Study reveals Jonathan the tortoise maintains youthful mitochondria

April 1 saw widespread media reports claiming the death of Jonathan, the giant tortoise estimated to be nearly two centuries old. The announcement proved false, originating from a social media fraudster posing as the animal’s veterinarian who solicited cryptocurrency donations amid the confusion. Despite the hoax, public reaction highlighted enduring fascination with the reptile, which has resided on Saint Helena since the late 1800s.

Genomic Analysis Reveals Youthful Traits

Jonathan is currently recognized as the oldest known land animal, though exact age remains uncertain at approximately 194 years. He belongs to the Seychelles giant tortoise subspecies (Aldabrachelys gigantea hololissa), typically living 100 to 150 years. While some individuals may exceed this range, precise tracking is difficult due to their longevity surpassing that of researchers. A study published today in Science Advances provides the first detailed look into his genetic makeup.

Scientists from Kallel, a nonprofit dedicated to longevity research, led the investigation. Senior author Stephen Clark, a neuro-oncologist and Kallel founder, explained that a cheek swab allowed for genome sequencing without blood draws, which are restricted for protected species. The team also analyzed the epigenome, comprising chemical compounds that regulate gene activity by switching genes on or off through DNA methylation.

Mitochondrial Aging Patterns Identified

The research compared Jonathan’s epigenome against that of Tank, a five-year-old Aldabra tortoise, marking the first time such data was examined across a 189-year chronological gap. Previous studies had sequenced other Aldabras but did not analyze their epigenomes. Clark noted that while epigenetic changes over time are known, large-scale comparisons were previously absent.

Findings indicate Jonathan maintains remarkably youthful mitochondria. When his DNA methylation levels were contrasted with methylomes from animals aged between five and 91 years, his mitochondrial gene profiles resembled those of the five-year-old subject. In comparison, the 91-year-old specimen exhibited significantly older epigenetic markers.

Future Research and Human Applications

Kallel aims to leverage these insights to identify pathways targeting human longevity. Clark stated the organization seeks drugs that influence the epigenome to preserve mitochondrial youthfulness. Future work will involve further analysis of Jonathan and other Aldabras, alongside investigations into the genetics of additional long-lived species. Progress depends on philanthropic support available to the nonprofit.

Regarding Jonathan’s current status, Clark described him as an exceptional subject. Although blind, the tortoise retains intact hearing. Researchers anticipate he could live substantially longer if protected from infections and environmental hazards.