Dr. How's Science Wows

Thought for the day – imagination!

April 6, 2013July 5, 2014nao

This is one of my favourite quotes …

“I am enough of an artist to draw freely upon my imagination. Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world.”

― Albert Einstein

….it always makes me think of my daughter, she has the most amazing imagination I have ever come across; when she was very young she told me I was not her real mum and one day she would have to leave me and go back to her real family! Apparently she is a fairy princess and when the wicked witch attacked their kingdom her parents changed her into a baby in my tummy to keep her safe!

I see her imagination as a wonderful gift and feel humbled and nervous about the responsibility of keeping it nurtured and alive while she grows!

…just a thought!

"Thought of the day"….Why do hens lay unfertilized eggs?

April 5, 2013August 28, 2016nao

Following on from this weeks blog about all things eggy – today’s thought is …”Why DO hens lay unfertilized eggs?”

It seems like quite a wasteful process, don’t you think? All that protein, fat, nutrients, calcium that go into the making of one hen’s egg – what is the point in going to all that trouble if there will be no offspring at the end of it?

Here are a few of my thoughts on the matter…

Firstly, we are looking at the fairly recent domestication of the species; in the wild it is likely that roosters would be naturally part of the flock and all eggs produced would be fertilized. In the domestic situation roosters are often not present but the evolution of the hen has not (as yet anyway) been modified!

If we look at egg production in any species we will notice that eggs are usually released and developed in a cyclic manner (we humans are no different). If you see this cyclic process as being wasteful at times then the label will fit for most animals, not just the humble hen!

photo credit: martinteschner via photopin cc

Finally, you could suggest that it is a downside to the evolution of the egg shell! Animals that produce soft shelled eggs usually have a requirement for water in the reproductive process. In fact, for many of these species the eggs are fertilized outside the female body. Although the addition of an egg shell removed the dependence on water for reproduction, it also removed the possibility of fertilisation once the egg is laid!

So there you have it, these are some of my thoughts on the subject. I am not suggesting that any of these points are backed up with scientific findings…. the are just the random thoughts of this simple scientist! Maybe you have your own theories to add?

…just a thought!

"Mammy I hatched an egg!"

April 3, 2013July 5, 2014nao

As a mother of three young children I have had many charming moments that I feel I will remember forever…. first steps, first words, how they pronounced a certain word, the list is endless. Memories to cherish for a lifetime…. and then I forget!! Startling but true! More moments forgotten than remembered. However, certain things will stay with me forever…. like when my daughter was five and we got chickens for the first time; she was beginning to learn the joy of finding and collecting the eggs each day. One day she came to the back door with her bounty only to trip at the step and drop an egg. The poor thing burst into tears with the dramatic exclamation…

……………………………….”MAMMY, I HATCHED AN EGG!

Image credit: Graham Ettridge

I will never forget that one! It was hard to keep a straight face as I tried to console my sobbing child. With all the egg activities and treats of the Easter it has certainly got us talking and thinking about eggs in this house, have you ever wondered about these marvels of nature?

WHAT IS AN EGG MADE OF?

Firstly, what exactly is an egg made of and what purpose does each component have?

Image source: http://www.exploratorium.edu

The shell: the egg shell is made of calcium carbonate (95%), just like the enamel of our teeth (see previous post). The other 5% of the egg shell is made up of calcium phosphate, magnesium carbonate and proteins. Although the shell gives the egg it’s strength you might be surprised to learn that it actually contains up to 7,000 tiny holes (pores); these pores allow air and moisture pass through the shell.

The bloom/cuticle: this is a protein coating outside the egg shell that acts as a natural barrier to bacteria and dust while reducing moisture loss.

The membrane: there are two layers of membrane just inside the shell called the outer and inner membrane. These membranes are like layers of skin and contain a protein called keratin, which is found in our own nails and hair!

The yoke: the yellow of the egg contained within a membrane called the vitelline membrane. The yolk is the part of the egg that feeds the developing embryo – it has a very high protein content and is also rich in vitamins and minerals. The yolk contains all of the egg’s fat and cholesterol. The yolk is the primary food store for the developing chick.

The Albumen: this is the white of the egg; it has a high protein and water content. The albumen cushions the developing chick and keeps it moist while still in the egg.

