What Makes up Everything?

October 14, 2015 / Humans, The world around us / 0 Comments /
Header image of a black board with chalk calculations

Start with a human

Lets start with a very complex organism – say, a human. Humans are made up of a number of organ, like the brain, heart and liver. Organs are usually self-contained, and have a specific function in the body, for example, the liver is there to filter out toxins and neutralizes toxins. These organs are quite big in the scheme of things, and if you hold out your two fists together that is the size of your heart. These organs are made up of tissues, which are an organisation of similar specialised cells that perform a specific task, and a typical example of a tissue is muscle. Cells in muscles are specifically designed to produce force which help us to move.



Tissues are the smallest thing we can see with our eyes, and these tissues are made up of individual cells, which can only been seen under a microscope. A skin cell is approximately 30 micrometers (30µm) in size, and this means that you can fit just over 30 skin cells in 1mm. These cells are then made up of tiny structures called organelles, which fulfil a similar role to the cell as organs do to our body. Organelles have specialised functions which include creating proteins, protecting DNA and creating energy. All cells are very similar in this composition, even plant cells to some extent (but there are some key differences too). All of these organelles are made up of molecules, and the size of these molecules can vary quite dramatically. The most commonly known molecule is DNA, which if stretched out, would form a very thin thread of about 2 meters. In contrast, a glucose molecule is about 1.5µm (20 times smaller than a skin cell). You will struggle to see some of these smaller molecules with a microscope.



All molecules are made up of atoms in various compositions. . Glucose for example, contains six carbon atoms, twelve hydrogen atoms and 6 oxygen atoms, and water contains hydrogen and oxygen. Hydrogen is the smallest of all atoms, and is only 53pm wide, which is 0.0000000053cm. Hydrogen atoms are so small you can only just see them under an electron microscope



These particles have never been seen, but we know they are there through experimentation.

All atoms, no matter the size, are made up of 3 particles. Neutrons, protons and electrons. Neutrons ( which have no charge) and protons (which have a positive charge), make up the nucleus of atoms, which gives it an overall positive charge. Electrons have a negative charge and ‘whiz’ around the nucleus in a hazy cloud. An oxygen atom will have 8 protons, 8 neutrons and 8 electrons. For a long time people believed that these particles were the smallest unit which makes up the universe, but then quarks were discovered.


Quarks make up the protons and neutrons, and there are 8 types of quarks:

  • Top Quark
  • Up Quark
  • Down Quark
  • Bottom Quark
  • Strange Quark
  • Charmed Quark

Yes – these names are real.

Quarks have partial charges, for example, an up quark has a charge of +2/3, and a down quark has a charge of -1/3. A proton is made of 2 up quarks and 1 down quark, which is what gives it a total charge of +1 (2/3+2/3-1/3 = 1).

Quarks are widely accepted to be the ‘fundamental particles’, and that there is no smaller particle which makes them. In fact quarks cannot exist on their own, and can only exist when they form neutrons and electrons, so deciding if they truly exist is up for debate.


What makes up Quarks?

It is a bit of a brain twister. Our minds are wired to think there is always a smaller unit because this is how the world around us works, but this logic doesn’t play well in particle physics. There may well be something smaller than a quark which makes up quarks – but it isn’t thought to be likely. Quarks possibly only exist because they have energy, and so you could argue that energy makes up everything.



Everything, including you, me the screen you are reading this on and the grass outside is made up of a combination of tiny fundamental particles called quarks. Alternatively, you could argue that these quarks may only exist because they have energy, and so everything is made up of energy.

Or, you could argue that everything is made up of space, because there is a large gap between the atoms nucleus and the surrounding electrons, which by volumes, takes up much more space than the actual particles in the atom, so we are mostly just space.

This Youtube video will give an overview of the information found on the article tab. If you want to know more about the topic, or want to see where the information came from, have a read of the article after you watch the video.

The most fundamental particle is called a quark. Nothing makes up a quark (that we know off), but it is thought that energy may make up quarks, in which case, energy makes up everything.

What are ‘Pins and Needles’?

September 5, 2015 / Humans / 0 Comments /
Pins and needles

‘Pins and needles’ is that horrible sensation you get, usually in a leg or arm, which does feel like you are being jabbed with thousands of small needles (or pins). It is usually accompanied by numbness, or as numbness is starting to subsite, and in some circumstances can be quite painful. So in this article, I’ll explain what causes it.


