The elephant: the largest living land animal

Elephas_maximus_(Bandipur)From the killer whale whose heart is large enough to fit a small car inside, to the crocodile whose lungs are able to move around within its body cavity to alter its centre of gravity: the animal kingdom contains some of the most fascinating and unusual organisms that live on the Earth. It’s the fascinating adaptations found throughout the animal world that fuels our interests in these animals.

For years the extraordinary elephant has roamed south-eastern Asia and Africa.  Weighing up to six tonnes and reaching up to four metres in height, the elephant is an extremely impressive animal; in fact the largest of all land animals. Despite their vegetarian diet, getting into a fight with an animal of this size should be avoided at all costs!

The big question is how have their systems adapted to meet the needs of this monstrous body?

We know the elephant has in excess of 200 bones that make up its skeleton- hardly surprising given that it needs to support its sheer size. In keeping with its frame, the elephant also has a huge skull, but what is perhaps surprising is its relatively small mouth.  Due to the nature of the tough vegetation that elephants eat, they have evolved to have 8 teeth the size of bricks.  The surface of the teeth are covered in tough enamel ridges that grind vegetation into a pulp as the jaw moves back and forwards.  As old teeth become excessively worn, new teeth are produced at the back of the mouth. The new tooth gradually moves forward, pushing the worn one towards the front of the jaw.  It is this conveyor belt action that allows elephants to eat throughout their entire lifetime.

Another fascinating, and obvious, feature of the elephant is their tusks. They are basically huge incisor teeth, used primarily as a defence mechanism (who wouldn’t be scared of two huge sword-like projections?) as well as for foraging food.  Male elephants also use their tusks to dominate other males, and to help find themselves a mate. The pair of huge tusks is an obvious show of natural selection; in this case, the bigger the tusks the better. The largest known tusk was a whopping 3.5 metres in length.

However, in recent years we have seen a dramatic reversal in the tusk stakes. Due to pressures from hunters and poachers, having large tusks makes these elephants a prime target. It is for this very reason that we are now seeing a very obvious reduction in the size of elephant tusks.

Elephant_snorkelingYet another amazing adaptation we see in elephants originates from within their lungs. Unlike most other mammals, elephants’ lungs lack a pleural space separating their lungs from the ribs.  Instead, connective tissue connects the lungs to their ribcage and diaphragm. But what advantage might this have? Scientists believe that this incredible anomaly may have arisen to aid elephants in ‘snorkelling’; elephants are the only land mammal that are able to entirely submerge themselves in water whilst taking in air from above the surface. Without the lung-rib connective tissue, blood vessels in the lungs would most likely not survive the huge changes in pressure exerted on them whilst snorkelling. By covering these vessels in a much tougher membrane, they are protected from damage from changes in pressure. The downside to this tough casing is that the blood vessels aren’t able to produce a lubricating fluid necessary to ensure that the lungs and rib cage slide over one another during respiration. Without the fluid, the tough connective tissue only allows a small degree of movement. Despite perhaps negatively impacting upon respiration, the benefits that this connective tissue confers to the elephant far outweigh the negatives.

Angry_elephant_earsPerhaps even more fascinating is how an animal of this size, living in extremely hot regions of the world, manages to prevent overheating. They haven’t exactly been blessed with the ideal body shape to stay cool. To address this mystery, scientists used heat-mapping techniques to measure the external temperature of an elephant throughout the day, while also measuring the temperature from within the elephant.  Results found that whilst the surface of the elephant can reach up to 55 degrees Celsius, internal temperatures are kept far lower at around 35 degrees. So what exactly is allowing the elephant to remain cool?  We know that the answer lies with their ears. As with their skull, elephants have the largest ears in the animal kingdom. But these ears serve a very important purpose; they act as a massive fan working to cool down the elephant. By effectively ‘flapping’ the ears back and forth, air is forced back over the body. Big arteries from the body carry blood close to the ears surface via a series of smaller vessels. The ears are well equipped to deal with this, as they are extremely thin. It is this flapping motion of the ears that allow much of the heat from the body to be carried away, and hence prevents overheating.

