Since the beginning of this blog, we have discussed the ways evolution, selective breeding, biology, and neuroscience have combined to create the most popular pet in the world. From their earliest start as a domesticated species to the many active roles dogs now play in our society, the story of the dog is complex, and it is still actively changing. The role dogs play in science is changing, too. Classical biology has several “model organisms” which are used for the majority of research. These organisms are varied – they include fruit flies, zebra fish, mice, rats and more – but the characteristic that these organisms share is that they are widely studied, usually because they are easy to obtain, keep, or breed in a laboratory setting. Increasingly, however, researchers are beginning to worry that these model organisms present too narrow a scope for research. While each species certainly has its advantages, could we be missing out on valuable knowledge by sticking to these same organisms? How much of a fruit fly’s biology is equivalent to a person’s?
Dogs present a unique model species for scientists. They are subject to more regulations than a fish or mouse (which often have very limited protections in place), and since most dogs are pets, it is often unclear how to place them in a sterile experimental environment free of confounding factors. That being said, dogs are one of the most accessible organisms available, and many labs, including those at Duke, Columbia, Yale, and others, have had great success at recruiting volunteers from the community. Since these dogs are being brought in by their owners, they are frequently able to describe the animal’s personality and behavior, more so than a lab tech might be able to describe a particular rat. Dogs are also incredibly trainable, and can be taught a wide variety of research-related protocols. They are currently the only animal (aside from humans) that have been trained to stay completely still for a fully-conscious fMRI study, and many breeds have now had their genomes fully sequenced. But do they have a place in neuroethology? Neuroethologists seek to understand how the brain controls behavior, and they often do so by addressing Tinbergen’s four questions to understand behavior. These include proximate questions including mechanism, or how the behavior is created, and ontogeny, or how the behavior develops over the animal’s lifetime. These also include ultimate questions including the what is the adaptive value of the behavior, and how the behavior has evolved over the history of the species.
Dogs are not only highly accessible and trainable, but they are a species that humans are largely responsible for evolving. Although dogs are not the either the conventional model organisms or “wild” species that neuroethologists tend to focus on, they absolutely deserve a spot at the table. Currently an incredible amount of work is being done into fields including dog behavior, cognition, and genetics, and unfortunately, much of this couldn’t be covered in the brief course of this blog. Below, I have posted five snapshots of new frontiers in dog research, with links to the full papers
1. “The genomic signature of dog domestication reveals adaptation to a starch-rich diet”
This article provides whole-genome resequencing of dogs and wolves and identifies 36 regions that were likely targets for selection during dog domestication. 10 of these likely assist starch digestion and fat metabolism which allowed dogs to adapt to a more human-provided diet than their largely-carnivorous wolf ancestors.
2. “Man’s Best Friend Becomes Biology’s Best in Show: Genome Analyses in the Domestic Dog”
This review article continues the trend of genomic analysis, focusing on how canine geneticists have gained new information in the study of morphology, disease susceptibility, and behavior. It even provides strong suggestion that dog genetics may hold valuable clues for solving similar human diseases, including several cancers and autoimmune disorders.
3. “Scent of the familiar: An fMRI study of canine brain responses to familiar and unfamiliar human and dog odors”
This paper diverges from the genetic view to look at one of the first successful unrestrained, unsedated canine fMRI studies. The researchers focused on the caudate nucleus, since it is correlated with positive expectations, and they found that the caudate responded maximally to the scent of the dog’s familiar human, even more so than to familiar dogs. This is yet another paper suggesting that we are just as important to dogs as they are to us.
4. “Jealousy in dogs? Evidence from brain imaging”
This paper again uses fMRI to look at canine brain area activation, this time focusing on the amygdala. It also combines owner-reported personality assessments from the tool C-BARQ to analyze if more “aggressive” dogs showed more amygdala activation when seeing their owners giving food to another animal. They did, validating that differing levels of activation in certain brain areas correspond to canine temperaments. They also showed that this level of activation decreased with repeated exposure, offering repeated exposure as a potential training plan for owners with jealous or aggressive dogs.
5. “Enhanced spatial ability in aged dogs following dietary and behavioural enrichment”
Finally, this article takes a more behavioral approach, but it is an example of the direct benefit that studying dogs can provide to humans. The antioxidant-rich diet and exercise interventions verified in this paper have become the gold standard for sustaining canine cognition through the aging process, and show promising signs in human trials, too. Eating well and taking walks are two things that can help your dog – and yourself!
Thank you for joining me on this journey into the world of the dog. Although this is the end of my blog series, this is just the beginning of the research that can be done with our closest companions. The articles above do a good job linking behavioral observations to biology and neuroscience, but they also show that we have a long way to go. I look forward to more reading, more learning, and more integration of different scientific fields as we work to form a complete picture of the dog, and many of the other creatures with whom we share our world.
Axelsson, E., Ratnakumar, A., Arendt, M.-L., Maqbool, K., Webster, M. T., Perloski, M., Lindblad-Toh, K. (2013). The genomic signature of dog domestication reveals adaptation to a starch-rich diet. Nature, 495(7441), 360–364. https://doi.org/10.1038/nature11837
Berns, G. S., Brooks, A. M., & Spivak, M. (2015). Scent of the familiar: An fMRI study of canine brain responses to familiar and unfamiliar human and dog odors. Behavioural Processes, 110, 37–46. https://doi.org/10.1016/j.beproc.2014.02.011
Cook, P., Prichard, A., Spivak, M., & Berns, G. S. (2018). Jealousy in dogs? Evidence from brain imaging. Animal Sentience, 117, 1-14.https://animalstudiesrepository.org/cgi/viewcontent.cgi?article=1319&context=animsent
Nippak, P. M. D., Mendelson, J., Muggenburg, B., & Milgram, N. W. (2007). Enhanced spatial ability in aged dogs following dietary and behavioural enrichment. Neurobiology of Learning and Memory, 87(4), 610–623. https://doi.org/10.1016/j.nlm.2007.01.001
Parker, H. G., Shearin, A. L., & Ostrander, E. A. (2010). Man’s Best Friend Becomes Biology’s Best in Show: Genome Analyses in the Domestic Dog. Annual Review of Genetics, 44, 309–336. https://doi.org/10.1146/annurev-genet-102808-115200