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The importance of moving from evolution as abstraction to particular history

Given the diversity of philosophical conclusions that can be drawn from natural selection when considered in abstract terms, it is vital that actual data from natural history (and physics where applicable) be used to help us narrow the options. It is no longer possible for informed commentators to characterise evolution as pure contingency or deterministically convergent upon a single end-point. The question has instead become: to what degree is evolution on Earth (and elsewhere in the universe) constrained and which of the four views above is closest to the actual state of affairs?

Thankfully, recent work in palaeontology and palaeobiology has made considerable headway towards resolving this debate. According to Cambridge palaeobiologist Simon Conway Morris, the constraints may be very great indeed, which lends support to the ‘universal biology’ view. In his recent book Life’s Solution: Inevitable Humans in a Lonely UniverseS. Conway Morris, The Crucible of Creation: The Burgess Shale and the Rise of Animals (Oxford: Oxford University Press, 1998). he explores which aspects of the history of terrestrial biology appear to be constrained by universal laws and which may be due to chance. Interestingly, rather than argue that one or the other factor dominates, he suggests they both do.

Conway Morris supports his argument in two ways: by showing how terrestrial DNA-based biochemistry is demonstrably superior to alternatives,For example, ammonia ice does not float. See S. Conway Morris, The Crucible of Creation: The Burgess Shale and the Rise of Animals (Oxford: Oxford University Press, 1998). 25. and by showing how different organisms have converged upon the same solution when independently facing similar problems.See Conway Morris, Life's Solution: Inevitable Humans in a Lonely Universe 18, 164, 167, 170, 235. One particularly interesting case is chlorophyll. According to Conway Morris, it is difficult to conceive of an alternative mechanism for photosynthesis. In fact, terrestrial evolution has converged upon chlorophyll even though it is poorly optimised for converting the particular wavelengths of light received from our Sun. This leads him to wonder if life on planets orbiting different kinds of stars would also converge on chlorophyll.Conway Morris, Life's Solution: Inevitable Humans in a Lonely Universe 109-110.Importantly for our next discussion, he considers intelligence to be universally adaptive, and so an inevitable outcome of natural selection given sufficient time and resources.See Conway Morris, The Crucible of Creation: The Burgess Shale and the Rise of Animals 106, 196. In fact, if there are intelligent extra-terrestrials he expects them to be pseudo-mammalian bipeds with stereo camera eyes.Conway Morris, Life's Solution: Inevitable Humans in a Lonely Universe 208.

However, there is another side to the story. While many of the basic building blocks of life are plentiful, the chances of there being a hospitable planetary environment in which life can begin and flourish, are remote in the extreme. Here there are no known laws that can influence the likelihood. Our Earth owes its biology-enabling nature to a long list of accidents which make Earth-like planets unlikely elsewhere. This leads Conway Morris to guess that life is not common, i.e. it is a ‘lonely universe.’Conway Morris, Life's Solution: Inevitable Humans in a Lonely Universe 38, 42, 72-104, 328.

Conway Morris’s work is of great help as we try to add flesh to the abstract bones of natural selection and determine the degree of constraint it is under. However, it is still early in the debate. Ironically, the data driving Conway Morris’s view comes mainly from the Burgess Shale fossils in British Columbia and the K-T extinction. This is the same data that led Gould to the opposite conclusion. Gould emphasised the large number of species that did not make it through the K-T extinction, and concluded that life on Earth today is due to our ancestor’s lucky survival through this catastrophe. Conway Morris, however, believes that the drive to convergent solutions is powerful enough to overwhelm events even as disruptive as the K-T extinction. Where Gould consider the K-T impact one (among many) contingent causes of the rise of the mammals, Conway Morris suggests it only brought it forward by some thirty million year”See Conway Morris, The Crucible of Creation: The Burgess Shale and the Rise of Animals 222. and “although there may be a billion potential pathways for evolution to follow from the Cambrian explosion, in fact the real range of possibilities and hence expected end results appear to be much more restricted.”Conway Morris, The Crucible of Creation: The Burgess Shale and the Rise of Animals 202.

While there is a need for further research and debate it looks as though the view of biological history as essentially a capricious random walkSee also Dennett’s description of the ‘Library of Mendel’ Dennett, Darwin's Dangerous Idea: Evolution and the Meanings of Life 107. with arbitrary end-points may be headed for extinction. If Conway Morris is correct and evolution is highly constrained by universal laws this finding will mark an important milestone in the philosophy of biology and philosophy of science in general.

If there is evidence for a ‘universal biology’ it will link evolution with the ‘fine-tuning’ and Anthropic Principle debates in astrophysics. It was recognised several decades ago that a number of physical constants have values that allow for life where other configurations of constants would preclude it. Thus far it has not been possible to argue persuasively that the laws of physics give rise to life, but by coupling cosmic fine-tuning with Conway Morris’s work, this kind or argument is now a possibility. Importantly, there is currently no ‘scientific’ explanation for why the constants have these particular life-related values. Speculations vary between postulating an infinity of universes where the values are randomised by some as yet unknown process, and the admission that the values are simply ‘given.’

New data may yet point in the opposite direction and so support Monod’s view, but it is now conceivable that scientific data could come to support the view that the universe is fine-tuned for intelligent life. The debate over convergence has added urgency to the closely related question of directionality in evolution, to which we now turn.

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Go to Evolution Topic Index

The importance of moving from evolution as abstraction to particular history

[1] Does Evolution ‘do the work of a friend’ for the Christian Religion?
Setting the scene - why focus on providence?
[2] Supposed challenges from the evolutionary sciences to theology
Intellectually fulfilled atheists?
A challenge to human uniqueness and status?
A challenge to purpose in creation?
A threat to the veracity of scripture?
Evolution ‘explains away’ theology?
A challenge to Christian morality?
The challenges in wider context - Darwin as a scapegoat?
[3] The current state of the evolutionary sciences
Different ways of conceptualising Darwinian evolution
Evolution as chance and necessity
Evolution as an algorithm
Evolution as movement within a ‘fitness landscape’
Ongoing debates: contingency versus convergence
Ongoing debates: what are the key causal factors in biological history?
Ongoing debates: the environment as the principle cause?
Ongoing debates: convergence as the principle cause?
Ongoing debates: ‘Universal biology’ as the principle cause?
Ongoing debates: directionality and progress
Ongoing debates: the origin of life
Different levels and kinds of selection?
[4] Responses from theology
Evolution, probabilities and providence
Responses from contemporary theologians
Holmes Rolston III
Keith Ward
John Haught
Arthur Peacocke
An increased role for general providence?
Theology of Creation in the light of evolution: three scenarios
[5] Concluding remarks
Sources

Source:

Adrian Wyard
Adrian M Wyard MSt

See also:

Evolution
The Relation of Science & Religion
Purpose and Design
Genetics
The Argument From Design
The Anthropic Principle
Opinions
Charles Darwin
DNA Double-Helix