Book Review

Claudio Flores Martinez

Edited by Sara Imari Walker, Paul C. W. Davies and George F. R. Ellis:
From Matter to Life. Information and Causality.

Hardcover: 514 pages
Publisher: Cambridge University Press; 1 edition (April 10, 2017)
Language: English
ISBN-10: 1107150531
ISBN-13: 978-1107150539
€25 (hardcover), €20 (eBook)

Life Viewed from the Top-Down

How important is the role of information in life? What actually is information? Can information have causal consequences? This collection of essays is a perfect approach for those who are eager to learn how a new informational paradigm is going to shape 21st century biology.

Photo: Jarkko Laine

What is life? This question has been pondered by ancient philosophers (during classical antiquity), naturalists (in the middle ages and early modern times) and scientists (from the Enlightenment and the birth of the scientific age onwards) for thousands of years. A closely related problem is how bio-complexity is changing over time, or if it does so at all, considering that the immutable Platonic ideas formed the basis of Western thinking until the mid-19th century, and at what scale(s) these organic transformations are occurring.

A recent Lab Times article discussed the “Extended Evolutionary Synthesis” (EES), which was designed to broaden the theoretical outlook of the now dusty “Modern Synthesis” of Neo-Darwinism, initially developed during the 1940s Lab Times 3-2017, page 20ff). However, a small but growing group of researchers is going even further than that by claiming that informational and computational hierarchies (not exclusively constituted by DNA) embedded within living matter are the major driving forces of organic change, i.e. evolution. In their view, “information” has causal primacy over matter. But let’s step back a little bit.

Re-defining living systems

Top-down theorists such as Arizona State University physicists Sara Walker, (who is leading ASU’s “Emergence” group), and Paul Davies (director of ASU’s BEYOND: Center for Fundamental Concepts in Science), propose that the organisation, structure and function of living systems cannot be completely explained by a materialist-reductionist “bottom-up” approach.

Yet, their theories are not transcending the boundaries of physics, but are rather re-defining these very limits by exploring the role of information in living systems. Together with their colleague, George Ellis (Professor Emeritus at the University of Cape Town), Walker and Davies published a thought-provoking collection of essays (From Matter to Life – Information and Causality), compiled from an interdisciplinary workshop on “Information, Causality and the Origin of Life” that took place at BEYOND in 2014.

The phenomenon of evolutionary convergence might serve our current purpose of encapsulating the complex and unusual ideas of these trailblazing theorists. In their eyes, on an abstract systems theoretical level, convergent evolution of organismal complexity is the result of biomolecular networks that are organised and structured by information hierarchies via top-down causation.

More “top-down” than “bottom-up”?

Top-down causation refers to the causal role of information in living systems. More specifically, it describes the process whereby higher levels of organisation (e.g. nervous systems or organ tissues) in structural hierarchies constrain the dynamics of lower levels of organisation (molecular dynamics of metabolites, transcription and translation). In a classical molecular biology framework it is assumed that purely physical effects determine the dynamics of lower levels of organisation and, by extension, strictly govern interactions occurring at higher levels as well.

Information, however, can acquire a causally efficacious role in physical systems without violating the principle of the closure of the physical world. In fact, an emerging school of thought in evolutionary biology is advancing the hypothesis that the transition from non-life to life, abiogenesis, can be aptly described as a transition in causation and information flow. Informational takeover events (in contrast to the notion of genetic takeover events) appear to have occurred during all of the major transitions in evolution. At any given higher level of biological complexity, novel top-down informational hierarchies are defining lower level molecular, cellular or organismal operations.

This idea is closely related to the concept of functional equivalence classes. Functional equivalence occurs when a given “higher-level” state leads to the same high-level outcome, independent of which “lower-level” state instantiates it. Equivalence classes are defined in terms of their function, not their particular physical instantiation: operations are considered (functionally) equivalent (i.e., in the same equivalence class) if they produce the same outcome for different lower-level mechanisms. Genome-wide convergent substitutions in echolocating mammals (bats and dolphins), convergent expansions in the proto-cadherin family of octopus and vertebrate genomes, or a variety of biochemical systems underlying bioluminescence, from eubacteria, to dinoflagellates, comb jellies and fireflies, are excellent examples of functional equivalence.

Thumbs up for a new paradigm

The editors have arranged the contributions of leading experts from the complexity sciences in five chapters, which deal with different aspects of top-down causation, for example its role in shaping the origin of life, structuring complex ecosystems or engineering human-made technological and societal systems via functional equivalence. In this sense, top-down causation can be regarded as a meta-theory that is blurring the borders of biology, physics and information theory. For those who are eager to learn how a new informational paradigm based on a new kind of physics is going to shape 21st century biology, this book presents the perfect primer. Thumbs up for top-down.

Letzte Änderungen: 28.08.2017