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An old dog, it turns out, can teach humans new tricks. “In recent years the dog has grown to be one of the most important animals for researchers who aim to understand the biological background of complex traits,” says Eniko Kubinyi, an ethologist at Eötvös Loránd University in Budapest, Hungary. Previously dogs weren’t considered good models for studies into animal behavior because they were thought to be an “artificial species” shaped by humans, Kubinyi says. But this view has changed over the past 25 years.
A key driver is the Family Dog Project at Eötvös Loránd University. It was founded in 1994 on the principle that the family home is dogs’ natural environment. Over many thousands of years, the group states, “dogs have evolved to survive in the anthropogenic environment.” The group has initiated the Senior Family Dog Project, or EVOLOR, to look specifically into cognitive aging. Kubinyi, principal investigator of the project, says dogs have a number of key advantages as an aging model for humans.
Methusaleh dogs have led researchers to genetic markers for aging in the blood and brain.
Living with people means dogs experience near-identical social and environmental influences on a daily basis. They show off a host of cognitive skills in their interactions with us. Chemicals, air pollution, noise pollution, and lack of exercise—suspected risk factors of cognitive decline—affect dogs just as they do us. Dogs are also susceptible to comparable age-related diseases, such as a form of dementia similar to Alzheimer’s.
The rapid rise in big data and citizen science, in which members of the general public contribute to scientific projects, has made it easier to get people to volunteer their pets for participation, Kubinyi says. “When we started the project, we established a group for devoted owners who promised to come to the lab several times every year, and we collected longitudinal data about those dogs.” The Senior Family Dog Project has collected data via behavioral tests and surveys on more than 20,000 dogs. “We found age-related differences in brain activity, cognition, personality, the gut microbiome, gene expression, and gene variants in several aspects similar to human aging,” Kubinyi says. “We’ve found parallels time after time.”
In a recent study of 217 Border collies that ranged in age from 6 months to 15, the team, together with the Clever Dog Lab in Austria, found similarities with humans in the dogs’ personality traits as they age.1 The dogs’ interest in problem-solving tended to rise until middle age—about 3 to 6 years—before leveling off. Novelty-seeking changed little until middle age and then steadily dropped. Like humans, dogs’ personality traits stayed fairly stable over time. Young dogs that were most active tended to remain so when older.
The team found that older dogs seem to experience a similar “positivity effect” to older people, reacting less to negative sounds such as crying than positive ones such as laughter.2 “I have a 13-and-a-half-year-old Labrador, and when I say ‘come here,’ she just doesn’t listen to me,” Kubinyi says. “But when she hears me move her box of food, she comes immediately. Old dogs seem to listen to what they want to hear.” Which might tell us something about the wisdom of aging. “In humans, old people are more attuned to positive emotions and less to negative emotions,” Kubinyi says. The study ends on a sage reminder. Personality changes occur unevenly over the dogs’ lives, and individual border collies differ significantly in their personality development. The dogs’ differences, Kubinyi and her colleagues write, caution against “over-generalization of the global age trends.”
The Family Dog Project is also establishing a basis for understanding the specific underlying neural and genetic links to aging, including through methods such as electroencephalography, functional magnetic resonance imaging, and genetics tests. One study backed up the analysis of activity patterns in sleeping dogs’ brains as a biomarker of cognitive aging across species3; another found that better canine performers in memory tests tended to have lower levels of certain Actinobacteria in their gut,4 mimicking some observations in people with Alzheimer’s disease. “This is preliminary research, but there were parallels with human research,” Kubinyi says, adding that it could also shed light on the best types of diet to keep dogs healthy as they age.
On the genetics side, by analyzing the whole genome sequence of two mixed-breed canines aged 22 and 27—far older than the average dog lifespan of about 10 to 13 years, and dubbed “Methuselah dogs” after the long-lived biblical figure—the researchers identified more than 80,000 novel genetic mutations compared with 850 dogs of normal lifespan.5 So far they have found genetic markers for aging in the blood and brain.
The dogs’ interest in problem-solving tended to rise until middle age before leveling off.
One of the keys to future research is EVOLOR’s recent establishment of a Canine Brain and Tissue Bank, a repository for ongoing study formed by collecting samples donated by owners of euthanized pet dogs. Among those making use of the data is the Dog Aging Project at the University of Washington, Seattle. Already researchers have managed to gauge the degree to which cognitive decline in dogs is associated with increased levels of key proteins linked to Alzheimer’s disease in people.
Over the next decade, the project will follow tens of thousands of pet canines. The involvement of many owners interested in volunteering their dogs will enable extensive data collection, offering more insight into aging-based influences than possible through lab research, says Evan MacLean, an evolutionary anthropologist working on the project. This participation, MacLean says, “is going to allow us to ask questions that would be impossible using traditional laboratory approaches.”
Daniel Promislow, co-director of the Dog Aging Project, says the existence of so many breeds helps researchers understand the effect of size on healthy longevity and susceptibility to different diseases. It should also give some clues about why larger breeds tend to be shorter-lived, opposite to the usual pattern seen across species of mammals. “Given that dogs are so much shorter-lived than humans, we should be able to identify the genetic and molecular pathways associated with aging diseases faster,” Promislow says. The project is also looking into the effects of rapamycin, a drug originally developed to prevent rejection of organ transplants, that’s been shown to slow aging in animals.
In a project called EMOMETER, Kun Guo, a cognitive neuroscientist at the University of Lincoln, United Kingdom, is investigating the emotional lives of dogs and how they respond to people’s emotional signals. “The long history between humans and dogs may promote co-evolution of certain cognitive abilities,” Guo says. He says studying dog cognition will bring multiple benefits for improving both dogs’ well-being and our own. “Given that dogs play important and multifunctional roles in our society, appropriate understanding of their cognitive capabilities and constraints would allow us to have a realistic expectation of dogs and help ensure their welfare.”
Stephen Lea, a psychologist at the University of Exeter, U.K., says that recent longitudinal studies provide a new opportunity to investigate the effects of domestication on the evolution of cognition. Quite aside from that, he says, it’s hugely important for us to see eye-to-eye with our pets so we can take better care of them: “We have a moral responsibility to ensure that the animals we choose to keep are happy.”
Gareth Willmer is a London-based freelance journalist and editor who covers science, technology, and global development for a range of websites and publications. This article was originally published in Horizon, the EU Research and Innovation magazine.
References
1. Turcsán, B., et al. Individual and group level personality change across the lifespan in dogs. Scientific Reports 10, 17276 (2020).
2. Smit, I. Szabó, D., & Kubinyi, E. Age-related positivity effect on behavioural responses of dogs to human vocalisations. Scientific Reports 9, 20201 (2019).
3. Borislavov Iotchev, I., Szabó, D., Kis, A., & Kubinyi, E. Possible association between spindle frequency and reversal-learning in aged family dogs. Scientific Reports 10, 6505 (2020).
4. Kubinyi, E., Bel Rhali, S., Sándor, S., Szabó, A., & Felföldi, T. Gut microbiome composition is associated with age and memory performance in pet dogs. Animals 10, 1488 (2020).
5. Jónás, D., Sándor, S., Tátrai, K., Egyed, B., & Kubinyi, E. A preliminary study to investigate the genetic background of longevity based on whole-genome sequence data of two Methuselah dogs. Frontiers of Genetics 11 (2020).
Lead image: Javier Brosch / Shutterstock
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