Elephant_trunk_(1)And finally, I couldn’t talk about the mighty elephant without mentioning its most recognisable piece of anatomy. The trunk. This ingenious piece of machinery is involved in many things that elephants do; feeding and drinking, snorkelling, washing, playing, communicating, feeling, and manipulating amongst many others. This original piece of anatomy seemed to have evolved long ago through natural selection. The sheer size of an elephant’s body and head made bending down to pickup food an onerous task. This difficulty caused the trunk to evolve. Over many years it is thought that these animals slowly evolved to have a shorter jaw, but with a longer top lip.  As they became taller and taller, the upper lip gradually elongated until it resembled a trunk that was able to feed without having to bend down.

You might think of these animals as large, bulky and clumsy, but this is in fact far from the truth. They are amazing feats of engineering. We know that elephants are actually very elegantly made and adapted to suit their body’s needs from their trunk, their cooling system and to their lungs. Today elephants are the only animals of such size, so it is obvious that their size doesn’t hamper them; their body is doing something right.

Post by Samantha Lawrence

The Health Benefits of Kissing

Pucker up, because it seems kissing has a number of important health benefits ranging Kissing1from improving mood and stress levels, to actually enhancing our bodies natural immunity to illness.

Mouth to mouth kissing is a behaviour seen in almost 90% of all human cultures, and used as a non-verbal communication of intimacy, affection and love. For centuries scientists have been pondering the origins of this primitive behaviour and whether it has a functional purpose in our lives.

So where did kissing come from? Apparently, the earliest record of kissing dates back to 1500 BC where references to  ‘drinking moisture from the lips’ were mentioned in Northern Indian Vedic texts. What’s more is that the Kamusutra, which details over 30 different types of kissing, dates as far back as the 6th century AD. According to Philematologists (scientists that study kissing!), it is hypothesized that kissing evolved from an early primitive behaviour known as the ’maternal permastication of food’, which quite literally involved the mouth to mouth contact between a mother and child in the exchange of food during infancy. Despite kissing not being a necessary requirement for successful reproduction, it is hypothesized that sexual kissing may have evolved from this display of care and affection, to eventually promote pair bonding and to facilitate in assessing mate suitability. While mouth to mouth contact is seen in numerous animals as part of courtship rituals, sexual kissing appears to be unique to our species, and may explain why our inverted shaped lips appear to differ from all other animals, almost as if they were shaped for such a purpose!

Despite the seemingly unhygienic nature of kissing, and the fact that it does expose us to the risk of oral infection, this primitive affectionate behaviour represents an evolutionary benefit in conferring protection from diseases that may impose more serious consequences. Mouth to mouth contact essentially exposes each person to the diseases of the other, which while not sounding particularly clean, can actually enhance our own immunological control of exposure to infection. Kissing2According to research by the journal ‘Medical Hypotheses’, kissing represents an evolutionary conserved biological behaviour that boosts our immunity to the Human Cytomegalovirus (HCMV). HCMV is a particularly nasty type of the Herpes virus that can carry a significant teratogenic risk for women i.e. it can have a severe impact on the their unborn children during development, if primary infection occurs during pregnancy. The risks to infected neotates include a number of serious development abnormalities such as enlargement of the liver and spleen, as well as a number of neurodevelopmental disorders including abnormal brain growth, seizures, cerebral palsy and mental retardation. For 30% of infected fetuses the disease is lethal, and as a result, numerous pregnancies are terminated if infection is detected. HCMV is transmitted in saliva, urine and semen. As the disease is only symptomatic during the active phase, it is not an easy virus to readily detect and thus avoid, especially when trying to conceive. In order to avoid infection of the HCMV during pregnancy,  researchers have hypothesized that kissing has evolved to allow women to control the time of inoculation, and that transmission of small amounts of the virus at this point through the saliva will confer immunity to the condition and prevent the presentation of symptoms.