The air cell: this is a pocket of air at the wide end of the egg, created between the outer and inner membrane. The air cell gets bigger as the egg ages.

The chalazea: these are spiral ropes of egg white that keep the yolk in place.

WHAT ANIMALS LAY EGGS?

Animals that lay eggs are called oviparous and they include birds, fish, amphibians, many reptiles, many arachnids and insects, some molluscs and two mammals – the echidna and the platypus. Mammals that lay eggs are referred to as momtremes.

A BIT OF EGG EVOLUTION

The reptile is credited as inventing the egg shell, allowing their young to develop outside the mother’s body. All true dinosaurs are reptiles and they all laid eggs. The development of the egg shell has been a fundamental step in evolution as it allowed the embryo develop in self contained egg, without the requirement for water. This removed animals’ dependence on water for breeding.

HOW IS AN EGG MADE?

In the hen it takes about 24 to 26 hours to produce an egg. An egg is made from the inside out, starting with the yolk which is released from the hens ovary and moves through various parts of the body where another element of the egg is added until finally the finished egg reaches the vent and the egg is laid. Within 30 minutes of laying an egg, the process will start for the hen all over again.

SO WHAT GOES ON INSIDE THE EGG?

The embryo has started to develop in the egg while it is still being made within the body of the hen. Once the egg is laid the development of the embryo will only continue if conditions are correct. If the temperature and humidity levels are right (temp approx 22oC, relative humidity 50% ) the development of the embryo will continue after the egg is laid. This process continues for approximately 21 days. If the egg is being hatched under a broody hen then the hen must turn the eggs regularly.

THE HATCHING PROCESS

Image credit: http://www.waldeneffect.org

Finally, when the time is right, its time to crack out and see the world. The young of many egg-laying species are equipped with an egg tooth – a tooth like projection on the end of a beak (birds) or protruding from a jaw (reptiles) that helps the young animal tear through the membrane and break through the hard shell. The egg tooth will eventually be reabsorbed or fall off.

Chicks and many other animals will hatch from the larger, rounded side of the egg. That is because this is the end where the air cell is usually located. Once the chick becomes too larger to receive enough oxygen from inside the egg it will use it’s egg tooth to pierce through the inner membrane into the air cell space. This provides them with an extra supply of oxygen, just enough to sustain them as they continue the hatching process and crack and break though the egg shell.

We have been lucky enough to hatch a few broods of chicks over the years and it is always so exciting to meet the little ones for the first time.

This is chips – one of our brood!

So the only other question to be addressed is “which came first – the chicken or the egg?” but I think that’s a blog in itself, perhaps for another day!

AN EXPERIMENT TO TRY – HOW STRONG IS AN EGGSHELL?

You would be amazed how strong an egg shell is, although you might want to try this one over a sink!
Hold a raw egg between your thumb and first finger, holding at the two ends and then apply pressure – as hard as you can! You might be surprised to notice that the egg doesn’t break!

If you repeat this but apply the pressure to the sides of the egg, things might not go so well and you might find yourself covered in egg!

So why is this? Although an egg shell can be very fragile, it’s shape can provide it with great strength. This is because the egg is dome shaped at the top and the bottom, just like a bridge structure; this structure means that when you apply pressure the force is distributed evenly over the shell, not just on one point, hence the egg does not crack!

Further reading:
Anatomy of an egg
Eggshell
Poultry reproduction and incubation

The Thorn bug

April 2, 2013July 5, 2014nao

Week 1st – 7th April 2013

Did you guess this weeks CAN YOU NAME THIS CREATURE?

I got some correct responses…. it was a thorn bug ( a treehopper). These bugs can be found on all continents except Antartica. As you can see from the photo, they are excellent mimics of thorns on the plants and trees on which they feed.

These thorn-like protrusions on their backs act as a wonderful camouflage to prevent detection by predators. They also act as protective armour if attacked. These insects cut into the stem of the plant and feed on its sap. The females of most species cut into the bark to lay their eggs and often sit on their eggs to protect them. In some species there is even collaborative egg minding between females!

Another of nature’s wonderful creations!

