ANTH 101 – Human Diversity Discussion - DUE TOMORROW

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13.  Race and Human Variation

Michael B. C. Rivera, Ph.D., University of Cambridge

Learning Objectives

Review the illustrious and (at times) troubling history of “race”

concepts.

Recognize human diversity and evolution as the thematic roots of our

discipline.

Critique earlier “race” concepts based on overall human diversity being

lower compared to other species and human genetic variation being

greater within a population than between populations.

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Explain how biological variation in humans is distributed clinally and in

accordance with both isolation-by-distance and Out-of-Africa models.

Identify phenotypic traits that re�ect selective and neutral evolution.

Relate a more nuanced view of human variation with today’s ongoing

bioanthropological research, implications for biomedical studies, ap-

plications in forensic anthropology, and sociopolitical/economic

concerns.

Humans exhibit biological diversity. Cognitively, humans also have a natural desire

to categorize objects and other humans in order to make sense of the world around

them. Since the birth of the discipline of biological anthropology, we have been in-

terested in studying how humans vary biologically and what the sources of this vari-

ation are. Before we tackle these big problems, this �rst begs the question: Why

should we study human diversity?

There are certainly academic reasons for studying human diversity. First, it is

highly interesting and important to consider the evolution of our species and how

our biological variation may be similar to (or different from) that of other species of

animals (e.g., other primates and apes). Such investigation can give us clues as to

how unique we are as a biological organism in relation to the rest of the animal king-

dom. Second, anthropologists study modern human diversity to understand how

different biological traits developed over evolutionary time. If we are able to grasp

the evolutionary processes that produce and affect diversity, we can make more ac-

curate inferences about evolution and adaptation among our hominin ancestors,

complementing our study of fossil evidence and the archaeological record. Third, as

will be discussed in more detail later on, it is important to consider that biological

variation among humans has biomedical, forensic, and sociopolitical implications.

For these reasons, the study of human variation and evolution has formed the basis

of anthropological inquiry for centuries and continues to be a major source of in-

trigue and inspiration for scienti�c research conducted today.

An even more important role of the biological anthropologist is to improve public

understanding of human evolution and diversity, outside of academic circles. Terms

such as race and ethnicity  are used in everyday conversations and in formal set-

tings within and outside academia. The division of humankind into smaller, discrete

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categories is a regular occurrence in day-to-day life. This can be seen regularly

when governments acquire census data with a heading like “geographic origin” or

“ethnicity.” Furthermore, such checkboxes and drop-down lists are commonly seen

as part of the identifying information required for surveys and job applications.

According to the Oxford English Dictionary (2018), race is a term that should be used

to describe one or more of the following:

a major division of the human species based on particular physical

characteristics;

the biological origin of a group of people, or ancestry;

the fact or condition of belonging to a racial division or group, or the social

qualities associated with this;

a group of people sharing the same culture and language;

any group of people or things with a common feature or features;

a population within a species that is distinct in some way, especially a

subspecies.

So many various de�nitions for one word already suggests that perhaps the con-

cepts or meanings behind biological diversity are complicated. Even though the

terms race and ethnicity are used often in commonplace settings, there is no con-

sensus among biological anthropologists as to what races are, whether they even

exist, and, if they do, how the term should be applied to the human species mean-

ingfully. If biological anthropologists cannot reach a consensus on how to view hu-

man diversity, how can we possibly expect there to be a clear perspective on the na-

ture and causes of biological variation outside of scienti�c academia? Ideas about

ethnicity that people hold have huge social and political impacts, and notions of race

have been part of the motivation behind various forms of racism and prejudice to-

day, as well as many wars and genocides throughout history. This is how the role of

the biological anthropologist becomes crucial in the public sphere, as we may be

able to debunk myths surrounding human diversity and shed light on how human

variation is actually distributed worldwide for the non-anthropologists around us

(Figure 13.1). Recent work in anthropological genetics has revealed the similarities

amongst humans on a molecular level and the relatively few differences that exist

between populations that one might be tempted to see as signi�cantly distinctive. Previous: Modern Homo sapiens

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Figure 13.1 Humans are biologically and culturally diverse. (Top left: Hadzabe members in Tanzania; top right: Inuit family in traditional seal and caribou clothing; bottom left: Andean man in traditional dress in Peru; bottom right: Dr. Jane Goodall.)

Science communication and education that centers upon race and our species’ vari-

ation is interesting and important. Throughout this chapter, I will highlight how hu-

mans cannot actually be divided into discrete “races,” because most traits instead

vary on a continuous basis and human biology is, in fact, very homogenous com-

pared to the greater genetic variation we observe in other closely related species.

The reason we know this now is thanks to technological developments that have

taken place over the last 50 or so years. Molecular anthropology, or anthropological

genetics, revolutionized and continues to add new layers to our understanding of

human biological diversity and the evolutionary processes that gave rise to the pat-

terns of variation we observe in contemporary populations. The study of human

variation has not always been unbiased, and thinkers and scientists have always

worked in their particular sociohistorical context. For this reason, this chapter

opens with a brief overview of race concepts throughout history, many of which re-

lied on unethical and unscienti�c notions about different human groups. Previous: Modern Homo sapiens

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THE HISTORY OF “RACE” CONCEPTS

“Race” in the Classical Era

The earliest classi�cation systems used to understand human diversity are evi-

denced by ancient manuscripts, scrolls, and stone tablets recovered through ar-

chaeological, historical, and literary research. The Ancient Egyptians had the Book of

Gates, dated to the New Kingdom between 1550 B.C.E. and 1077 B.C.E (Figure 13.2). In

one part of this tome dedicated to depictions of the underworld, scribes used pic-

tures and hieroglyphics to illustrate a division of Egyptian people into the four cate-

gories known to them at the time: the Aamu (Asiatics), the Nehesu (Nubians), the

Reth (Egyptians), and the Themehu (Libyans). Though not rooted in any scienti�c

basis like our current understandings of human variation today, the Ancient Egyp-

tians believed that each of these groups were made of a distinctive category of peo-

ple, distinguishable by their skin color, place of origin, and even behavioral traits.

