These individual differences are of the highest importance for us, for they are often inherited, as must be familiar to every one; and they thus afford materials for natural selection to act on and accumulate, in the same manner as man accumulates in any given direction individual differences in his domesticated productions. — Charles Darwin, On the Origin of Species
One of the regular readers/posters has mentioned her Akita a few times so I decided to learn a little more about the breed. My preference has always leaned towards the Pastoral and Gundog groups (Herding & Sporting), so I was only familiar with the basics of the Akita. For example, I was unaware of the American/Japanese split among the breed fanciers.
In my exploration of the breed I came across as study on the behavioural genetics of the Akita. But before I get to the study, a quick blurb about genes and animal behaviour seems appropriate.
Even before the advent of modern molecular methods, there was strong indication that certain personality traits were inherited; today the short list includes DRD4, 5-HTT, MAO, SLC6A4, DAT1, BDNF, COMT, vasopressin, TH, cortisol and the subject of this study, the androgen receptor gene. All these genes have been linked to various personality traits in human or non-human animals. Many of the ones mentioned above and many more not mentioned influence the same or related traits, so these genes are not only interacting with the environment but also with each other.
As I mentioned in Nature vs Nurture, genes don’t act in a vacuum. They don’t create personality, they are part of complex and dynamic set of interacting variables that play a role in the development of personality and behavior. Genes do not create behavior. No gene CAUSES aggression or novelty seeking or herding or social bonding or anxiety or any other trait. There is no ball gene, dominance gene or pee-in-the-house gene; rather they set the stage for environment to act; they tilt the odds (usually only slightly) towards one option over others.
The study “Androgen receptor gene polymorphisms are associated with aggression in Japanese Akita Inu” (doi: 10.1098/rsbl.2011.0087) explores the relationship between gene variations (polymorphism = many forms) of the Q2 region of exon 1 in the androgen receptor (AR) gene and personality traits in the Japanese Akita Inu.
To minimize the variables, all dogs in the study were fawn coloured, intact and sexually mature who lived inside as pets and all had male owners. Other aspects of the study:
- 3 alleles of AR gene were detected
- the alleles differed in the number of CAG repeats in exon 1
- (CAG)23, (CAG)24 and (CAG)26
- allele frequency varies with coat
For the analysis the researchers designated the S (short) for the 23 variant and the L (long) to the 24 and 26 versions. This makes the five different genotypes: S/– and L/– for the males and S/S, S/L & L/L for the females.
You might be wondering why the males only have single letter designation. It’s because the gene for the androgen receptor is found in the X chromosome, this means females (XX) get two copies and males (XY) get only one. The astute reader is thinking, “Doesn’t that mean the females are doubling up on gene products?” The answer is “No.” It is because of something known as chromosome dosage compensation – if you’ve ever seen a Calico cat then you’ve seen dosage compensation in action. The technicalities are not germane to this article but it is a fascinating topic so I’ve included a couple of links in the notes for the biology enthusiast.
The authors report higher aggressive scores in males (no effect on females) carrying the short genotype [(CAG)23] allele than those with the long genotype [(CAG)24 or (CAG)26] variant. There was no observed difference in the other 4 personality traits surveyed – playfulness, distractability, neuroticism, sociability in either gender.
Finally, if you finish reading this article and you are thinking, “My/that Akita is aggressive because he has a short (CAG23) AR gene”, then I’ve done a terrible job.
Konno A, Inoue-Murayama M and Hasegawa T. Androgen receptor gene polymorphisms are associated with aggression in Japanese Akita Inu. Biol. Lett. 2011 7, 658-660. doi: 10.1098/rsbl.2011.0087