Lacewing Larva

April 2, 2013July 4, 2014nao

Week 25th – 31st March

Last weeks “can you name this creature?” image was supplied by Molly, who is ten years old. Molly spotted this in her garden and, with the help of her Dad, Michael at Nature Learn, has shared it with me for this slot. A big thanks to Molly!!

Lacewing larva – photo credit Michael and Molly Bell

So did anyone guess what creature this is?

It is a LACEWING LARVA! A hard one this week I know, but we did give you some good clues!
I thought Molly did particularly well to spot this little guy as they only grow to between four to seven mm in length!

So now you know what it is do you want to learn some more?

These lacewing larva are a welcome addition to any garden as they like to dine on soft bodied insects, particularly aphids! They like to hang out in humid environments and can be a great gardening aid to any greenhouse or poly tunnel! They also feast on the eggs of certain other insects and spiders, as well as mites and mealy bugs. All in all a real asset to the garden!

Although the larva stage does not last more than two to three weeks these little guys certainly have a big appetite …. consuming up to 600 aphids during this period. The larva must make direct contact with it’s prey… injecting digestive enzymes into it and sucking back up the digested body parts once the enzymes have done their work!

Lacewing larvae are also experts in the art of camouflage, they often cover their bodies in debris to hide them from predators. This debris often includes bits of body parts from their own prey!

Science through the eyes of a child!

April 1, 2013July 4, 2014nao

As a mother I have watched with fascination at how my children grow and learn, constantly testing, evaluating and questioning life around them. For Newton (at the age of 23) it was apparently an apple from a tree that led to his evaluation of gravity but have you ever observed a toddler in a high chair dropping their spoon? Every parent I know has gone through this phase with eventual exasperation, but look at it through the child’s eyes…. why does it always fall down? Why does it not fall upwards and stick to the ceiling? Over and over again they test their results, natural scientists!

It has become an interest of mine to observe how our environment, lifestyles and educational facilities feed this wealth of natural scientific curiosity. As my children passed through playschool and Montessori I observed the wonderful manner of learning and development through play and interaction that is encouraged through the guidelines of Aistear (the Early Childhood Curriculum Framework).

“Tell me and I forget; show me and I may remember; involve me and I learn.” Benjamin Franklin

Now that my older children have moved into primary school I notice things are very different from my day. Technology has made it to the classroom! Chalk and blackboard have largely been replaced with interactive white boards and computers.

The internet has opened up a wealth of learning for our children where they can link to others on an international level to promote their learning in STEM (Science, Technology, Engineering and Maths) subjects. Our local school uses Manga High for interactive maths games, quizzes and learning. Children are being educated in computers and programming technology through the global collaboration that is CoderDojo!

What about how science is taught in our primary schools? The curriculum encourages children to learn through investigation and exploration of their physical and natural surroundings. Teachers are encouraged to promote hands-on learning and it is certainly a requirement in the training of new teaching staff. Online resources are available to encourage and assist in the teaching of science in the classroom. The reality depends on how comfortable the teacher feels with the subject, the class sizes and time! In my experience of bringing interactive science to the classroom, I have found the two types of teachers that show the most enthusiasm for what I do are those that are madly into science themselves and those that are totally intimidated by it!

Outside of the school environment there is more to stimulate the young scientist than ever before. The Aquarium is a favourite in our family, as is the Zoology department at our local University. We took in an interactive display on oscillation at the Science Gallery, on our last trip to Dublin. The National History Museum is next on our list along with a science walking tour. School holidays can now be filled with science camps, construction camps and outdoor nature workshops, to name but a few.

My observations have shown me how much has changed since my school days. I learnt science from a book with little emphasis on questioning. I am pleased to see that my children learn in an environment that encourages questioning and active exploration. Just as they began their scientific enquiry with the early dropping of the spoon, they are moving through a life that is rich in scientific options, wonder and promotion. It is even written into their school curriculum! I have also learnt through my children, I am learning now more than ever, by simply….. looking at life through the eyes of a child!

This article originally appeared as a “guest post” on sciencecalling.com

"What’s for dinner?"