Nerve shut down

Nerves throughout your body fire throughout the day, and this is how you can ‘feel’ your arm or leg without touching it. These nerves require a constant supply of nutrients from the blood, particularly oxygen and glucose to continue to fire. When you sit in a funny position, you can apply pressure to blood vessels which reduces blood flow to a part of the body (usually an arm or leg). This reduction of blood flow reduces the amount of glucose and oxygen which reach this part of the body, eventually starving nerve cells of these nutrients. At this point your limb will’fall asleep’, which means that the nerves in that area are not longer able to fire. The nerve still wants to be firing as normal, and these impulses effectively queue up.

At this point, pins and needles are unavoidable.


Nerves wake up

When you remove the pressure/ move position you restore blood flow the nerves. As the nerves recover they are hyperactive and irritable, and continuously fire to release the backlog of nerve impulses, and it is this continuous firing of nerve signals is what we feel as pins and needles. This is where the limb ‘wakes up’, and the longer the blood flow has been restricted to the limb results in an increase in the pins and needles sensation. If the blood flow has been restricted for a long time, then it could be painful!


When pins and needles might be bad

Generally, pins and needles are a good thing, and indicates that blood flow is being restored back to a part of the body, and the sensation lasts a short period of time. However, continuous/ prolonged pins and needles, or experiencing it when blood flow isn’t restricted to an area could indicate some illness, the most common being diabetes. So if you experience pins and needles when you think you shouldn’t, then it could be a worrying sign, and isn’t caused by reduced blood flow in the way explained above.



‘Pins and needles’ is usually caused by restricting blood flow to nerves, which causes them to lose the ability to send signals. This results in a part of the body going numb, and is often said to ‘go dead’ or ‘go to sleep’. When blood flow is restored to the nerves, they are very irritated and hyperactive, which causes them to continually fire signals to the brain whilst the part of the body ‘wakes up’.

The feeling of pins and needles is very common, and should be short lasting – generally it is nothing to worry about. However if you experience pins and needles for long periods of time, or when you think you shouldn’t, it could indicate an underlying or developing illness, the most common of which being diabetes.

This Youtube video will give an overview of the information found on the article tab. If you want to know more about the topic, or want to see where the information came from, have a read of the article after you watch the video.

When blood is cut off from a part of the body, the nerves will be started of nutrients such as glucose. When blood is restores, all the nerve signals which the nerves wanted to send all of a sudden get sent all at once, which give the sensation of pins and needles.

Why You Twitch Before Falling Asleep

August 27, 2015 / Humans / 0 Comments /
Why Do We Twitch When We Fall Asleep?

If you’ve ever been happily falling asleep only to startle yourself with a jerk/ twitch of the leg, then you have experience what is known as a hypnic jerk, or a hypnagogic jerkDon’t worry, these are common, don’t indicate any illness, and are experienced by about 70% of the population. It is completely involuntary, and in this article, I’ll explain why it happens.


Falling asleep

Before we look into the causes of these hypic jerks, its best to understand some of what happens when you fall asleep. You see, throughout your sleep your brain is very active and plays out dreams you won’t remember. To your mind, these dreams are quite real, so to avoid you acting them out and hurting yourself and anyone you share a bed with, you produce 2 chemicals which inhibit motor neurons, which stop your muscles moving, and effectively make you paralysed, and this is called sleep paralysis. This paralysis doesn’t come into full effect for about an hour, and so this is why you experience these twitches as you fall asleep, but less so during your sleep. That being said, some people can still experience them during their sleep, but it is much less common.


Why You Twitch Before Falling Asleep

There are two main theories for the hypnic jerk:

InstinctHypnic jerks are thought to be an evolutionary kickback from when we slept in trees like monkeys do.

It’s thought that the hypnic jerk is an evolutionary kickback from when we slept up trees. As we fall asleep our muscles relax, and our brain might interpret this as falling, which if you sleep in a tree, is very bad, so instinctively our muscles contract in an attempt to grab onto something and stop us falling. This theory is supported by the fact that many hypnic jerks are accompanied by a feeling of falling, and I know from personal experience that when I have a hypnic jerk, it is just as I feel like I’ve started falling down (which just adds to the disruption of my sleep).

