On Race

Contents

• 1. What is Race?
• 2. Race as a Social Phenomenon
  • 2.1. The Origin of Race
    • 2.1.1. A Relatively Recent Invention
    • 2.1.2. Western European Imperialism and Colonial Expansion in the Americas
    • 2.1.3. From Slavery to Racial Slavery
    • 2.1.4. The Emergence of Race
  • 2.2. A History of Race Ideology
  • 2.3. A Time Before Race
  • 2.4. Racial Projects and Racism
• 3. Race as a Biological Concept
  • 3.1. Human Variation and Race
  • 3.2. The Myth of Racial Diseases: Sickle Cell Disease
    • 3.2.1. Background on Human Genetics
    • 3.2.2. The Genetics of Sickle Cell
    • 3.2.3. The Evolutionary Role of Sickle Cell
  • 3.3. Genetic Genealogical Testing
• 4. FAQ
• Notes

1. What is Race?

Race was invented as a way to categorize groups of humans (and by extension, individuals) based on physical and social characteristics. The meaning of race, such as the perceptions and stereotypes assigned to different races, and the categories of racial groups are continually changing and are contingent on the social context of a particular time and place. Two aspects of race include:

• Race as a social phenomenon
• Race as a biological concept

These two aspects are, of course, interrelated. Outdated and unscientific conceptions of race as biological categories have historically been used to justify racial hierarchies. Conversely, the desire to justify racial hierarchies has motivated scientifically inaccurate attempts to establish different racial groups as distinct and static biological groups.

2. Race as a Social Phenomenon

As stated by Goodman et al., “We live in a society saturated with race.”. Racial thinking is used as a way to understand the diverse forms of human physicality and social expression. Often, racial thinking is inaccurate and inadequate for understanding and explaining the nature and various mechanisms of human diversity. Nonetheless, it plays a major role in shaping our interpretations of individual and group differences as well as our social networks and material relations. We identify with racial categories and experience the associated effects of in-group and out-group racial dynamics. The reality of race begs some interesting questions: has race always existed? How did race become so central to our lives?

History has shown that various social constructs have existed through which people use to create shared understandings about the world. Social constructs are malleable, with new modes constantly forming and deforming, and are contingent on the social, political, and economic context of a particular time and place. Like gender and class, race is a social construct: a system of ideas, identities, and material relations that developed historically. The body of existing anthropological, historical, and sociological knowledge has shown that race, in its modern form, emerged gradually within the context of Western European imperialism and colonial expansion beginning in the 15th century. We will find that the incredible pervasiveness and durableness of race formed from a historical development where the “forces of tradition, religion, law, and science conspired, and at times competed, to define and influence human diversity.”

2.1. The Origin of Race

2.1.1. A Relatively Recent Invention

Audrey Smedley explains, in her article “The Origin of the Ideology of Race,” how race is a relatively recent invention:

Contemporary historical studies have revealed that “race” was a relatively recent invention in human history (Allen 1994; 1997; Fredrickson 2002; Hannaford 1996; Smedley 2007). Historians point out that our popular beliefs about human races did not exist before the late 17th century. These authors agree that race was essentially a cultural invention about human differences that had its basis in social, political, and economic conditions. . . .

“Race” originated as a folk ideology about human differences and was constituted of beliefs and attitudes about these differences. These attitudes and beliefs emerged over a period roughly beginning in the 1690s and continued over the 18th century, a period which also coincides with numerous laws establishing American slavery. From the late 18th century on, these popular beliefs were buttressed by the appearance of scientific arguments that were designed to confirm them. . . .

2.1.2. Western European Imperialism and Colonial Expansion in the Americas

Continuing, Smedley explains the history of how the modern conception of race gradually formed within the context of Western European imperialism and colonial expansion in the Americas:

In 1607, the English began settling colonies in North America, following the pattern of the Spanish and Portuguese, with the objective of acquiring wealth. The early colonists, who took over most of the land, unsuccessfully tried to force conquered Indians to work. However, the Indians did not take well to forced labor; many died of European diseases and others escaped to unknown territories. The English then turned to importing indentured servants from the British Isles, many of them Irishmen captured in wars. These were poor men and some women who were allowed to work off their transportation debts and subsequently obtain their freedom. The need for labor was acute: early colonists barely survived on what they could produce themselves, and we know the death rate was high. They soon learned that the one product that would bring them considerable wealth was tobacco, a highly labor-intensive crop.