March 21, 2013July 4, 2014nao

I had planned a different blog for today but something funny happened yesterday evening and it has lead me down a different path! My children commented on the nice smells from the kitchen and asked me what was for dinner…. “Carbonara” I replied. The two oldest started to chat and whisper to themselves and I was bracing myself for some kind of “I don’t eat that” protest, but instead they just asked the question again…..”What did you say we are having Mum?”. This time they heard my answer more clearly and the two of them cracked up laughing. I couldn’t understand what was so funny until the laughter subsided and they told me…..

……………………………”WE THOUGHT YOU SAID CARBON DIOXIDE!”

This lead to a super nerdy science discussion over dinner about all things carbon dioxide like. The little three year old was very proud of himself telling the others how he made carbon dioxide is his science video with mammy. I have posted this one before but here is a link if you want to see the little Einstein in action!

I was surprised at how much the children knew and how interested they were about carbon dioxide. It is a simple but essential molecule that is an integral part of life on earth.

WHAT IS CARBON DIOXIDE?

Carbon Dioxide is a colourless gas. It is made up of one carbon molecule bound to two oxygen atoms and is written as CO2.

Image source: explainscience.tumblr.com

WHERE DO WE FIND IT?

Although CO2 makes up less than .04 % of the gases in air it is crucial for the existance of life on earth as we know it. Most of us know that we need oxygen to breath but plants need CO2 for their survival. Green plants take CO2 in from the air and, using energy from the sun, break the molecule down into carbon (C) and two oxygen molecules (O2). The carbon is kept by the plant and converted into starch and sugar. This process is called Photosynthesis. The O2 is then released into the air by the plant.

Image source: nskamericas.com

So how does CO2 get replenished back into the air again? This happens through a process called respiration! Animals (including us humans) breath in O2 into our lungs and pass it to every cell in our bodies, through our bloodstream. Our cells need this O2 to grow and to make the energy that powers the body. During the body’s energy making process some of the carbon (from our food) is combined with the O2 forming CO2. This is a waste product in our bodies so it is carried back to the lungs to be released into the air in our breath.

THE CARBON CYCLE

You can start to see a cycle emerging in all this; plants take in CO2 and convert it to food (sugar and starch) and O2. The O2 gets released into the atmosphere. Animals eat the plants and break down the sugar and starch, combining the C part released with O2 forming CO2 again! This is called the carbon cycle.

Other things contribute to the carbon cycle: Carbon is present in our bodies, in fact it is present in all animals, and plants, even rocks and dirt. When bodies and plants die and rot this carbon ends up in the earth. Over time some of this carbon get converted into fossil fuel such as coal, peat or oil.

When we burn these fossil fuels the carbon gets combines with oxygen releasing CO2 back into the atmosphere.

Image source: eschooltoday.com

Another step in this cycle is what the plants do at night! In the absence of sunlight plants switch to respiration, which means that, just like us, plants take in O2 and release CO2.

SUBLIMATION

CO2 exists as a gas at standard atmospheric temperature and pressure. It will freeze into a solid state at temperatures below -78oC. Solid CO2 is often called “dry ice”. Dry ice can be used to create a fog or smoke effect and is a great ingredient in many fun science experiments. One of my favourites is making a big bubble using dry ice – I found this demo showing how (click the image below to link to the experiment). If you ever do get some dry ice make sure you work with an adult supervising as it is VERY COLD!

An interesting fact about CO2 is that it does not exist in a liquid state at standard atmospheric pressure. This means that under normal conditions dry ice will turn straight into a gas as it thaws (i.e. it does not go from solid to liquid to gas as most substances do). This process (solid straight to gas) is called sublimation.

GLOBAL WARMING

Some of the gases within our atmosphere are known as greenhouse gases as they absorb some of the sun’s heat that is reflected off the earth and stop it escaping into space. CO2 is one of the greenhouse gases naturally present in our atmosphere.

These greenhouse gases maintain the earth’s temperature and this process is called the greenhouse effect. If the level of a greenhouse gas changes significantly then we experience global climate change. Global warming is the term used to describe an overall increase in global temperature due to an increase in greenhouse gases in our atmosphere. Increased levels of CO2 are thought to be the main contribution to current global warming; These increases are primarily due to the large number of fossil fuels burned by humans and a vast and steady decline of trees globally. Recent reports show a 30 percent increase in atmospheric CO2 levels since the dawn of the industrial revolution. While there is still much debate about the extend of global warming it would appear that consequences such as melting ice caps, rising water levels, global temperature increases, droughts and floods must, at least in part, be attributed to human actions!

