Throughout our evolutionary history our body hair has gradually been lost, except for the hair on our heads, and our eyebrows.These bits of hair have remained. Unlike the hair on our heads, our eyebrows do not keep us warm – they are too small for a start, and offer almost no insulation. They do have 2 important roles in the body though.
You may not realise it, but eyebrows are an extremely expressive part of the face. Along with the mouth they can indicate anything from anger, to happiness, or even quizzical. You can move them around a lot, and we innately understand what their different positions mean. Raising both eyebrows for example, show surprise, whereas lowering both eyebrows is often disapproving or angry. You can’t show these emotions easily without the eyebrows! When we looked into pareidolia (seeing faces in object that don’t have faces), it was clear that recognising faces and emotions was a key part of our evolution. Eyebrows are an important part of this! After all, you wouldn’t give someone a hug if their eyebrows are down.
We also use our eyebrows for non-verbal communication. A common type of ‘eyebrow communication’ is a quick eyebrow flash upwards to say “hello“. You may even not realise that you do this, but next time you walk past someone in a hallway, you’ll find yourself doing this gesture. Eyebrows can also be used to emphasise words that are of particular importance. A long raise of the eyebrows whilst saying a word adds emphasis and meaning to that word.
Sure, we could still do these expressions without having hairy eyebrows – but they wouldn’t be half as clear.The expressions would blur into the rest of your forehead. Having hairy eyebrows is important.
Eyebrows are great for diverting water (particularly rain) and sweat away from the eyes.Their arcing shape over the eye, along with the horizontally laying hairs are perfectly designed to drain any water that would go in your eye, down the side of your face. It isn’t so important now we have umbrellas, coats, and spend all our time indoors, but getting water in your eyes makes doing any task difficult. Our eyes are one of our most sensitive senses, and we rely on them quite heavily.
Eyebrows are not one of evolution’s strange quirks – they have a role, and it is still valuable today. Eyebrows are important for expressing emotions and help us to communicate better by helping to add meaning and emphasis to words. They also fulfil a more practical role, and prevent water and sweat from getting into your eyes. Eyebrows are great!
Image courtesy of Jon Colller.
Intelligence is the ability to acquire information, apply knowledge, and an ability to engage in abstract thinking (i.e, thinking about times/ places and imagined situations). The intelligence of the general population follows a bell shaped curve (as shown in the image below). From the graph, you can see 50% of the population fall in-between an IQ of 90-100, which is thought of as average. However, there are a very small number of people (2.2%) which have an IP of 70 or less (which are classes as mentally retarded), and an equally small group of people with an if of 130 or more, who are extremely intelligent.
If this variance is due to your environment – then you may be able to change your intelligence, which is great! It would also mean you can lose intelligence though…
However, if it is all down to genetics, then it cannot be changed, no matter how hard you try. So, is intelligence genetic, environmental, or a combination of both?
Most tests on the impact of genetics vs environment have shown that genetics make up for 50-80% of intelligence. It is quite a scope because testing the impact of genes vs science is very difficult. The only way to do this with any reliability to to use identical twins. As twins have identical genes, you can eliminate the impact genetics has on what you are measuring (such as IQ).
Identical twins are not particularly common, so studies haven’t been terribly reliable. However, in 2008 a group of researches managed to test 2,602 pairs of twins to identify the impact of genetics vs environment on intelligence. Twins often share the same environments (taught by same teacher etc), but it was not the case with all the twins in the study. This allowed the researches to pick out what was causing the differences in performance. This study is the largest of its type, and so is thought to be the most reliable.
The research concluded that genetics accounts for at least 60% of the variance in intelligence, which agrees with previous studies, but gives a more accurate figure. The remaining 40% is a result of environmental factors. However, although this test clearly highlights the difference in genetic vs environment when it comes to taking academic tests, it doesn’t look at other forms of intelligence.
Intelligence is can be thought of as either being fluid or crystallised.
Fluid intelligence is the ability to solve brand new problems and use logic. It is adaptive, out side the box and on-the-spot intelligence. It would be the intelligence you rely on if you are lost and have to find your way home, or if you are faced with a problem for which there is no solution yet available. This kind of thinking is very common in left handed people, and is what makes them good problem solvers.
Crystallised intelligence is the ability to learn and apply knowledge. For example, memorising the meaning of words in another language and then responding in that language to questions. It is an applied kind of intelligence, which generally, is taught and tested for in schools. ‘Can you remember the name of this bone‘, and ‘what happens if I mix chemical A with chemical B‘ etc.
The study mentioned above only really studies to effects of environment on crystallised intelligence. Perhaps this crystallised intelligence is 60% genetics, and 40% environmental, but what about fluid intelligence?
