The question of the world’s longest-living lizard leads to a surprising answer involving an ancient lineage and a unique biological profile. The species holding the longevity record is often mistaken for a lizard but belongs to a far older, distinct evolutionary group. Its extraordinary age is linked to a profound slowing of the life cycle, affecting growth rate and reproduction. Understanding this record-holder provides insight into the limits of vertebrate longevity.
The World’s Longest-Lived Reptile
The reptile that achieves the greatest age, potentially living over a century, is the Tuatara (Sphenodon punctatus), a species endemic to New Zealand. Individuals have been documented to live for more than 100 years; for example, a male named Henry reproduced at the estimated age of 111. This lifespan places the Tuatara second only to some species of giant tortoise among all living reptiles.
The Tuatara is not technically a true lizard, despite its superficial resemblance. True lizards belong to the order Squamata, while the Tuatara is the sole surviving member of the ancient order Rhynchocephalia. This lineage diverged from the ancestors of lizards and snakes approximately 250 million years ago, making the Tuatara a unique evolutionary outlier. Its distinct skull and teeth structure confirm its separate classification, even though its scaly appearance often leads to misidentification.
Secrets Behind Extreme Lifespan
The Tuatara’s longevity is directly linked to its slow metabolism and adaptation to cool environments. Unlike most reptiles, the Tuatara maintains a low optimal body temperature, typically between 16° and 21° Celsius, which significantly slows its physiological processes. This reduced metabolic rate minimizes the accumulation of cellular damage, a process associated with aging in faster-living animals.
This slow pace of life extends to nearly every biological function, including growth and reproduction. Tuatara continue to grow larger for a remarkable period, up to 35 years of age, which is far longer than other reptiles. They do not reach sexual maturity until they are between 10 and 20 years old, representing a significant delay in reproductive timing. This drawn-out life history effectively stretches the entire lifecycle, contributing to the species’ age.
Recent genomic studies have revealed genetic factors that contribute to their resilience against aging. The Tuatara’s genome contains a high number of genes involved in producing selenoproteins, which protect against oxidative stress and cellular deterioration. These genetic defenses, combined with their slow physiology, allow the Tuatara to maintain bodily functions over many decades.
Notable Long-Lived True Lizards
Since the Tuatara is not a true lizard, the distinction for the longest-lived member of the order Squamata falls to other species. Large lizard species, such as iguanas and monitor lizards, exhibit long lifespans compared to smaller reptiles, though they fall short of the Tuatara’s record. The Grand Cayman Blue Iguana (Cyclura lewisi) holds a documented record for longevity among true lizards.
One male Grand Cayman Blue Iguana, nicknamed Godzilla, was estimated to have lived for 69 years, spending 54 years in captivity. Other large lizards, like the Komodo Dragon, typically live for about 30 years in captivity, though wild lifespans may exceed 60 years. These species represent the maximum age potential within the true lizard group, demonstrating that their longevity mechanisms differ from the Tuatara’s unique evolutionary strategy.