en

Cultures

Have you ever been to situations where you found the other people's behavior/way of speaking/appearance (or even skin color - see below!) unusual?

This often happens because we come from different cultures.

As the world opens up and everyday we may surround ourselves with people we don't know, I thought learning about different cultures can help us understand other people's behavior, culture and traditions.

This site will hopefully give you more insight into different cultures, you can discover them and learn more about why we may behave differently.

And I really hope it will reduce racism too!

*Of course, behavior is not only due to cultures, but they can often influence us*

Have you ever been wondering about why our world is so colorful?
How come that some of us have "black", "brown", "yellowish" or "white" skin color?

Skin color in humans is primarily determined by the amount and type of melanin produced by cells called melanocytes, which are found in the epidermis, the outermost layer of the skin. The biological background behind someone's skin color can be understood through the following key factors:

Melanin: Melanin is responsible for the color of the skin, hair, and eyes. It is produced by melanocytes and distributed to other cells in the epidermis. There are two main types:

  • Eumelanin: This is the most common form of melanin and comes in two varieties, brown and black. It is responsible for darker skin tones.
  • Pheomelanin: This type is yellow to red in color and is more common in people with lighter skin, particularly those with red hair.

(The more melanin, particularly eumelanin, the body produces, the darker the skin color will be.)

People living in equatorial regions have higher melanin production, particularly eumelanin, which provides better protection against the harmful effects of ultraviolet (UV) radiation from the sun.

In regions with less intense sunlight, such as northern Europe and parts of East Asia, there was less evolutionary pressure to maintain high levels of melanin. In fact, lighter skin allows more efficient production of vitamin D in conditions of low UV exposure:

  • Ultraviolet (UV) radiation from the sun has been a significant evolutionary pressure shaping skin color in human populations. UV radiation can cause damage to DNA and increase the risk of skin cancer. However, it is also necessary for the synthesis of vitamin D, which is crucial for bone health and immune function.
  • In regions near the equator, where UV radiation is intense year-round, darker skin evolved as a protective mechanism. High levels of eumelanin in the skin absorb and dissipate UV radiation, reducing the risk of DNA damage and skin cancer.
  • In contrast, in regions farther from the equator, where UV radiation is weaker, lighter skin evolved to allow more UV rays to penetrate the skin, facilitating sufficient vitamin D production. This adaptation was particularly important in areas with long winters and limited sunlight.  

The lighter skin in East Asians is partly due to specific variants in the OCA2 and DDB1 genes, which influence melanin production and distribution. However, the "yellow" undertone is thought to be a result of a particular balance of pheomelanin and eumelanin, along with the way light interacts with the skin. 

The diversity in human skin color is a result of a complex interplay between genetics, environment, and evolution. The type and amount of melanin produced in the skin, influenced by various genes, determine whether someone has a black, brown, or lighter (including the historically termed "yellow") skin tone. Evolutionary pressures, particularly those related to UV radiation, have played a significant role in shaping the distribution of skin colors across the globe. 

Skin color is an adaptive trait that has evolved over thousands of years to meet the specific environmental challenges faced by different human populations, reflecting the incredible diversity and resilience of the human species.