For a long time, improving IQ seemed impossible, which flies in the face of the notion that 40% of intelligence is environmental. However, part of the reason for this is getting reliable data for improving IQ is very difficult. For example, someone who did a test today, might do better on a similar test tomorrow because the kind of questions are more familiar. Does this show an increased IQ? Alternatively, the next test you give them might be a bit harder than the previous, so they may not do as well. Does this mean their IQ has gone down?
You can’t give people the same test, because they will remember the answers, but equally you can’t give people different tests because they are different, and so might be harder/ easier. Then there are other factors to consider which impact performance too. Has a pet recently died? Are they feeling unwell? Have they guessed some the the answers right?
Testing for IQ changes isn’t straight forward, and so many researches claim that because it can’t be tested for, we don’t know if it can actually be done.
However, there is research out there to suggest that fluid intelligence can be improved. Researches have shown that doing n-back tests to improve working memory also improve fluid intelligence significantly, although more research is still needed to know how much. Perhaps this kind of environmental change can improve your intelligence, at least the fluid type.
If you want to give an n-back test a go, you can do the puzzle below.
Aside from this though there is very little research showing that intelligence can be improved, although it is quite possible.
Many things are claimed to increase your IQ, and they essentially involve being healthy. The list includes cutting out junk food, exercising regularly, doing word/ number puzzles, sleeping at night and reading. Whilst all these things might well improve your quality of life and make you more mentally sharp, the evidence that it can improve your IQ is very vague. It is also suggested that supplements like caffeine and ginkgo biloba help to increase IQ, which is unlikely, but they might improve focus.
The current research shows that genetics account for about 60% of intelligence variation, with the other 40% being environmental. However, this research in this area is still quite limited.
Testing to improve intelligence is very difficult. If 40% of intelligence in non-genetics, then intelligence should be able to be altered to some degree. Research has struggled to show this consistently, and this is in part due to the nature of testing intelligence. So far, it seems that doing n-back tests and similar working memory tests do improve fluid intelligence, and there is reliable research to support this. Additionally, living a generally healthy lifestyle and exercising, eating well and sleeping well are thought to improve intelligence.
Image courtesy of Kevin Dooley
Fingerprints regularly come up in crime films and are used to identify suspects at a crime scene. Identifying individuals by fingerprints is a very recent development though. During our long evolution you can be sure that our fingerprints were not used for this, which begs the question – what were they for? There has been some research into the purpose of the fingerprints, and although no one can say for sure what purpose they served during out time as hunter-gatherers, there are some good theories.
Aside from being on our toes, fingerprints are unique to fingers, and are particularly prominent towards the end of our fingers. The role of the fingerprints therefore, must be related to the role of our hands (and toes). This takes you to the next logical step of them helping to grip or hold things.
The idea that our fingerprints acted like the treads on tyres or the soles of running trainers was a long standing theory. It makes a lot of sense, and we know that ridges similar to that of our fingerprints do improve grip of tyres on the road, and trainers of tracks. However, this theory was disproved in 2009 by a study published in the Journal of Experimental biology which tested the frictional force of fingerprints. If this theory was true, then fingerprints should increase the friction against a surface, however, this study found the opposite. The reason for fingerprints not improving grip this way is because they are flexible and elastic, whereas car tyres are hard. If our fingers were harder, then fingerprints would probably improve grip. However, this is not the case.
A related theory suggests that fingerprints help drain water away, which would help improve grip on objects by allowing better contact (and so increased friction) between the skin and the object we are gripping. This is somewhat related to why our fingers go wrinkly in water, and although quite possible, it is not known for sure.
Although fingerprints don’t help us grip in the obvious way, they may still help grip. The ridges of our fingerprints allow our fingers to stretch easier and behave more elastic. In being stretchy like this fingers can grip rough or moving object better than if they were ridgid. This elasticity can also help prevent damage to fingers by allowing them to stretch rather than rip. This allows is to grip objects that are moving or have some force applied without damaging ourselves. You can see how this elasticity relates to grip yourself by gently holding a cup/ glass in the finger tips of one hand, and moving the cup/ glass up and down with the other. The fingertips in the gripping hand will comfortable move with the glass without ripping the skin, and will maintain a surprisingly good grip still.
There is also evidence to suggest that the ridges which make up fingerprints play a role in our identifying textures and fine details on objects. When fingers run across a surface the ridges that make up fingertips vibrate as they drag and spring back into position. This vibration is picked up by specially adapted nerve cells called pacinian corpuscles. This vibration information passes onto the brain and in conjunction with other nerves, helps to build up an accurate picture of the fine details of the texture of the object.
As fingerprints are well known to be unique to the individual, could it have something to do with their function?
The unique nature of fingerprints is largely down to genetics. With everyone having unique genetics, it isn’t surprising that everyone has unique fingerprints in the same way we have unique facial features too. Fingerprints do go beyond genetics though. Genetically identical twins have similar fingerprints, but they are different. When in the womb, if the fetus touches the womb wall it develops ‘friction ridges‘ which, which develop into fingerprints. As no two fetus can can touch the womb wall in the same way at the same time, the ridges do form differently.
