Figuring out what to feed a dog never used to be so complicated. For generations, dogs simply ate whatever the people in the family ate. Or, to be more precise, whatever they didn’t eat — dogs were often fed the leftovers from a family’s meals.

Then came commercial dog food. Kibble, canned, semi-moist — all were convenient and were touted as much more healthful for our canine companions. Over the past 10 years or so, dog food has gone gourmet, with organic foods, human-grade foods, foods that cost more than the average family spends on groceries for the humans … but is it better for the dogs?

The latest fads are raw food and no grain or low carb diets, all touted as closer to dogs’ “natural” diet. The “natural” diet is defined by looking at what wolves eat. Wolves eat a high-protein diet, with lots of bones mixed in. They are opportunistic omnivores and will eat fruit, greens, and vegetables if they find them or if meat is scarce, but they thrive on a high protein diet. Carbohydrates can lead to inflammation, some argue, and aggravate problems, such as arthritis, that feature painful inflammation. Raw diets are easier to digest. The less processing the better. Dogs may have evolved considerably since diverging from their wolfish ancestors, but their digestive system hasn’t changed. In short, the Paleo Diet for dogs. (The Paleo Diet encourages eating lean meats, seafood, vegetables and fruits and avoiding dairy, grains, legumes and processed foods.)

Or so one theory goes.

Yet another theory points to a recent study that shows that, in fact, dogs’ digestive systems have changed as they’ve become our housemates— they’ve evolved the ability to process and use (small amounts of) carbohydrates more efficiently than their ancestors. Their life sharing the sofa and the remote with their couch potato humans has made them more amenable to snacking on (and digesting) potato chips. This could be a boon for dog food manufacturers who pack their products with inexpensive and starchy fillers.

This theory is based on research by evolutionary geneticist Erik Axelsson. He was looking for genetic differences relating to dogs’ and wolves nervous systems. But he found something surprising: He found that the three key genes involved in digesting starch are different in dogs and wolves.

While several theories are debated concerning how dogs became domesticated, all involve wolves spending enough time around humans — and humans’ food and leftovers — to form a relationship. That the wolves hanging out with the humans evolved to eat the kind of food the humans ate makes sense. (And hey, if our early ancestors were eating starch, doesn’t that make the Paleo Diet irrelevant and wrong? Pass the popcorn!)

Which theory is right? What should we be feeding Fido?

First of all, dogs are not wolves. In dog training, myths based on idea “dogs are the same as wolves”  have done untold damage to dogs’ relationships with their humans. Is the same sort of damage now being done to their health through misguided nutritional guidelines?

Modern humans eat a wider variety of foods than our long-ago ancestors did, and our bodies work differently — though a diet high in unprocessed, whole foods and low in simple carbohydrates is still the healthiest option. The same is true, I believe, for our dogs.

In a discussion of Axelsson’s study, PetMD.com’s Daily Vet blog recommends a balanced approach. If your dog’s diet includes grains, whole grains are recommended. Less-processed food is preferable to highly processed. Starches should only form a small part of the dog’s diet.

What might matter more than whether your dog’s food includes brown rice and barley or is completely grain-free is the quality of the ingredients and the relative proportions. As I wrote in “Ask the Thinking Dog” last spring, choosing a safe, healthful dog food can be challenging. I look for U.S.-sourced, high-quality ingredients and avoid food processed in any of the large pet-food factories that are the source of the never-ending recalls. Our dogs eat Fromm Family kibble and Sojo’s, but each dog’s needs are different, so you’ll need to figure out how best to meet your dog’s needs.

A word of caution: While discussing your dog’s diet with your vet is a good place to start, I have found that many vets strongly recommend foods that they sell — but that might not be the best choice for your dog. For example, several vets over the years have recommended putting our dogs on prescription diet foods, available only (and at extremely high cost) through the vet. In most cases, a “prescription” food is not necessary, and a higher-quality food can be purchased less expensively elsewhere.

Do your research! Understanding what proteins and other ingredients work best for your dog can help you choose the correct (non-prescription) food. Talk to the people at a locally owned (not big-box) pet supply store that sells a variety of high-quality foods. Often, these folks are quite knowledgeable. Talk with other dog people, and pay attention to how your dog’s energy level, digestive system, and skin and coat health are affected by different foods.