There was sad news from the Galapagos islands this week – Lonesome George is dead. Lonesome George was the last known living member of the subspecies, Chelonoidis nigra abingdoni and was about 100 years old. Tortoises can live for a really long time, and the second oldest recorded lifespan for a tortoise was Tui Malila, who was given to the royal family of Tonga by the explorer James Cook in 1777 who died in 1965. The oldest recorded lifespan for a tortoise is Adwaita, who lived in the Alipore Zoological Gardens of Kolkata, India and was believed to have been 255 when he died in 2006, but this cannot be confirmed.
Did you know that some organisms are thought to be immortal? Not just Time Lords either, animals that you may have seen. What this means is that individual cells (the building blocks of everything living) are replaced at the same speed at which old cells die. In most organisms there is a time limit on how many times cells can split and reproduce before the DNA becomes too damaged. In some animals there is no limit on how many times a cell can reproduce. This means that in theory, this animal can live forever.
All sound a bit too much like sci fi? Well some coral colonies have been found to be about 4000 years old, but that’s cheating as while the colony can live indefinitely, each individual part of the colony can’t. But we do also know that fully grown lobsters do not die more often than young lobsters and that older lobsters are often more fertile (can reproduce more easily) and do not become any slower or less fit. Why? Let’s just say something incredibly complicated to do with DNA and an enzyme called telomerase. If this is actually true, then surely we expect there to be lots of really really old lobsters wandering around? Well yes and no. Firstly, it is incredibly hard to accurately work out the age of a lobster, as they all grow at different rates depending on sea temperate, how much food they’ve eaten etc. but secondly, in the wild sadly very few animals die of old age, most die of disease, an accident or by being hunted. If a lobster lives past a certain age, they will get to a size where they need more food than younger, smaller lobsters, and they are more easily visible to predators, this means that they are both less likely to find enough food and more likely to be caught.
And with that, I’m off to write a sci fi movie…
Image extracted from the public domain ‘New Student’s Reference Work‘.
Blog post by Linda Seward of Seward Technical Writing, providers of original science content.