Do We Eat Spiders in Our Sleep?

image for the article 'do we eat spiders in our sleep'.

You may have heard from a friend or colleague that we eat spiders in our sleep. I’ve even heard it said that you can eat up to 8 a night (but generally its 8 a year). It is a common urban legend, so here, I’ll investigate the possibility of eating spiders, and see if there is any truth behind it.

 

Spider Science

Spiders are extremely well adapted to survival, and it is no wonder that they have thrived in almost every corner of the world. Along the legs of spiders are chemoreceptors1 , which to you and me, is something similar to a nose. These chemoreceptors on the legs of spiders can sense a number of chemicals, and are there to avoid predators, and to seek out prey.

If a spider was to come close to a human mouth it would sense the many 1000’s of different chemicals in their breath. From the toothpaste, to the evening meal and even the carbon dioxide we breath out. A spider would be able to tell that a massive and dangerous mouth is nearby, and it would move in the opposite direction.

 

Unlikely odds

When people hear that they eat spiders in their sleep, they often imagine a tiny spider dangling on a web down into your gaping mouth by accident. However, this isn’t likely to be the case. Most people will instinctively sleep on their side or their front, not their back, which means that a spider must actively crawl into your mouth. based on their highly sensitive chemoreceptors (and not to mention their eyesight) its very unlikely that they will ever crawl into a mouth.

Furthermore, when you are asleep, your mouth is far from being gaping. In fact, your mouth rarely opens more than 25% of its full open position, which means the gap for a spider to ‘accidentally’ fall into, or even crawl into, is quite small. This makes it very unlikely that a spider would end up in your mouth.

 

Near impossible to measure

Aside from the above 2 points, which make the chances of a spider going into your mouth extremely small, how would we ever measure this? Think about it – how (and why) would researchers go about counting how many spiders people eat in their sleep in a year. They would have to carefully watch or film someone sleeping for a year, and count how many spiders go in their mouth. Ideally, this would have to be done for a large population size to minimise the risk of chance, and different sleeping locations (e.g in the country and in the city).

This would take a massive amount of time and money, and frankly, no one in their right mind would do it.

 

Summary

The chances of eating spiders in our sleep is extremely slim due to the spiders ability to detect/ avoid us, and the difficulty in getting into our mouths in the first place. The myth that we eat 8 spiders a year is nothing more than a myth, simply because testing for it is too difficult, and pointless.

So, you can sleep safe in the knowledge that you won’t be eating any spiders tonight (or rather, the changes of eating spiders is very very low).

 

References

1. Encyclopedia of Entomology, Volume 4, By John L. Capiner

Image courtesy of  Martin Cooper

 

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 one knows for sure, but the chances of you eating any spiders in your sleep are extremely low.


Why have we Retained Hair on our Heads?

May 20, 2015 / Humans / 0 Comments /
Picture of crazy frizzy hair as supporting media for the article 'why do we only have hair on our heads''.

Very few animals indeed have such a strange hair growth pattern as that of humans. If you imagine any other animal with only hair on their head, you realise that it is unusual (not to mention funny), and is just as unique as a peacock’s tail.

Our entire body is covered in a thin layer of hair, except our head. Sure, some people have more body hair than others, but head hair is by far the thickest on the body, even for those who are hairier than normal (ok, the exception is bald, hairy men, but there are other reasons for this). So why do humans have a lot of hair on their heads, but not much on our body?

 

Heat retention

The head has a large surface area and a large blood supply, which means large amounts of heat are lost through the head. Having hair on your head acts as an insulating layer, which prevents heat loss. The body loses less heat per unit area compared to the head, which is probably why we have lost some of our body hair, but kept head hair. In addition to this, wearing animal skins and clothes on our body would have reduced the need for body hair.

Heat retention is probably the most likely, and important factor for the reason we have head hair, but there are other potential reasons which may have also contributed to some degree.

 

Homoaquaticus

This is a favorite theory of our evolution, and although it is lacking some real evidence. Sometimes referred to as ‘water-ape’, this theory suggests that as early man we grew up by the coast. Here we could hunt for food on land, but also wade out to sea to search for food. Imagine an ape wading out to sea and coming back – they would be dripping wet, and would get cold. So, we evolved to lose our body hair, so we wouldn’t stay wet for so long once out of the water. The hair on our head remained to retain body heat, but also because our heads didn’t really go underwater, because we needed to breath.