The first Africans who arrived in Virginia colony in 1619 were not initially considered slaves. They had Spanish or Portuguese names and were familiar with European culture. Like other poor laborers, they were treated as indentured servants who could also achieve their freedom after paying their debts. Some of these Africans worked hard and acquired land, houses, livestock, and tools on their own. . . . Moreover, there is little or no evidence that Africans were treated differently from other people of the same class. They were assimilated into colonial society as were others. When they acquired land, they participated in the assembly, the governing body of the colony, voted, served on juries, and socialized with white planters.

Historian Edmund Morgan writes,

There is more than a little evidence that Virginians during these years were ready to think of Negroes as members or potential members of the community on the same terms as other men and to demand of them the same standards of behavior. Black men and white serving the same master worked, ate, and slept together, and together shared in escapades, escapes, and punishments. (1975:327)

He adds, “It was common for servants and slaves to run away together, steal hogs together, get drunk together. It was not uncommon for them to make love together” (327). Indeed, there was no stigma associated with what we today call “interracial” marriages.

Until the early 18th century, the image of Africans among most Europeans was generally positive. They were farmers and cattle-breeders; they had industries, arts and crafts, governments, and commerce. Moreover, they had immunities to Old World diseases, they were better laborers under the tropical conditions of the southern settlements; and they had nowhere to run and hide once transplanted to the New World (E. Morgan 1975; Smedley 2007).

To summarize the situation so far as of the early 18th century, we find that racial thinking had not yet taken hold. Slaves and indentured servants - irregardless of their ancestry, whether they were from Africa or Europe - worked alongside each other and were treated similarly. Those with ancestry from Africa were treated similarly to other people of the same class and were assimilated into colonial society.

The social, economic, and political situation of the mid 17th century would set the context through which colony leaders were motivated to impose social controls over the population to prevent rebellion. By then, economic inequality had developed to where few men from among the earliest settlers controlled most of the fertile land, having established large plantations growing crops such as tobacco. Poor servants who had achieved freedom, which included people with ancestry from Europe, Africa, and the Americas, found it difficult to acquire land and were unhappy with the corruption and abuse of power on the part of the wealthy men who ruled the colonies. The class conflict between the poor and the wealthy land owners incited rebellions, robberies, and contempt towards colony leaders.

The most famous rebellion occurred in 1676 where Nathaniel Bacon led an uprising of thousands of poor workers, composed of an alliance between European indentured servants and Africans, to advance their class interests and to confront the corruption of colony leaders. As Smedley explains,

Led by Nathaniel Bacon, this uprising of thousands of poor workers in Virginia was the first major threat to social stability. The rebellion dissipated after Bacon’s death, but British royal commissioners sent out to suppress the uprising realized the population at large had supported the rebellion and were “sullen and obstinate.” On one occasion they faced a dissatisfied “rabble” of “400 African and 600 or 700 European bond laborers, chiefly Irish” (Allen 1994:218).

2.1.3. From Slavery to Racial Slavery

The state of social discontent by the end of the 17th century, which culminated in Bacon’s Rebellion, scared colony leaders and the wealthy and motivated them to seek new ways to protect their class interests and power. As described by Smedley, “The colony leaders soon recognized the need for a strategy to prevent such occurrences in the future and to ensure that a sufficient number of easily controlled laborers were made available to plantation owners.”

Colony leaders and the wealthy, in their quest to impose effective social controls over the population and to ensure the existence of a sufficient force of easily controlled laborers, began to target those with African descent. Given the varied physical characteristics of the working population, colony leaders and wealthy perceived that they could separate them and demarcate some for permanent slavery. Part of this demarcation included designating a lower class based on the easily-perceivable characteristic of skin color.