It is now understood that affectionate behaviour has a number of stress-relieving effects. As stress, mainly via the ‘stress hormone’ cortisol, has a number of detrimental influences on our endocrine, nervous and immune systems, kissing may in fact confer significant health benefits by reducing these effects. Interestingly, not only does kissing improve our mood and thus reduce stress levels, it may actually act to reduce a number of parameters that are exacerbated by stress. Stress can elevate blood cholesterol levels, in one manner through stimulating the release of cortisol. Chronic elevation of cholesterol can lead to the build up of plaques and the clogging of arteries that may eventually trigger the development of coronary heart disease. It was identified that an increase in kissing behaviour between marital couples during a 6-week trial period lead to a decrease in blood cholesterol levels, and thus an improvement of blood lipid composition and reduced risk of cardiovascular complications.

Surprisingly, kissing may also enhance your dental health! While it wouldn’t be recommended as a replacement for brushing your teeth in the morning, the extra saliva generated during a kiss washes bacteria off your teeth, and as a result encourages the break down of oral plaque. Kissing also burns calories and raises your metabolism too. According to the research, a vigorous kiss burns up to two calories a minute and can almost double your metabolic rate (the rate at which you can process food). And it makes sense, as kissing involves the coordinated contraction of more than 30 facial muscles, the constant exercise improves muscular tone in the face.  One in particular, known as the orbicularis oris muscle, is used to pucker the lips and has been informally termed the kissing muscle. It has been suggested that the regular contraction of these muscles during a passionate kiss enhances muscle strength and tone and may actually contribute to maintaining a youthful complexion. So a passionate kiss may be the perfect non-surgical remedy for keeping your face young!

Kissing3On what is seemingly quite an obvious level, kissing enhances the release of endorphins in the brain and has a number of other emotional health boosting benefits that improve mood and mental well-being, reduces depression and stress, and most importantly promotes intimacy and pair bonding. So not that we need an excuse, but it seems that appreciating the importance of a good kiss will benefit your health and mental well-being in more ways than one, and if not for anything else, then use it as a happiness boost!

For more information see;

Hendrie CA and Brewer G (2010): Kissing as an Evolutionary Adaptation to Protect Against Human Cytomegalovirus-like teratogenesis. Medical Hypotheses 74: 222-224.

Floyd K, Boren JP, Hannawa AF, Hesse C, McEwan B and Veksler AE (2009): Kissing in Marital and Cohabiting Relationships: Effects on Blood Lipids, Stress, and Relationship Satisfaction. Western Journal of Communication 73: 113-133.

Diving narcosis and laughing gas

Photo by Derek Keats

I watched a programme the other day about a deep sea mystery. A strangely high number of experienced deep sea divers had been lost on diving trips in a particular bay, and no one seemed to know why. The presenter, being a decent diver himself, went for a dive in the bay and noticed that he could make out the sunlight shining through the water at the other end of an underwater tunnel. His conclusion was that the now deceased divers saw this light and thought they could swim through the tunnel to the other side. What wasn’t obvious to the divers was that this light was deceptively far away and they would have to swim very fast for a long time to make it to the other end of the tunnel before running out of oxygen. But what could cause these supposedly experienced divers to make such a rash, fatal decision?

Nitrogen narcosis can give you tunnel vision, making it harder to read diving instruments. Image by RexxS

Above sea level, nitrogen is a pretty boring gas – it makes up about 80% of the air around us and doesn’t normally do us any harm. However, a problem arises when we breathe it in under high pressure – such as when diving. Several gases, including nitrogen, carbon dioxide, and oxygen are normally dissolved in our bloodstream. When you dive deep underwater, the increase in pressure exerted on your body by the surrounding water causes more of these gases to dissolve into your blood through your lungs when you breathe from the gas tank (because going deep-sea diving without a gas tank would be an even less recommendable thing to do). In fact, for every 10m a diver descends, their blood holds an extra 1.5 litres of dissolved nitrogen.

All that extra nitrogen rushing round in the bloodstream has weird, wonderful, and incompletely understood effects on the brain, collectively known as nitrogen narcosis.

