Jonah Lehrer in Cages and Cancer:
"In short, the paper demonstrates that mice living in an enriched environments - those spaces filled with toys, running wheels and social interactions - are less likely to get tumors, and better able to fight off the tumors if they appear.
The experiment itself was simple. A large group of mice were injected with melanoma cells. After six weeks, the mice living in enriched environments had tumors that were approximately 75 percent smaller than mice raised in standard lab cages. Furthermore, while every mouse in the standard cages developed cancerous growths, 17 percent of the mice in the enriched enclosures showed no sign of cancer at all."
Jesse Berring in Cur cognition: Do stray dogs have qualitatively different kinds of canine minds? (via 3quarksdaily):
"...when dogs are housed in an animal shelter, they usually experience a severe form of psychological stress caused by exposure to novel or threatening surroundings, separation from attachment objects, unpredictability of external events, lack or loss of control over the environment, and so on. This stress activates their hypothalamic-pituitary-adrenal (HPA) axis and pumps out explosive levels of cortisol, which is the major hormonal indicator of response to stress. Coppola and her colleagues found that, regardless of breed, age of dog and sex, those shelter dogs that received a pleasant “human interaction session” on Day 2 of their incarceration had significantly lower cortisol levels on Day 9—that is to say, the benefits of this simple pet and play session were found a week later, even without any subsequent interaction with human beings during the intervening days."
The second article is more about the perceived cognitive abilities of dogs:
"Udell and her group in Florida, however, say that these impressive social cognitive abilities in dogs may not represent the “default” canine cognitive system. In their review of this literature on dog social cognition, the authors point out that:
The currently available data suggest that populations of dogs differing in [breeding] and in environmental and lifetime pressures might display different behavioral responses to the actions of humans. Despite this fact, the great majority of subjects in studies of the origins of domestic dogs’ human-compatible social cognition have been pet dogs living in human homes, with human-oriented working dogs representing the remainder of the subject pool.
In other words, Udell and her coauthors’ contention is similar to arguments made by many researchers studying human psychological evolution—that our ability to make claims about “human nature” are seriously limited by the fact that the data upon which such claims are made are derived almost entirely from middleclass American undergraduate students between 18-22 years of age and recruited from a psychology department subject pool. She’s basically arguing that existing social cognition research on Canis lupus familiaris has largely neglected large demographic swells of the species and therefore does not necessarily paint an entirely accurate portrait of this species’ natural (default) psychological stance."