Nerve confusion

Another theory, which is also very likely to be the cause of some hypnic jerks, is that the nerves ‘misfire’, which cause a sharp muscle contraction. Throughout your day, you nerves are constantly ‘firing’, and causing muscle contractions, particularly in muscles in the legs. The firing of these nerves is something the body is equipped to do very regularly, but is controlled by your focused and conscious mind (thankfully). However, as you drift off to sleep your muscles and mind relax, you might even start drifting off into a dream, and your mind becomes less pre-occupied with muscle movement. Nerves which have been firing all day may then ‘misfire’, almost out of habit, which causes your muscles to twitch.

This is kind of similar to boiling water on a stove. Continuous energy from the stove caused the water to boil continuously in the same way continuous signals from our brain cause nerves to move muscles continuously. When you remove the water from the heat, most of the water will quickly cool and stop boiling, but some of the water will still be hot enough to boil, and will still form bubbles for a short period of time. These parts of the water which continue to boil after the heat is removed is is similar to our nerves continuing to fire even though our brain isn’t signalling them to.

This would explain why hypnic jerks can be experienced without the feeling of falling.


Are hypnic jerks bad?

These nighttime twitches are not bad for you, and don’t mean you are ill, but they are associated with stress or sleep deprivation, which obviously isn’t good for your health for a number of reasons. They are also associated with alcohol consumption and caffeine, which ideally should be avoided around bed time because they can disrupt your sleep in more ways that just causing hypnic jerks.

It’s worth noting that just because you experience hypnic jerks doesn’t mean you are stressed, but being stressed can increase the chances of experiencing hypnic jerks. Probably because it will interfere with your natural sleep process (possibly in a similar way to caffeine/ alcohol).



A twitch or jolt as you fall asleep is called a hypnic jerk. It is quite common and doesn’t cause you any harm (unless you hit something/ someone). The actual cause isn’t known for sure, but there are 2 accepted theories, both of which can cause the twitches. The first is that the muscle contraction is an evolutionary kickback from sleeping in trees, where we needed to grab branches to stop ourselves falling out of trees. The second is simply that our nerves misfire as our body relaxes, which causes a muscle contraction.

images courtesy of Theophilos Papadopoulos and Jonathan Leung

This Youtube video will give an overview of the information found on the article tab. If you want to know more about the topic, or want to see where the information came from, have a read of the article after you watch the video.

As your muscles and mind relax, muscles which have been regularly ‘firing’ may ‘misfire’, and cause a twitch. It is also possible that as we relax our mind feels like we are falling, and so twitches to grab onto something.

What Causes Brain Freeze?

August 23, 2015 / Food, Humans / 0 Comments /

Brain freeze is that terrible pain you get in your forehead or the front of your face when you eat something cold, usually an ice cream. You know that the chilled treat caused the brain freeze, but not why or how. Fortunately the pain goes away just as fast as it came, which you are often thankful for – you can now get on with your ice cream. It’s odd that pain can comes and go so quickly though, especially just from eating food, and its not even like the ice cream even touches the part of the brain that hurts! So whats going on? In this article I’ll explain what causes brain freeze, see if brain freeze causes any actual harm to you, and look at ways to reduce its effects.


What Causes Brain Freeze?

The cause of brain freeze is the sudden constriction of blood vessels to the brain, and the consequential increased blood flow to the brain, specifically through the anterior cerebral artery. If you look at the image on the right provided by the University of Rochester, you can see the main blood vessels around the brain, and the anterior cerebral artery goes right through the middle. Front view outline of man showing major arteries, cerebral arteries, and brain.

There is a lot going on inside the skull, and so things are packed quite closely together. When you eat ice cream or drink something cold, the blood vessels nearest the roof of your mouth will feel the cold, and quickly constrict in reaction to the cold. This constriction reduces blood flow to the brain.

With the brain being such a key organ, the body doesn’t like restricted blood flow to it, and so tries to increase the blood flow. The increased blood flow over compensates, and too much blood is sent to the brain. This causes a large amount of blood to go through the anterior cerebral artery.

It is this increased blood flow through the anterior cerebral artery that causes brain freeze.

This causes pain because the skull is an inflexible closed unit. When the blood flow increases through the anterior cerebral artery, the artery expands, which puts pressure on the brain. The pressure stimulates pain nerves, and you get brain freeze.


Does brain freeze do any damage?

Brain freeze is generally considered to be safe, and has no long lasting effects. Scientists are interested in the exact mechanisms of brain freeze because there is thought to be some connection between the mechanisms of brain freeze and migraines, and sometimes even induce brain freezes in volunteers. This wouldn’t be done if it wasn’t completely safe.


