In the cold analysis of some evolutionary psychologists, dogs are little more than "social parasites," exploiting our parental instincts to ensure we continually feed and house the little mooches.

But here is a case where the sober gaze of science overlooks one critical piece of data: dogs are the best. If they're parasites at all, they may just be nature's masterpiece.

A mosquito can't draw a blood meal without stabbing its hypodermic needle of a nose into your arm. Tics hitch aboard with face harpoons while various leeches lock down with sets of saw-like jaws. Dogs, on the other hand, just sidled up to humans one day and flashed a set of big wet eyes. We've basically been feeding them under the table and taking them out for evening poops ever since.

Their total survival strategy amounts to being really, really cute and companionable. As far as nature's designs go, with its adolescent insistence on sticking fangs, horns, and claws onto everything, the dog comes out as a pretty elegant evolutionary vehicle.

Photo by John Moore / Getty Images

How, when, and why this all started is the subject of a growing body of scientific research and postulation. The leading theory holds that wolves started scavenging food waste along the edges of human campsites or settlements.

"The most brazen among them may have overcome any fear of these new, naked human animals and begun feasting on the scraps pile," writes Alexandra Horowitz, an animal cognition researcher at Barnard College in her work Inside of a Dog: What Dogs See, Smell, and Know. "In this way, an accidental natural selection of wolves who are less fearful of humans would have begun."

Over time, their looks changed from menacing to downright adorable: heads, teeth, and snouts shrunk as almond eyes grew big and round, juvenile features that persist into adulthood. These neotenous characteristics may serve as "social releasers" that trigger our caretaker impulses, according to Archer.

Successive generations became increasingly adapted to life among people by becoming increasingly like people, "developing rudimentary forms of our social wizardry," wrote John Homans in What's a Dog For?

A 2013 study published in Nature compared the genomes of various dog breeds to wolves, and spotted 36 regions where the species diverged. The changes broke down into two major categories, those associated with digesting starches and metabolizing fats (which would have been crucial for animals living off of human food scraps) and those linked to brain function.

Kerstin Lindblad-Toh, a researcher at Uppsala University in Sweden, who led the study, explained the latter finding in an interview with me last year: "A wolf that wants to live with people needs to be able to read human body language and not be scared of them."

One place on the genome where dogs separate from wolves is a location that, in humans, is correlated with Williams Syndrome, a condition whose symptoms include cheerfulness; social fearlessness; cute, elfin facial features; and sometimes a degree of mental disability.

"This is the so-called party gene," Wayne told me. "Syndrome sufferers are often the life of the party. They're very engaging, and there are always people surrounding them."

Wayne wasn't available for an interview, but previously told National Geographic that he was "intrigued" by the finding and hoped to study it further. He and Lindblad-Toh both, however, cautioned against reading too much into any one genomic factor.

Photo by Matt Cardy / Getty Images

Still, the parasitic view of pets argues that you can't justify the resources we expend on them in evolutionary terms, those tens of billions of dollars that Americans will drop this year on biscuits, bones, squeaky toys, and hot dog outfits. "In the case of pets, bearing these costs is maladaptive," Archer wrote.

Indeed, maladaptive is about the nicest way of describing the amount of money I personally spend each month on doggy day care for my little mutt Moxie, a black dog with floppy ears and an overdeveloped herding instinct. But I don't think my relationship with her is nearly as one-sided as this view argues.

Photo by Vjeran Pavic / The Verge

On a recent afternoon, Moxie and I visited a dog park near my apartment in Berkeley, California, as we often do several times each day. As I tossed a tennis ball, she bounded after it with a speed and intensity that, for a moment, masks the fact she's an absolute klutz at fetching. She lunges, vaults, and cranes her neck, but bites down on empty air, always, every time.

And she couldn't care less. Moxie is a happy little being, devoid of pretension, guile, or ambition. And witnessing that kind of droopy tongued joy has a way of rubbing off, and a way of making all those dog park visits and day care bills worth it.

My own alternative Darwinian interpretation is that dogs are an emotional luxury afforded to us as we stepped out of the wild, building homes, raising livestock, and cultivating fields that would collectively free us from the daily struggles of mere survival. Dogs cheer us up when we're sad. They're good company when we're lonely. They're a distraction from all the small annoyances and larger tragedies of life. Dogs, in short, make us happy.

And once the hard costs of evolution are accounted for — food, shelter, and sex — what's more important than that?