Nitrogen narcosis is experienced by all divers – to varying degrees – and feels essentially like being drunk. Because of this similarity, nitrogen narcosis is often referred to as the ‘Martini effect’. Divers liken every 10m below sea level as the equivalent of having one martini – meaning they feel increasingly intoxicated the deeper they get. Even at comparatively shallow depths (10-30m below the surface), a diver will become less co-ordinated and a bit giddy – 20m lower they’ll start making mistakes and bad decisions and may start laughing for no reason. At 50-70 metres, they may start experiencing hallucinations, sleepiness, terror, poor concentration and confusion, and at 90m they risk losing consciousness or even dying.

So, the worse symptoms of nitrogen narcosis aren’t exactly like getting drunk, because even a huge amount of alcohol doesn’t give people hallucinations (though some alcoholics experience hallucinations when withdrawing from alcohol). Actually, the closest similarity to nitrogen narcosis you can find on dry land is from breathing laughing gas, or nitrous oxide.

A pretty sexist cartoon from ages ago showing some ‘scolding wives’ being prescribed laughing gas. I wonder why they were usually so unhappy with their husbands.

Nitrous oxide has been used by doctors to relax patients since 1794 and it is still used today as a form of pain relief for women during childbirth. It has been in the press a lot recently, dubbed ‘hippie crack’, as it’s often used recreationally (though usually not legally) for its mild hallucinogenic and euphoric ‘feel good’ effects, which have often been likened to nitrogen narcosis. So how does nitrous oxide affect the brain?

Although nitrous oxide is hugely understudied, there are several theories about how it can affect the brain. Because gases like nitrous oxide and nitrogen are really fat-soluble, they may interfere with cell membranes (which are made from fatty molecules) disrupting their normal function. In the case of brain cells, this may alter the way they communicate with one another. In addition, the dissolved gas molecules may directly bind to the receptors on the surface of brain and nerve cells. Nitrous oxide is used as a mild anaesthetic because it has been shown to block NMDA receptors – which normally ‘excite’ the brain – and because it activates potassium channels, which further suppress brain cell excitation. All this means is that brain activity is generally depressed and so users are more prone to making bad decisions or losing concentration.

As I mentioned before, nitrous oxide is also good for pain-relief, as it’s believed to activate opioid centres in the brain. When activated, the opioid system – the same one stimulated by drugs like heroin and morphine – then disinhibits certain adrenergic cells in the spinal cord, which dampen down any feelings of pain.

While there have been reports that nitrogen narcosis also decreases the perception of pain, it’s obviously difficult, and, well, not very practical to test the potential of high pressure deep sea diving on pain relief. Instead, what should be studied more are the effects of nitrous oxide on the nervous system. We’ve used the stuff for more than 200 years and yet the biology behind its uses and its dangers is still not fully understood. What’s more, the fact that people use nitrous oxide recreationally (and probably will continue to do so in spite of its non-legal status in many countries) means we really ought to know what its short and long term effects on the brain are. Unlike the mystery of the missing deep sea divers, the full extent of the ways in which nitrous oxide works remains unsolved.

Post by Natasha Bray

Night Nurse: The problem of night-time noise in hospitals

hospitalPicture the scene: It’s been a long day, you’ve been violently ill and feel like every ounce of strength has been drained from your body. Finally, after being poked and prodded, interrogated and tested, you find yourself in a warm bed with a soft pillow behind your head. Drained and slightly disoriented, you manage to overcome the nagging nausea and discomfort and eventually your eyelids grow heavy and the days trials begin to wash away as you drift into a gentle sleep… AAARRGGHH, you’re suddenly jolted awake as a distressed cry pierces the air. Confused and groggy you turn to see an elderly woman moaning and sobbing in a bed to your left, alarm bells ring and soon a young nurse is by her side cooing gently and diffusing her confused rage. Flustered, you turn your head away and close your eyes, trying to blank out the unfolding scene. You must have fallen asleep again, since the next time you awake the drama is over, but now you notice a small frail woman standing at the foot of you bed tugging your sheet. “Excuse me” she mutters politely, “I don’t know where I am and I need to get home, can you help?”. After trying in earnest to console her, you drag yourself out of bed and fetch a nurse to help settle her back into bed. Soon after this you are awoken a third time, now by a pair of nurses loudly chatting a few meters from your bed. Exasperated, you notice that their conversation isn’t even about their patients and instead centres around some dodgy sounding shenanigans that occurred on a staff ‘night out’.

