and medical research rather than environmental science, and he was employed by NASA to develop equipment to analyse Mars' atmosphere. Hitchcock's background was philosophy, and she was to test his logic.

After the initial formulation, Lovelock's main collaborator has been Lynn Margulis, a biologist who couched the theory in more careful terms: of trends rather definitive equilibrium. (Margulis' reputation, however, is built on much more significant work, on the origin of organelles in eukaryotic cells: that is, that the organs of cells with nuclei emerged through symbiosis of separate entities). Her contribution to Gaia allows that no species has guaranteed passage through the bottlenecks of time.

But a major criticism of Gaia is its teleological nature: that is, that it implies some intention or purpose behind the planet's formation.

Recently, Peter Ward, an American biology professor, wrote a book that proposes the opposite: the Medea hypothesis, which says that life is constantly trying to kill itself and its own environment (The Medea Hypothesis: Is life on Earth ultimately self-destructive?). His overview in New Scientist is worth reading: it contains much background information about Earth's environmental changes.

My concern is that none of this is saying anything in particular. There is no guarantee that life in any form will survive a major disaster such as global nuclear war or a sufficiently large meteor impact. In fact, current projections are that the Earth will become totally lifeless within 500 to 1,000 million years, purely through the expansion of the sun - and that compares to the 3.8 billion years it has taken to develop to this point.

Behind both Lovelock's and Ward's articulation is the fact that Earth's environment and atmosphere has changed quite drastically over its history, causing mass extinction - several times, and life itself is the frequent culprit, due to cumulative changes in chemical composition of atmosphere and oceans. One such event was the evolution of photosynthesis 2.3 billion years ago. This entailed the absorption of carbon dioxide, and the emission of oxygen: a double whammy. On the one hand, oxygen was pure poison to most life at the time. On the other hand, over the course of 200 million years, the sucking out of carbon dioxide froze the oceans: this (first) snowball earth lasted 100 million years.

(although we credit the most well-known extinction event with an external cause - the meteor 65 million years ago that wiped out non-avian dinosaurs - most were due to events of local origin, pointing to imbalances that build up over time, usually from biological causes.)

There is no guarantee that the planet would return to a life-sustaining balance. Nor is there viable evidence that life deliberately tries to kill itself, or will ever succeed. Yet what it does say is that the variety of life is such that it has survived a number of cataclysmic changes. Pretty much all environmental niches that we can identify have corresponding life forms that could survive it (albeit most of the extreme cases are microbial).

On an immediate level, if we make the planet inhospitable for ourselves, other life forms will surely survive. For what it's worth. But human intervention has been nothing like any previous climate change bar the meteor: all others have been far more gradual. In terms of our lifetime, it's slow, but on a less anthropocentric scale, we are inducing a real shock to the planet. Yes, climate change is natural, but not in the framework in which we live. And the ride will be somewhere between bumpy and catastrophic, depending on our capacity to move forward together on the issue quickly enough.

The cell as computer

Making sense of the material world is a gradual process that we all achieve to different degrees over the course of our lives. The further removed a paradigm is from a day to day human experience, the harder it is to put it in a meaningful context. Whether too vast or too small in size (stellar phenomena or microscopic to sub-atomic action), or too long or short in time (evolution; quantum actions), it helps to find a way to express meaning in terms we live each day.

Living cells are computers. This is a very succinct analogy which can help to conceptualise the complexity of cellular life and action.

Of course this metaphor is not new, but it looks to be very well put in a new book, Wetware: a Computer in Every Living Cell, by Dennis Bray (and reported in New Scientist).


Stentor Roeselii is a pond-dwelling single-celled organism. It exhibits behaviour that is akin to being directed by a brain. If a jet of water is squirted at it, it will duck down, then come back up cautiously. Another, identical squirt would be ignored. Squirt an irritant chemical at it, and it will "arch its stalk-like body out of the way, move from side to side", retreat, then finally tear itself free from its mooring and drift off to a new home.

