The Reason Bowhead Whales are the Longest Living Mammals
Now we know that we don’t just wear out like an old shoe. Aging rates are governed by genes, gene regulation (epigenetics), increased oxidants and inflammation from inappropriately activated genes, and molecular signaling cascades activated by oxidants and inflammation.
Scientists from across the world are investigating why bowhead whales live so long. Just look at the number of institutions involved in this one paper in the link. At over 200 years, the maximum lifespan of the bowhead whale exceeds that of all other mammals. The bowhead is also the second-largest animal on Earth, at about 90 tons. Those whales are a thousand times bigger than a large man and they have a thousand times as many cells. Despite its very large number of cells and long lifespan, the bowhead whale is cancer resistant. This phenomenon has been explained by the evolution of additional tumor suppressor genes in other larger animals. Elephants have more cells too. They have more tumor suppressor genes. (p53 gene). That makes sense. Cancer develops at the level of genetic change in a single cell. Large animals have many more cells, and they would require more cancer suppressor genes to avoid malignancy.
Look at the image above. It is a strand of DNA. As you can easily see, DNA structure is like a twisted ladder. The rungs or steps of the ladder contain the four variable computer code. That computer code is central to every living thing. It determines how the fetus and child develops. It determines how fast we age and when we get chronic disease. DNA stability is critical to cell function and health. Oxidants and other factors can break the side rails of the ladder. That is called a DNA strand break. If one side rail of the ladder breaks, that is a single strand break. If both side rails break, that is a double strand break.
DNA strand breaks have a profound and detrimental impact on health, acting as a fundamental driver of aging and a causal factor in numerous diseases. Our cells are constantly bombarded by agents that cause DNA damage, both from internal metabolic processes and external environmental exposures. While robust DNA repair mechanisms are in place, the accumulation of unrepaired or misrepaired DNA strand breaks over time can lead to severe consequences. Strand breaks in DNA may make the gene inactive. That may cause cell death or lead to a senile or senescent dysfunctional cell. If the strand break repair is mismatched, that may represent a DNA mutation that causes cancer.
One of the common genetic changes in older animals are DNA strand breaks. Bowhead whale cells repair strand breaks and mismatches with uniquely high efficiency and accuracy compared to other mammals. The bowhead whale relies on more accurate and efficient DNA repair to preserve normal gene structure and function. “This strategy which does not eliminate damaged cells but repairs them may be critical for the long and cancer-free lifespan of the bowhead whale.”
This is very important research. DNA strand breaks with poor repair capacity is a major mechanism of aging in humans. Genes that have breaks in DNA are changed in ways that may cause them not to function or cause the cell to grow wildly. That one change in a single cell can cause cancer. Our DNA repair systems are not as effective as those in the Bowhead whale and that is one of the reasons we don’t live as long as they do. It is a big reason we lose function as we age.
Fortunately, new science helps us understand what causes DNA strand breaks in humans. Many of you have taken vitamin E for its antioxidant properties. You know that oxidants are a major factor that causes aging and chronic disease development. We are learning more and more about that topic. As we age, we make more oxidative particles, and our antioxidant defenses drop off. That imbalance between oxidant excess and antioxidant defenses is called oxidative stress. It leads to free oxidant particles in the cells that bind with proteins and DNA to degrade function and cause DNA strand breaks. It is like a steel knife. Oxidants cause steel to rust. A rusty knife is not as strong or as sharp. It does not work as well. If the process continues the knife may not work at all. It is the same with our cells.
Oxidative stress is a major contributor to DNA damage, including DNA strand breaks, which accumulate in older animals and plays a significant role in the aging process. Oxidative stress occurs when there's an imbalance between the production of reactive oxygen species – highly reactive molecules containing oxygen (like free radicals) – and the body's ability to neutralize them with antioxidants. Oxidants are naturally generated during normal metabolic processes, but can also come from external sources like pollution, radiation, and smoking. These highly reactive oxidants can attack and modify various cellular components, including DNA. As animals age, several factors contribute to an increase in oxidative stress and a decrease in the efficiency of antioxidant defense systems and DNA repair mechanisms.
This is critical information for human health and longevity. If you are seriously interested in a longer healthier life, this is a central topic for you to understand. There are several thought leaders in longevity that point to a single intervention like rapamycin to extend healthier life. Others point to lifestyle measures. That is not the best strategy. If you are serious about a longer healthier life, the best past forward involves lifestyle measures and certain medical interventions in combination. You need a coordinated and integrated strategy.
Bowhead whales have better DNA repair mechanisms. We can achieve the same thing by reducing the oxidant production that causes strand breaks in the first place. Caloric restriction, weight loss, and aerobic exercise all reduce oxidative stress or oxidant/antioxidant imbalance. Lisinopril, losartan, eplerenone, and spironolactone for high blood pressure, statins for high cholesterol, and metformin for diabetes are all powerful antioxidants that work to prolong healthier life. This is the new frontier of medicine. We are understanding more and more about the computer code that governs chronic diseases and aging. That understanding enables us to intervene in specific ways that prolong healthy lifespan and full function.
Very interesting post.