Although there is still some debate as to why we have fingerprints, the research done on fingerprints does paint quite a good picture. Fingerprints help you to grip objects, and maintain a strong grip even if an object is moving. You can see how this would be useful as a hunter gatherer when you are trying to hold down some prey, weight a weapon (which, as you wield will try and slip out of your hand) and even building things. The success of humans is our hands and our ability to utilise tools effectively.
Another interesting feature of fingerprints is how they increase the sensitivity of our touch to pick out fine detail in objects. Although there is no clear scenario where this is beneficial, it is certainly an interesting feature.
Image courtesy of Phixaakh
Wouldn’t it be great to have a genuine craving for some broccoli? Or really want nothing more than to gorge yourself on cellery and kale? Can you imagine if everyone was like this? Heart disease would be non-existent, cancer would be unheard of and everyone would live to a ripe old age. But people don’t like vegetables, instead they want pizza, chocolate, take-aways and anything with lots of fat or sugar in, but these are all bad for us. It seems strange that we didn’t we evolve to like vegetables which would prevent these diseases, but instead crave all the foods which will make us ill.
To understand this, we need to go back to the environment we evolved in, not the environment we live in today. A look at humans 20,000 years ago will show us the world we lived in and that are genetics are designed for, and although 20,000 years is a long time for you and me, in terms of evolution it is a blink of an eye. 20,000 years ago there were no farms or agriculture of any sort, and we lived as hunter gatherers.
Now it is difficult to know exactly what hunter gatherers ate. They would generally have eaten what they can get their hands on, which would depend on the region they lived in, so there would be some broad variation. However, a look at one of the last remaining hunter gatherer societies can give us a very good idea of what it was like.
A tribe called the Hadza are a tribe in Africa which are still living as hunter gatherers today, and are considered to be the last true hunter gatherer societies on the planet. Typical of hunter gatherers, they do not farm or store much food, and they rely on hunting animals and gathering plants for food daily, which means they live a very active lifestyle.
Sugar is a very good source of energy, and it is what the body prefers to ‘run on’ because it is very easily metabolised. When you live an active hunter gatherer lifestyle, high energy and easily metabolised foods are important, so naturally, hunter gatherers have evolved to enjoy and seek out sugar. However, the only source of pure sugar for the Hadza is honey, which as you can imagine is quite hard to find, and even harder to harvest. Most of the sugar they consume will be from fruits, and the Hadza eat a lot of one particular fruit called the baobab (particularly in the wet season) but the sugar content is quite low per portion and it contains lots of fibre, vitamins and minerals – all of which are very nutritious and slow down the rate at which the sugar is absorbed. This avoids the sugar ‘spike’ and following slump that some people experience when eating highly processed sugary foods.
Getting much needed energy and essential micro-nutrients from sweet tasting foods like fruit makes them beneficial to eat, and so hunter gatherers have evolved to seek out and enjoy sweet foods. Interestingly, humans are one of a very few species which cannot produce vitamin C in their body. This is most probably because we ate so much sweet food which is high in vitamin C.
The only significant source of fats for the Hadza and hunter gatherers is animals, and animals don’t like to be caught, which makes fat relatively rare. However, fat is a fantastic source of energy and contains twice as much energy per gram than carbohydrates. The high energy content of fats makes them desirable for the same reason as sugars. Fats also have a number of roles in the body such as promoting a healthy circulatory system, and supporting the immune system.
In addition to this, fats are virtually always accompanied by meat. Meat is the best source of much needed protein which is needed to grow and repair the body, and also contains various other vitamins and minerals which are not very abundant in fruits. This makes wanting to eat fats very beneficial, and so naturally, hunter gatherers evolved to crave fat.
Plants are very easy to find and eat. They don’t run away, and grow all over the place. This means that they were probably eaten quite commonly and were turned to when nothing else (particularly meat) couldn’t be had. They weren’t a high priority because they are low in energy (sugar and fats), and although they would be high in micro-nutrients, these weren’t in short supply in the diet of hunter gatherers. The abundance and low nutritional importance of vegetables meant that craving them never evolved.
As hunter gatherers we have evolved to seek out high energy and nutritious foods because this is important for our lifestyle and survival. These high energy foods would not only provide us with plenty of energy, but also a number of nutrients, and so high energy foods provided a whole nutritious package for survival. Vegetables were much easier to find, and less essential for survival because of their low energy contents, so we never evolved a craving for them to the same extent as we do fatty foods and sugar. This built in sugar cravings lead us to develop highly processed foods which are high in sugars and fats, but devoid of any micro-nutrients.