Bray characterises such an organism as a chemical computer. Ultimately, the programme written out in the DNA (and so it cannot be reprogrammed per se). But the complex set of actions (output) are all induced by chemical reactions that occur as a response to stimulus (input). The chemical reactions are not simple, but they are effectively laid down by DNA, which also dictates the form, that is the composition of this "bag of biochemistry". We cannot yet come close to duplicating this because we haven't broken the barrier to the point where we can build computers at anything more than an electronic level.

In a similar fashion, a multicellular organism could be seen as a large group of chemical computers that includes complex mechanisms (chemical interactions) to bind them to working collaboratively. (By the time we get to the sophistication of an animal with a decent-sized brain, though, the ultimate outcome could be said to be non-deterministic, simply because of the complexity and miniturisation... but that determinism is another debate altogether.)


Comparing biochemical action to advanced miniaturised computing is a very useful way to help understand how life builds up from its building blocks to the level of complexity we now see.

Scientific revolution as one of perspective

Jacob Bronowski discussed some scientific revolutions in The Ascent Of Man. Specifically, those of Copernicus, Newton and Einstein.

(In human terms, Bronowski grouped together as social revolutions the American, the French, and the "English", or industrial revolution.)

Elsewhere, Stephen Jay Gould mentioned Freud's take on three pillars torn down in removing humanity from its pedestal as centre of the universe. Freud listed Copernicus, Darwin, and Freud himself (this was meant to be about shattering the illusions of the rationality of humans). To that list, Gould added the notion of deep time as something linking the revolutions of Copernicus and Darwin.

Bronowski was a mathematician by trade, Gould a paleontologist; this informs their choices.

Copernicus' paradigm shift gives us our cultural use of the term 'revolution'.

Bronowski's characterisations illustrated the revolutionary nature of some of these changes. For Copernicus, the observed movement of heavenly bodies could not not be explained with simplicity from where he was located: the patterns were not related to the observer's perspective. The movements made more sense from a heliocentric perspective, and thus humans were not of or at the centre of the universe.

It's inevitable that the spiritual establishment, the Catholic church, would decry, forbid this challenge to established thought, of which they were the sole arbiters. The challenge to authority it represented was bad enough to invoke punishment and censorship for a long time afterwards. The challenge to humanity's position (in the centre of the universe) was intolerable then as it would be in most ages.

Darwin's dislocation of humanity as a unique creation, to become a mere player - albeit a major one - in a succession and a panoply of species is also destabilising. Even now, the Vatican is unapologetic over its reaction, even as it acknowledges evolution as a validity (being "compatible with the bible").

Bronowski characterises Einstein in intellectual flight as imagining he was travelling on a beam of light - in effect, outside the grasp or capability of human life. Again, a paradigm shift invoked by an imagination that was able to think outside the framework of the human scale.

Those I find easy to identify as revolutionaries are Copernicus, Darwin and Einstein. For each of their breakthroughs, the human scale was an emotional barrier, but ultimately proven a simply inadequate perspective. And in each case, the scientist's conception far preceded scientific verification. Those men were revolutionary because they were capable of extending their thinking towards the universal.


I've referred several times to the significance of deanthropocentrism in the study of evolution. It's not a pure necessity in coming to grips with the very basics, but deep understanding is so much more of a struggle where the effort is not made to remove one's human shackles. As a reward, the ability to displace oneself from the human scale has constant application at all levels of understanding of the field.

I cannot claim these three are the only revolutions in this fashion. And I cannot say we are finished. We may never complete the journey because we may never be able to say we have reached the universal.


But our forward progress has an immediate stumbling block. One of the great barriers to successful stewardship of this planet is our perception of our inalienable right to exploitation of the whole of its resources... even to destruction. The pace travelled so far does not yet seem to fast enough to overtake the perils of anthropocentrism.

