Well, when it comes to causation of biological effects, you never know. Now, the latest off the Big News ticker is that dogs are hot when it comes to the heart. That is, having a dog or other pet reduces one's risk of having a coronary. Hot diggety dog! We had begun worrying whether the furry nuzzlers were going to be the next "studies show that..." story to dampen our lust for what makes life interesting.
Fortunately, our fears were laid to rest by the NY Times story that reassures us that our leash on life is perhaps longer than we had thought.
Now this high-powered study funded by the American Heart Association (we hope the donors to the AHA don't object to the serious purpose to which their donations are used) provides comfort that will last at least until the next story hits the headlines; hopefully, that'll be more than just a day or two, but we can't hope it'll last a dog's lifetime.
How on earth are we to evaluate causation when every day some new major cause is identified? Do we now need to add dog-ownership to smoking, alcohol consumption, frequency of sexual intercourse, marital status, red meat, eggs, male baldness, stomach flab thickness, and who knows what else, and--you didn't think we'd forget to include it!--our genometype to be able to predict to within a range of about 80% whether we'll have a heart attack or not.
Since every study concludes not with the phrase The End but "More research is needed, the lead investigator says", we assume that the AHA now plans to do the same study again not just for parakeets, tropical fish, hamsters, and kitty cats, but also for each dog breed, and for female and male (and spayed and neutered) dogs, and whether adopted as a pup from the kennel or as a stray from the pound. That will mean a juicy menu of probably 1,000 separate studies (4 sexual conditions, 2 adoption conditions, and around 125 breeds), which is great for the research welfare system (not to mention the range of cat, bird, fish, etc. studies).
Unfortunately, another study just about to be published (we hear) will show that investigators will not live long enough to complete such studies, and that one epidemiology team is planning a study of whether doing such endless frustrating studies itself is yet another risk factor for heart attacks. Hot diggety dog!
Oh, well, maybe some day someone will figure out a better way to investigate complex causation.