Naked mole rats are affectionately known as an odd freak of nature. They can live for up to 30 years (which is absolutely astonishing for a rodent its size), are resistant to pain, and are practically immune to cancer (only two known individuals ever were found with cancer). Now, scientists have discovered another interesting fact regarding these rodents: they can last 18 minutes without oxygen.
Most people can’t last 2 minutes without gasping for air, so it’s quite a shock that a small rodent can do this for 18 minutes! Granted, the naked mole rats lose consciousness nearing the 18 minute mark, but they completely recover after being exposed to normal oxygen levels. They have a handy trick that has been evolved throughout their generations. Their secret is that they switch from using glucose as energy to using fructose as energy. To break down sugar, humans as well as almost every other mammal go through glycolysis, which uses up oxygen. Glycolysis happens immediately during the breakdown of glucose. However, with fructose, the process of glycolysis happens in later steps. This means that the production of energy can go on without the use of oxygen for a time.
It makes sense that a different kind of energy production would evolve among naked mole rats. They live and burrow underground with as many as 300 other naked mole rats. This makes oxygen a bit of luxury. Having a way to survive in an environment with a much lower oxygen concentration would be extremely beneficial.
Evolution is one of life’s most powerful tools. Fueled by natural selection, it allows life to improve over generations. It makes people wonder why certain hereditary diseases are so common. However, sometime we have to take a closer look.
One classic example is Sickle Cell Anemia, or sickle cell disease (SCD), which is a hereditary disease that causes blood cells to have an irregular, sickle-like shape instead of their normal round shape. This causes complications in carrying oxygen and a risk of blood cells getting stuck and clogging blood vessels. It is common in certain parts of Africa and Asia. It would seem odd that a deadly hereditary disease would be common, but there is a secret this diseases possesses.
SCD is recessive (having 2 recessive alleles). However, if a person is heterozygous for this disease (one recessive and one dominant allele), they are actually resistant to malaria. The parasite that causes malaria has a hard time getting into sickle-shaped cells. Heterozygous individuals have some of their cells sickle shaped, but not enough to exhibit symptoms. Therefore, it is advantageous for a person to be heterozygous for SCD. Apparently, the resistance to malaria is worth the risk of having SCD.
SCD isn’t the only disease that is resistant to malaria. Hemoglobin E disease, common in Southeast Asia, is similar to sickle cell anemia, except that its symptoms are much milder. For some people, it’s a benign disease, but its effect on malaria is still the same.
However, despite being a much better alternative, it isn’t very common in Africa. This is mostly due to the fact that, even if it’s imperfect, sickle cell anemia is already there (The Power of Random). Despite being a better alternative because of its milder symptoms, the niche of malaria-prevention has already been filled and prospered for many generations. It will take a lot of time for Hemoglobin E disease to be more common in Africa, if it ever becomes more common.