How to stop brain freeze

Brain freeze is over pretty quickly, so you don’t have much time try and cure it before your body sorts itself out, but the best thing to do to cure brain freeze is put your tongue to the roof of your mouth. This helps to warm up the blood vessels and normalise blood flow as quickly as possible. Alternatively, if you have a warm glass of water/ cup of tea nearby, drink some of it (as long as it isn’t too hot). This will again help warm up your blood vessels.



Brain freeze is caused by an increased blood flow through the anterior cerebral artery, which put pressure on your brain, which causes pain. It is a short lasting effect though, and doesn’t cause any permanent damage. The best thing to reduce brain freeze is put your tongue at the top of your mouth, or drink something warm.

Image courtesy of James

This Youtube video will give an overview of the information found on the article tab. If you want to know more about the topic, or want to see where the information came from, have a read of the article after you watch the video.

The cold food constricts blood vessels to the brain. To compensate for this, more blood is pumped through the blood vessels which causes them to expand and put pressure on the brain, which hurts!

Why do Onions Make you Cry?

August 15, 2015 / Food, Humans / 2 Comments /

Onions, particularly white onions, can bring a grown man to tears. They are delicious additions to meals, but such a pain (literally) to prepare. As soon as you start cutting an onion up, your eyes will start to sting, and by the time you have gotten to the end of it, your eyes will be stinging like crazy and you will probably have tears running down your face. So, here I’ll look at why onions make you cry, why red onions don’t seem to have the same effect, and what you can do to avoid onions making you cry.


Why onions make you cry

When you slice an onion you break apart the cell walls which releases all the chemicals in the onion. These chemicals will mix, and the volatile ones, will disperse into the air. Some of the chemicals released are amino acid sulfoxides and they will mix with enzymes which can convert them into a compound called propanethiol S-oxidewhich is a known lachrymatory factor, (means a ‘tear inducing’ factor). This lachrymatory factor is particularly volatile, and quickly disperses into the surroundings, and into your eye. This chemical causes tears be produced, but doesn’t cause the pain.

Propanethiol S-oxide is a particularly unstable molecule, and when it makes contact with the water in your eye it convert into sulfuric acid, which is an irritant, and causes the itching. Being an irritant, the eye will produce more tears to try and dilute it. With your eyes being teary, there will be plenty of water for the propanethiol S-oxide to react with, so the longer you are cutting the onions, the worse it will get.

So the reason that onions make you cry when you cut them, is down to a chemical called propanethiol S-oxide, which is stimulates tear production, and irritates your eyes.


Can anything be done to stop it?

There are a number of solutions for stopping onions from making you cry:

1. Use a sharp knife (not the most effective)

The sharper the knife is, the cleaner the cut, and so the fewer onion cells destroyed. This means less chemicals are released into the air, less propanethiol S-oxide is made, and so your eyes will be less irritated. Obviously, some onion cells will still be broken, and so some chemicals will be released, so this will only reduce the irritation, not stop it.

2. Cut the onion under water (effective, but awkward)

Cutting the onion under water is a bit awkward, but the water does prevent any of the volatile chemicals being released into the air. Instead, when the onion is cut open the chemicals will dissolve in the water, meaning no eye watering chemicals can reach your eyes.

3. Eye protection (effective, but you will look silly)Cutting onions with goggles on stops onions making you cry, but you can look silly!

Wearing sealed eye protection like goggles will prevent the chemicals getting to your eyes. Its not as awkward as cutting under water, and more effective than just using a sharp knife, but you might look a bit silly – so expect to be ridiculed by anyone around.

From personal experience, I’ve found that wearing contact lenses offers quite a lot of protection (and you don’t look so silly). Eventually you do feel a slight stinging, but nothing compared to without contacts in. Obviously, you need contacts to try this though.


Why don’t red onions make you cry?

Red onions don’t make you cry because they don’t contain as much of the tear inducing chemicals. I haven’t been able to find a comparison of the chemical composition of different onions, but it stands to reason that red onions don’t make you cry is because they contain less of the thing that makes you cry. It is plausible (but less likely) that red onions contain additional chemicals which mop up and neutralise the propanethiol S-oxides in the air, but my bet is that they contain less of the chemicals to create propanethiol S-oxide.



