Darren Naish looks at the surprisingly controversial origins of the domestic dog — dogs might not have evolved from wolves:
As a rough rule of thumb, the domesticated forms of wild mammal species (1) revert back to wild-type after being feral for a few generations, and (2) readily interbreed with their wild ancestors. If domestic dogs are wolves, then the many populations of feral dogs that live world-wide should theoretically have reverted back to being wolf-like in appearance and behaviour. But they haven’t. Instead, domestic dogs always end up looking like pariah dogs — the relatively small (11-16 kg), socially flexible semi-domesticated and feral dogs of the Old World tropics.