Dolphins are human too

I must recap on a recurring theme of this blog: a meaningful study of evolution requires a continual process of re-orienting oneself away from the human perspective.


Deanthropocentrism. No other discipline mandates this. The nearest one gets is the physics of vast (and minute) scales of time and/or space, but this becomes an academic exercise with little direct meaning to the observer.


Not so evolution: the ramifications are often direct and clear. We are not the most successful form of life, from the perspective of either a lengthy run, or the most numerous or ubiquitous, or the greatest mass (that's bacteria). We have shaped our environment like none before, achieved consciousness, left artifacts. But all that can fade with the ravages of time. We are here strictly by lucky contingency. As but one example: if the K-T meteor hadn't struck, we would not have developed this body shape and would still be huddling under the shadow of dinosaurs.


All of which must be anathema to creationists. Ah, but that's their lot.


I'm reminded of another dent to our pedestal today, by a news report of a friendly dolphin. Moko, in New Zealand, is apparently at ease with humans, playful even. This dolphin let a stranded mother and baby sperm whale back out to sea, at Mahia Beach in Northland.


Volunteers had failed in four attempts to direct the whales back out to sea. The whales were visibly distressed, adjudged doomed, but "as soon as the dolphin turned up they submerged into the water and followed her". They never came back, but an hour later Moko returned.


A Conservation Department official speculated the dolphin had heard the whales' distress calls.



Plan, purpose, altruism, compassion. Some of the traits we typically, erroneously, ascribe to higher-functioning humans only.


Such a story - about dolphins in particular - is not new. But it's a timely reminder that we are blindly self-centred, pay too little heed to the world around us. We don't have a monopoly on these advanced qualities. In fact, some of our more basal capabilities are notably absent in dolpins.

Linking us to starfish

More precisely, this post is about the connection between vertebrates and echinoderms (starfish, sea urchins, and so on).


The New Scientist article mentioned in the last post describes this connection, which seems fairly uncontentious on the whole, with broad agreement in the sources I've consulted (Tudge, Dawkins, Palaeos, Wikipedia).

It goes like this, according to the article: echinoderm -> hemichordate -> sea squirt -> lancelet -> vertebrate.


By phylum, the latter three are all chordates, but sea squirts and lancelets are more basal than the vertebrates we know and love.

Tunicates (sea squirts) - © Martin Riddle

They constitute the three sub-phyla of the Chordata phylum: respectively Tunicata (Urochordata, until recently), Cephalochordata, and Vertebrata. Wikipedia lists the number of species for each as approx 3000, 30, and 58,000 respectively.


The article suggests lancelets were probably neotenous tunicate larvae. Funny to see sessile marine creatures (pictured above) related to vertebrates. But from what I've read, most sessiles seem to have a motile juvenile phase. So the above is what we could have looked like if we'd continued developing, rather than reproducing early then trundling off down a different path. Rather a plank in the eye for creationists, I'm afraid, but an object lesson in deanthropocentrism.



I recommend this entry in a Nature.com blog about tunicates (it's where I got the nice picture). Eerie.

Refinement of evolutionary theory

A quick summation of evolutionary theory might be in order. Different books tend to make up different equations on what constitutes current thinking, so I might just take the flattened versions, in the main, of Wikipedia.

Darwinism: Evolution by natural selection (I find "survival of the fittest" a particularly misleading phrase - and it's not really used by those in the know anyway). The generally accepted use excludes some misconceptions Darwin had or didn't rule out [not having a handle on genetics at the time], including Lamarckianism, the fallacy that acquired characteristics could be inherited. However, this general use is more strictly neo-Darwinism (below)

neo-Darwinism: Not correctly in current use; refers to refinements of Darwinism to about 1895. Wikipedia redirects this to the following (modern evolutionary synthesis), although there is an extant article on neo-Darwinism if you have the link - here. Incorporates refinements from Alfred Wallace (often mentioned along with Darwin when books are in the mood to be more correct), which specifically exclude Lamarckianism.

