Intragenomic conflict and Intrapersonal Conflict

Here is the abstract of a working paper that is part of my Common Currency project. This one has dragged on for some time. I’m not sure when I first gave a talk on the topic, but it was probably late in 2012, and I’ve peddled this stuff at various venues between now and then. Along the way I’ve read loads of interesting biology, and learned a lot. I’ve also changed my mind a few times over the details, but seem to have stabilized on a view that I think I can defend. I hope to have a full draft paper that is fit to be posted on this site before the middle of 2015.

Intragenomic conflict and Intrapersonal Conflict

David Spurrett (UKZN)

Abstract

It is now recognised that different parts of the genome of a single individual, especially autosomal genes inherited from a male parent and from a female parent, can sometimes have conflicting interests. One mechanism allowing these conflicts to be expressed in some species, including mammals, is genomic imprinting, which modulates the level of expression of some genes depending on parent of origin. Several leading biologists, including William Hamilton and Robert Trivers, but particularly David Haig, have suggested that this intragenomic conflict may explain, or predict, some kinds of intrapersonal motivational conflict in humans. Here I seek to assess this suggestion, especially as developed by Haig (2006).

There are two (potentially) complementary ways in which genomic conflict might be related to motivational conflict. One concerns pattern in behaviour, and the other concerns the processes, or mechanisms, by which behaviours are selected. (This corresponds roughly to the distinction between ultimate and proximal explanation.) A conflicted pattern in behaviour won’t be consistent with a single preference ordering, whereas a conflicted process of behaviour selection will be in some way constitutionally disunified, or fractious. In the first case I argue that the phenomenon of intragenomic conflict has at most the consequence that pattern in behaviour won’t correspond in any simple way to the collective interests of the genes as understood from a perspective neglecting genomic conflict. This just isn’t the same thing as being inconsistent with some preference ordering. The failure of an inference from genomic conflict to individual behavioural inconsistency, however, leaves open the possibility that genomic conflict is expressed in the behaviour selection process.

The case of mechanisms is more complicated because of the large variety of available models of the behaviour selection process. I review a number of leading proposals, and argue in each case that intragenomic conflict either does not predict conflict over behaviour selection, or would at most modulate the conflict already predicted by the model. Considered in relation to existing psychological models, then, it seems as though genomic conflict does not predict conflict. Finally, I develop a suggestion hinted at in Haig, and argue that there are indeed coherent scenarios in which conflicting genes could influence behaviour, on the model of mind-controlling parasites rather than by inputs to an established behaviour selection system. Whether any conflicting genes in fact operate in these ways is, of course, an empirical matter.

References

Haig, D. (2006) Intrapersonal conflict. Pages 8-22, in M.K. Jones and Fabian (eds.) Conflict. Cambridge University Press, Cambridge.

Table of contents

1. Introduction

2. Intrapersonal Conflict?

3. Intragenomic conflict and genomic imprinting

3.1. Intragenomic conflict

3.2. Imprinting and PSGE.

4. Haig on intra-personal conflict

4.1. An adaptive rationale for inconsistency?

4.2. A mechanism for sub-personal conflict?

{4.3. Conditional strategies and mind-controlling parasites}

{5. Objections and clarifications}

5.1. What about Badcock and Crespi?

5.2. Behaviour isn’t special, but consistency is.

5.3. What about Haig’s remarks on common currencies?

5.4 Who cares?

6. Conclusion

{Curly brackets denote a section that might not make it into the final paper.}