These creatures, it turns out, are far smarter than the best human genetic-modification scientists when it comes to identifying a superior naartjie - or mineola, as those irritating fruit purists insist on calling them.

And developing a superior naartjie - or orange, or lemon, or grapefruit - is all that stands between a nation's citrus industry and catastrophic ruin. It's the Cold War arms race all over again - no sooner do you develop a better naartjie than your competitors in the US and Australia and Argentina and Spain, and maybe Zimbabwe too, go one better. Their naartjie is juicier, plumper, easier to peel, a nicer colour, whatever. And then the supermarkets of London, Paris, New York, Shanghai and Pofadder stock the opposition's naartjie, instead of yours. And you go bankrupt.

In the normal course of events, South Africa's citrus farmers hate baboons. The animals raid their orchards, steal their fruit, swing on the trees just for fun and - oops! - break branches. Then they play tug of war with the irrigation pipes.

Enter a particularly picky baboon troop from Citrusdal. The owners of ALG Estates, one of the citrus estates outside the town, grumbled every year, like all the neighbours, about the depredations of baboons. But then the owners - a family of Van der Merwes, by the way, although that is neither here nor there - noticed there was one particular naartjie tree that the baboons seemed to favour.

Closer investigation revealed that the naartjies from this tree ripened at least two weeks earlier than those on all the other trees, and, what's more, they were sweeter. The significance of this is hard to overemphasise (for a citrus farmer). It means you can get your fruit on a ship to California two weeks before anyone else, corner the market, and become obscenely wealthy. You can buy yet another Toyota Hi-Lux bakkie, take an extra week's holiday in Hartenbos, rent a Leon Schuster DVD - the sky's the limit.

Who knows what happened to this tree to make it special - perhaps the sun flared one day, causing what we experts call a coronal mass ejection and spraying a burst of extra-strong electromagnetic thingamajigs all over Citrusdal. One of these probably bumped into a strand of DNA and caused the magic mutation. That's my theory, anyway.

Now the Van der Merwes are cloning their celebrity tree, but so far they have been a bit slow to cotton on to the potential marketing bonanza of the Citrusdal baboon troop, which still languishes in anonymity. If this were Stellenbosch, and baboons had discovered a vine that produced superior wine, we would immediately have Chacmas' Choice chardonnay, Best Baboon Blend, Precocious Primate pinotage, Monkey Business merlot, Soul of the Ape chenin blanc.

The baboons themselves would all have cute names, rhinestone-studded collars and rakish red bandanas. "We LOVE our eco-baboons," the estate-owners would gush, tossing them organic peanuts. "And they're Fairtrade certified, of course."

It goes without saying, but I had better say it anyway, that the citrus produced in Citrusdal and along our Olifants River valley is incomparably better than the inferior fruit grown in less hospitable climes to the north, like Mpumalanga. Why would rugby fans up there throw their naartjies at the referee, if they were not inedible?

One of the reasons for the superiority of our fruit is that our baboons are smarter than the Mpumalanga baboons. We have the oldest orange tree in the southern hemisphere growing on the banks of our Olifants River; we know this because it says so on the official Cederberg tourist map, with the year of the planting ceremony: 1777.

So our baboons have more than two centuries of intensive citrus research behind them.

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• Anton Ferreira is a freelance writer who lives within a naartjie's throw of the original Olifants River.