Ginkgo is a living fossil. It is the oldest surviving tree species, which has remained on the planet, relatively unchanged for about 200 million years. A single ginkgo can live for hundreds of years, maybe more than a thousand. They have survived some of the greatest catastrophes in our world, from the extinction of dinosaurs to the atomic bombing of Hiroshima.
So what is the secret of its longevity?
In the rings and genes of Ginkgo biloba trees in China, some of which are more than 1,000 years old, scientists are beginning to find answers.
“In humans, as we age, our immune system begins to not be as good,” said Richard Dixon, a biologist at the University of North Texas. But in a way, “the immune system in these trees, even though they are 1,000 years old, resembles that of a 20-year-old child.”
He and his colleagues in China and the United States compared young and old ginkgo trees, aged between 15 and 1,300 years, in a study published Monday in the Proceedings of the National Academies of Science. Upon examining the genetics of vascular cambium, a layer or cylinder of living cells behind the cortex, they discovered that ginkgo grows indefinitely until old age.
That is because the genes in the cambium do not contain any senescence or death program, they say, but continue with their defense program even after hundreds of years. Old trees also produce as many seeds and their leaves are as ingenious as those of young trees. Although it has not yet been tested, researchers believe that other old trees, think of the 4,800-year-old Bristlecone known as Methuselah in eastern California, may have a similar pattern of genetic programming.
Although ginkgos live a lot, they do age. Trees grow and leave: above, with a cell-generating region called apical meristem, and outside, with the vascular cambium. Over time, weather or other things damage the apical meristem, limiting the height of a tree. And every year, the leaves die and fall off.
But the cambium, contained within the trunk of the tree, remains intact and active. They discovered that cell division tends to decrease after 200 years. But the cells are still viable. They generate defenses and transport water and nutrients so that the tree grows and stays healthy.
Sometimes trees can be reduced to only hollow stumps, but with the cambium intact, they can still produce leaves and flowers or Even live like stumps.
Finally, even ginkgo trees die. But there is a big question: why?
Essentially, trees like ginkgo could live forever, says Peter Brown, a biologist who runs Rocky Mountain Tree Ring Research and was not involved in the study. “Being modular organisms, every year they are putting new wood, new roots, new leaves, new sexual organs,” he said. “They are not like an animal, like us. Once we are born, all of our parts are there, and at some point they simply begin to yield.”
Trees do not necessarily die of old age, he says. Something (pests, drought, development) kills them first.
He and others presume that studies on other trees such as redwoods or Methuselah would produce similar results. And although humans are quite different from trees, contemplating them has some purpose.
Peter Crane, evolutionary biologist and author of “Ginkgo: The Tree That Forgotten Time,” said that contemplating long-lived trees could help us see beyond the future of what many of us tend to look at
“It’s a way to gauge how fast our world is changing and remind us that we shouldn’t always think in the short term.”