For years, dog and cat owners have been bickering over the relative merits of each type of pet.

But in recent years, scientific researchers have started to weigh in—and most of their findings so far come down firmly on the side of dogs.

Compared to dogs, scientists have found, cats don't seem to have the same sort of emotional attachment to their owners, and show genuine affection far less often than you might think. Further, they're an environmental disaster, killing literally billions of birds in the US every year—many of them from endangered species.

Cats don't have the same sort of emotional attachment to their owners

Most alarmingly (and as explained in this 2012 Atlantic article), there's compelling evidence that a parasite often found in cat feces can subtly change people's personalities over time, increasing rates of neuroticism, schizophrenia, and perhaps even suicide.

In other words, research is telling us that cats are selfish, unfeeling, environmentally devastating creatures. If you need to convince someone not to get a cat, here's the research you need to show them.

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