There were, of course, other institutional reasons why those with African descent were targeted:

• Sources of workers from England began to decline in the latter part of the 17th century as jobs became more available at home
• The slave trade with Africa increased as internal warfare in Africa made more and more people available for the slave trade
• Within the context of increased slave availability from Africa, Africans were now being brought directly from Africa rather than from African communities established in Europe or other European colonies
• Africans who were brought directly over from Africa were not Christians and were unfamiliar with European languages, customs, and traditions
  • Thus, they were vulnerable to exploitation
  • Being non-Christians, traditional religious protections for particular sects could be disregarded
  • Colony leaders argued that, being from Africa, they had no rights under British laws and could therefore be subject to forced and permanent labor

The rights and social, political, and economic mobility of Africans, who were now being brought directly from Africa, began to be restricted. Anthony Parent finds that

a powerful planter class, acting to further its own economic interests, deliberately brought a new form of servitude, racial slavery, to Virginia over the period 1690–1725. In this period, dozens of laws were passed restricting the rights of Africans and their descendents, imposing permanent slavery on them, and forbidding masters to set them free. By 1725, even free Negroes were prohibited from voting.

2.1.4. The Emergence of Race

As the laws began to change in order to restrict the social, political, and economic mobility of Africans and to demarcate them as permanent slaves, new social categories - what we would think of as race in the present - emerged in response. Smedley describes how

Colonial leaders were simultaneously doing something else: they were laying the basis for the invention of the idea of race and racial identities. They began to homogenize all Europeans, regardless of ethnicity, status, or social class, into a new category. The first time the term “white,” rather than “Christian” or an ethnic name (English, Irish, Scots, Portuguese, German, Spanish, Swede), appeared in the public record was seen in a law passed in 1691 that prohibited the marriages of Europeans (“whites”) with Negroes, Indians, and mulattoes (Smedley 2007:118). A clearly separated category of Negroes as slaves allowed newly freed European servants opportunities to realize their ambitions and to identify common interests with the wealthy and powerful. New laws offered material advantages and social privileges to poor whites. In this way, colony leaders consciously contrived a social control mechanism to prevent the unification of the working poor (Allen 1997). Physical features became markers of racial (social) status. As Virginia’s governor William Gooch asserted, the assembly sought to “fix a perpetual Brand upon Free Negroes and Mulattos” (Allen 1997 :242).

To summarize, race is not just an abstract idea. Echoing the the analysis of race as a social construct, we find that it is a system of ideas, identities, and material relations. It developed historically within the context of Western European Imperialism and Colonial Expansion in the Americas where colony leaders, by the end of the 17th century, sought ways to control the population to ensure that a sufficient number of easily controlled laborers was available to plantation owners. To do this, a series of laws were passed to strip the rights of Africans in order to establish a reserve of easily controlled workers. The institutional reasons Africans were targeted include the desire of the powerful and wealthy to easily separate the working class based on physical characteristics (effective and easily identifiable social control), the increased slave availability from Africa, the changing migration patterns of Europeans and Africans, and the unfamiliarity of Africans who were brought over from Africa with European languages, customs, and traditions.

As Africans were legally targeted which constituted new material relations, new social categories - notably, race - emerged. The clearly separated category of Africans as slaves meant that freed Europeans identified common interests with the wealthy and powerful. New laws offered material advantages and social privileges to those who were “white”, a term which first emerged in 1691 in a new law that demarcated European ethnic groups as “whites” and prevented the marriage of “whites” with Negroes, Indians, and mulattoes. Within the new material context of Africans as slaves, race began to hold a suffocatingly strong grip on how we understand human diversity as material oppression and privilege began to be essentialized with racial categories.

2.2. A History of Race Ideology

The development of the material relations that gave rise to racial slavery was motivated by colony leaders and the wealthy to maintain a population of easily controlled laborers who were available to plantation owners. Developing alongside the institutional rearrangement (through law) of material relations was new social ideas, ideologies, and identities. In our case, we find that race ideology developed alongside the establishment material relations which constituted slavery targeted at Africans within the colonies of the Americas. Race ideology developed because humans assign social meaning in order to interpret and justify the changing material landscape. As Africans were institutionally degraded of their social class and mobility, new ideas, what we now call race, were introduced to interpret and justify their new social position. Conversely, these new racial ideas would then be used to interpret and justify the distribution of material conditions among different racial population. This feedback loop is essentially the classic cycle of material relations (the distribution of control over capital) reinforcing the social superstructure (law, politics, art, culture etc.) and vice versa. As Smedley puts it,

What colony leaders were doing was establishing unequal groups, called races, and imposing different social meanings on them. As they created the institutional and behavioral aspects of slavery, the colonists were simultaneously structuring the ideological components of race.