Unfortunately this story is not fictional, this is an actual account of a night I recently spent in hospital whilst receiving treatment for a kidney infection. Further to this, I don’t believe my experience was isolated. Over the past two years I have been unfortunate enough to experience both first and second hand the nocturnal practices of four separate NHS hospitals. One, as described above, was my own personal experience, while the remaining three have been accounted to me by both my late grandma and my fiancé’s nan. Each account has shared a common thread specifically, sleep deprivation blamed on excessive night time noise – usually from both fellow patients and staff.

loudThe World Health Organisation recommends that hospital patients are not exposed to noise over 35-40 decibels, the equivalent of a loud whisper. However, a range of studies have found that noise levels in hospital wards often significantly exceed 60 decibels, even during the night (60 decibels being equivalent to a regular conversation). Noise levels in this range are expected to cause sleep disturbances and have been highlighted in patient surveys as being responsible for increased stress and lack of sleep.

Sleep is an essential biological function and lack of it has been associated with a range of adverse outcomes including; altered immune function, metabolic dysfunctions and psychological disturbances including depression, stress and anxiety. Although most studies of sleep disruption are performed on healthy volunteers, it makes sense that those recovering from illness will also benefit from a good night’s sleep; a fact which was recognised over 100 years ago by Florence Nightingale in her ‘Notes on Nursing’, where she writes: “Unnecessary noise then is the most cruel absence of care, which can be inflicted either on sick or well…. A nurse who rustles (I am speaking of nurses professional and unprofessional) is the horror of a patient, though perhaps he does not know why. The fidget of silk and of crinoline, the rattling of keys and of shoes, will do a patient more harm than all the medicines in the world will do him good.”

Noise levels undoubtedly affects some patents to a greater extent than others and studies are yet to conclusively link hospital noise levels with sleep disturbances or negative patient outcomes. However, it has been suggested that disrupted sleep can cause additional stress to acutely ill or injured patients and may potentially impede successful recovery. Anecdotally, I often wonder whether the hospital environment played a significant role in my grandma’s passing. She was a kind, quiet woman who loved her own home comforts. I still remember the distress in her voice when she explained to me how she couldn’t sleep because her fellow patients and the nursing staff were always so loud, even at night. She was a sensitive soul and it was painfully obvious that the hospital environment caused her distress. The cause of her passing was officially registered as ‘frailty of age’. However, I wonder whether the degeneration of her condition and her ultimate decision to refuse food was linked to distress caused by her surroundings, and whether things would have been different had she been cared for at home?

bedI have no doubt that nurses and doctors perform the best job they are capable of, given the structures in which they are expected to work. However, I also think it’s time that hospitals dedicate more time and resources to optimising patient comfort and ensuring that they achieve adequate recovery sleep while under hospital care. Ironically, much of the noise present in the hospital environment is created by measures put in place to improve patient health and safety. This includes: loud machinery, a high density of staff working to care for patients and uncarpeted floors, which reduce the risk of infection but can be loud underfoot or under the wheels of rolling equipment. Noise sources such as these must be assessed and noise reduction measures brought into place. Indeed, some hospitals are already addressing these issues by training staff about noise reduction and by providing patients with ear plugs and eye masks (to reduce the effect of continuous light in hospital wards). It is promising to note that such interventions, alongside structural alterations designed to reduce noise, appear to have a positive effect on reported patient satisfaction and recorded levels of noise on hospital wards. Therefore, I believe that practical noise reduction measures are a must for the future of all public hospitals. A good review of hospital noise and practical solution to these problems can be found here.

Note: I have no intention of revealing the names of hospitals mentioned in this report since, I believe this is a wide-spread problem involving hospital structure and not specifically the fault of any individual establishment.

Post by: Sarah Fox