Science has turned it’s attention to natural and renewable energies that provide some solutions to preventing and potentially reversing many of the current issues observed with global warming.

“We need to support the companies that support the earth.“

Woody Harrelson

AN EXPERIMENT TO TRY

Did you know that some types of fire extinguishers contain CO2? You can make a “mini” fire extinguisher using just vinegar and breadsoda….. but I thought I would let the experts show you!

Further reference:

The carbon cycle
Living in the greenhouse

What’s your favourite colour?

March 5, 2013July 4, 2014nao

With three children in my house I get asked a lot of questions. “Whys?” “What ifs?” “How comes?” are all part of the household daily dialogue. Apparently, the average three year old asks at least 50 questions a day, although I reckon our resident three year old easily doubles this number! I have noticed, of all the many questions my youngest asks, the most frequent one is….

……………………”MAMMY, WHAT’S YOUR FAVOURITE COLOUR?”

Your favourite colour seems to be one of the most defining aspect of your character when you are three years old! Apart from your food preferences, I think it is the first main expression of personal preference. The answer to this question can change at any given moment, but my three year old has been consistent with his favourite colour of yellow and I have to admit it really fits with his personality – but why do different things appear different colours? I thought this week I could share a bit about the science of colour!

To understand the science behind colour we need to consider a bit about the science of light. Light, either from the sun or a light bulb, may appear white to us, but it is actually made up of seven different coloursmixed together; these colours are red, orange, yellow, green, blue, indigo and violet.

Light is a type of energy called electromagnetic (EM) energy. EM energy actually travels in waves, even though we see light as straight lines. Light is the only type of EM energy that humans can see. The wavelength of light determines it’s colour. Light with the longest wavelength is red. Light with the shortest wavelength is violet.

SO HOW DOES LIGHT RELATE TO COLOUR?

When we look at a red flower, what are we really seeing? When light shines on an object, some of that light gets bounced back (reflected) off the object. The rest of the light gets absorbed by the object. We see the object as the colour that it reflects. So, when we are looking at a red flower we are looking at a flower that has absorbed all the light that is shining on it EXCEPT red light. It is reflecting red light so that is the colour it appears to the human eye. When an object appears white it is reflecting all the light shining on it and when an object appears black it is absorbing all the light and not reflecting any of it.

Scientist and artists sometimes look at colour in two very different ways; a scientist, observing light, will say that when you combine all the colours you end up with white (as discussed above). An artist may see it all very differently, when we mix paints, for example, if we mix all the colours together we will end up with black!MIXING COLOURS

Image credit: www.gelighting.com

AN EXPERIMENT TO TRY:

You can try this yourself at home: use torches to create the coloured light…fix two different coloured pieces of cellophane (say red and green) over the end of two torches (one colour on each torch). Shine the torches on a white wall or piece of paper. When you overlap the red and green colours you should get yellow! Now repeat with paint – mix red and green paint and what do you get? Not yellow this time but brown!

HOW ARE RAINBOWS MADE?

When light travels through water it slows down and the light bends. Different wavelengths of light bend to different degrees so the light gets split up into its component colours. This is how rainbows are made…
when sunlight travels through drops of rain each colour of light bends to a different angle and the white light is separated out into it’s seven colours.

Photo credit: Eric Rolph

Did you ever notice that usually when you see a rainbow there is a second, more faint rainbow around the first one? This second rainbow forms because some of the light is reflected off the back of the raindrop and bent a second time! These secondary rainbows appear more dark as the light has been bent twice and the colours appear in reverse. Check it out next time you see a rainbow!

HOW DO ANIMALS SEE COLOUR?

Some animals, such as cats and dogs, rely more on what they can hear or smell, than on the colours they see. Their colour vision would not be as good as humans. Like Humans, many primates and marsupials have good colour vision that they may use to allow them to recognise prey or food. Good colour vision is common among fruit eating animals as it allows them determine ripe from un-ripe fruit.