Modern evolutionary synthesis: the general basis of evolutionary thought since the 1940s. Genetic variation happens through chance mutation (and recombination in sexual interaction/selection); evolution happens through changes in the frequency of alleles (variants within a species) between one generation and the next, through natural selection and genetic drift. You can see how Wikipedia puts it here.

There's some subsequent argument on the unit of evolution: is it the gene (Dawkins)? The individual? The Species? or the Clade? (Gould seems to argue for some combination or synthesis of these.)

Some books put together an equation, with many incomplete variants such as:

reproduction + natural selection + mutation = evolution

From my readings, I would add some attendant concepts that help round out conceptualisation of evolution.
anthropocentrism - the great barrier to clarity in understanding is our own location at this point in evolutionary time and space. We too easily see things to our own scale and bias. The path to modern human has been, as one writer said "zigzaggy" over a period of time that is impossible to properly place in perspective.
the environmental niche - that is, an environment and its attendant organisms, whether it is isolated or experience some movement in or out of the environment
genetic drift (as mentioned above) - that is, even aside from mutations that are more favourable within the environment, there are changes (mutations) that have no nett effect on the individual or species survivability within that environment. The smaller the population, the more prone to drift, where isolated from other members of the same species and even when the environmental niches are equivalent. Change still happens.
redundancy and multiple use - a great engine for evolutionary change is available when two body parts can fulfil the same function, or one part can serve two functions. For example, a swim bladder in a marine creature that eventually facilitates air-breathing and develops into a lung; or bones in the jaw that help perform rudimentary auditory functions, then over time become exclusively used for hearing.
environmental change - more of a fundamental than most people admit, in my reckoning. Even aside from catastrophes that result in mass extinctions, environmental niches are never static in geological time scales. The whole planet is not static: plate techtonics, over time, affect global and local environments.


On another note, it's too easy to pretend environments don't change, and that without human interference, the planet would be a happy little paradise of biodiversity. That's simply not true - on geological time scales. But on the time scale of human history, it's sad but true: we have rocked the boat far too quickly.

Taking a much, much longer look.

Popular understanding of evolution is deeply flawed for a couple of reasons. First, the concepts are often subtle, and open to antithetical interpretations when reduced to one-liners. Second, we're understandably anthropocentric, and it's hard to think fully outside our own context.

I was once just as guilty as anyone of misconstruing why giraffes have long necks (due to the best mutations surviving in an environmental niche, not a lifetime of stretching!)


If I take a much longer view of time and the Earth, my conclusions are mixed, but on the whole positive.

In terms of Earth's history, we are in the Holocene epoch (for the past 11,500 years) of the Neogene period (the past 23 million years), within the Cenezoic era. That era is only 65 million years old, yet the Earth's geological history lasts 4,500 million years. The start of the Cenezoic era is marked by the meteor that caused the last main extinction event (K-T), which eliminated non-avian dinosaurs and gave mammals the opportunity to fill in the environmental niches left void.


And, of course, we're now in the middle of another major extinction event. And we are the cause of it.

The event will be marked by fossils in the geological record when this epoch and period is gone. As well as fossils the rock record will also show human artifacts.

By that time, we will have gone through some trauma. We will have changed the global environment; the only question is how far we have to go before we can band together sufficiently to stop the slide. We will need a new word for suffering, because the current global refugee situation is nothing compared with what we will face.

On the plus side, we will probably have forced our way out of the cycle of ice ages and interglacial periods that has characterised the planet for most of the Cenezoic era.

I also expect we'll have genetic technology largely under wraps. This means the ability to revive extinct species, but a species is just one aspect of an integrated environmental niche, and recovering them would be much more complex.

And, to paraphrase an old Church song (Fog), in a thousand years, we will all be digitised computer memory. That is the sole fate for most of us, although it's a more visible fate than most of those who died a thousand years ago.

