Pigs like mud (with the exception of Cinders, the muck-phobic little porker who escaped the sausage machine two summers ago after her owners took pity and fitted her with tiny gumboots). Hippopotamuses like mud, too. But then pigs and hippos are wired to wallow – they don't sweat and mud keeps them cool. What's our excuse?
As Britain's parks and fields turn to dustbowls in what is shaping up to be the hottest, driest year for more than a century, humans all over the world are adding water to channel their inner swine.
The tackles were especially dirty last week at the Swamp Soccer World Championships in Hyrynsalmi, Finland, where goalkeepers had an excuse for being rooted to the spot, up to their knees as they were in a thick, black sludge.
The therapeutic qualities of a good soak were evident at the Plain du Nord festival in Haiti on Sunday, where believers plunged into great pools of mud as they asked the voodoo spirits to bless them and their children with riches and good health (before having a good wash, presumably).
If exposure to dirt strengthens our resistance to disease and allergies – scientists call it the "hygiene hypothesis" – then the Chinese army is a force to be feared. Hundreds of soldiers of the country's counter-terrorism unit were seen flat on their backs in a brown murk on Tuesday as they grappled with giant logs in what looked like the world's dirtiest training exercise.
Elsewhere, love blossomed at a mud festival in Boryeong, South Korea, beards became caked in grime at the "mud pit belly flop contest" during this month's Redneck Games in Georgia, in the United States, while at Esch in the Netherlands, 200 people celebrated as they broke the world record to get the most people ever into a pool of mud at the same time.
But for all our childish revelling in mud, that comes in colours from red-brown to deep black, we will never look as content in the mire as our thicker-skinned friends with their curly tails. But for mud lovers of all species, it was the hippo who said it best.
"Mud, mud, glorious mud," goes the chorus to "The Hippopotamus Song", the classroom favourite by the British comedy duo Flanders and Swann. "Nothing quite like it for cooling the blood... So follow me follow, down to the hollow... And there let me wallow in glorious mud."