The system of slavery that the colonies established towards the end of the 17th century and into the early 18th century was not, in and of itself, racial slavery. It became racial slavery when race ideology developed alongside it in order to interpret and justify the rearrangement of material conditions along racial lines. In this sense, racial slavery is the the material relations of slavery holistically combined with race ideology.

The cultural basis which race ideology initially borrowed from was the idea of a “savage.” Smedley describes how

The first “savages” that the English had created in their minds were the “wild Irish.” In the late 16th century, after centuries of conflict and brutal warfare with the Irish, Queen Elizabeth declared that the Irish were natural “savages” incapable of civilization.

With the “savage” characterization firmly implanted in the minds of the English from their experience with the Irish, the next population to be designated with the label were Native Americans. As Smedley puts it,

Native Americans had been deemed “savages” when they resisted English appropriation of their lands, but this image began to change in the late 18th century to a more benign “noble savage.” By then most Native Americans were dying out or had been forcibly driven onto reservations, a process begun in the previous century in the northeast colonies.

Continuing, Smedley describes how colony leaders invented race ideology by applying the savage characterization to Africans after reducing them to permanent slavery:

Now, by reducing Africans to permanent slavery, prohibiting owners from freeing slaves, and preventing their education and training, the English invented a new savage. From the 18th century on, negative characterizations of Africans formed part of a new rationalization for enslavement. These became the stereotypes of races and race differences that we inherited in the 19th and 20th centuries.

We find that the initial stereotypes of race ideology, which designated Africans as “savages,” did not invoke differences in physical features but rather identified Africans as uncivilized heathens. Defenders of slavery, however, continued to develop race ideology by incorporating physical and behavioral aspects into it:

The defenders of slavery exaggerated human group differences and developed an ideology about these differences that dehumanized “the Negro” and demoted him in popular eyes to a status closer to the apes, placing the onus of slavery on its victims. . . .

Race ideology was based in a belief in the existence of separate, distinct, and exclusive groups that were made unequal by God or nature. African Americans, the most inferior, were at the bottom of the hierarchy, European whites (some of them) were at the top. Each race was thought to have distinct physical and behavioral traits. Thus, we have the continuing stereotype of African Americans as lacking in intelligence, lazy, overly sexed, loud, irrational, musical, emotional, and superstitious. Finally, it was believed that these race differences were inherited and immutable; thus, they could not be transformed or transcended (see Smedley 2007).

We find that in the course of race ideology development, defenders of slavery were looking for any physical and social difference between Africans and other populations. These differences would be tied into a social narrative that was used to justify the social positions of Africans as slaves. Over the course of this development, both physical and behavioral traits would end up being essentialized to race and become considered as inherited and immutable.

By 1865, the Civil War had ended slavery but did not end race, which continued to mark social status and be used as a lens to interpret and understand human diversity. Smedley describes how

After the Civil War, white Americans had been so deeply conditioned to the beliefs in the inferiority of the low-status races (blacks and Indians) that they could not accept them as equal citizens. They made enormous efforts to keep them separate and inferior and were largely successful as the statistics regarding the well-being and social and economic status of blacks and Indians demonstrate even today (Jones 2009; Macartney 2011).

2.3. A Time Before Race

2.4. Racial Projects and Racism

Common discourse over race can be confusing and unproductive because the terms and ideas used to conceptualize race are often ill defined, too broad or too narrow, and contradictory. Historian George Frederickson has observed that “Although commonly used, ‘racism’ has become a loaded and ambiguous term.” Often, the term “racism” is used to exclusively describe actions that are performed by individuals who have a conscious intent to discriminate based on race. Examples include actions such as a hiring manager denying an applicant based on stereotypes about the applicant’s perceived race or hate crimes committed based on the victim’s perceived race. But as pointed about by Omi et al., “Missing from such a narrow interpretation of racism [based exclusively on conscious intent by individuals] are the ideologies, policies, and practices in a variety of institutional arenas that normalize and reproduce racial inequality and domination.” One would miss out on how the modern system of private ownership in housing, which in the present could be argued to employ an insignificant number of consciously racist workers, nonetheless still continues to segregate land resources among different racial groups. One would miss out on how African Americans in the present are still affected by the redlining policies that started in the 1930s and continued into the 70s even if the workers organizing housing resources do not have any conscious racial intent.