Many species of birds and fish have better colour vision than humans. If you consider how elaborately colourful these animals often are then it is not too surprising to accept that they must be able to see these lovely displays of colour among their own species. Pigeons, for example are thought to be among the best animals at detecting colour and can see millions of different hues.

Reptiles and amphibians are thought to have colour vision equal to, or better than, that of humans.

Many insects can see light (colour) that is not visible to humans. Bees, for example, can see Ultra Violet (UV) light. This allows them to see UV patterns on flowers, leading them to the source of nectar.

Finally, a myth buster…do bulls really “seeing red”? Infact, no they don’t – they are colour blind. The only reason that they charge the red cape is because it is fluttering in front of them!

Image credit www.valencia-property.com

A good night’s sleep!

February 26, 2013July 11, 2014nao

I awoke this morning to find NO CHILDREN at all in my bed. A very rare event indeed. I can’t remember the last time that happened but I am certainly not complaining. It was lovely to have a full night’s sleep with no interruptions for a change. I was perfectly happy to have little Rohan crawl into bed beside me at the reasonable hour of 7 am for a cuddle. Turns out it wasn’t Rohan but a “baby Dolphin” and I was the “Mammy Dolphin” and the bed was actually the sea. It did not take long for Rohan’s clever little mind to start to wonder….

……………………. “HOW DO DOLPHINS SLEEP IN THE SEA, MAMMY?”

SO, HOW DO DOLPHINS SLEEP?

Dolphins (and whales) are mammals just like us, they need to breathe in air. Unlike us, dolphins have adapted their bodies breathing system (respiratory system) to be able to go long periods between breaths. This allows them to stay under water for up to 30 minutes at a time before they need to surface and take the next breath. The other difference between dolphins and other land mammals is that we breathe involuntarily (without thinking about it) while they make a conscious decision to take a breath.

HOW CAN DOLPHINS SLEEP IF THEY NEED TO STAY CONSCIOUS TO BREATHE?

Dolphins have overcome the problem of having to stay conscious to breath by only shutting down one half of their brains at a time while sleeping. This process is called unihemispheric sleep and basically means that one half of the brain sleeps while the other half stays awake and alert. Interestingly, one eye stays open while the dolphin sleeps, it is the eye on the opposite side to the sleeping brain. This allows the dolphin to stay alert to its environment at all times, a requirement necessary for its survival.

Scientist determined unihemispheric sleep in dolphins by monitoring brain activity in captive dolphins using a process called electroencephalography. This process involves attaching electrodes to the dolphins head and tracking brain wave activity as electrical pulses. Such research suggests that dolphins are in this sleep state for approximately eight hours a day.

Studies into the unihemispheric sleep patterns of some mammals suggest hopeful correlations and potential solutions to human sleep disorders such as narcolepsy.

WHERE DO DOLPHINS SLEEP?

There is no real reason why dolphins can’t sleep anywhere within the ocean, but, given that they need to surface fairly frequently to breathe, it is most likely that they sleep just below the surface.

DO ANY OTHER ANIMALS SLEEP LIKE THIS?

Mammals, other than dolphins, that use unihemispheric sleep include whales, porpoises, manatees, sea lions and seals.

This types of sleeping has been observed in some birds and is suggested as a probable form of “sleeping on the wing” for migrating birds.

"Tooth & Nail"

February 19, 2013July 22, 2014nao

We waited a long time for my sons front tooth to finally come out – it spent the last week sticking horizontally out of his mouth – in a “Nanny Mc Phee” kind of fashion! Finally, last week, it did come out and there was great salutation and rejoicing – from me anyway. With suitable formality and ceremony the said tooth was placed in the very special “tooth bag” that we have for such occasions and carefully placed under his pillow. As I lay with him that night we chatted about all things “toothy” and just before I kissed him goodnight he threw me one of his wonderful questions…..

“MAMMY, HOW COME THE TOOTH FAIRY COMES WHEN WE LOOSE A TOOTH BUT IF WE LOOSE A NAIL THERE IS NO NAIL FAIRY?”……

Look at that for a smile!