Onions make you cry because when you cut them open, you destroy their cell wall, which causes sulfoxides to mix with enzymes, which converts them into a chemical called propanethiol S-oxide. This chemical induces tears in the eye, and also gets converted into sulfuric acid when it comes into contact with the water in your eye. This acid is an irritant, and so causes stinging, and even more tears. You can reduce the by using a very sharp knife, which means less chemicals are released. Alternatively, you can cut the onion under water, which means the chemicals cannot get into the air, or possibly wear some swimming goggles, to stop the chemicals reaching your eye.

Red onions don’t make you cry because they simply contain less of the tear inducing chemicals.

Images courtesy of Susy Morris and Tizah

This Youtube video will give an overview of the information found on the article tab. If you want to know more about the topic, or want to see where the information came from, have a read of the article after you watch the video.

When you slice onions open, you break onion cells, which releases the chemicals it contains. One of these chemicals is called  propanethiol S-oxide, which stimulates tears, and another group are called sulfoxides, which sting the eyes and cause them to water even more.

How Long Can You Live Without Water?

July 30, 2015 / Humans / 1 Comment /
How long can humans survive without water article

A similar question to ‘how long can you live without food‘, but with some key differences. Your body is able to store energy to some extent as fat, meaning some people can survive without food longer than others. The body cannot store water, so the answer to how long you can survive without water will be much more accurate and consistent. So, assuming you, right now, a perfectly well hydrated person with clear urine is no longer allowed water, how long would you survive?


How Long Can You Live Without Water

I’m going to make some reasonable assumptions to make this easier – you are in a moderate climate so won’t be sweating excessively, you are well fed and hydrated for, you won’t be doing any exercise and you are not elderly or an infant. Essentially, if you will be doing nothing which causes you to lose excess water.Humans can survive 3-4 days without water.

Well, unsurprisingly there is no specific research for this, because it would be very cruel (not to mention illegal) to do this kind of research. In fact, most researchers agree that there is too little known about how much water we need and what our requirements look like.

The best answer I can get from a scientific body is the complete absence of water ‘will be lethal in a few days‘, which anyone could have guessed, and is quite vague. Further digging around and I’ve found that the general consensus is that you can only live 3-4 days without water before you die. In hotter climates, or if you are exercising, this could be as low as 1-2 days, but it depends on the climate and the exercise you are doing. In normal conditions which I described above, it is 3-4 days. However, you won’t just feel normal and then drop dead, you will steadily feel worse and worse as you go through the stages of dehydration.


Stage of dehydration

Early stages of dehydration

Most people will be familiar with the symptoms of early dehydration, and they are easily reversible but drinking some water. These usually will kick in a few hours after drinking when your body has lost roughly 2% of its total fluid. These symptoms are:

  • Dry mouth
  • Thirst
  • Dark urine
  • Tiredness


Moderate dehydration

Symptoms of moderate dehydration will kick in when you have lost about 5% of your fluid, and these symptoms will probably develop over day 2-3. These symptoms are:

  • Increased heart rate
  • Muscle cramps
  • Tingling/ numbness in limbs and extremities
  • Extreme tiredness and poor physical performance
  • Fuzzy thinking and dizziness


Late dehydration

The symptoms of late stage dehydration will occur when you have lost about 10% of your fluid, and will start to develop through days 3 and 4 without water. The symptoms are:

  • Painful urination
  • Muscle spasms
  • Loss of ability to think straight
  • Loss of consciousness
  • erratic heart beat
  • ….then death


How do humans die from dehydration?

It would be great if water wasn’t so essential to body functions, maybe then we could survive longer without it. Sadly, water is needed for pretty much every that goes on in the body. One of the first signs of dehydration is dark urine, and this is because water is needed to transport waste chemicals such as urea out of the body. As water gets lost through urination, respiration and perspiration, the amount that the body can afford to lose decreases, meaning more is lost through urination, which is the greatest cause for water loss. This is far from fatal though.

If dehydration continues, less and less water will be filtered out of the blood as urine, which can put a lot of strain on kidneys. Your blood volume will also decrease because water is a major component of blood. This reduced volume puts strain on the circulatory system, particularly the heart, which increases heart rate to try and compensate for the loss of water. The reduced volume also causes the blood to becomes thicker, which leads to difficulty in providing nutrients to parts of the body, which can cause tiredness, tingling in extremities and poor physical performance. Also, as a healthy brain is about 73% water, the brain will start to become dehydrated, which can cause fuzzy thinking. You may recognise all these symptoms are part of moderate dehydration, and although it’s not fatal just yet, you can start to see that functions in the body are struggling.

Breathing also increases to try and compensate for the reduced blood volume,, and usually the body temperature will rise due to reduced sweating.