To help us better understand race and racism in a way that fully captures their meaning and effects, we will introduce the conceptual tool of a racial project. As described by Omi et al.,

A racial project is simultaneously an interpretation, representation, or explanation of racial identities and meanings, and an effort to organize and distribute resources (economic, political, cultural) along particular racial lines. Racial projects connect what race means in a particular discursive or ideological practice and the ways in which both social structures and everyday experiences are racially organized, based upon that meaning. Racial projects are attempts both to shape the ways in which social structures are racially signified and the ways that racial meanings are embedded in social structures.

Racial projects occur at varying scales, both large and small. Projects take shape not only at the macro-level of racial policy-making, state activity, and collective action, but also at the level of everyday experience and personal interaction. Both dominant and subordinate groups and individual actors, both institutions and persons, carry out racial projects. The imposition of restrictive state voting rights laws, organizing work for immigrants’, prisoners’, and community health rights in the ghetto or barrio are all examples of racial projects. Individuals’ practices may be seen as racial projects as well: The cop who “stops and frisks” a young pedestrian, the student who joins a memorial march for the slain teenager Trayvon Martin, even the decision to wear dreadlocks, can all be understood as racial projects. Such projects should not, however, be simply regarded and analyzed as discrete, separate, and autonomous ideas and actions. Every racial project is both a reflection of and response to the broader patterning of race in the overall social system. In turn, every racial project attempts to reproduce, extend, subvert, or directly challenge that system.

Racial projects do the ideological work that conditions us to understand human diversity in racial terms while simultaneously doing the structural work of organizing humans along racial lines, both materially and culturally. With our understanding of racial projects in mind, we can now define what racism is. Referencing Omi et al., “A racial project can be defined as racist if it creates or reproduces structures of domination based on racial significations and identities.” Similarly, anti-racist projects are those that “undo or resist structures of domination based on racial significations and identities.”

Under our conception, we find that most activities and institutions in life are racial projects in some way. Racial reparations are racial projects and redlining is a racial project as they both organize resources based on race. Commonly, one hears that some project takes race into account and immediately dismisses it as racist - but doing so would miss out on the nuance of whether that project reproduces or dismantles racial hierarchy. With the conceptual tools we have so far developed, we can ask a more precise question: in what ways is the racial project racist or anti-racist? Redlining, which has historically reproduced racial structures of domination by limiting the social mobility of African Americans, is then a racist project. Racial reparations, such as the Civil Liberties act of 1988 which compensated Japanese Americans who had been interned during World War II, can be argued to be anti-racist because it dismantles (to some effect) the structures of domination that had been built from the internment of Japanese Americans who were stripped of their social class and mobility. To reiterate, a determination of what ways a racial project is racist or anti-racist has multiple dimensions - it could reproduce racial structures of domination in certain aspects and could destroy them in other aspects. Such a determination requires an analysis of the empirical, material, and cultural motivations and effects of the racial project.

3. Race as a Biological Concept

Race ideology has historically motivated attempts to develop a definition of race based on distinct and static biological groups. The purported existence of biologically distinct and static groups of people have been used to justify social division along racial lines by claiming that they merely reflect biological reality. As described by Goodman et al.,

It was not until the late 18th century that naturalists influenced by European Enlightenment models of rationality and empiricism enlisted science to justify the folk taxonomy of race. Science, they hoped, could rationalize these contradictions of freedom, slavery, and genocide by establishing a basis in nature for the existing social order.

Following the late 18th century efforts to create scientific taxonomies of race, race scientists during the Great Depression attempted to establish a genetic basis for the transmission of racialized traits. They hoped to justify economic and social inequality by showing how intelligence and other behavioral characteristics such as criminal behavior and work ethic were simply reflections of genetics (which were divided along discrete and static racial lines) and thus inherited and inevitable.

