One explanation is that the selective pressure for dark skin decreases as UV intensity decreases . At the same time there is selection for lighter skin to absorb more UV radiation, which is needed for vitamin D production.
What makes skin dark in color Choose the best answer?
A person’s skin color is determined by the amount of melanin in his or her skin. Melanin is a dark brown to black pigment produced 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.
What is the selective pressure for darker skin color?
6. Indigenous populations in low-UV environments tend to have lighter skin tones. One hypothesis is that, in low-UV environments, the selective pressure for dark skin is low . Instead, there is selective pressure for lighter skin, which absorbs more UV radiation, since UV is needed for vitamin D production.
Which of the following statements apply to the variation of human skin color?
Which of the following statements apply to the variation in human skin color? Human skin color variation is primarily determined by the type and amount of melanin pigment in the skin . Human skin color variation evolved recently in hominid evolution, once some populations of our human ancestors migrated out of Africa.
Which of the following contributes to variation in pigmentation of skin color?
Human skin color, determined by the pigment melanin , is a highly variable trait. The reason for these variations has been an enduring mystery of biology. Although sunlight exposure contributes to skin pigmentation, much of the variation we see is likely genetic.
What are three types of selection pressures?
- Resource availability – Presence of sufficient food, habitat (shelter / territory) and mates.
- Environmental conditions – Temperature, weather conditions or geographical access.
- Biological factors – Predators and pathogens (diseases)
How is skin color determined?
Skin colour or pigmentation is determined by three pigments or chromophores : Melanin – a brown/black or red/yellow polymer produced by melanosomes in melanocyte cells. ... Dietary carotenoids (e.g. carrots) – to a much lesser degree, and is often seen as a yellow colour on the palms.
What are the three factors that affect skin color in humans?
- melanin: Any of a group of naturally occurring dark pigments responsible for the color of skin.
- melanocyte: A cell in the skin that produces the pigment melanin.
- keratinocytes: Cells that take up and store melanin.
- eumelanin: The type of melanin mainly responsible for brown and black skin.
Which skin color is most common?
The variety of human skin colours is immense, but we have very few words to describe that range of colour in detail. For that reason, I would have to say the most common skin colour is brown .
What is fair skin tone?
Fair – The lightest range of skin tones . You likely burn easy, and have light or red hair. Light – Generally those with skin considered “light” have warmer undertones (we’ll get to that in a second) than those with fair skin. ... Medium – You have a tan skin tone with warm golden or olive undertones.
Is variation in human skin color an example of incomplete dominance?
Human skin color is another example of incomplete dominance because the genes that produce the melanin (pigment) for either dark or light skin cannot show dominance over the other. Thus, the offspring produced have an intermediate skin color between the parents.
Is skin color an example of a gene?
Polygenic Inheritance : Human skin color is a good example of polygenic (multiple gene) inheritance. Assume that three “dominant” capital letter genes (A, B and C) control dark pigmentation because more melanin is produced.
What role do you suspect melanin plays based on this information?
Melanin is a pigment produced in the skin that helps protect cells from cancer-causing UV rays . ... Individuals with lighter skin incur greater damage from UV and thus have significantly higher risk for skin cancer.
Which skin tone is most attractive?
A new study by Missouri School of Journalism researcher Cynthia Frisby found that people perceive a light brown skin tone to be more physically attractive than a pale or dark skin tone.
Which hormone is responsible for skin whitening?
Melanocyte-stimulating hormone describes a group of hormones produced by the pituitary gland, hypothalamus and skin cells. It is important for protecting the skin from UV rays, development of pigmentation and control of appetite.
Which substance is responsible for skin Colour?
Melanin content of skin is the main determining factor of skin and hair colour; hair is considered a form of skin with regards to pigmentation. Melanin is synthesized by melanosomes found in skin cells called melanocytes.
