Today I will tell you about an amazing little creature. When you ask someone to name an amazing animal or a spectacular creature, they would most likely name lions or tigers or some other large creature. Indeed, most symbols that are based on animals tend to be based on a few animals- the same few animals have been used repeatedly in history and in romantic or magical tales. But today I will tell you about a little creature which does not look as spectacular as a tiger, nor does it have the strength of an elephant and it is not as beautiful as a butterfly. It is a small, ugly animal. But, I hope to convince you in this VERITAS that it is an amazing animal. So amazing that Science magazine named it “Vertebrate of the year” in 2013.
I am talking about the naked mole rat. If you search for its pictures on the internet, you will agree that it is pretty ugly and not so impressive to look at. But it has some characteristics which make it one of the most remarkable creatures that exist. But before we go into these remarkable characteristics, let’s talk about the more “commonplace” characteristics. The naked mole rat, as the name suggests, lacks hair on its body. It is 8-10 cms long and weighs about 30-35 grams. It has tiny eyes and its eyesight is very poor- so basically the eyes just help detect darkness and light. It does not need to see because it spends its entire life underground. Colonies of naked mole rats live in a complex system of subterranean tunnels in the arid and semi-arid regions of East Africa. The colonies can contain upto 300 individuals( the average size is 80 individuals) and the tunnel systems can be several kilometers long.
Now, let’s talk about the characteristics that make this an amazing creature. So amazing that it does deserve the “Vertebrate of the year” title that Science gave it in 2013. Let me first list the amazing characteristics and then explain each one of them in detail: social behavior, thermo-conformance, resistance to cancer, lack of pain and extraordinary life span.
- Social Behaviour: Bees, Ants, Wasps and Termites live in what we call Eusocial societies- In Greek Eu means real or good. So Eusocial societies display the highest form of social behavior. Eusocial societies have a single breeding female and the rest of the females are workers/defenders. So there is a complex division of labour. For a long time scientists believed that Bees, Ants, Wasps and Termites are the only species that display eusociality. Now, all these are insects and wasps, bees and ants belong to the same order. So scientists believed that eusocial societies are the result of certain genetic characteristics. But then they discovered the naked mole rat. Now, the naked mole rat is a mammal and is very far genetically from bees and ants but still it displays eusocial behavior. This was an amazing discovery and scientists realized that social systems in species may arise out of environment factors or evolutionary pressures. It is now understood that since living conditions for naked mole rats is very difficult so the only way they can survive is by living in large families in which some individuals do nothing else but find food, others only defend the family from predators( like snakes) and the queen only reproduces. If each individual reproduced, the family would not survive because of the competition and also because reproduction is costly in terms of time and energy and digging tunnels and finding food needs a lot of energy. So most individuals are not involved in reproduction at all and they just support the queen who has very similar genes to them- the genes are being passed on through the queen and not each individual. To give you an idea of how difficult it is for mole rats to find food consider this: naked mole rats eat tubers and sometimes the tubers are very far away from the mole rat tunnels. They do not come out of their tunnels but need to tunnel to the tuber. The tuber gives out no smell and the naked mole rats have very bad vision. So they are blindly searching for tubers by digging tunnels in all directions. No single individual can survive like this. They can succeed only if they make huge teams and dig in all directions; even then it may take them several weeks to find a tuber. Therefore the amazing fact that naked mole rats has told us is that the formation of societies and social structures is not just related to genes- there is a very strong environmental influence as well.
- Thermo-conformance: Animals have an internal body temperature which they need to maintain in spite of the temperature of the environment outside. For example, we humans have the internal body temperature of about 37 degrees C and we need to maintain that using internal processes( like sweating, shivering etc). In other words, we humans are thermo regulators because we need to maintain a specific internal body temperature. All animals that are thermo-regulators can be divided into two kinds: warm blooded- those who can maintain temperature using internal processes and cold blooded- those that need to maintain their body temperature by moving to warm/cool areas. But naked mole rats have solved the temperature problem in a very interesting and “innovative” manner- the naked mole rat just adapts to the temperature of the environment outside! So it is not a thermo regulator, it is a thermo-conformer. Thermo conformers are very rare- the naked mole rat is the only mammalian thermo-conformer.