3.1. Human Variation and Race

Certainly, humans vary biologically. The incredible diversity of humans is immediately visible in our phenotypic variety. And when looking at the level of human genetics, we also find incredible variation. Modern scientists understand human genetic variation in terms of populations. We know that variations in DNA and allele frequencies tend to vary gradually and continuously across environmental and geographical transitions (called clinal variation) and that different biological traits have different clinal distributions. Such an understanding about human genetic variation is directly at odds with the idea of discrete, static biological groups. Knowing that biological traits tend to vary continuously means that making a racial distinction between a trait such as skin color is arbitrary and lacking in taxonomical significance. Skin color varying continuously as a function of geographic distance simply does not lend itself to any clear separation.

Borrowing from Goodman et al., we list five key facts about human variation and how they are incompatible with a racial conception of human variation:

1. Evolution, rather than race, explains human biological variation. Race-as-biology is based on the false idea of fixed, ideal and unchanging types. Race categories were first a European folk idea from an era in which the world was seen as fixed and unchanging. As is outlined in the history of mismeasurement (chapter 4). European scientists once thought the world was fixed and static. All of that changed with evolutionary theory. The illusion of unchanging racial types is completely incompatible with evolutionary theory.
2. Human variation is continuous. Allele frequencies, or variations in DNA, tend to vary gradually. Therefore, there is no clear place to designate where one race begins and another ends. Skin color, for example, the physical characteristic we most often use to distinguish “races,” slowly changes from place to place and person to person.
3. Human biological variation involves many traits that typically vary independently. Skin color, for example, is only correlated with a few other traits such as hair and eye color, leaving unpredictable the huge number of other traits. While we might be able to predict that someone with light skin is more likely to have light hair, we are unable to predict virtually any other traits.
4. Genetic variation within so-called races is much greater than the variation among them. One might assume that genetic variation among races is great; however, there is actually little genetic variation among the groups we have come to call races. For example, two individuals who might identify as “white” might well be far more genetically different from one another than from someone self-identified as “black.” Moreover, rather than seeing Europeans and Asians as “races,” they may be more accurately seen as different-looking subsets of Africans, since the human population descended from human beings living on that continent. Given these genetic realities, race simply fails to account for the genetic variation among us.
5. There is no way to consistently classify human beings by race. Race groups are impossible to define in a stable and universal way, and if one cannot define groups one cannot make scientific generalizations about them. Race groups are unstable primarily because the socially determined color line changes over time and place. Someone considered “white” in Brazil can be considered “black” in the United States; someone who lives as “white” in the United States today might have been considered “Mexican” a generation earlier. Roma and other “dark” babies in Romania are classified as inferior, and even “black” and were often put up for adoption at the fall of the Communist regime. In the United States, where white couples clamored to adopt them, these children were seen as “white.” Their racial classification was totally nationally dependent. Since there is no consistent way to classify human biological diversity using race categories, we cannot use these categories to say anything scientific about human biological diversity.

Given what we know about human population biology, we find that race inaccurately describes and explains human variation. Unfortunately, the myth of race being genetic has continued to be passed down a cultural canon that purports it to reflect biological reality. As Goodman et al. summarizes,

This conflation of race and human biological variation is no less than the chief weapon of racists. How this conflation came about is doubtlessly intentional in part and serendipitous in other parts. Once the conflation was fixed, it could be used by deeply intentional racist scientists and others to support slavery and other race-based institutions. More important still, the racial smog caused many to see racist institutions as natural, and instead of fighting racism, we aided and abetted racism. It is time to disarm.

3.2. The Myth of Racial Diseases: Sickle Cell Disease

In the United States, sickle cell disease is often viewed as a “black” disease. This mythos views sickle cell disease as affecting a particular racial type: Africans. It understands Africans as constituting a discrete and static biological group whose particular genetic composition lends itself to sickle cell disease. This false conflation between race, genetics, and consequently diseases has historically misled scientists and physicians who saw sickle cell disease as a “disease of the negro blood.”

3.2.1. Background on Human Genetics

Deoxyribonucleic acid (DNA) is a molecule composed of nucleotides arranged in two long strands which form a double helix that carries the biological instructions for the development, functioning, growth, and reproduction of living organisms. Nearly every cell in a person’s body has the same DNA and it is generally located in the cell nucleus. In this nucleus, the DNA molecule is packaged into thread-like structures called chromosomes. In humans, each cell generally¹ contains 23 pairs of chromosomes for a total of 46.

