what causes Dandruff?

Dandruff is a harmless, chronic condition that occurs when the scalp becomes dry or greasy and produces white flakes of dead skin that appear in the hair or on the shoulders. People most often think of dandruff as anything that produces a flaky scalp.

Although it is harmless, dandruff can be embarrassing for those who have it. Dandruff usually starts between the ages of 10 and 20 and affects up to 40% of people over the age of 30.

Skin cells are formed continuously on the scalp, so the shedding of dead skin cells is a normal process. With dandruff, however, skin cells are shed at a faster rate than normal. Oil from the scalp causes the skin cells to clump together and appear as white flakes.

Dandruff can be caused by a number of things, including dry skin; sensitivity to hair products; and skin conditions such as psoriasis, seborrheic dermatitis, or eczema.

The overgrowth of yeast can also cause dandruff. This overgrowth can be caused by stress, hormones, too much oil on the scalp, or problems with the immune system.

The symptoms of dandruff include white flakes of dead skin in the hair and on the shoulders, as well as an itchy, red, or scaly scalp. Common dandruff flakes are usually scattered throughout the scalp.

If seborrheic dermatitis is the cause of dandruff, the symptoms usually appear gradually. The scalp becomes dry or greasy and feels itchy. As skin cells die, they turn to yellowish scales. A bad case of seborrheic dermatitis can also cause symptoms in other parts of the body. Yellowish or reddish scaling can appear on the hairline, in and around the ears, or on the nose and chest. Affected newborn babies may get a thick and crusty rash on the scalp, called cradle cap.

The flakes associated with psoriasis look like silver scales, which may also commonly be apparent on the ears, extremities, trunk, palms, and soles.

why does human hair turn gray?

Have you ever watched someone try to cover up gray hair by dyeing it? Or maybe you wonder why your granddad has a full head of silver hair when in old pictures it's dark brown. Getting gray, silver, or white hair is a natural part of growing older, and here's why.

Each hair on our heads is made up of two parts:

1. a shaft — the colored part we see growing out of our heads
2. a root — the bottom part, which keeps the hair anchored under the scalp

The root of every strand of hair is surrounded by a tube of tissue under the skin that is called the hair follicle (say: FAHL-ih-kul). Each hair follicle contains a certain number of pigment cells. These pigment cells constantly make a chemical called melanin (say: MEL-uh-nin) that gives the growing shaft of hair its color of brown, blonde, black, red, and anything in between.

Melanin is the same stuff that makes our skin's color fair or darker. It also helps determine whether a person will burn or tan in the sun. The dark or light color of someone's hair depends on how much melanin each hair has.

As we get older, the pigment cells in our hair follicles gradually die. When there are fewer pigment cells in a hair follicle, that strand of hair will no longer contain as much melanin and will become a more transparent color — like gray, silver, or white — as it grows. As people continue to get older, fewer pigment cells will be around to produce melanin. Eventually, the hair will look completely gray.

People can get gray hair at any age. Some people go gray at a young age — as early as when they are in high school or college — whereas others may be in their 30s or 40s before they see that first gray hair. How early we get gray hair is determined by our genes. This means that most of us will start having gray hairs around the same age that our parents or grandparents first did.

Gray hair is more noticeable in people with darker hair because it stands out, but people with naturally lighter hair are just as likely to go gray. From the time a person notices a few gray hairs, it may take more than 10 years for all of that person's hair to turn gray.

Some people think that a big shock or trauma can turn a person's hair white or gray overnight, but scientists don't really believe that this happens. Just in case, try not to freak out your parents too much. You don't want to be blamed for any of their gray hairs!

Is Sperm good for our skin?

Sperm is one of the vital components when planning to start a family. Like a women's egg, a man's sperm must be healthy in order to reach and penetrate the egg.  Though sperm is mainly used for procreation, it can have extraordinary benefits for everyday life.

In sperm, a crystalline polyamine compound called Spermine can be found. This particular compound is also known as an antioxidant. It is believed to diminish wrinkles, smooth skin and help with taming or preventing acne. Bioforskning, a Norwegian company, has synthesized the compounds into a facial cream.  According to Bioforskning, the cream Spermine is 30 times more effective than vitamin E and can delay the aging process by 20 percent. However, nature's most natural facial cream can cost you a whopping $250.  

