The oldest living thing on earth, some will tell you, is the earth itself. Others will deny that the planet itself is alive, and point to coral reefs, which are tens of thousands of years old. However, these, like the earth itself, are not single entities but composed of thousands of individual living things. Therefore those looking for the oldest individual life form on the planet will probably agree that these are trees.

Trees have been around for a long time. The oldest trees ever known are Wattieza trees. These grew about 380 million years ago, and grew to heights of eight meters. In creating the first forests, these trees changed the climate of the planet forever.

None of these survivors are still alive, but the oldest trees are older than most human civilizations. Trees of over a thousand years old are not dramatically uncommon, and the oldest trees are between four and five thousand years old. One such tree is the Fortingall Yew in Scotland. This tree was a sapling when Stonehenge was being raised in about 2000 BC, and though it has suffered considerably through the efforts of humankind it is still every year able to put out a fresh crop of leaves to signal that it plans to spend another year on the planet.

Another tree which would be even older were it not for the efforts of well-meaning scientists is the Prometheus tree in the United states. A young scientist called Currey was doing research into the effects of glaciers in the area. Every year trees produce another layer of wood, and by counting these layers scientists can tell exactly how old a tree is. By seeing how much wood grew each year scientists can tell what the weather was like. Currey found a tree which looked old enough for his purposes, and tried to drill out a section of the wood. However, the drill broke, and Currey did not have another. Rather than abandon his entire research project, Currey asked for permission to cut the tree down.

Because the tree was in a US national park, he had to ask permission for this. Once this permission was given and the tree was cut down it was discovered that a mixture of ignorance, incompetence and sheer bad luck had just killed the oldest living thing yet discovered on earth. The tree had started growing before the great Pyramid of Gaza was built, when Moses led the Hebrews from Egypt, it was 1300 years old, and it was almost two thousand years old when Rome was founded. It was over 2500 years old when Julius Caesar was born, and was around 4700 years old when it met Mr Currey.

Prometheus was a type of tree called a bristle-coned pine. These trees can live to great age, and for some reason those which live in areas where the soil is low in nutrition and moisture seem to live the longest. Another tree from the same area is called Methuselah, and is the oldest known living thing. This tree is named after a character in the Bible, which says "And all the days of Methuselah were nine hundred sixty nine years" yet even at the time these words were first written, Methuselah the tree was already going strong, and is now a healthy 4,723 years young.