The olive tree has sustained humankind since prehistoric time. Some venerable European specimens with gnarled and twisted trunks are 2,000 years old; and most religions revere this truly extraordinary tree.

About 20 species and hundreds of cultivars of olives or Olea are members of the ash family. The silver-gray, evergreen, olive leaves are the icons of the Mediterranean, and perfectly suited to the hot, dry, long summers and cool wet winters of this region.

Trees reach about 45 feet in height and in the spring they often display exquisite white, fragrant flowers. As the oblong fruits mature, they change color from green to violet to almost black.

Olives are first produced at about the age of seven and trees continue growing olives until about 800 years old.

Olive trees are renown for providing shade and fruits rich in oil and food.

Over 6,000 years Semitic peoples of Syria cultivated the olive for food and traded it as oil.

About 3,500 years ago the Egyptians began using olive oil in their embalming fluids and they adorned their dead with olive branches. They too learned to cultivate and trade the oil.

Some 2,500 years ago the Romans invented the screw press method of extracting oil, which for the most part remains unchanged today.

During the Roman occupation of Libya, 106 BC-439 AD, they constructed an aqueduct from Jebel to Leptis Magna some 100 miles and transported olive oil by pouring it onto the water at one end to be carried to the other where it was skimmed off and then exported.

At the time of the fall of the Roman Empire olives were cultivated throughout the Mediterranean basin and a central commodity of trade in the Middle East, North Africa, Spain and Morocco.

Spanish explorers brought olives to Peru in the 1560s and in 1769 the Franciscan Father Junipero Serra established Mission San Diego de Alcala where he planted olive trees.

By 1900 the California olive industry began to flourish and in 1905 Ehmann Olive Co. began canning ripe olives, soon becoming the table olives of choice in the U.S.

Today, there are over 1 billion olive trees on the globe with an average estimated age of 175 years old, covering over 27.5 million acres.

Spain is the largest producer controlling 45 percent of the olive oil and 35 percent of the world’s table olives. Italy, Greece and Turkey are the other main producers.

California produces .02 percent of the world’s olive oil and 6.7 percent of the table olives.

Harvesting olives is labor intensive and groves require year-round attention. Almost all the picking is done manually, accounting for the higher prices of olive oil.

Olives are crushed into black paste and the juice is squeezed out of the paste; no heating is involved hence the term “cold press.” Water from the olives that is present is separated, leaving only oil. Heat is applied to the remaining paste to further extract oil used only for cooking.

It takes 11 pounds of olives to make a quarter gallon of oil.

Ninety percent of the global olive production goes into manufacturing oil, the remaining 10 percent of the olives, green or black are either salt-brined-pickled or dry-salted and then eaten.

Extra virgin oil has less then 0.8 percent acidity, fine virgin oil has less than 1.5 percent acidity, whereas ordinary olive oil has less than 3 percent acidity.

If you fry or cook with olive oil it diminishes the health properties of the oil. Consider cooking with refined avocado or sunflower oil for high heat. Olive oil is best used at room temperature on salads.

Olive oil is best stored in a dark, cool place; both heat or direct light breaks it down.

Olive oil contains no cholesterol, but plenty of vitamin A, D calcium and iron. Many cultures take a couple tablespoons twice daily. Olive oil is effective at increasing high-density cholesterol (the beneficial sterol) and has earned it, rightfully so, the moniker “a protector of cardiac health.”

It is effective at regenerating skin cells and dissolving scar tissue.

According to Greek mythology, Athena, the Goddess of Wisdom, gave the olive to the Athenians.

Jesus visited Mount Olive after the Last Supper; there in the olive garden at Gethsemane an angel appeared and gave him strength.

In the Islamic tradition the olive is known as the World Tree described in the Koran for its oil as “the light of the heavens and the Earth.”

In the Jewish faith the olive wood symbolizes “peace of the immortal soul.” Also the olive tree is referred to as the Tree of Light for its oil is used to light the seven-branched candlestick or menorah.

In the Bible, a dove sent by Noah from the Ark returned with an olive branch.

Today, the olive branch symbolizes peace.

Dr. Reese Halter is a distinguished conservation biologist and author of the award-winning “The Insatiable Bark Beetle,” Rocky Mountain Books.

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