Had we evolved to crave vegetables, you can guarantee that we humans would have found a way to concentrate that ever it was we craved about vegetables, and produce highly processed and artificial forms of that particular nutrients, which may well have lead to widespread health problems too!
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Historically, sugar and fat were the important foods to eat because they were scarce, and provided much needed energy. We evolved to crave these foods, because they were essential to survive. Plants on the other hand, were readily available, and easy to find, so their nutrients were not essential.
The appendix is a strange little organ. It can be removed from the host with having no negative effect- something which cannot be said for any other organ. The appendix seems to do nothing for us, but we all have one for some reason. Although no one can say for certain why we have an appendix, there are some pretty good theories about it and modern research, which I will go into in this article.
The appendix is a tiny organ which comes off the large intestine (see image to the right). In the scheme of things it is indeed very small, but it is likely to have shrunk in size as it has become more and more obsolete throughout or evolutionary history. When it was a more valuable organ, many people believe that it would have been much larger.
From its location we can get a good idea of its historic role in the body (even if it no longer is needed for it). Being attached the the large intestine tells us that its role is closely associated with it. The large intestine is home to the vast majority of probiotic bacteria in our body, is responsible for the absorption of some vitamins, large amount of water, and contains a significant amount of immune cells. Although some nutrient absorption goes on here, the vast majority of this occurs in the small intestine, so it’s unlikely the appendix was directly involved in absorption or digestion.
As the appendix is considered to be obsolete in modern man also suggests that there is something about our lifestyle changes in our recent evolutionary history which has resulted in the appendix not being needed.
Theory of plants – This theory suggests that our appendix helped us to digest plant matter, particularly cellulose, which we struggle to digest today. breaking down the cell walls of plants would allow vital vitamins and minerals to be released which has obvious health benefits. The reason our appendix has become obsolete is because we cook most of our food which breaks down the tough cellulose. This theory is supported by the fact that some purely herbivorous animals have a large structure similar to an appendix which is thought to help them break down tough plant material (such as koala bears), although there are not many examples of this. Rather than producing enzymes to digest this tough plant material, the appendix most likely contained special bacteria which can break down the cellulose for us. This is quite possible considering the appendix is attached to the most bacteria dense part of the body.
Theory of probiotics – This theory suggests that the appendix served as a kind of probiotic safe house. In any circumstance where the bacteria population of the digestive system would be flushed out or killed (such as diarrhea), the bacteria from the appendix would repopulate the large intestine with beneficial bacteria and prevent pathogenic bacteria populating it (which would cause further illness). The shrinking of the appendix is a result of improved hygiene, farming and the cooking foods, because all of these things reduce the risk of foodborne illness. This again is supported by the proximity of the appendix to the large intestine.
It is very possible that both theories hold some truth as to the historic role of the appendix.
Yes, the appendix is largely thought of as an obsolete organ, and although you can happily live without, it does still have a role in the body. Relatively recent research has shown that the appendix has a large concentration of immune cells, particularly a group of cells called lymphocytes, which help to eliminate waste from the digestive system and fight infection. The research on this is limited, and so details are quite sparse, but it does look like the appendix still does offer us some benefit after all.
For a long time the appendix has been thought of as a largely redundant and mysterious organ. Its role throughout our evolution is still debated, but is probably related to hosting beneficial bacteria, whether these bacteria are specialised for digesting plant matter or simply a backup for when we have specific illnesses we do not know. Regardless of its historic role, the appendix does still serve a function in the body. Recent research has shown that the appendix has a role in maintaining and protecting the digestive system from pathogens and helping to remove waste, and so it is not as redundant as previously thought.
Images courtesy of Blausen.com staff, Blausen gallery 2014 and AJ Cann
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 appendix is thought to have acted as a storage of probiotic bacteria for our digestive system in case we ate food that had gone off. There is also evidence that it contains high concentrations of immune cells which can help fight infections and eliminate waste in the digestive system.
