* What: 135th annual Scottish Gathering and Games

* Where: Alameda County Fairgrounds, Pleasanton

* When: 8 a.m. to 6 p.m. Saturday and Sunday

* How much: $13 adult ($20 adult weekend pass); $9 ages 11-16, 65 and older and the disabled; $4-$6 box, grandstand and bench seats; free ages 10 and under

* Call: 800-713-3160;

Men (and presumably women) have thrown sticks and stones for as long as they have had fingers and opposable thumbs to grasp them. One anthropological theory has proposed that tossing rocks might have helped develop the left hemisphere of the brain. Pitching a rock at a rabbit during hunting, therefore, may have eventually lead to language development.

So imagine the brainpower being flexed this weekend at the Scottish Gathering and Games at the Alameda County Fairgrounds in Pleasanton, where spectacles of raw manhood (and womanhood) will take place.

Thousands will converge upon this dusty corner of the earth for gossip, meat pies, sheepdog trials and an armada of Highland bagpipe players from around the world. Then there are the games. Of course people will play golf, a pastime that has so consumed the Scots that the Scottish Parliament, fearing it was distracting the citizen army from its archery practice, thrice issued a ban. People will also play soccer; this year the age bar has been raised to over 40 to allow singer Rod Stewart’s team, the Exiles, to participate. (As for “the wrinkled rocker himself,” says one organizer, he probably won’t show up.)

The true test of language, though, is explaining the Heavy Events, the athletics that command befuddled awe from first-time spectators. Describing the events is easy enough: toss a heavy or light hammer, loft a stone and see how high up it goes, pitch a heavy or light stone and see how far out it goes, and upend a slimmed-down tree trunk.

Such descriptions make these vein-popping feats sound like brutish circus tricks. But one way to understand the games is to trace their lineage. The Scottish American Athletic Association the Sacramento-based organization that certifies judges and establishes rules in Heavy Events publishes a detailed history by Charles Black, who competes in the games.

The early history of these events is largely a matter of speculation, he points out. Still, the origins seemingly lie entangled in agricultural routine, martial warfare and excessive machismo.

“There are a couple of different theories,” says Jerry Jardine, the chairman of the gathering of the clans. “One is that many hundreds of years ago when the clans the Scottish clans and the Scottish countries were going to war, they would need to toughen up. It was the pre-medieval rendition of boot camp.” So the warriors would race, pitch stones and lob tree trunks in an effort to strengthen themselves for the battles ahead.

Certainly sounds less bloodthirsty than the origins of the Highland fling, which supposedly was the equivalent of a victory dance, Jardine says. “You were dancing over the dead bodies of your enemies you had killed. It was a dance of joy.”

As for the origins of the Heavy Events competition, read on.

* Light and Heavy Hammer Toss: While Jardine suspects it was “mainly put on for the young ladies,” Black notes that the lighter hammers (16 pounds for men, 12 pounds for women) came from blacksmiths or wheelwrights shops and the heavier ones (22 pounds for men, 16 pounds for women) were from the rock quarries. Whoever throws their hammer the farthest wins.

* Light and Heavy Putting the Stone: Clach neairt, as the Gaelic goes, may have come from the Greeks. Another theory tracks it to the clach cuid fir or “manhood stone,” in which rocks are hoisted to waist height, plunked atop a low wall or thrown for distance. Whoever throws their stone the farthest wins. Men toss 16-22 and 17-26 pounds, women 8-12 and 11-18 pounds.

* Weight for Height: “Imagine a pole vault and you’ve got a weight, a heavy, heavy weight I don’t know, maybe 90 pounds. And you hold it down between your legs, give it a swing to get it going, and you throw it up in the air over the bar, and they keep raising the bar.” Jardine links this to the sheaf toss, still done in Scotland, in which gamers try to toss a bale of hay with a pitchfork over a bar. Whoever throws their stone the highest wins. Men throw 56 pounds; women throw 28; masters, 42.

* Weight for Distance: Originally, the weights used were scale weights used to balance bags of grain and potatoes. Whoever throws their weight the farthest wins. Men and women toss 14, 28, 42 and 56 pounds.

* Caber Toss: The supreme heavy of the Heavy Events is the spectacular and inexplicable caber toss. Unlike the other competitions, here it is accuracy and not distance that determines the winning toss. The competitors balance a slimmed-down tree trunk that looks like a telegraph pole in their hands and “the idea is to throw it up and tilt it over,” Jardine explains. The one who gets it to land closest to 12 o’clock (imagine noon on a clock) is the winner. The cabers weigh 100 to 160 pounds and range from 16 to 22 feet tall.

Outside the competition are two exhibition events: the caber challenge and the strong man walk. Black calls the latter “the farmer’s walk,” which probably originated when workers had to move milk churns or logs. Its modern reintroduction might be due to the awesome deed of Donald Dinnie, who lifted two stones totaling 785 pounds by their iron rings and walked across the Bridge of Potarch. (Why Dinnie did it, we dinna know.)

Attention will be focused on these demonstrations of heaving, but perhaps the most fearsome hurling happens in the clans’ tent, where there’s a ladies’ event of note. A female competitor stands before a male cardboard figure with a raised kilt. She holds a haggis, which is the Scottish delicacy of boiled sheep or calf stomach stuffed with lungs, hearts and other innards, as well as suet, seasoning and oatmeal. Then, Jardine says, she attempts to throw it into the man’s uplifted kilt. Besides glory, the winner is rewarded with a ribbon.

The origin of the event and the recipe for haggis is perhaps best left unknown.