As dehydration continues even further, important biological systems start to break down completely. The volume of the blood becomes even lower, putting even more strain on the heart, and even the heart is struggling to get enough water for it to function properly. This will become too much for the heart and will lead to nutrients not reaching muscles in limbs, which can cause muscle spasms. More and more water will be lost from the brain, which will further affect thinking, and ultimately cause unconsciousness. Eventually, the heart will no longer be able to function, and is usually the cause of death from dehydration.


Summary – How long can you live without water

Although there is not a great deal of research into this, it is generally accepted that you can’t survive more than 3-4 days without water. During this period, many biological functions will start to fail, but the cause of death from dehydration will be heart failure.


Image courtesy of John ‘K’

Why do Men go Bald?

July 4, 2015 / Humans / 0 Comments /
Image for the article 'why do men go bald'.

This is something you may have wondered about, but equally may not have, because male baldness is something which is so common in society that it often isn’t spared a thought. But really, it is odd. Just like only having thick hair on our heads, male baldness is something which is quite unique to humans, yet rarely thought about (well, until you start to go bald perhaps). So here, I will explain why baldness occurs, and why it only happens in men.


Hair growth cycle

It is first important to understand the growth cycle of hair, which can be split into 3 phases:

  1. Anagen phase (growth) – This is simply where the hair is growing.
  2. Catagen phase – During this phase the hair follicle stops growing (and effectively starts dying).
  3. Telogen phase During this phase a new hair follicle replaces the old one, which is shed, and the cycle begins again.

Studies on human hair has shown that 80-90% of hair is in the anagen phase (i.e is growing), 1-2% is in catagen phase (i.e not growing) and 1-20% in in telogen phase (i.e undergoing replacement with a new follicle)1.


Causes of Hair loss

There is no one cause for hair loss, and even more frustrating, there is still much unknown about this phenomenon. However, there are a number of areas which do play a role in hair loss.


Poor nutrition (and even over nutrition) have been linked to hair loss. One particularly important nutrient is zinc, and it has been noted that when a zinc deficiency is restored, skin and hair growth improve too. Chances are, unless you live quite a healthy diet full of unprocessed plants and animals, you will be deficient in zinc to some extent, although this doesn’t mean it is the cause of baldness.

A deficiency of vitamin D, which again, is commonly lacking in many Western societies, is also associated with hair loss. However, the link between vitamin D and hair loss isn’t very well understood, and more research is certainly needed.

Although there is little doubt in my mind that nutrition does play some role in baldness, it doesn’t explain why women don’t go bald, and hair loss only strikes males in their 50’s (unless they are seriously under nourished, then it can strike at any age). There is clearly more to this than nutrition.


Hormones have strong link with hair loss, and it is a good explanation of why men go bald, and women don’t.

The hair follicles are particularly sensitive to a male hormone called DHT, which shortens anagen phase (growth phase) of the hair, and makes the hair follicle much smaller. Over time, this could damage the follicle and prevent hair production, and this is thought to be the cause for 50% of hair loss amongst men.This is quite a unique feature of male humans, and isn’t even shared amongst other primates.

Other hormones are also linked to hair loss, such as the thyroid hormones, which in dogs has been shown to cause hair loss in 25% of the sufferers, and could have similar effects in humans. Problems with the thyroid gland are not uncommon, and so may be a slight contributor to hair loss.

GeneticsBaldness is inherited from the mother's genes. I

Genetics seem to play the biggest role in the cause of baldness in men, interestingly, it seems to be genes which are inherited on the mother’s side. This means the best way to predict baldness would be to see if/ when your maternal Grandfather went bald, and see if your Mother’s brothers went bald. If they all went bald at a young age, it doesn’t look good for you.

Although there will be a number of genetic factors involved, one of the key genetic factors thought to cause baldness in men is the how the hormones and receptors are distributed in the hair follicles.


Summary – why do men go bald

Although scientists admit that there is still much to learn about the mechanics of baldness, the causes seem to be relatively well understood.

The primary cause for baldness seems to be genetics, which influence hormone production and hormone receptors is the hair follicles. These hormones are thought to cause about 50% of male baldness, and possibly more. As these hormones are exclusive to males, only males will go bald this way.

The cause for the remaining 50% of baldness cases is not so clear, and may be a combination of nutritional, lifestyle, infectious, other genetic factors or other hormones factors such as thyroid hormones.