Although not an accepted theory of evolution by most people, losing body hair but head hair would offer an advantage to early humans looking for food at sea.

Besides, how else do you explain why humans and sea mammals have a similar bone structure in the flipper and hand? Why would a whale or dolphin need those bones in its hand? Food for thought, but not concluding evidence.

 

Attraction of the opposite sex

Hair decoration to attract a mate has been going on for an incredibly long period of time, and our ancestors have gone to great lengths to gather special gels to make their hair ”attractive”. Ancient bog body discoveries almost always find that the person had gone to a surprising amount of effort to have their hair in a certain way. It is possible that having a good head of hair 3000 years ago would have increased your chances of getting a mate, and passing your hair genes on.

Ok, so 3000 years is not long in terms of evolution, but this does offer a bit of support as to why head hair has endured the test of time so well. This also mirrors this explanation for the purpose of the aforementioned peacock’s tail. potentially more truth here than you think…

 

Summary

The most acceptable, and most probable reason for having hair on our heads and not the rest of the body is to retain heat. We probably lost the matching body hair because we started wearing animal skins/ clothes which made body hair redundant.

It is of course possible that there are other contributing factors which have ensured an advantage to those who are particularly folically gifted; and they may include the ‘water-ape’ theory and using hair as a tool to attract the opposite sex.

Picture courtesy of MorkiRo

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.

It is an evolutionary adaptation for the need to keep our heads warm to conserve heat. Clothing meant that we didn’t need body hair so much, so that gradually was lost.


Can You Die from Eating Too Many Bananas?

May 10, 2015 / Food, Humans / 2 Comments /
picture of bananas for the article -can you die from eating too many bananas'

You may have heard that if you can die from eating too many bananas, usually around 6-8, because you can get potassium poisoning. Here, I’ll investigate the potassium content of bananas, and see if there really is enough in them to kill you.

 

Potassium in a banana is not just ‘potassium’

According to the United States Department of Agriculture (USDA), a medium banana will contain an average of 422mg of potassium. This potassium will be in a number of organic forms, but the form most abundant in a banana is potassium citrate. This is of importance, because the toxicity depends on the chemical form the potassium is found in, as well as the dosage.

To illustrate this importance, the LD50 (dosage which kills 50% of the population) of potassium citrate in a rat is 7200mg per kg body weight, whereas the LD50 for potassium chloride in most mammals is 3020mg per kg body weight.

Potassium makes up just over 38.2% of the weight of potassium citrate, so, assuming the vast majority of potassium in a banana is potassium citrate, the total amount of potassium citrate in a banana is 1105mg.

 

What is the lethal dosage of potassium citrate for humans

The L50 for potassium citrate in humans is unknown, but is greater than 2000mg/kg body weight (which classifies it as a very low risk chemical, meaning the exact LD50 dosage isn’t important to identify).

However, as most mammals seem to regulate potassium and other minerals in a similar fashion, for the proposes of this little investigation we can make the assumption that the LD50 of potassium citrate for humans will be similar to that of rats – 7200mg/ kg body weight (this is in keeping with the Thermo Fisher statement of the LD50 being greater than 2000mg/kg body weight).

 

How many bananas will kill a human

It takes 45.6 bananas to provide a fatal dosage of potassium citrate to a humanUsing the above information, we can calculate the number of bananas which will be lethal to a human. Assuming the average weight of a man is 70kg, this makes the LD50 for potassium citrate to be 7200×70 = 50400mg (or 50.4g).

This would make the LD50 for bananas to be 45.6 bananas, not 6-8 as some people claim.

 

Further food for thought

This 45.6 banana estimate doesn’t take into account the digestion rate, or excretion rate for potassium (let alone the rate you can eat bananas), and so in reality is likely to be much higher. We know that the body can excrete potassium extremely efficiently and quickly when it needs to. In fact the concentration in plasma potassium levels from eating 2 bananas has been described as ‘marginal‘, suggesting that healthy kidneys are very good at filtering potassium out.

 

Where did the 6-8 myth come from?

Perhaps the oral lethal dosage for potassium has been confused for the lethal IV dosage, which for dogs is 170mg/ kg body weight (according to Wiki), which is a hell of a lot lower than 7200mg. If this was the case, the LD50 would be calculated at 10.7 bananas, which is pretty close to 8.