- Immunity to Pain: Almost all animals experience pain when their skin comes in contract with acid or capsaicin( the stuff that gives “heat” to chili peppers). This is due to a neurotransmitter known as substance P which is present in the skin. The naked mole rat does not have substance P and is thus immune to the pain of acid or the burning sensation caused by capsaicin. P substance also causes long term inflammation in injuries and also after surgery. Thus, scientists are studying the naked mole rat to get some clues on how this pain can be managed/reduced. This is a very important field of study. There are people who live in chronic pain eveyday of their lives and we need a way to help them. The naked mole rat may offer us some clues. Note that the pain of inflammatory diseases like Arthritis is also caused because of acid buildup in tissues- so the research on naked mole rat’s pain immunity is directly applicable. Now, lets ask why the naked mole rat is immune to acid pain? It lives in deep tunnels in large groups so there is a carbon dioxide buildup inside the tunnels. We breathe air that has less than .1% C02. The naked mole rat lives in tunnels in which C02 can reach upto 10%. And C02 causes acid buildup in body tissues. So the naked mole rat evolved to be immune to the pain caused by this acid buildup.
- Resistance to Cancer: In all creatures Nature has mechanisms in place to control cell growth and division. A single cell moves freely and multiples without any inhibition. But when a normal cell comes in contact with another cell, it stops multiplying and tries to move away. This prevents cells crowding in a small area. The aim of nature is to stop growth when there is no space to grow and to not have cells crowd into a small area. This is called contact inhibition. But cancer cells do not have the property of growth inhibition and keep growing even when they are crowded into a small space. They keep growing even when there is no space- they grow on top of each other. Almost all animals can develop these cancer cells. But, not our amazing naked mole rat. Scientists have never found a mole rat that has cancer! And the reason is that the cells of the mole rat are hyper sensitive to contact inhibition. Or, in other words, the cells of a naked mole rat are much more likely to stop dividing when they come into contact with other cells than any other creature. In most creatures the gene p27 is responsible for contact inhibition. But in the naked mole rat there is an additional gene p16 which is even more active and prevents overcrowding at much lower population densities than p27. So even if one of the gene( p16 or 27 ) fails, the other still prevents overcrowding and cell division during crowding and thus prevents cancer. In humans we have only p27 responsible for growth inhibition and if that fails, we get cancer. Scientists are trying to understand the cancer resistance of naked mole rats and want to use that research to find a way to prevent cancer in humans.
- Long Lifespan: A common mouse or rat lives for about 4 years. The naked mole rat can live upto 30 years. In the rodent world the naked mole rat is the longevity world champion. Ageing is caused by oxidative stress. Oxidative stress refers to the buildup of free radicals in the cells of our body. Free radicals come from metabolic processes in our body but these are harmful. Our body has ways of dealing with free radicals( basically a kind of detoxification) but over time the balance between creation of free radicals and their destruction is lost and there is a buildup of free radicals or, in other words, oxidative stress occurs. The naked mole rat has a very interesting way of dealing with this oxidative stress. Its metabolic processes become very slow when there is less food. During these times, therefore, the production of free radicals is dramatically reduced. Thus by controlling its metabolism and making it very slow for long periods the naked mole rat avoids oxidative stress for a longer period of time and lives a very long life. Oxidative stress is also responsible for diseases like Parkinson’s, Alzheimer and other age related disorders. Thus finding out why the naked mole rat lives longer may give us clues to cure these widespread and debilitating diseases.
Isn’t the naked mole rat an amazing creature? From it we may learn how to live longer, have less people suffer from Alzheimer’s disease, cure cancers( or prevent them from happening) and cure people of tremendous pain that they suffer from every day for years! Don’t underestimate the little ugly creatures. This reminds me of an urdu sher:
Hairat se yuun na dekhiye, zarra hua to kya hua!
Apni jagah pe janeman zarra bhi aaftaab hai.
( don’t look at it with disdain, though it may appear no more than a speck of dust to you!
But remember that in its place the speck of dust is no less important or amazing than the enormous sun)
============= ============ =================== ============== ========= =====
Go wondrous creature, mount where science guides
go measure earth, weigh air, state the tides,
instruct the planets in what orbs to run
correct old time, regulate the sun
====== ======= =========== ============================== =============