Not only can sperm provide healthy skin, but also it can be used as an anti-depressant. In a recent study, researchers demonstrated that women who were directly exposed to semen were less likely to be depressed. The study stated mood-altering hormones that are present in semen can be absorbed through the vagina. Some of these mood-altering chemicals include, but are not limited to prolactin, a natural anti-depressant; oxytocin, which assist in enhancing one's mood and serotonin, a widely known antidepressant neurotransmitter.

Sperm is also directly linked to the frequency and intensity of a woman's morning sickness. According to SUNY-Albany psychologist Gordon Gallup, the frequency of morning sickness is directly related to the frequency of insemination during pregnancy.  Gallup and graduate student Jeremy Atkinson revealed women who undergo artificial insemination may experience worst cases of vomiting, and nausea.

When it comes to cooking, although semen may be the farthest thing from your mind, according to "Natural Harvest-A Collection of Semen-Based Recipes," semen is very nutritious. The cook book advertises semen as an "inexpensive" ingredient that can give any food an "interesting twist."

Lastly, if by any chance you are in dire need of invisible ink, semen may suffice. During World War I, the British Intelligence Service discovered semen can act as invisible ink. Unlike other chemicals used, semen did not react to means of detection such as iodine vapor.

Unless you are a part of an intelligence serve of some kind, invisible ink may not be essential, however if you ever need a facial Spermine may be a great option. 

Do Werewolves exist?

Throughout history, werewolves have played an integral part in the cult literature as creatures that were not of men or wolf – but both. Most common legends attest to how these creatures can shape-shift from a man to a wolf or wolf-like creature by the light of the full moon. Silver is the only weapon that can stop them, and the disease of lycanthropy can be spread by a mere scratch or bite.

Although Hollywood has romanticized the thought of werewolves and how not all of them are vicious killing machines, is there anything to worry about for the common man walking home one night during the light of the full moon? It is doubtful since no real evidence has ever been brought to public knowledge aside from folktales and lore. Why should the belief of werewolves be met with suspicion and skepticism?   Can we answer the question… do werewolves exist?

Translations from ancient times often lead to the creation of rumors and myths.

For example, Procopius of Caesarea recorded a battle between the Roman Empire and the Isaurians. These South Asian people were merely farmers when they were called to battle in the fifth century. In the recording, Procopius recalled how the Isuarians were slain due to their inability to wage war against Rome. He referred to most of these people as Lycaones. Many believe this to be related to the latin word, Lycaon – an animal of the wolf kind. In reality, Lycaones refers to the Lycaonians – a people of Asia Minor positioned relatively close to the Isuarian lands that were incapable of battle due to inexperience.

This isn’t the only incident in where misunderstanding of texts has created myths and legends

In the late 16th century, rumors of the werewolf stretched far and wide across Europe. When Peter Stubbe committed heinous crimes against the people of Bedburg, his ferocious nature was akin to that of a wolf. In much the same way that Vlad Tepes was depicted as a vampire, Stubbe’s actions earned him a reputation as he killed in much the same fashion a wolf would while taking down prey.

The story of the Werewolf of Bedburg was literature developed in order to help a people understand the cruel and inhumane nature that psychopaths can embrace. Peter Stubbe could no more change shape into a wolf as Vlad the Impaler could turn into a bat.

Humans often attempt to build myths and legends around certain aspects of existence in order to understand current situations. Five hundred years ago, most of the people on the planet knew the Earth was flat. Two hundred years ago, certain people on the planet believed the shining objects in the sky were gods looking down upon them.

Throughout history, those suffering from hypertrichosis were viewed as werewolves merely because the condition forces the growth of thick hair on the face and body. Could you imagine being hunted merely because you grew hair covering your face?

The human body is not developed well enough to force inter-species transformations. Bones would have to break, muscles and tendons would snap, and the shock to our systems would be catastrophic. The DNA of a human would unravel like a rug with a loose string and a child yanking on the end.  It’s physically impossible to quickly morph into a much larger species.

why do humans have different eye colors?