Wiedemeyeer K, Schill WB, LOser C Skinmed. 2004 Jul-Aug; 3(4):209-14.

Images courtesy of Edson Chilundo and Neil Moralee

Does Reading in Dim Light Damage Eyesight?

July 1, 2015 / Humans / 0 Comments /
Feature images for an article discussing if reading in dim light damages eyesight

I was always told as a child to turn on the light if I was reading or playing games, because doing these things in dim light would damage my eyes. I assumed this to be true, and didn’t question it at the time, but now I’m older, I’ve grown a little sceptical of this theory. So, I trawled through the research journals to see what evidence there is.


Dim light & sight

It is not surprising to find no specific research into this because it would be unethical to test the theory and risk permanently damaging test subjects eyesight just to prove/ disprove the theory. However, in ophthalmology (eye doctor) circles, it is widely accepted that reading in dim light doesn’t damage eyesight, and this is outlined in educational material published for patients1.

This is supported by the fact that reading conditions have gotten much better with the invention and development of lighting, yet cases of myopia (short sight) are increasing. Historically, all reading would have been done by candle in very poor lighting, which, if the theory is true, would have caused far more cases of myopia than there were, and the cases of myopia should be decreasing, not increasing.

Finally, there is no identified biological mechanism by which dim light can cause myopia, so there is no real scientific substance to the theory.


So where did the myth come from?

Dim light can cause difficulty in focusing, which can make reading text particularly difficult. This happens because the rods in the eye do most of the ‘seeing’ at low light, and the resolution of rods is quite low compared to the cones ( the colour ‘seeing’ parts of the eye). Having difficulty in focusing can give the impression that your eyes are being damaged.

In addition to this, in dim light most people will squint to try and focus better, and in doing so, reduce the rate at which they blink by as much as 50%. One of the purposes of blinking is to lubricate the eye, and by reducing the rate at which you blink, your eyes can feel dry and sore – which can again be interpreted as them getting damaged.

Finally, although dim light doesn’t damage your eyesight, reading, and other prolonged close work can damage your eyesight, particularly at a young age when the eyes are still developing, and the association between people who do a lot of reading and myopia is well documented. In fact, it has been hypothesised that intelligence was a cause of myopia, because people in professions which required a high level of intellect (such as medicine or law) often needed glasses. In reality, the cause is probably the excessive reading they have had to do to achieve their career goals.



Despite no actual clinical trials testing the effects of dim light on eyesight, it is generally accepted that dim light has no effect on eye sight. The myth seems to have come about from a combination of a difficulty to focus on text in light, dry and sore eyes as a result of squinting in an attempt to focus, and the association of reading and other close work with damaged eyes and short sight.



1. Rubin ML, Winograd LA. Taking care of your eyes: a collection of patient education handouts used by America’s leading eye doctors. Gainesville, FL: Triad Publishing, 2003

Image courtesy of Sarah C

This Youtube video will give an overview of the information found on the article tab. If you want to know more about the topic, or want to see where the information came from, have a read of the article after you watch the video.

No, but it can make your eyes strain, and feel dry and sore, which gives the impression of damage.

Why Do Humans Have Nails?

June 22, 2015 / Humans / 0 Comments /
Picture of nails for an article explaining the reason for why we have nails

Nothing in our body grows as fast as our nails do, aside perhaps, for our hair. They are strange little additions to our toes and fingers really. Perhaps once something like a claw, they don’t seem to have much purpose in modern life, so why do we have nails, and why do they grow so fast?

Here I’ll discuss the purpose of the finger/ toe nails, and explain why they grow.


What is the purpose of nails?

Protection – This is obvious to anyone who have dropped something heavy on their toes or fingers. The nail is a hard surface which offers some (but arguably not enough) protection to the delicate bone underneath. The tip of the finger bones (called phalanges) is actually extremely fragile, and you do not want to get it damaged or chipped, so the nails purpose is to spread the pressure of heavy objects to reduce the damage to the bone. Sadly, this doesn’t make hammering your thumb any less painful, but does protect the bone.

You can see how effectively this is actually. If you just press your finger nail on the top, the pressure quite effectively dispersed to the sides. This is thanks to the curving shape of the nail.

Accuracy – Yes, nails have another purpose other than protecting the fragile bone underneath, and that is to help us grasp minute objects. We are talking things like splinters, which our chubby fingers just cannot grasp, but can cause pain and even infection if not removed. In the days before tweezers, fingernails (and teeth I guess) would have been our only way to grasp very small objects.

