Why are people different skin colors, skin tones?

Why are people different skin colors, skin tones? Let's find out the answer for this fact right here.

People noticed interesting facts that long ago that people from different parts of the world often had different skin colors. For example, people who lived in the tropics usually had darker skin than people who lived in colder climates.

Over time, scientists who studied the human body learned that variations in skin color appeared to be adaptive traits that were passed through genes from parents to children. These traits corresponded closely with geography and the Sun's ultraviolet (UV) radiation.

A person's skin color is determined by the amount of melanin in his or her skin. Melanin is a dark brown to black pigmentproduced by special cells called melanocytes. Melanin's purpose is to protect the skin from the Sun's harmful UV rays.

Ultraviolet radiation can cause skin cancer. Melanin acts as a natural sunscreen by absorbing these UV rays. The more melaninyour skin has, the darker your skin will be and the more protection it will have against UV rays.

People with light skin have just a little melanin. People with darker skin have more melanin. People with yellow skin tones have more or another type of pigment called carotene. 

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People who live in the tropics are exposed to more of the Sun's harmful UV radiation. As a result, their skin tends to become darker as the body produces more melanin to counteract the effects of the Sun's rays. Over successive generations, genes are passed down from parents to their children, including the tendency to produce a certain amount of melanin given the area where they live.

Likewise, northern peoples tend to have lighter skin colors, because they don't receive as many of the Sun's harmful UV rays. As a result, their bodies do not need to produce as much melanin, which makes their skin color lighter.

Also, lighter skin tones in northern areas allow more UV rays to penetrate the skin to help produce the essential amounts ofvitamin D that the body needs. The body must always strike a careful balance to make sure it receives just enough UV radiation to make essential vitamin D, while avoiding overexposure that can lead to skin cancer.

For example, in some northern coastal areas, such as Alaska and Canada, you'll notice that native peoples tend to have darker skinthan you might otherwise expect. This is usually because they eat a diet rich in seafood that provides all the vitamin D their bodies need. As a result, their skin produces more melanin, which makes it darker.

Of course, in today's modern world of international travel, people of all races, ethnicities, and nationalities travel and live all over the globe. Their individual bodies adapt to conditions where they live over time, and they pass on these traits to their children, which helps explain the myriad skin tones we see all around us every day.

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Depression during pregnancy may affect children's mental health

Depression in pregnancy is thought to affect up to one in five women globally in the late stages of pregnancy and shortly after birth. It is characterised by low mood and feelings of hopelessness, and is brought on by a number of factors that can include life events such as bereavement, and changes in brain chemistry.

Depression in pregnancy and children's mental health problem

Previous work from a team at Imperial College London suggests depression during pregnancy may affect the development of the baby while in the womb, as well as affecting bonding between mother and child after birth.

Now, the same team have shown that depression or anxiety can reduce the enzyme in the placenta that breaks down the 'stress hormone' cortisol, possibly causing more foetal exposure to the hormone. The foetus may also undergo epigenetic changes under stress, where underlying DNA stays the same but expression of that DNA is altered, perhaps affecting mental health during childhood.

Until now, much of the research into depression during pregnancy has focused on high income countries. The team argue that the problem is more common in low- and middle-income countries, and hence more resources are now needed in these areas to help expectant and new mothers. Not only is more investment needed in research, but also the development of appropriate low cost interventions that are specific to these areas.

Depression in mothers in low- and middle-income countries is common during and just after pregnancy. Women are more likely than in richer countries to experience intimate partner violence and have little social support. Furthermore, unintended pregnancies are more common, as are malnourishment, infections, and crowded living conditions.

The risk factors are often more intense and more common than in high-income countries. These factors also intensify one another -- for example, a malnourished mother or child may have too weak an immune system to fight an infection, exacerbating the mother's stress which then contributes to depression.