Or perhaps there has been some mix up with the understanding of potassium, and the infamous potassium cyanide, which only takes a few hundred mg’s to kill someone… Who knows?  (seriously, if you know, please comment and let me know!).

 

The bottom line

Potassium poisoning from bananas seems to be a myth, but this isn’t to say eating 6+ bananas rapidly is good to do. There is a lot of sugar in a banana, and the large amount of potassium, although not fatal, may affect the mineral balance of your plasma. For example, sodium and potassium are two closely linked minerals, and its possible that a large amount of potassium excreted may also excrete a large amount of sodium too (for better or for worse).

Images courtesy of Steve Hopson and Simon Strandgaard

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.

You would need to eat at least 45 bananas very quickly to come close to potassium poisoning – kind of impossible.


Why do we Age?

April 12, 2015 / Humans / 0 Comments /
An old lady - supporting material for the article 'why do we age?'

The most widely accepted theory for why we age is the Free Radical Theory of Agingor as it is better known today – The Mitochondrial Theory of Aging. This theory essentially states that the reason we age is due the amount of free radicals we are exposed to, and there is a convincing amount of evidence to support this theory. Before we go into the details of this theory, you need to understand what is happening inside our cells when we age.

 

Aging in the cell

At the end of all of our genes is a sequence of DNA which doesn’t code for anything in the body. At college level biology, this was sometimes referred to as ‘junk’ DNA, but it does have a purpose. These bits of ‘junk’ DNA are called telomeres and their job is to protect DNA from damage and unravelling. They themselves get damaged, and can even be repaired by specialised enzymes, but the damage to telomeres has no effect our genes function – which is good for us. However, as our cells replicate and divide, these telomeres become shorter and shorter. This reduces the amount of protection the DNA has, thus, increasing the damage it will sustain.

So, as we age our cells divide/ replicate more, which makes our telomeres shorter, which makes our DNA more vulnerable to oxidative damage.

 

Radical damage

There are numerous sources of radical damage – diet, pollution, sun, and even exercise, but the biggest source of radical damage is ourselves. When our cells produce energy, they create a very reactive radical called superoxideWe produce lots of it, and our body is well equipped to neutralise it with specialised enzymes, but it cannot all be mopped up, and some damage is inevitable.

As our body ages and our telomeres shorten, our body is less well equipped to repair/ protect our genes from super-oxide, and so our genes can get damaged. This leads to the development of the typical signs of aging – stiff joints, reduced mental agility, cancerous cells and wrinkly skin – all of which are know to be caused prematurely by high exposure to sources of radicals, such as regular use of sun beds, or long-term smoking.

Just think, have you ever seen someone who has spent too many hour on a sun bed/ regularly smokes who has more wrinkles than they should at their age? That’s radical damage for you.

The radical damage from superoxide and other radicals can be minimised with a good diet high in antioxidants and precautionary measures such as not smoking. This can limit, or even delay the development of the signs of aging. But as our main source of radical damage is our own cells, both from the shortening telomeres, and production of superoxide, aging is sadly inevitable.

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.

We age because our ability to protect ourselves against radical damage diminishes over time. This leads to more radical damage to our genetics.


Can Babies Eat Strawberries?

March 27, 2015 / Humans / 0 Comments /

Babies can eat strawberries, but you must be careful because young babies may have an allergic reaction to them. The general recommendation is that you shouldn’t give strawberries to babies under the age of 6 months. Beyond 6 months, they can slowly be introduced, perhaps as strawberry purée or very small chopped up pieces.

 

Why are babies allergic to strawberries?

It seems odd that such a delicious and natural food is a common allergen in babies. However, strawberries contain a relatively large amount of a chemical called histamine. Histamine is a chemical which stimulates our immune system, particularly the inflammatory response, and babies are particularly sensitive to it.

You may have heard of histamine (or more likely anti-histamine) in the context of hay fever or pet allergies. This is because pollen/ pet hairs trigger the release of histamine in our body – causing puffy faces etc. An anti-histamine inhibits the action of histamine, which reduces the symptoms. It is not recommended to give babies anti-histamines though.

Typical signs of an allergic reaction to strawberries are itchy/ red skin (similar to hey fever), which are typical responses to inflammation.

