It's AumSum Time.
Why do we have birthmarks?
Because tattooing is expensive dude.
No.
Birthmarks are colored marks on our skin.
Which are present at birth or appear shortly afterwards.
Birthmarks are of two types, vascular and pigmented.
Vascular birthmarks are caused when a lot of blood vessels clump together.
Or they are stretched wider than usual.
Let's see some common vascular birthmarks.
First, port-wine stains.
They are reddish purple stains which appear as if someone spilled wine on the skin.
Second, hemangiomas.
They are usually raised, bright red strawberry-like marks.
Third, stork bites.
They are faint red or pink spots.
Now, pigmented birthmarks are generally caused.
When cells called melanocytes grow together in clusters.
Let's see some common types of pigmented birthmarks.
First, brown or black colored moles.
Second, bluish purple Mongolian spots.
Third, Café au lait spots.
Their color is similar to the color of coffee with some milk.
Why do we have different eye colors?
So that we can produce different colored eye lasers.
No.
Colored part of the eye is called iris.
Iris contains a pigment called melanin.
Melanin is of 2 types, pheomelanin and eumelanin.
The color of our eyes is dependent on the amount and type of melanin produced.
If we have more melanin with higher concentration of eumelanin.
Then we will have darker eye color such as brown.
However, if we have less melanin with higher concentration of pheomelanin.
Then we will probably have blue or green eyes.
Now, according to a study.
The amount and type of melanin produced in our eyes, is mainly determined by 2 genes.
OCA2 and HERC2 present on chromosome 15.
Since these genes are inherited from our parents.
We will probably have an eye color similar to our parents.
But, note that sometimes, certain mutations in the genes can produce different eye colors.
Why do we have seasons?
Because of season fairies.
No.
It is mainly because of our earth's axis.
Our earth's axis is tilted at an angle of about 23.5 degrees.
Hence, as the earth revolves around the sun.
Sometimes the northern hemisphere points towards the sun.
While sometimes the southern hemisphere.
This causes seasons.
Oh man.
It is too complicated.
Alright.
Let us observe the northern hemisphere to learn more about seasons.
When the northern hemisphere points towards the sun.
The sunrays directly strike the northern hemisphere.
Thus, the temperatures are high, resulting in summer season in that region.
However, when the northern hemisphere points away from the sun.
The sun rays fall slanting on it.
Thus, the temperatures are low, resulting in winter season.
But when the northern hemisphere is neither tilted towards nor away from the sun.
The temperatures are moderate, resulting in spring and autumn seasons.
Topic: Eyes.
Why do we have two eyes instead of one?
You don't know?
Ok, to understand this better, close your right eye.
Now, are you able to see the table kept on your right side?
You are not able to see it, right?
Ok, Let me tell you why.
Both our eyes work together and help us to see, judge and perceive a view accurately.
Having two eyes provides us with a wider field of view.
When both our eyes are open, we get a horizontal field of view of about 180 degrees.
However, with only one eye open.
We get a horizontal field of view of only around 150 degrees.
We are unable to view around 20 to 30 degrees.
Hence, we were not able to see the table when our one eye was closed.
Hey.
Did you know that our eyes see the same object from a slightly different angle?
You don't believe me?
Alright.
Look at this object.
Both your eyes see the object like this.
Now, when you see only with your left eye, the object will look like this.
While, when you see only with your right eye, the object will look like this.
Our eyes send these two slightly different images to the brain.
The brain blends or combines both the images to make a three dimensional image of the object.
Hey.
But what is the use of a three dimensional image?
A three dimensional image helps us to understand how far or how near an object is from us.
Facilitating better depth or distance perception.
This means having two eyes enables us to judge the distance of the object.
Or the depth at which the object is placed from us.