Eye color is the result of variations in the amount of melanin, a pigment found in the front part of the iris of the eye.  The lack of this pigment results in blue eyes, some pigment gives green and lots of pigment gives brown eyes.

 

So light brown eyes just have a bit less melanin than darker brown eyes.  All of the different shades of eye color happen the same way.  Blue-green eyes have an amount of melanin between green and blue, hazel eyes have an amount of pigment between green and brown, etc.  

 

Some people have eyes that have different colored patches.  For example, blue eyes with a green or brown circle around the pupil are pretty common.  In these eyes, different parts of the iris make different amounts of melanin.  

 

What we don't have yet is a good handle on how this all happens genetically. Scientists have a pretty good model based on two genes that can help explain blue, green, and brown eyes.  This is the model we based our eye color calculator on.

 

Scientists have even found the key gene, OCA2, which can explain why some people have brown eyes and some people don't.  Despite some work, scientists haven't been able to find the key gene involved in green eyes.  This is most likely because there is more than one gene.

 

A new study has identified three new genes that affect eye color. Scientists don't know what each of these genes exactly do and they don't know how to use them in eye color calculators just yet.  But given what we know about eye color, we can make some pretty good guesses about what these genes probably do...

 

Most likely these genes are either responsible for making melanin themselves or they control how much melanin other genes make.  Either way you end up with different shades of eye color based on the combination of genes that you have.

 

What I thought I'd do for the rest of the answer is first go through some background about genes. Then I'll talk about the new genes scientists found and finally I'll give a few examples of how these new genes can be involved in producing different shades of eye color.

 

Genes are Instructions

 

Your genes have the instructions for making and running you.  Each gene is made of DNA and has the instructions for some small part of you.

 

So there is a gene that decides whether or not you have red hair.  And one that decides whether or not you can taste a bitter chemical called PTC.  And so on.

 

Some traits are too complicated to be the result of a single gene.  These traits come about when lots of genes work together.

For example, it takes a set of genes to instruct a cell to be a nerve cell.  It also takes a set of genes to tell a cell in the iris of the eye to make specific amounts of melanin.

 

Now it isn't actually the genes that do any of this. Genes have the instructions for proteins, which do the actual work.

  

For example, OCA2 (the eye color gene we talked about earlier) has the instructions for making something called the P-protein.  And the P-protein is a key player in making melanin in a cell.

 

It is important to mention that people with different colored eyes don't have different eye color genes.  They have different versions of the same genes, which make slightly different versions of the same proteins.

 

For example, everyone has an OCA2 gene.  What gives different people different colored eyes is the version of the OCA2 gene they have.

 

Some people have a version of OCA2 that makes a lot of P-protein in the iris.  These folks have brown eyes. Other people have versions of OCA2 that either make less and/or a weak form of the P-protein.  These folks make very little melanin in the iris and so most end up with eyes that aren't brown.  All of these folks, no matter the eye color, have an OCA2 gene.

 

Think of genes as playing cards. A deck of cards has 4 versions of an ace (diamonds, clubs, hearts, and spades).  But no matter the suit, an ace is an ace in most card games.  The same thing can be said about genes.  No matter the version of OCA2, we all still have an OCA2 gene.

What is new?

In the recent eye color study scientists looked at the DNA of people with a variety of eye colors ranging from the lightest blue to the darkest brown. The researchers found three new regions in their DNA that can be associated with eye color.

 

One of these regions is a gene called LYST. This gene was previously linked to coat color in cattle and eye color in mice. 

 

The other two genes have never been linked to eye color before. Scientists believe that these genes are also responsible for the different shades of color observed in the human eye.

 

Now it isn't surprising that scientists found more than one other gene. We always knew there were more than two genes involved in eye color because there are more than three eye colors out there.

 

Unfortunately we don't yet know the specifics of what these genes do. But based on what we know about eye color, we can imagine some possible functions for these new eye color genes.  

 

By now you know that OCA2 is a very important eye color gene. So there could be other genes that influence how OCA2 works. In fact we already know of a gene called HERC2, which does just that.

