What’s the Oldest Living Thing on Earth?

The oldest human lived to be 122 years old, yet that amount of time only makes a small fraction of the lifespan of some other living creatures on our planet. On every continent, we can find ancient life forms which have been living for thousands, or even millions of years.

Oldest Living Creature on the Planet

Our planet is dotted with ancient trees which represent the oldest individual examples of their species. The oldest of them have been around between 2,000 and 5,000 years, and possibly provided food and shape for the earliest human civilizations.

However, the real champions of longevity are clonal colonies of plants. According to experts, the oldest living thing on Earth is 6,000 tons of Mediterranean seagrass. Also known as Neptune grass or Mediterranean tapeweed, Posidonia oceanica is an angiosperm plant that forms vast underwater meadows.

Carlos Duarte from the University of Western Australia in Perth sequenced the DNA of Posidonia oceanica from 40 sites which span 2,174 miles (3,500 kilometers) of seafloor, from Spain to Cyprus. One patch off the island of Formentera was identical over 9 miles (15 kilometers) of coastline.

Just like other seagrasses, the vegetation system of Posidonia oceanica reproduces through cloning. This means that the meadows spanning several miles are genetically identical, and it is considered a single organism which shares only one root system.

From the plant's annual growth rate, the experts calculated that the Formentera meadow could be between 80,000 to 200,000 years old. It even surpassed a Tasmasian shrub named Lomatia tasmanica, which is believed to be 43,600 years old.

Scientists believe that the seagrass has been able to reach such a long lifespan due to its ability to reproduce asexually and generate clones of itself. Meanwhile, organisms that can only reproduce sexually inevitably get lost at each generation.

Despite the historical robustness of the seagrass, Duarte reported that the patch of Posidonia oceanica is currently threatened by climate change. Since the Mediterranean is warming three times faster than the world average, the meadows decline by 5% each year.

Other Organisms With Long Lifespan

When it comes to non-clonal organisms, there are individual creatures that are equipped with traits to hold off, and even stop or reverse, the aging process. With their incredible longevity, these organisms provide a glimpse into the past that help us understand our current environment.

The oldest living land animal is a Seychelles giant tortoise (Dipsochelys hololissa) named Jonathan, believed to be 191 years old. He has lived on St. Helena island off the coast of West Africa since 1882, when he was presented to the island's governor as a gift.

Meanwhile, the oldest aquatic animal is an ocean quahog (Arctica islandica) which was collected off the coast of Iceland in 2006. From the initial counts of its shell's annual rings, the clam was thought to be around 405 years old. However, it was re-examined in 2013 using more precise techniques and the count rose to 507 years old. It was named Ming, after a Chinese dynasty which was in power when it was alive.

When it comes to microorganisms, the oldest living bacteria was revived at the California Polytechnic State University by Raul Cano. This bacteria, which had been taken from a bee trapped in an amber, was estimated to be 25 to 30 million years old. Bacteria are known for surviving for a very long period since they can completely stop their metabolism until ideal conditions are met.