Tears seem to have no purpose when we cry. They make your eyes blurry, make your nose run and generally don’t do anything helpful. There seems to be no obvious evolutionary reason as to why we would produce tears when we cry, but we do. The reason we do this is actually because the part of the brain which controls emotion is closely related to the part which controls tear production, so when one triggers, so does the other, and I will explain this in greater detail. Tears are produced from the lacrimal gland (a little gland you can see if you gently pull down your upper cheek) to lubricate the eye, provide nutrients to the eye and keep the eye clean. There are 2 types of tear which attract most attention in research – the basal tear, which is something you produce all day long, and is there to simply maintain the eye, and the reflex tear, which is produced to wash out irritants (such as those from onions). However, there is a third type of tear- the psychic or emotional tear, which is the kind of tear produced at times of heightened emotion. This tear is different from the previous 2 because it doesn’t require a physical stimuli, and its purpose is not obvious. It also contains more protein, manganese, potassium, prolactin and serotonin than the other 2 types of tear. Emotion is a complex and broad aspect of human biology. It is mainly controlled in the limbic system (see diagram to the right), and a part of this system called the hypothalamus plays a very important role in the expression of emotion such as laughing out loud. During times of heightened emotion (either happy or sad), this part of the brain is particularly active. Two important neurotransmitters used in this region of the brain are acetylcholine and serotonin, and so production/ activity of these neurotransmitters in increased during times of heightened emotion. In addition to this, times of heightened emotion often are accompanied by some form of stress response, particularly is you are sad, angry or scared. The stress response (also sometimes referred to as the ‘fight or flight’ response) causes a number of hormones to be produced including prolactin, growth hormone, cortisol and a chemical called norepinephrine (also known as noradrenaline) which acts as both a hormone and neurotransmitter. Both acetylcholine and norepinephrine are both known to be potent stimulators of the lacrimal gland. In addition to this, prolactin and a hormone called adrenocorticotropic hormone (ACTH), which stimulates the production of cortisol also influence the lacrimal gland, but to a lesser extent than acetylcholine and norepinephrine. With all of these lacrimal stimulating chemicals being produced there is little wonder that tears are produced in times of heightened emotional situations, almost by accident. Tear production when you cry seems to have no real biological significance, and it would appear that they are produced almost by accident. However, we are very social beings, and understanding others feelings and emotions is a vital part of our success as a species. Crying very clearly shows your emotional state, and helps to communicate to people around you how you need to be treated and how you are feeling. This in turn will help build bonds and enable a swift recovery from the cause of distress, which only makes for a stronger community. So no, they appear to have no physical importance like the reflex or basal tear, but it is possible they have a social importance. The emotional or psychic tear is very different from the other 2 types of tear, both in why it is produced, and what it does. At times of heightened emotion the brain releases a number of neurotransmitters and hormones as part of an emotional and stress response. Many of these neurotransmitters and hormones are also activators of the tear gland, and so can stimulate the productions of tears, almost by accident. Image courtesy of Yoshihide Nomura 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 we get very sad (or very happy) the body produces a number of hormones to make us feel that way. By chance, these hormones also stimulate the tear glands, and when lots of these hormones are being pumped around our body, the tear glads get over stimulated, and produce too many tears.
Purpose of a tear
Emotion in the body
A closer look at the lacrimal gland
Do tears when crying serve a purpose?
Tears seem to have no purpose when we cry. They make your eyes blurry, make your nose run and generally don’t do anything helpful. There seems to be no obvious evolutionary reason as to why we would produce tears when we cry, but we do. The reason we do this is actually because the part of the brain which controls emotion is closely related to the part which controls tear production, so when one triggers, so does the other, and I will explain this in greater detail.
Tears are produced from the lacrimal gland (a little gland you can see if you gently pull down your upper cheek) to lubricate the eye, provide nutrients to the eye and keep the eye clean. There are 2 types of tear which attract most attention in research – the basal tear, which is something you produce all day long, and is there to simply maintain the eye, and the reflex tear, which is produced to wash out irritants (such as those from onions). However, there is a third type of tear- the psychic or emotional tear, which is the kind of tear produced at times of heightened emotion. This tear is different from the previous 2 because it doesn’t require a physical stimuli, and its purpose is not obvious. It also contains more protein, manganese, potassium, prolactin and serotonin than the other 2 types of tear.
Emotion is a complex and broad aspect of human biology. It is mainly controlled in the limbic system (see diagram to the right), and a part of this system called the hypothalamus plays a very important role in the expression of emotion such as laughing out loud. During times of heightened emotion (either happy or sad), this part of the brain is particularly active. Two important neurotransmitters used in this region of the brain are acetylcholine and serotonin, and so production/ activity of these neurotransmitters in increased during times of heightened emotion.
In addition to this, times of heightened emotion often are accompanied by some form of stress response, particularly is you are sad, angry or scared. The stress response (also sometimes referred to as the ‘fight or flight’ response) causes a number of hormones to be produced including prolactin, growth hormone, cortisol and a chemical called norepinephrine (also known as noradrenaline) which acts as both a hormone and neurotransmitter.
Both acetylcholine and norepinephrine are both known to be potent stimulators of the lacrimal gland. In addition to this, prolactin and a hormone called adrenocorticotropic hormone (ACTH), which stimulates the production of cortisol also influence the lacrimal gland, but to a lesser extent than acetylcholine and norepinephrine.
With all of these lacrimal stimulating chemicals being produced there is little wonder that tears are produced in times of heightened emotional situations, almost by accident.
Tear production when you cry seems to have no real biological significance, and it would appear that they are produced almost by accident. However, we are very social beings, and understanding others feelings and emotions is a vital part of our success as a species. Crying very clearly shows your emotional state, and helps to communicate to people around you how you need to be treated and how you are feeling. This in turn will help build bonds and enable a swift recovery from the cause of distress, which only makes for a stronger community. So no, they appear to have no physical importance like the reflex or basal tear, but it is possible they have a social importance.