Genes, which are particular sequences of nucleotides in DNA, are the basic functional units of heredity which encodes the instructions for the synthesis of proteins and other functions. Most genes are the same in all people, but a small number of genes (less than 1 percent of the total) are slightly different between people. Alleles are forms of the same gene with small differences in their sequence of DNA nucleotides. These small differences contribute to each person’s unique physical features.

3.2.2. The Genetics of Sickle Cell

The genetic variant called sickle cell is responsible for sickle cell trait and sickle cell disease. Humans that inherit two copies of the sickle cell gene have sickle cell disease which is a phenotypic variation of the red blood cell. Normal red blood cells are flexible disks that can move easily through small blood vessels whereas sickled red blood cells are crescent-shaped and can coagulate and get stuck in small blood vessels causing anaemia. On the other hand, humans that inherit one copy of the sickle cell gene have sickle cell trait which offers a resistance to malaria without the detriments of sickle cell disease.

While most phenotypic variations such as skin color or the risk of heart disease are remarkably complex, the genetic condition that gives rise to sickle cell is exceptionally simple. The genes responsible for sickle cell disease are those that code for the shape of the hemoglobin molecule (an essential protein that carries oxygen in red blood cells). As explained by Goodman et al. the genetic condition

boils down to . . . the gene . . . on chromosome 11. It [the gene] makes what is called the beta chain or beta globin molecule, a string of 146 amino acids that is essential to the shape of the hemoglobin molecule. At the sixth position a simple point mutation occurred and changed a letter A to a G that changed the amino acid from a guanine to a valine. Like that, the beta chain wraps differently. Getting one or two of the sickle cell alleles makes a big difference. One copy = sickle cell trait; two copies = sickle cell disease.

3.2.3. The Evolutionary Role of Sickle Cell

Malaria is a disease caused by Plasmodium parasites. The parasite infects humans through the bites of infected mosquitoes. The parasite grows and multiplies inside red blood cells causing them to burst, releasing more parasites into the blood and infecting more red blood cells. This destruction of red blood cells can cause severe anaemia and other health complications.

Malaria is a dangerous disease and a major public health threat. As described by Goodman et al.,

The Center for Disease Control has estimated that there are as many as 500 million cases of malaria each year, and more than one million people die annually. Malaria remains the leading cause of death in Africa for children under five years of age. Malaria persists in part because the conditions that have always led to infected mosquitoes coming into contact with humans – stagnant waters in hot, humid climates – persist. Furthermore, the mosquitoes that carry malaria, in particular Anopheles, develop resistance to insecticides, and the parasite itself can develop resistance to antibiotics.

Since malaria is among the most debilitating and deadly diseases, a genetic adaptation that provides humans with a survival advantage over the disease is thought to likely have been selected through natural selection. Scientists have linked sickle cell, a genetic variation that can provide increased resistance to malaria, to evolution as a genetic adaptation. One should keep in mind, however, that the sickle cell variation is a balance between inheriting one copy of the gene (which provides sickle cell trait and thus provides malarial protection without sickle cell disease) or two copies (which causes sickle cell disease).

Surveying the distribution of the genetic variation that causes sickle cell disease, we find that the trait is found in those who have ancestry from particular regions of the Middle East, India, Mediterranean, and Africa. Those regions with increase prevalence of sickle cell are also generally the same regions that were historically affected by malaria which is in line with the malarial adaptation theory.

In conclusion, we find that sickle cell disease is a result of evolution within the context of malaria. It is more common in those who have ancestral roots from particular regions of the Middle East, India, Mediterranean, and Africa. Contrary to popular mythos, race has nothing to do with the genetic adaptation. African Americans with ancestry from northern and southern Africa, for example, are not likely to have sickle cell. The overrepresentation of sickle cell disease in African Americans in the United States has to do with migration patterns, including the Atlantic slave trade, where Africans who relocated to the America had ancestry from regions where sickle cell is more common.

3.3. Genetic Genealogical Testing

4. FAQ

Notes

1. Not all humans have a total of 46 chromosomes. Down syndrome, for example, is a condition in which a person has an extra copy of their 21st chromosome. ↩