When is best to introduce babies to strawberries?

can babies eat strawberries?The advice for preventing food allergy in infants is to delay introduction of potentially allergenic foods (e.g peanuts) until 3 years of age. However, this advice was based mainly on expert opinion and not evidence-based research.

In fact, delaying exposure to foods which commonly trigger an allergic reaction can actually increase the risk of developing an allergic reaction to that food later in life. Now, recent research suggests that early introduction of potentially allergenic foods at 4 to 6 months of age might actually provide a form of protection and help prevent an allergy, but scientists admit that more research is needed.

So, from the research there is still no clear answer, although it looks like the best time to introduce small amounts of strawberries is shortly after the 6 month mark. This way the introduction is within current guidelines to minimise risk of a reaction, but is still early in the babies life, which can help prevent the baby developing an allergy later in life.

When you do introduce strawberries be sure to keep an eye out for symptoms of a possible allergic reaction, such as puffy or itchy skin.

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.

Yes, but strawberries are a common allergen to babies. Current guidelines for introduction are around 6 months.


Is Coffee Good For Kids?

February 25, 2015 / Humans / 0 Comments /
is coffee good for -kids

Caffeine, the chemical reason for drinking coffee, is a heavily debated subject. It has both benefits and drawbacks in adults, but when it comes to kids, it’s a different story. Children are not only smaller than adults (and so more sensitive to chemicals such as caffeine), they are also ‘under-developed’ (for want of a better word). Their chemistry is different to that of adults, and so coffee can affect them differently. There is a large amount of concern that coffee can have a much more dramatic effect on children than adults, and potentially cause a number of ailments. Here I’ll explore the effects of coffee on kids.

 

Caffeine DependencyKids are more susceptible to caffeine dependancy

It is a reasonable assumption that children will develop caffeine dependency from a much lower dosage, and with less frequent of consumption than that of an adult. Dependency in adults has
been reported from consumption of as little as 100mg/ day.This is of real concern when you consider that a cup of instant coffee contains around 100mg. The possibility that a child could develop dependency from consuming just 1 cup of coffee on a regular basis is worrying. There is admittedly very little research on child dependency from coffee, and how this can impact their later life.

The lack of research in this area makes it difficult to say how good or bad caffeine is for children with regards to dependency.

 

Risk of Diabetes

A study back in 1994 found that children under the age of 15 years old who regularly consumed more than 2 cups of coffee a day had a significant increased risk of developing type 1 diabetes. This study highlights the difference in effect caffeine can have on children and adults, as coffee consumption has been shown to protect against the effects of type 2 diabetes in adults. As type 1 diabetes is irreversible, and associated with a whole host of other diseases including cardiovascular disease, then regularly drinking this much coffee certainly isn’t good for kids.

Blood Pressure

There is research which has shown that caffeine consumption increases blood pressure in a dose-dependant fashion, (i.e, more caffeine = greater increase in blood pressure) which increases the risk of developing hypertension (high blood pressure). The increase in blood pressure is not long lasting though, and coffee would have to be regularly consumed for this to become a serious concern.

Brain developmentCoffee may affect brain development

We know that the brain is still developing during childhood, and even through the teenage years. One area which is still developing in particular is the orbitofrontal cortex and the temporal lobe, which contain adenosine receptors. It is these receptors which caffeine inhibits, and so it is possible, and has been suggested by many, that caffeine can affect brain development. There is currently nothing more than theory to support this though.

Anti-nutrient

Caffeine is a know inhibitor of nutrients such as iron, which is of particular importance to children during growth. Although one cup here and there is unlikely to significantly impact nutrient absorption, regularly drinking coffee could have a negative impact. The extent of this is of course affected by other dietary/ lifestyle factors, and is not just down to coffee consumption.

Are there any benefits?

Yes, coffee in moderation is good for you, and has demonstrated antioxidant activity and anticarcinogenic activity – both things a modern diet always needs. The question at what dosage this is suitable for kids to be drinking is  still unanswered.

 

So…Is Coffee Good For Kids?

From the research I’ve looked at, coffee generally isn’t good for kids to be consuming regularly. The odd cup here and there is unlikely to do any harm, but they probably shouldn’t get into the habit of drinking coffee.

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.

Coffee and caffeine are not good for kids.