The emotional or psychic tear is very different from the other 2 types of tear, both in why it is produced, and what it does. At times of heightened emotion the brain releases a number of neurotransmitters and hormones as part of an emotional and stress response. Many of these neurotransmitters and hormones are also activators of the tear gland, and so can stimulate the productions of tears, almost by accident.
Image courtesy of Yoshihide Nomura
When we get very sad (or very happy) the body produces a number of hormones to make us feel that way. By chance, these hormones also stimulate the tear glands, and when lots of these hormones are being pumped around our body, the tear glads get over stimulated, and produce too many tears.
I’ve got nothing against left handed people – I am one. But the existence of left handed people defies the evolutionary logic that if a trait is favourable, it will become persistent throughout the entire population. Unfavourable traits get lost pretty quickly, and even neutral traits can fade out in the gene pool. A great example of this is a giraffe. The long neck trait is very desirable because it allows you to reach food that is harder to get. This meant that the longer necked giraffes are more likely to survive and bread/ pass on the long neck genes, and before you know it, all giraffes will have long necks. There is no small population of giraffes with short necks.
Being right handed is clearly be the most favourable trait, with about 90% of the population being right handed. You would expect the left handed genes to fade away many thousands of years ago, but it hasn’t. In fact, left handers have consistently made up around 10% of the population for as long as we know, right back to the earliest humans, so there must be a reason for left handed people to exist.
There are 2 reasons why people can become left handed. The first is genetic. You can see from the table below that left handed parents are more likely to have left handed off spring, and right handed parents are more likely to have right handed off spring. The genetics are not particularly straightforward because there are thought to be a number of genes involved in making someone left handed, and no one really knows which.
The second reason is that trauma or stress at birth such as oxygen deprivation to the brain can cause damage to the left hemisphere of the brain and cause dominance to shift. Research has shown that birth complications like this result in an increased number of left handers.
There is no way of determining the cause for an individuals left handedness, but the fact that there is a genetic link is very interesting, and suggests that there is so advantage to being left handed.
lets look at the key differences between left handed people and right handed people:
They think differently – Evidence published in the American Journal of Psychology showed that left handed people were much better at tasks which required divergent thinking, which requires creative thinking and exploring different solutions. This shows that left handed people are often better at problem solving than right handed people, and this is supported by the fact that left handed people tend to pursue careers in science, art and technology. All of which require a large amount of creativity and problem solving. The study showed that there was no difference in convergent thinking (required no creativity), suggesting that left handers may be better thinkers. However, other research has shown that left-handers are not so good with language and communication skills.
Better at sports – It is a well acknowledged fact that the left handed people are over represented in professional sports, particularly ones where you are in direct competition with another player like boxing or tennis. In 2015 left handed tennis players made up 40% of the top players, which is 4 times more than the proportion of lefties in the general population. The advantage is so well known that some top tennis were taught from a young age to play left handed even though it wasn’t their dominant hand, and this is something Rafael Nadal is famous for.
This is thought to be because left handed people are so uncommon, most players will practice against a right handed player. Right handed players practice against right handed players, and left handed players practice against right handed player. Everyone knows how to read and play against a right handed opponent, but everyone has very little experience playing against a left handed opponent. This is supported by research published in the British Journal of Psychology which showed that novices and experts alike find right handed shots much easier to predict than left handed ones.
Increased risk of mental disorders – It has been observed that the risk of developing mental disorders such as schizophrenia and autism increases with left handedness. This could very well be due to the mental trauma at birth that causes some people to become left handed.
Other differences of note include left handed people are often shorter in height, live slightly shorter lives but earn about 4% more than their right handed counterparts.
We have ascertained that there are some significant differences between left handed people and right handed people, and that being left handed is at least in part an inherited trait. Despite being apparently the lesser of the 2 traits, it has remained throughout the gene pool – why?
Despite the potential health risks (shorter lives and association with metal disorders) being left handed is an advantage in a population which is right handed dominant, and this is why it has not become an extinct trait.
Historically left handed people would have had the upper hand in a fight, which would increase their chance of survival, and are able to ‘think outside the box’, which would allow them to tackle problems that their tribe would otherwise struggle with.
On the surface, the pros of being left handed seem to outweigh the cons (after all, not all lefties suffer from autism), but left handed people only have an advantage in a right handed population. A right handed person would enjoy all the same benefits in a left handed population, and more. They would not only be better at fighting, but bigger too, making them formidable and make the right handed trait much more favourable. Right handed people would dominate left handers to the point that the left handed trait is rare, at which point it become an advantage. This is the state we find ourselves in today- a working equilibrium of handedness.
