At 13,000 years, tree is world’s oldest organism

It began life during the last ice age, long before man turned to agriculture and built the first cities in the fertile crescent of the Middle East. It was already thousands of years old when the Egyptians built their pyramids and the ancient Britons erected Stonehenge.

The Jurupa Oak tree first sprouted into life when much of the world was still covered in glaciers. It has stood on its windswept hillside in southern California for at least 13,000 years, making it the oldest known living organism, according to a study published today.

Scientists believe the tree, composed of a sprawling community of cloned bushes, is the oldest living thing because it has repeatedly renewed itself to ensure its survival through successive periods of drought, frost, storms and high winds.

The Jurupa oak, named after the Jurupa Hills in California’s Riverside County, belongs to a species called Quercus palmeria, or Palmer’s Oak. It was this fact that first alerted scientists to the idea that all was not what it seemed when it came to this particular stand of scrubby oak bushes.

“Palmer’s Oak normally occurs at much higher elevations, in cooler, wetter climates. In contrast, the Jurupa Oak scrapes by in dry chaparral, wedged between granite boulders and stunted by high winds, atop a small hill in plain sight of suburban backyards,” said Professor Jeffrey Ross-Ibarra of the University of California Davis.

Another peculiarity was how the plant grew as mass of bushes that failed to produce fertile acorns. This suggested that it was a group of clones that had all stemmed from one individual, which was confirmed by DNA analysis.

This single Jurupa oak extends over 25 yards and is extremely slow growing. The scientists said that it could only have got this big by clonal growth, resprouting from the roots following wildfires. After a while the centre of the colony degrades, leaving the haphazard collection of stems visible today.

“Ring counts show that the Jurupa Oak is growing extremely slowly. At its current rate of about one twentieth of an inch [of growth] per year, it would have taken at least 13,000 years for the clone to reach its current size. And it could be much older,” said Michael May, a member of the research team.

The scientists believe the oak began life in a far colder climate during the last ice age, said Andrew Saunders, another member of the team. “This literally appears to be the last living remnant of a vanished woody vegetation that occupied the inland valleys at the height of the last ice age,” he said.

If the age estimate it correct, the oak would be 10,000 years older than the oldest American redwood tree. The study is published in the on-line journal Plos One.