A dialogue with Denis Noble

A few weeks ago, I mentioned that Denis Noble would be engaging in a dialogue on this blog about physiology, evolution, genomes, and agency. Denis Noble is a physiologist and author of several books on physiology and evolution, including The Logic of Life, The Music of Life: Biology Beyond the Genome and most recently Dance to the Tune of Life: Biological Relativity. I’m pleased to include his first post below. I will be responding over the next few days to the points he lays out.

Dear Scott

Purpose and Desire is a really great read. I like the style.

I can’t help noting that we seem to be very much on the same wavelength on almost everything. The ways in which we view Weismann, the tautologous nature of much of evolutionary theory and, most important of all, the agency of organisms, are very similar indeed.

In this dialogue I would like to focus on the agency of organisms and what the experimental evidence shows.

To start with definitions, here are the relevant definitions that my brother, Raymond, and I published in a recent article in the MDPI journal BIOLOGY (http://www.mdpi.com/2079-7737/6/4/47):

2. Definitions

Agency: an agent acts, it does not just react in the way, for example, in which a billiard ball is caused by another ball to move. Organisms are agents to the extent that they can interact socially with other organisms to choose particular forms of behavior in response to environmental challenges. This definition of agency can therefore apply to microorganisms, such as bacterial films and eukaryotic slime moulds, that form interacting communities as well as to multicellular organisms. In principle, it can also apply to the subcellular networks responsible for buffering organisms against many forms of DNA variation.

Goals: Goals can be ascribed to agents since choice of action involves directionality in their actions. A goal in this sense is the situation towards which the agent’s action leads. Goals arise naturally from within the agent’s cognitive behavior, albeit in interaction with other agents. This kind of behavior can be called natural purposiveness. Goals can therefore be ascribed empirically on the basis of observation of the behavior of organisms.

Teleology: The possession of goals is what defines teleology. Some biologists prefer the word teleonomy to emphasise the view that goals in organisms (sometimes with the qualification ‘other than humans’) are only apparent. Since our use of the word ‘goal’ enables empirical physiological tests for the presence of the required natural purposiveness we see no need to avoid the word teleology. 

Natural purposiveness: Natural purposiveness is an emergent property of multi-level evolved systems. It is easier to understand and appreciate its significance within the principle of biological relativity, i.e., no privileged level of causation.

Neo-Darwinism: Classical neo-Darwinism was formulated by August Weismann [15,16] and others in the late nineteenth century to expunge the inheritance of acquired characteristics from Darwin’s theory. Blind variation followed by natural selection was claimed to be entirely sufficient (Weismann’s allmacht). This is clear from his extensive argument with Herbert Spencer. Many biologists today redefine neo-Darwinism in various ways (see e.g., the on-line dialogue between one of us and David Sloan Wilson (https://thebestschools.org/dialogues/evolution-denis-noble-david-sloan-wilson/) and the relevant entry in the Encyclopedia of Evolution). Redefining a term does not however change the fact that the original theory using that term is no longer the complete story. Our position can therefore, to some degree, be seen to return to Darwin’s multi-mechanism viewpoint, though with vastly extended empirical evidence.

Gene-centrism: We will refer to gene-centric views of evolution several times in this article. There are two senses in which we view neo-Darwinist theories as gene-centric. The first is the view that the genome is “the Book of Life” , i.e., that the development of an organism is essentially a read out of the DNA sequences, in interaction with the environment. The hidden assumption here is that inheritance depends on DNA alone. Sometimes this is spelt out, as in the distinction between the ‘replicator’ (DNA) and the ‘vehicle’ (the rest of the ‘disposable’ organism). The second sense is that, even though it is the phenotype that is selected in evolution, only those aspects of the phenotype that are represented in DNA are inherited. 

These definitions are conceptual, as are all definitions, but they endow the theory we develop here with empirically testable predictions.

I would like to ask what you think of these definitions and whether they might be improved. 

The reason I ask is that I think critics will focus on whether the experimental evidence holds up. 

Before we discuss that, agreeing on at least a preliminary basis for definitions is important. Of course, one outcome of this dialogue is that we might find ways of tightening up the definitions.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

w

Connecting to %s