I'd expect that ultimate survival will be due to our ability to conquer the tyrannical distances of space. If, for example, those who embark on the journey are those best suited for that vastly different evironment (whether involving cryogenics or not), there will be some genetic selection. That will be our only form of future evolution: that which we mark on ourselves.

[Or, in isolated environments, those left behind will change the natural way. However, evolution is a simple equation of the speed of adaptable mutations versus the speed of environment change. Evolving naturally would be, as it always has been anyway, a gamble.]


And now that we have digitised the past for the future's benefit, I have confidence there will always be music to lift the spirit.

Stephen Jay Gould, and random mutation

"Conceptual locks are far more powerful than factual lacks as barriers to scientific understanding" - S.J.G.

Stephen Jay Gould was a prominent evolutionary biologist, whose significant achievements included the concept of punctuated equilibrium (previously discussed here), and a welter of lucid writing that seeped into popular consciousness more than any other writer in his discipline since Darwin.

He died in 2002, but not before publishing a series of books based on over 25 years worth of essays for the magazine Natural History.

I'm currently journeying through his collection Eight Little Piggies (Jonathan Cape, 1993). His writing style is clear but erudite. The essays are interesting and easy to follow. But there is a trap that I believe is common to most discourse on evolution, both at a lay and a professional level: it is so very easy to misconstrue concepts. They are often subtle, writ on different scales to our own (in terms of both time and species). On the one hand, there are many fallacies built around the key phrases that sum up the popular conceptualisation of evolution, such as "survival of the fittest" and "natural selection". On the other hand, there are so many disputes between the professionals that consensus-building seems to take substantially longer than in harder physics disciplines such as cosmology or subatomic theory. This is because theory is necessarily built on small populations of fossils that each new discovery has potential to cause paradigm shift.

And interlaced throughout is the burden of anthropocentricism, the framework that lures people into thinking too much in the context of the here and now species.

And so Gould's essays are sometimes straightforward in their ramifications, but often require a re-read to catch the "correct" nuance and avoid the hidden missteps and solipsisms.

So I go carefully. And start with some clear concepts picked up from this book.

The first essay, Unenchanted Evening, follows the course of a species of snail (Gould's original academic focus) on the French Polynesian island Moorea. He traced the meticulous work of Henry Crampton last century, who made incredibly detailed studies of the Partula.

Gould illustrated how the body of measurement, description, and sampling was valuable not just as a comprehensive snapshot, but an excellent baseline for future study of changes in that species.
Unfortunately, it was driven to extinction. First, another species of snail was accidentally introduced that drove Partula to the brink, then a third species was intentionally introduced to control the second - but which instead clinched the fate of the Partula.

Biological control is fraught, absolutely. As any Queenslander ever plagued by cane toads will tell you. Introduced to control a sugar cane pest (which they never did), they are toxic and gradually spreading their way across the whole of Australia.


Yet there was a meaningful conceptual outcome of Compton's work. The island of Moorea is based on a volcano, and its topography is such that there are ridges and valleys all around the island. The Partula snail was partial to the valleys but not the ridges, so the population consisted of a series of sub-populations that were to a great extent isolated from each other. And each of those populations was physically different in form and colour. The question was whether those differences were due to unidentified differences in those niche environments, or random differences.

Crampton interpreted the differences as being due to three major causes: isolation, mutation, and natural selection. Isolation simply created the conditions for independent populations. Crampton saw natural selection as mainly negative, simply in terms of unhelpful mutations not surviving. And so the differences were due to random mutation.

"the role of the environment is to set the limits to the habitable areas or to bring about the elimination of individuals whose qualities are otherwise determined, that is, by congenital factors".

This has parallels with Darwin's Galapagos finches, with the difference here that there is no firm necessity for the sub-population differentiations.

Gould rated Crampton's labours and conclusions very highly.