Just try and pick up a needle without grasping it with your nails – it is very difficult!

Why do nails grow?

Knowing the purposes of finger and toe nails makes understanding why they grow quite simple. They are (or would have been historically) subject to damage from things hitting them, dropping on them and scraping against them. As nails are not living tissue in the same sense as our skin is, they cannot repair in the same manner as the rest of our body. Once a nail is damaged, it is damaged for good.

So instead of repairing the nails, our body just keeps producing them, which replaces old, damaged nails with new strong nails.

Perhaps with modern lives, our nails grow so much because they do not get damage like they used to. We don’t hunt, climb, build or fight like we would have done 10,000 years ago, and so our nails don’t get damaged. However, we are still genetically programmed for our nails to grow, even though they don’t usually need to.



The purpose of our nails to to offer protection to the delicate bones beneath them, and to help pick up minute objects. Without nails on our fingers and toes, we would be at risk of damaging to delicate phalanges, which can be extremely

Due to their importance in protecting phalanges, and their importance in picking up small objects, they must be kept in good condition. As they cannot repair themselves, the only way we can maintain healthy nails, is to keep growing new ones.

Image courtesy of Shannon Kringen.

How Long Can You Live Without Food?

June 17, 2015 / Humans / 0 Comments /
how long can you survive without food

There is actually no fixed period of time for how long you can live without food. Unlike water, which you can’t survive without for no more than a couple of days, you can survive without food for weeks, months, and in some circumstances over a year. These are extreme examples though, and so in this post I’ll go over how long the average person can go without food, and show you the longest someone has gone without food before.


Definie ‘without food’

‘Without food’ generally means that you can have supplements and water – just nothing to eat. To some, having supplements might seem like cheating, but you will see below examples of people not taking any supplements too.


Average time for survival

With the use of supplements and water, the cause of death will be from a lack of energy to perform essential biological functions, not from nutritional deficiencies. The amount of energy in the body can be estimated by calculated from the energy stores that are in the body. First, we can look at glycogen, which is a short/ medium term energy supply.

The average healthy well fed adult can store approximately 2000kcals of glycogen in their body, which equates to just over 1 days worth of energy for most people (assuming that very little exercise is being done).

You can then look at the amount of fat stores in the body. This will vary from person to person, however, a healthy male will have around 15% of their body mass as fat. Going with the average weight of a male being 70kg, this would give them about 11.25kg of total fat on their body.

However, not all this body fat can be used as energy – the body actually needs some a fat for insulation/ protection of organs etc. There is some discrepancy as to how much body fat the body will retain at all costs, but for the purposes of this calculation, we can say 2% of their body mass. This would give 9.1kg of fat which can be used for energy.

9.1kg of fat equates to 81900kcals (1g of fat being 9kcals). This would give someone an extra 43 days worth of sedentary living. So, by these rough calculations of the amount of energy the body can store, a healthy average person could live for about 40- 45 days.


Does the practice match the theory

Obviously due to the nature of the question, experiments cannot be conducted to find the answer – that would be very cruel and illegal. However, there have been some well documented incidences where people on hunger strikes have survived up to 40 days, which offers support to the 40-45 day estimate and suggests it is quite accurate. These people on hunger strikes would probably not have been taking nutritional supplements, which suggests this limit is both an energy and a nutritional limit for the body.


Record for not eating food

A 27-year old man has gone for a massive 382 days without eating food. He was obese, taking a multivitamin, and had close medical supervision, but it is still an impressive feat. This goes to show how much of a limiting factor energy is when it comes to survival.



The body needs energy and micro-nutrients from to survive – take food away, and the body will slowly start to ‘fall apart’. Biological functions will become less efficient until they can no longer go on due to lack of energy/ essential micro-nutrients. Assuming you can source energy from your own large fat stores, and micro-nutrients from a pill, you can go on for a long period of time (until your energy stores run out in fact). The record for this has been 382 days, but for most people, this is not achievable.

For the average person, it would appear from the limited data that you can survive approximately 40 days without food (as a result of energy and nutritional deficiencies), but signs of malnutrition will manifest much earlier than that.

Image courtesy of Christina Hendricks


This Youtube video will give an overview of the information found on the article tab. If you want to know more about the topic, or want to see where the information came from, have a read of the article after you watch the video.

The average person can survive for up to a maximin of 45 days, but many won’t live this long. The longest someone has gone without food is 382 days.