This fine book on evolution was well reviewed at the time and won the 2010 Royal Society prize for science books. Here is my review from Eurotimes . Or rather this is a draft, and readers will note one paragraph just trails off… I cannot find the final version online or in my email so I am not sure what followed! This review is focused on the ophthalmological aspects of the book, though not to the exclusion of the wider issues :
Life ascending.
Nick Lane
There are ten great inventions of evolution discussed in Nick Lane’s lucid, stimulating book – life’s origin,
DNA, photosynthesis, the complex cell, sex, movement, sight, hot blood, consciousness, and death. Lane
makes it clear from the outset that invention does not mean a conscious agency purposefully steered the
process, rather he is referring to the ten great innovations that have transformed life that were created
through natural selection. Readers of this journal will have particular interest in the chapter on sight, which
I will therefore focus on in this review, but the whole book is superbly written and extremely enjoyable.
The eye has long been a favourite topic of anti-evolutionists. In 1802, the English utilitarian philosopher William Paley
argued in his Natural Theology that the eye is an organ of such complexity that it is absurd to suppose
that the purposeless blunderings of evolution (evolutionary ideas pre-dated Darwin, of course) could have
produced it. He used the analogy of a blind watchmaker producing a timepiece, which later gave Richard
Dawkins the title of one of his books. Darwin himself is frequently misquoted by creationists and affiliated
persons in this context – he seemed the admit that “To suppose that the eye, with all its inimitable
contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for
the correction of spherical and chromatic aberration, could have been formed by natural selection, seems
… absurd in the highest possible degree.” Darwin went on the write, however, that “if numerous
gradations from a perfect and complex eye to one very imperfect and simple, each being useful to its
possessor, can be shown to exist” the problem is solved.
In fact, we now have models of the evolution of the eye that exceed those of other organs in explanatory
power. The Swedish researchers Dans Eric Nilsson and Susanne Pelger have modelled this succession
of steps, which is each generation is taken as one year, requires somewhat less than half a million years.
The eye does seem, at first glance, to pose a problem to evolutionary explanations of its origin. What’s
more the human eye, with its rods and cones located behind an array of nerves and with its blind spot
where the optic nerve leaves the orbit, does not at first, cynical glance to be especially well designed.
Furthermore, the cant charge of anti-evolutionists has been “what use is half an eye?”, and answering the
question of how a retina could have evolved, separate from the rest of the optic apparatus, is at first
glance difficult. “Evolution is cleverer than you are” is a famous dictum of the evolutionary biologist Leslie
Orgel, and Lane goes on to show not only that the eye is well adapted to its purpose, but that (I am not sure what I said subsequently)
His approach begins, entertainingly for readers of this publication, with the observation that “anyone who
has been to a conference of ophthalmologists will appreciate that they fall into two great tribes: those who
work at the front of the eye … and those who work at the back … the two tribes interact reluctantly, and at
times barely seem to speak the same language.” For this divide, ironically, reflects the half-an-eye
distinction and allows us to consider the evolution of both halves of the eye.
For the retinal part of the answer, Lane travels (literarily speaking – it was the marine biologist Cindy Lee
Van Dover who did the actual exploring) to the most hostile and extreme habitat on earth – black-smoker
vents on the deep ocean floor that support an ecosystem of hardy survivors. Among these is the
ironically named eyeless reef shrimp (Rimicaris exoculata), which as a larva has fully formed eyes.
These are not of use to the adult shrimp, so they are reabsorbed and replaced with a literal half an eye
– a naked retina.
Most doctors will remember rhodopsin, perhaps rather dimly. It is the light-sensitive protein at the heart of
the visual process, being involved in photoreceptor synthesis as well as the initial perception of light.
Rhodopsin evolved from an algal ancestor where it is used to calibrate light levels in photosynthesis.
Rhodopsin is used by some bacteria for a form of photosynthesis.
Lane synthesises the evolution of all the aspects of the eye, although one of the ophthalmological tribes
may feel their area of interest is dealt with in slightly less detail than their retinal brethren. The naked
retina was the first step on the journey. As different organisms’ sheets of light-sensitive were arrayed in
different ways, with some recessing into pits which allowed shadows to be cast and therefore an idea of
where light comes from to be assessed, the trade-off between resolving light and light sensitivity began to
tip the balance in favour of lens formation.
Writers in this field must be tired of having to handle the creationist/intelligent design issue. Lane’s book is
not aimed at this debate, although in the footnotes he refers the reader to “The Flagellum Unspun” by
Catholic biochemist Kenneth Miller which attacks the creationist idea of irreducible complexity, as
exemplified by the development of a flagellum. Lane quotes Miller on intelligent design advocates as
double failures, “rejected by science because they do not fit the facts, and having failed religion because
they think too little of God,” and discusses Pope John Paul II’s views of evolution and the mind (made in
the course of his 1996 pronouncement recognising that evolution was more than a hypothesis) with
respect and sensitivity. Lane is clearly that wonderful thing, an enthusiast able to explain and inform
effectively.
Séamus Sweeney 