‘Not only were we happy, but we knew it.’ –Rudyard Kipling
The cells that make up our body are constantly making new cells by dividing. A biological technicality causes us to lose a bit of DNA at the ends of our chromosomes (structures made up of DNA and proteins) after each replication. DNA contains the blueprint for our lives, so in order to make sure we aren’t losing crucial information during these divisions, the long molecules of DNA are protected by shorter segments of DNA at their ends called “telomeres.” An analogy would be the plastic tips on a shoelace that prevent it from unraveling. When a cell multiplies, the only part of the chromosome that is lost is a piece of the telomeres. But as we age, our telomeres get shorter, until they reach a critical point where the cell can no longer replicate without damage to its essential DNA. When this occurs, the cell becomes inactive or dies. Shortening of telomeres is linked to senescence and increased risk of disease. Other contributors to aging include oxidative stress (hence the appeal of antioxidants).
Lobsters have a perpetual supply of telomerase – the enzyme that can restore telomeres, helping cells avoid that fateful end. Humans also have telomerase, just not enough to overcome the constant shortening of telomeres. In fact, telomerase is often found in cancer cells, giving tumours a survival advantage.
[A] large supply of telomerase can be a double-edged sword. Lobsters are still more likely to die with age because their hard-shell exoskeleton moults and has to be regrown. This requires reams of energy, eventually too much. As a result, common causes of death for lobsters are exhaustion, immobility, and shell disease, although the leading cause is still predation.