 

HERC2 is needed for eye cells to read OCA2.  Some people have a version of HERC2 that can't do its job very well.  These folks' eye cells can't read the OCA2 gene very well either.

 

If OCA2 isn't read, no P-protein gets made.  And no P-protein means very little melanin in the iris, which means an eye color other than brown.

 

You probably noticed that I didn't say these genes lead to blue eyes.  Instead I kept saying they lead to the lack of brown eyes.

 

HERC2 and OCA2 can explain why many people's eyes aren't brown.  We need other genes to explain why eyes are green, blue, light brown, hazel and so on. This is where the new genes for the new study could play a role.

Making Green Eyes

Let's look at a couple of ways that these new genes might cause green eyes.  They might do this by turning the OCA2 gene up or down.

 

Imagine someone has a working HERC2 and OCA2 gene.  Without other genes around, this person would have brown eyes.  Now imagine that this person has a version of one of the new genes that turns the OCA2 gene down.  This person will now have green eyes instead of brown.

 

Now imagine someone with a weak HERC2 gene.  This person's OCA2 is turned way down so that he or she would have blue eyes if there were no other genes around.

 

But imagine that this person has a version of one of the new genes that turns the OCA2 gene up.  Now more P-protein gets made and so this person has green eyes.

 

As you can see, a single eye color can be obtained in multiple ways!  And our final eye color is determined by how all of these different genes and their different versions work together.

 

Think of the cells in the iris of your eye as melanin producing factories. The workers of these factories are proteins that serve like workers in an assembly line and carry out the different steps for making melanin.

 

So you can imagine that any of the new genes could have the instructions to proteins involved in the different steps of producing melanin. The shared efforts of these new genes could for example boost melanin levels to produce hazel eyes, or reduce total melanin resulting in blue eyes.

Why are the world's deserts located at 30 degrees latitude?

Deserts on Earth exist at 30 degrees latitude because of warm air, calm winds and virtually constant areas of high pressure forming in the atmosphere above. These deserts experience dry and hot conditions year-round and see plenty of sunlight, little wind and very little precipitation. This area of desert lands forms in the areas of latitude 30 degrees north to 30 degrees south of the Equator.

The region containing most deserts on Earth takes several names, including the Tropic of Cancer, Tropic of Capricorn and the horse latitudes. In these regions, the sun follows a high orbital path. It appears directly overhead at 12 p.m. at least once a year, a phenomenon occurring no other place on the planet. Although they exist at the same degrees of latitude, deserts bear different physical and biological features. They attain shapes and climates from surrounding landscapes.

Deserts situated near mountains generally experience less rainfall than deserts exposed in flat, open lands, as mountains absorb precipitation before it reaches deserts. The winds generated in the horse latitudes blow from a westerly direction and lack tremendous force. These winds lack the power for moving clouds across continents, which reduces precipitation in deserts. Although beneficial for desert climates, atmospheric conditions in the horse latitudes pose problems for sailors, whose boats slow to a standstill in the absence of winds.

How do ocean form?

Nearly 3.8 billion years ago, temperatures on Earth cooled below 100 degrees Celsius for the first time, allowing water, which existed on the planet in gaseous form, to condense into rain and collect on the planet's surface, according to the American Museum of Natural History. This water collected in low-lying areas, eventually becoming a primitive ocean.

This early ocean was likely very shallow and covered the majority of the Earth's surface, as continents did not exist yet and would not for some time, according to the American Museum of Natural History.

A report by the BBC indicates that the most recent of all supercontinents to form on the planet, Pangea, formed about 270 million years ago and split into sections about 200 million years ago. Pangea was a landmass covering almost one-third of the planet's surface. Scientists refer to the surrounding ocean as Panthalassa.

Pangea began splitting down the middle, allowing the Atlantic Ocean to form between South America and Africa and between North America and Europe, according to an article from the Rutgers University Department of Geologic Sciences. Signs of that split are visible on the floor of the Atlantic Ocean. Additional fractures allowed smaller oceans, such as the Indian Ocean, to form. The Pacific Ocean represents much of what was originally known as Panthalassa.