My grandfather always began his day by swallowing two tablespoons of olive oil. In his last years he lived alone, always taking care of himself, getting his exercise by walking three miles a day. I do not remember him being sick. He died at the age of 96 and his sister lived until she was 114.Perhaps their longevity genes were good, and I would never guarantee any one's long life by drinking olive oil, but there is a great deal to recommend it both as a cooking medium and for use in green salads.Olive oil is the only oil that some research suggests that helps prevent cancer and arthritis. Its beneficial effects on teh heart are documented. The latest study I've read is one from Kobe, Japan, where researchers used olive oil on the skin of lab rats, then exposed them to ultra violet rays without contracting cancer.Olives seem to do best in semi-arid climates, and green olives are the same as black olives, except that they are not yet ripe. Black olives are the ripened version of green olives.Interestingly, olive oil still processed in the in the same way it was proessed in centuries past, with one exception-instead of donkeys rolling the wheel, machines are now used. It is called "cold press".Green olives are dumped into a stone vat, and a vertical stone wheel is trundled in a circular movement smashing the olives. The oil that comes from the smashed olives is mixed wit water and allowed to settle for about 24 hours. Because the oil is less dense that tha water, it rises to the top of the vat. Then the top inch of olive oil is skimmed that becomes the "extra virgin" oil that is more expensive than the rest. After the first skimming, the oil and water are allowed to settle for another 24 hours and this time, about two inches are skimmed off creating what is called, "virgin" olive oil. The rest of the olive oil is just that-plain olive oil-and is used mostly for cooking, but rarely for salads. Any olive oil remaining that is high in acidity is used to make soap. The olive pits that were ground down in the process become glued together powder, much like cardboard, forming a layer on the bottom of the stone vat which ultimately is lifted out and sold as a fuel for heating stoves and grillind kebobs.In the Mediterranean olive are not picked from the tree until after the first rain, which generally doesn't happen until October or November. Until the rains the olives are covered with dust, which the rains wash away. Even more importantly, the rain decrease the acidity of the olives, taking away the bitter taste and producing a better flavored olives.Not all olive oil are created equal. Darker colored oil is richer in oleic acid. The higher the percentage of oleic acid, the better it is for your health. Oils from Greece and Spain have been rated the highest in oleic acid. If you want to reach the taste and the healthy benefits of olive oil, don't even think about buying "light olive oil". The biggest problem with "light"is that in order to get the taste on wants, more of the light is used, which ulminates in the same amount of calories that a lesser amount of real olive oil would offer. In short, don't bother.If the health benefits and taste do not convince you to use good olive oil, you should know that women in the Mediterranean swear that their smooth, olive-colored skin in the result of their use of olive oil both in food and on their skin after bathing.