Well, where do you start with that one? I hummed and hawed and spluttered and muttered some kind of an answer (which of course was countered and refuted) and beat a hasty retreat. The next day we went to visit family only to be met by another toothless smile from my lovely nephew. So naturally teeth were a hot topic of conversation for the weekend, so much so that my brother suggested they become the topic of my next blog. Not terribly enamoured with the idea (or should I say “enameled”) I changed the subject. However, the seed had been sown and the idea rattled around in my head for a few days. Today I have been chatting with my brother again, he has his own tooth woes this week with a few trips to the dentist and a tooth that didn’t fall out naturally. So, I figure I owe it to him….this ones for you Bro!

In for a penny-in for a pound… I guess I may as well keep my own son happy too and consider his question, so teeth and nails and the science there-of…although I make no promises on the whole “nail fairy” thing!

WHY DO CHILDREN LOOSE THEIR “BABY” TEETH?

When teeth begin to grow in a baby’s mouth the gum and jaw are not developed enough to allow for extensive roots to form under the tooth and so smaller, weaker roots are formed on these early teeth. By the age of (usually) six or seven the jaw has matured to a point that allows it to hold adult teeth- and their larger roots- securely. The smaller baby teeth start to get loose at this stage and fall out. Cue the “Tooth Fairy”!

WHEN DO BABY TEETH START TO FORM?

Baby teeth start to form when the baby is still in the womb, in fact the first part of their production begins when the fetus is only four weeks old. Once the baby is born the teeth usually start to push through the gum any time from about six months on. However there are exceptions to this – some babies are born with visible teeth – these are called natal teeth. Teeth sometimes appear within the first month after the baby is born and these are referred to as neonatal teeth. The full compliment of 20 baby teeth are usually all grown by age three.

Baby teeth usually fall out in the order in which they first appeared! Babies who get their teeth later than most will usually start to loose their teeth at a later stage too. This is certainly true in our house… my daughter finally cut her first tooth at the age of 11 months and lost her first baby tooth at the age of eight!

HOW LONG DOES THE “LOOSING BABY TEETH” PHASE LAST?

Loosing baby teeth and growing new ones usually takes six or more years.

The new adult teeth tend to be less white than baby teeth, often appear very large in the child’s mouth (at first anyway) and usually have noticeable ridges on them (that is because they have not been worn down from chomping and chewing)!

Adult teeth do not actually push their predecessors out of the gum. Instead a group of cells called odontoclasts form between the root of the baby tooth and the tip of the adult tooth. These cells are responsible for absorbing the roots of the baby teeth, leaving them without their anchor in the gum.

HOW MANY ADULT TEETH DO WE END UP WITH IN TOTAL?

The 20 baby teeth are ultimately replaced by 28 adult teeth. Then the four wisdom teeth get added, usually in our 20’s, bringing the total number of adult teeth to 32! However it is common for some, or all of the wisdom teeth to be completely absent from an adult. This may happen if the jaw is not big enough to accommodate the extra teeth. I myself got my wisdom teeth very late (and slowly) and only got three of them- I like to think I am wise enough not to need them all – but there are plenty who will argue that one!

WHAT ARE THE DIFFERENT TYPES OF TEETH?

A full set of baby teeth is made up of …

8 X Incisors
4 X Canines
8 X Molars

A full set of adult teeth contains…

8 X Incisors
4 X Canines
8 X Premolars
8 X Molars
4 X Wisdom teeth

Adult human dentition: image credit – www.tutorvista.com

INCISORS are for cutting.
CANINES (also known as CUSPIDS) are used for tearing.
PREMOLARS (also known as bicuspids) are used for tearing and crushing.
MOLARS are ideal for crushing and grinding.

WHAT ARE TEETH MADE OF?

Teeth have two parts, the top part that we can see, called the crown and the part we cannot see, the root, which below the gum. The root is embedded in the jaw bone.

Image Credits: www.enchantedlearning.com

Teeth are made up of…

ENAMEL…this is the shiny white part of the tooth that we brush. It is the strongest material in our bodies which makes it ideal for all the cutting, chewing, chomping and grinding that the teeth have to do. This layer contains a lot of calcium.

DENTINE… this is the layer just under the enamel. It actually makes up most of the tooth. Although a hard substance it is not as hard as enamel.

CEMENTUM… this covers the dentine part of the root of the tooth (below the gum) and helps to anchor the tooth into the jawbone.

