There’s been a little meme floating around the internet for a few years now that lobsters are “biologically immortal”. Although this isn’t actually true, like any other misconception about science, there is a bit of truth to it. In this case, the bit is a sequence on the end of eukaryote DNA strands, known as a telomere.
Telomeres are repeating sequences (TTAGGG in vertebrates) of DNA at the end of our chromosomes. Because of the way we replicate DNA, all of the telomere cannot be copied, and part of it disappears with every replication. This serves as a buffer against the actual genes being eaten away every replication and when the telomeres are gone, the cells stop dividing.
In 1961, Leonard Hayflick showed that cells will only divide a finite number of times. We later learned that this phenomenon, what we now call The Hayflick Limit, correlates quite well with the shortening of telomeres. For this reason, and the fact that research is showing they may be highly subject to oxidative stress, telomeres have been implicated as a key player in the aging process.
There is an enzyme which we actually have the gene to code for, known as Telomerase. Telomerase can rebuild telomeres, and it appears to be highly active in lobster cells, so that they don’t senesce the way our cells do. Telomerase genes are suppressed in our cells, and for good reason–it plays a key role in many cancers. One of the reasons cancer cells can out-compete normal cells is the activation of telomerase. This is why cancer cells are said to be “immortal” (It’s been shown that one of the things certain cancer-causing viruses do is contribute to the switching on of telomerase genes, but that’s a whole other story, which I might talk about in a future post).
The lobster telomerase can work without giving them cancer, but are lobsters really immortal? A recent article by Marina Koren in Smithsonian Mag explains that the lobsters do grow old and die–the mechanism is just different:
Finally, older crustaceans stop shedding their exoskeletons altogether—a clue that they’re near the end of their lifespans. They run out of metabolic energy to molt, and their worn-and-torn shells contract bacterial infections that weaken them. Shell disease, in which bacteria seeps into lobster shells and forms scar tissue, adheres the crustaceans’ bodies to their shells. The lobster, attempting to molt, gets stuck and dies. The disease also makes lobsters susceptible to other ailments, and in extreme cases, the entire shell can rot, killing the animal inside.
Ha! Fuck you, lobster!
So lobsters aren’t really immortal, but telomerase may lead the way to prolonging human life, if it’s possible to replenish the telomeres without turning ourselves into cancer.