The question of the oldest living organism on Earth challenges the common definition of an individual life. The answer depends on whether one seeks the oldest single, genetically distinct unit or an ancient, interconnected network that has persisted across millennia. The true record holders are biological systems that have mastered continuous existence, revealing extraordinary strategies from slow-growing trees to sprawling, self-cloning empires.
Defining the Measurement of Age
Biologists distinguish between two fundamentally different types of extreme longevity: non-clonal and clonal. A non-clonal organism is the more traditional idea of an individual, where all parts of the body are genetically identical and share the same chronological age, such as a single tree trunk or a solitary animal. Its lifespan is measured from birth to death of that distinct unit.
Clonal organisms, however, achieve vast ages by reproducing asexually, creating genetically identical offshoots that replace the decaying parts. In this system, the original genetic material and root network can be thousands of years old, even though the visible stems or fruiting bodies may only live for a few decades. This distinction moves the focus from the lifespan of a single body to the endurance of a single, ancient genotype.
Record Holders: The Oldest Individual Organisms
The Great Basin bristlecone pine (Pinus longaeva) holds the definitive terrestrial record among single-stemmed, non-clonal organisms. These trees thrive in the harsh, high-altitude deserts of the White Mountains of California. Their slow growth and dense, resinous wood contribute to their incredible durability, allowing one specimen, Methuselah, to be confirmed at over 4,850 years old. Another bristlecone pine in the same region was later found to be over 5,060 years old.
In the marine animal world, the Ocean Quahog (Arctica islandica) is the longest-lived non-colonial animal, a species of clam native to the North Atlantic. Researchers found one individual, nicknamed Ming, that was 507 years old when it was collected off the coast of Iceland in 2006. Its age was precisely determined by counting the annual growth rings on its shell, a process similar to dendrochronology in trees. The Greenland shark (Somniosus microcephalus) is the longest-lived vertebrate, with a maximum estimated lifespan of at least 272 years, and potentially over 500 years, determined by radiocarbon dating the proteins in the lens of its eye.
The True Longevity Champions: Clonal Colonies
When considering the age of an entire genetic organism, the records extend far past a few millennia and into the tens of thousands of years. These true longevity champions survive by continually replacing their individual parts, effectively achieving biological immortality. The most famous example is Pando, a massive clonal colony of Quaking Aspen (Populus tremuloides) located in the Fishlake National Forest in Utah.
Pando, which is Latin for “I spread,” is a single male organism composed of an estimated 47,000 genetically identical stems connected by one vast underground root system. While the individual trunks live for only around 130 years, the entire root mass is estimated to be between 9,000 and 16,000 years old. This makes Pando one of the oldest and heaviest organisms on the planet, covering 106 acres of land.
Other ancient clonal systems include the giant honey fungus (Armillaria ostoyae), which exists as a massive, subterranean network of mycelium. A single specimen in the Malheur National Forest in Oregon covers 2,200 to 2,400 acres and is estimated to be approximately 8,650 years old. In the marine environment, the Mediterranean seagrass Posidonia oceanica forms vast meadows of genetically identical clones stretching up to 15 kilometers. Due to its extremely slow growth rate, researchers estimate some of these seagrass clones could be as old as 100,000 years.
The Biology of Extreme Lifespans
Organisms that achieve extreme longevity often share biological and environmental mechanisms that slow the aging process, known as senescence. A primary factor is a significantly slowed metabolism and growth rate, which is a common adaptation in cold or nutrient-poor environments. For instance, the Greenland shark lives in frigid Arctic waters and grows less than one centimeter per year, conserving energy across its centuries-long lifespan.
Many long-lived species also possess highly efficient mechanisms for maintaining genomic integrity. This includes enhanced DNA repair pathways that continuously correct accumulated damage, limiting the genetic errors that contribute to aging and disease. The indeterminate growth patterns of plants and fungi allow them to continuously add new tissue and replace old parts. Environmental stability, such as the consistent cold of the deep sea, also reduces external stressors that can hasten an organism’s demise.