PULP… this is the inner most part of the tooth. It is the only living part of the tooth, made up of blood vessels and nerves and other soft tissues.

………………………AND NOW FOR A LITTLE BIT OF NAIL-SCIENCE…

WHY DO WE HAVE NAILS?

Why do we have nails and what purpose do they serve us? Nails are considered a protective layer at the sensitive ends of our fingers and toes. However their function goes well beyond protection, they are also great tools and implements for finer dexterity such as peeling, gripping and scratching.

WHAT ARE NAILS MADE OF?

Nails are made up of layers of protein called Keratin, this is the same protein that hair is made of and that we find in the outer layer of our skin. The different sections of the nail are described below:

Image credit: www.scholl.com

The nail plate- is the part of the nail that we see, made of layers of keratin.
Nail folds – this refers to the nail skin around the nail.
Cuticle – this is the tissue that covers the bottom of the nail to protect the newly formed nail cells.
Nail bed – this is the are of skin that is covered by the nail.
Lunula – this is the white “half moon” that we see at the base of the nail.

HOW DO NAILS GROW?

Nails do not actually grow from the top of the nail, they grow from the base of the nail, just under the skin. As new cells are made the older cells harden and get pushed out along the nail.

Fingernails grown about 3 milimetres per month. Usually fingernails grow faster than toenails. The fingernails on our dominant hand grow more quickly than the nails on the non-dominant hand (American Academy of Dermatology).

WHAT CAN OUR NAILS TELL US ABOUT OUR HEALTH?

Healthy nails are smooth and uniform in colour. Sometimes our nails get little white spots due to knocks and damage and these usually grow out of the nail with time. Nails may often develop ridges running from base to top, often becoming more dominent with age but these ridges are usually harmless. However notable changes to the overall colour or shape of the nail or surrounding skin can be more serious and such things should always be brought to the attention of a doctor (Mayo Clinic).

SO BACK TO THE ORIGINAL QUESTION…. WHY TOOTH FAIRIES BUT NO NAIL FAIRIES?

To address the original question of why we have tooth fairies but not nail fairies…. I am still not much the wiser. We could argue the value in a beautiful baby tooth, sparkling and white, full of calcium and minerals … all which might be of interest to the fairies. I really like the suggestion in Rise of the Guardians, that fairies take children’s teeth to guard the memories contained within. When you consider that they are made before we are even born then there is a strong argument to this proposal.

Image credit: greenpoint dental

But as for nails? I’m not so sure of this one. Most of what we call a nail is actually a clump of long dead cells. You could argue that the fairies might like to collect the Keratin that is found in our nails but this is already freely available from our hair, which we shed a lot of and is easily collected, if the fairies were so inclined! Some say that our toenails are of value as they are the part of our bodies that accumulates any gold, but I can’t find any strong evidence to back this one up. I have to conclude that fairies just do not have any interest in our nails, to be honest I would not greatly blame them, would you?

AND FINALLY AN EXPERIMENT TO TRY AT HOME:

Here is an experiment that can demonstrate to children what fizzy drinks can do to our teeth.

What you need:

3 hard-boiled egg (shell still on)
3 jars or glasses
A bottle of vinegar
A bottle of fizzy drink
A bottle of water (or tap water will do)

What to do:

Place a hard boiled egg into each of the three glasses. Cover one egg with vinegar, one egg with fizzy drink and one egg with water. Cover all three glasses and leave them like this overnight. Next day remove each egg and record what you find.

What happens:

If you examine the egg in the vinegar you should see that the shell has disappeared. If this is not the case, place the egg back in the glass and leave it for another day.

The vinegar is an acid (acetic acid); it reacts with the calcium in the egg shell (calcium carbonate) and breaks it down, producing a gas as it does so. You may have observed the gas as bubbles being formed, during the experiment. Effectively the vinegar (acid) eats away at the egg shell until it is all gone.

Now look at the egg that was left in the fizzy drink. You should see that the shell has been dissolved away (or at least partially) just like the vinegar. The enamel of our teeth contains a lot of calcium just like the egg. The fizzy drink is acidic, just like the vinegar. You begin to get an idea of what fizzy drinks can do to our teeth if we don’t look after them!

Now check the egg that was left in water, it should still contain a strong shell, the water should not have changed it!

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