Deck 14: Modern Human Biology: Patterns of Variation

Question 1

Imagine you're with a group of friends discuss-ing human diversity and the number of races. One friend says there are three clearly defined races, a second says five, while the third isn't sure. Would you agree with any of them? Why or why not?

Answer 1

The individuals are classified under various categories on the basis of similar traits and combinations of several characteristics such as skin color, face shape, nose shape, eye color, hair color and hair form (like curly or straight). These categories, traditionally, have been called as races. The term 'race' has been used as a synonym of 'species'. It has also been referred to various culturally defined groups since the 1600s.
Johann Friedrich Blumenbach, a German anatomist classified humans on the basis of skin color into 5 races; namely, white, yellow, red, brown and black. His system of classification was not accepted as these categories were arbitrary and many phenotypic traits, including skin color were not discrete phenomena.
His classification system omits all the individuals who do not fall under these 5 races. Therefore, I would not agree to any of them. There are various systems that classify humans into numerous races and each racial system follows a different basis of traits for human classification into specific race.
Across the world, the race of humans is with reference to their nationality origin, for example, the people native to Asia and Africa are called as Asian and African respectively. The people belonging to a country or continent are further classified according to a different racial system of classification on the basis of their respective phenotypic variations under various races.

Question 2

For the same group of friends mentioned in question 1 (none of whom have had a course in biological anthropology), how would you explain how scientific knowledge fits (or doesn't fit) with their preconceived notions about human races?

Answer 2

People across the world are classified under various categories on the basis of similar traits and combinations of several characteristics such as skin color, face shape, nose shape, eye color, hair color and hair form (like curly or straight). These categories, traditionally, have been called as races. There are different racial systems to classify individuals among the races and these systems vary from one region to another.
Homo sapiens arose from a common ancestor, thus all the humans across the world have similar general characteristics undoubtedly, but variations have been noticed as well. These variations are due to the migration of humans to different areas. The environmental conditions are not similar everywhere on the planet as some regions are cold or hot and others are temperate.
According to respective environmental conditions, humans either got to adapt to those conditions only or got modified genetically during the evolutionary course for sustaining on earth.
The phenotypical traits of an individual are influenced by genetic makeup as well as environmental factors. The people living in hot regions are generally dark in complexion unlike those who lives in cold or temperate regions. More the genetic similarity, more closely-related are the organisms.
In some cases, individuals belonging to quite different regions may have some similar phenotypic traits and some variations as well. According to one racial classification system, these individuals may be grouped together due to their similar traits.

Question 3

Explain how the concept of race has developed in the Western world. What are the limitations of this approach? How have current genetic studies changed this view?

Answer 3

Throughout the 18 th and 19 th centuries, American and European scientist concentrated on describing and classifying biological variations in humans and other organisms as well. Linnaeus classification, which was based on behavioral and intellectual abilities, divided the humans in 4 groups.
His ranking system reflected that the Europeans, to anybody were 'superior'. J.F Blumenbach, was a German anatomist. On the basis of skin color, he divided the races into 5 types: white, yellow, red, brown and black.
His classification was rejected as this omits all the individuals who do not fall under these 5 races. By the mid 19 th century, populations were ranked on a scale based on skin color, but, it again had the sub-Saharan Africans at the bottom. Whereas, the Europeans were ranked with northern light-pigmented populations.
Many Europeans believed that the dark-pigmented people were not civilized. The individuals were classified under various categories on the basis of similar traits and combinations of several characteristics. The characteristics include skin color, face shape, nose shape, eye color, hair color and hair form (like curly or straight). These categories, traditionally, have been called as races.
The term 'Race' has been used as a synonym of 'species'. It has also been referred to various culturally defined groups since the 1600s. When the Darwin's theory of natural selection came into existence, the concept of race was understood to be baseless.
The humans or Homo sapiens are polytypic species that refers to individuals varying in one or more traits among themselves. In western world, the physical traits such as skin color were used to classify humans into various categories.
Hence, it is not justified to classify the organism of same species on the basis of phenotypic characters such as skin color. This results in discrimination among humans native to various regions. The recent genetics studies revealed that the skin color is influenced by certain environmental or genetic factors.

Question 4

Explain how modern genetic studies can contribute to our understanding of biological variation in humans. Be as specific as possible.