Left handed people differ from right handed people in a number of ways, but the most notable is their creativity and dominance in sport.These advantages only exist because the population is predominantly right handed, and this is why the left handed trait has remained a minority trait, but not become extinct. The fewer the left handed people there are, the more advantage they have, but if the trait becomes too abundant, the have less of an advantage, and the trait declines in the population.
Image courtesy of beezart
Left handed people exist as a minority because their only advantage is as a minority. They are smaller, and think differently, to right handed people, which makes them difficult to fight (or play against in sports) and approach problems differently.
If left handed people were the majority of the population, these benefits would vanish, because they would be common.
Everyone will see faces and other familiar things in random objects, that in reality don’t resemble the thing they see at all. Faces are by far the most common thing to see in objects, but if you look hard enough at complex objects (say a cloud), you will usually be able to make it into something, but it a shark, a footballer or even a star destroyer. This phenomenon is called pareidolia and in this article, I will explain why it is so easy to see faces in so many objects.
There is a specific part of the brain which is dedicated to face recognition, and damage to this part of the brain can result in a severe difficulty in recognising faces (even that of people you know). This is called prosopagnosia, and is sadly common in people who suffer strokes. This region of the brain is very sensitive, and research has shown that some neurons in this region of the brain still trigger in non-face objects, which can make us think that we have seen a face – that is how sensitive this part of the brain is.
Our brains are extremely good at learning (even when we don’t think we are learning), and to some extent they are pretty good at guessing what life will throw at us. This way, we will be more prepared for situations and react quickly. For example, if we are in a dark and scary forest at night, our brain expects scary things. So if a little bunny rabbit jumped out of a bush, or a twig unexpectedly brushed our leg, we would jump/ scream/ run. Our reaction is based mostly on what we expect to happen (which in this case is being attacked by something scary). Go there on a nice sunny day with the family, and it is completely different – the rabbit is not scary but cute, and you don’t even notice the twig…It is all about what your subconscious expects based on experiences (including scary films).
The same kind of subconscious learning can be applied to pareidolia. We see faces everyday, in a variety of places, circumstances and environments, and so our brain expects to see them often. Not only that, but faces are always important to look at – is someone angry? Sad? Happy to see you? All these things can easily be read from looking at the face, and it helps you react appropriately and quickly. Quickly seeing and reading faces is essential to maintain a social structure in our society which has been a vital part of our success through our evolution and modern day. So our brains have learnt (or adapted) to see and read faces very quickly and easily. In fact, almost too easily, which is why we see faces in random objects.
The benefits of quickly outweigh the negative of quickly reading faces, which is why it is a favourable trait. Just think – if you misread a face in an apple, nothing bad is going to happen? But, if you fail to read enemy’s face to understand their intent, you could be dead. Having highly sensitive facial recognition is rarely a bad thing, but often a good thing.
There is also a rather tenuous but interesting reason to our highly sensitive facial recognition. predatory animals like tigers will rarely attack you if they think they have been noticed or are being looked at. It might sound a little far fetched but in India people wear face basks on the back of their heads when going into tiger territory, and since this, there have been no tiger attacks. By doing this, tigers cannot get out of the line of sight of a face, and so will not attack. This again goes back to the idea that seeing faces has no negative effects, but might save your life. If you are in the dense jungle if you see some vines that look like a tigers face, its no big deal. If you do see a tigers face though, you just might have avoided a nasty tiger attack.
So the most accepted reason for our highly sensitive face recognition is simply a survival mechanism. We have evolved to be be very sensitive to facial patterns, which will allow us to react appropriately to situations. The advantages of this are clear – we see an angry enemy and we know that we should run or fight (not try and hug them). Being able to quickly read faces could really mean life or death, and so having highly sensitive facial recognition has become a favourable trait. This facial recognition is so sensitive that we can see faces in random object where there really isn’t a face (called pareidolia), but there isn’t any disadvantage to this happening.
Our brains are extremely sensitive to face shapes because they give us a lot of meaning, and historically, this has been beneficial for survival. instantly recognising a friend from a foe, can mean life or death! Our brain is so highly attuned to ‘face shapes’ that it sees them in things that slightly resemble them.
Ever fancied the idea of being forever immortalized (or rather, your skeleton being immortalized) as a fossil? Fossilisation is a tricky thing to get right, you just need to consider the millions of dinosaurs that roamed the Earth before us, and the few fossils they left behind. So in this article I’ll explain what you need to do to give you the best chance at becoming a fossil.
You need to make sure that your bones are in excellent condition for fossilisation. To do this, you need to make sure your bones are as big and strong as possible, and this is best done through a healthy diet with particular attention to certain nutrients:
The first is calcium, which is a mineral that makes up a large part of the bone. Ensuring you have enough calcium in your body prevents the body from leeching calcium from the bone, and ensures that there is enough calcium to build strong bones. Dairy, especially milk, is a great source of calcium.
You will also need to make sure you are getting plenty of magnesium. Magnesium also makes up a large part of bone, and so is needed to make bones as big and strong as possible. Great sources of magnesium are leafy greens, fish and nuts.
Next, make sure you are getting plenty of vitamin D, because vitamin D promotes the mineralisation of bone. There is no use in having plenty of minerals if you aren’t getting enough vitamin D to utilise them. Great sources of vitamin D are dairy (making it doubly good for becoming a fossil), eggs and sunshine.
Last but not least, make sure you are getting enough vitamin K, which works alongside vitamin D to ensure that your minerals, including calcium are regulated in the body properly and bones are mineralised properly.
Doing this will make sure your bones are at their peak mass and density, which is very important in leaving a good fossil behind.
You need to carefully plan where your body will be laid to rest, and this is the most critical part. The best place would be a river bed (not a fast moving one though, else your body will be all over the place), or, ideally a peat bog or tar pit. These places have very few animals which will move your body, and layers of sediment will build up over your body quite quickly, which is good.
Being buried underground such as in a graveyard isn’t such a good idea, because sediment doesn’t build up in places like this, and your bones are more likely become dust than fossils.
You’ve done the hard part, and now all you need to do now is wait a long time, and, with a bit of luck, your body won’t be disturbed. The soft parts will then rot away leaving your strong bones behind. As layers and layers of sediment build up over the bones the pressure increases, and the sediment becomes a hard rock, which encases the bones. Ground water will then begin to dissolve the minerals in the bone until they are all gone, and there is just a bone shape hole in the rock (or rather, a bone shape mould). (This is why you want to make sure you bones are big and strong – you don’t want them to dissolve before the sediment becomes a rock, because no mould will be left, and you want the mould to be as big as possible to negate any dissolving which may have taken place before the sediment became rock).
Then, water will seep into this skeleton shaped hole in the ground, and minerals which are dissolved in the water will start to crystallize, and eventually form a rock in the shape of the skeleton – at which point, you are a fossil.
Then all you have to do is be discovered, and hey-presto! You are a fossil!
Image courtesy of Premasagar Rose
If you want to become a fossil, make sure you have good strong bones, get buried in a bog/ peat pit and then wait a few millions years…
Most people will have noticed that if you stay in a body of water for any extended period of time, your fingertips will go wrinkly. You may have even noticed your toes doing the same, but it doesn’t happen anywhere else on your body – ever wondered why?
Originally, it was thought our fingers went wrinkly because the outer layer of skin (which is made up of dead cells) absorbed water when we were submerged in water for any length of time. The absorbing of water like this would increase the volume of the outer layer of skin, but its can’t just expand out as a sponge would, because it is firmly attached to the underlying layers of skin. So, instead it would wrinkle, which increases its surface area and allows for the expanding surface layer. However, this is not the case.
When we are submersed in a body of water for any length of time, nerves in our fingertips trigger vasoconstriction. It is possible that the nerves are triggered by the water being absorbed by the outer layer of skin, but we don’t know for sure.
This vasoconstriction reduces the volume of the padding in finger tips and toes. You can feel this padding simply by gently pressing your finger tips with other fingers. This padding is essential for our fingers and toes and offers protection for everyday scrapes.The surface area of the finger tips stays the same, so when the volume decreases, the skin wrinkles. It is the same thing that happens to fruit when you dehydrate it. A grape is nice a smooth all around, like our plump little finger tips, but if you dehydrate a grape, it turns into a wrinkly little raisin. This is because all of the water, which makes up most of the volume in the grape has gone, and so the skin is forces to go wrinkly.
This is quite an interesting thing to happen – rather than it being an involuntary thing that just happens when we go into water, the body actively causes this to happen, which suggests there is a reason…..
And there is! Research has shown that wrinkly fingertips are very good at gripping wet objects, and they do this because the wrinkles create channels that allow water to drain away as we press our fingertips on to wet surfaces. This allows the fingers to make greater contact with a wet surface, giving them a better grip.
Being able to grip wet things in water has a clear advantage – it will allow is to climb out of water easier, hold weapons easier, or even keep hold of wriggling food we have just caught.
So, getting wrinkly fingers when we are in the water is not some bizarre result of our skin absorbing water, but rather, it is a very clever evolutionary trait which allows us to grip things better when wet. It is a fascinating evolutionary adaptation, and not one anyone would have thought about. For this small adaptation to be significant, you would think that we would have evolved in a much more aquatic environment than deep inland, and perhaps this offers a small insight into how our evolutionary ancestors lived – perhaps we evolved on or around the coast after all….
Image courtesy of Nicole Hanusek
Blood vessels constrict, which reduces the volume of the padding in our fingers, which causes them to wrinkle. The reason for this adaptation seems to be to improve our grip on wet objects.