Figure 13.2 ( from left to right) Depicting a Berber (Libyan), a Nubian, an Asiatic (Levantine), and an Egyptian, copied from a mural of the tomb of Seti I.

The Roman philosopher Pliny the Elder (23‒79 C.E.) also wrote about different groupings of people in his encyclopedia Naturalis Historia (Figure 13.3). In his opin-

ion, all people �t under one of three categories: civilized peoples, barbarians, and

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Figure 13.3 Front page of Pliny the Elder’s Naturalis Historia.

monstrous individuals. Pliny the Elder’s work was

deeply problematic. He believed that only Europeans

were civilized and not monstrous-looking, while other

groups of people lacked the ideal character and ap-

pearance. In both the cases of the Book of Gates and

Naturalis Historia, the worldviews of those who wrote

these volumes were also limited by how few and in-

frequent their encounters were with peoples else-

where around the world—that is, those not residing in

Europe, the Near East, or northern Africa. When faced

with only the level of biological diversity they could

see around them, distinguishing factors identi�ed by

these prominent thinkers relied simply on readily visi-

ble phenotypic traits, such as body size, skin color,

and facial shape.

The most well-known of early documents is perhaps

the Bible, where it is written that all humankind de-

scends from one of three sons of Noah: Shem (the ancestor to all olive-skinned

Asians), Japheth (the ancestor to pale-skinned Europeans), and Ham (the ancestor to

darker-skinned Africans). Similar to the Ancient Egyptians, these distinctions were

based on behavioral traits and skin color. More recent work in historiography and

linguistics suggest that the branches of “Hamites,” “Japhethites,” and “Shemites” may

also relate to the formation of three independent language groups some time be-

tween 1000 and 3000 B.C.E. With the continued proliferation of Christianity, this

concept of approximately three racial groupings lasted until the Middle Ages and

spread as far across Eurasia as crusaders and missionaries ventured at the time.

Finally, there is also the “Great Chain of Being,” conceived by ancient Greek philoso-

phers like Plato (427‒348 B.C.E.) and Aristotle (384‒322 B.C.E.). They played a key role in laying the foundations of empirical science, whereby observations of every-

thing from animals to humans were noted with the aim of creating taxonomic cate-

gories. Aristotle describes the Great Chain of Being as a ladder along which all ob-

jects, plants, animals, humans, and celestial bodies can be mapped in an overall hier-

archy (in the order of existential importance, with humans placed near the top, just

beneath divine beings) (Figure 13.4). Where he writes about humans, Aristotle ex- Previous: Modern Homo sapiens

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Figure 13.4 The Great Chain of Being from the Rhetorica Christiana by Fray Diego de Valades (1579).

Figure 13.5 Carl Linnaeus.

pressed the belief that certain people are inherently

(or genetically) more instinctive rulers, while others

are more natural �ts for the life of a worker or slave.

Nowadays, based on research by biological anthropol-

ogists, we currently recognize that these early sys-

tems of classi�cation and hierarchization are unhelp-

ful in studying human biological diversity. Both behav-

ioral traits and physical traits are coded for by multi-

ple genes each, and how we exhibit those traits based

on our genetics can vary signi�cantly even between

individuals of the same population.

“Race” during the Scienti�c Revolution

The 1500s and 1600s saw the beginnings of the “

Scienti�c Revolution” in European societies, with thinkers like Copernicus, Galileo,

and Da Vinci publishing some of their most important �ndings. While by no means

the �rst or only scholars globally to use observation and experimentation to under-

stand the world around them, early scientists living at the end of the medieval pe-

riod in Europe increasingly employed more experimentation, quanti�cation, and ra-

tional thought in their work. This is the main difference between the work of the an-

cient Egyptians, Romans, and Greeks, and that of workers like Isaac Newton and

Carl Linnaeus in the 1600s and 1700s.

Linnaeus is the author of Systema Naturae (1758), in which

he classi�ed all plants and animals he could observe un-

der the �rst formalized naming system known as

binomial nomenclature (i.e., how all organisms can be

named by their genus and species, such as Homo sapiens

or Pan troglodytes) (Figure 13.5). What was most anthro-

pologically notable about Linnaeus’s taxonomy was that

he was one of the �rst to group humans with apes and

monkeys, after noting the anatomical similarities between

humans and nonhuman primates. Linnaeus viewed the

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Figure 13.6 Discovery of the Mississippi by Spanish colonialist explorer Hernando DeSoto in 1541 (painted in 1853 by William H. Powell).

world in line with essentialism, a concept which dictates that there are a unique set

of characteristics that organisms of a speci�c kind must have—organisms would fall

outside taxonomic categorizations if they lacked any of the required criteria.

Despite these useful contributions to the biological sciences, Linnaeus still subdi-

vided the human species into four varieties, with overtly racist categories based on

skin color and “inherent” behaviors. According to him, Africans are all “black-

skinned” and ruled by an erratic nature; Native Americans are “red” in skin tone and

ruled by habit; Asians are “yellow-” or “brown-skinned” and ruled by belief; and Eu-

ropeans are “white” and regulated by custom. These standards for categorization

imply that Europeans are governed by carefully considered culture and custom, un-

like the unthinking Asians and Indigenous Americans in his framework who normally

act out of “habit” or “belief.” Moreover, Linnaeus’s traditional ranking also places

sub-Saharan, dark-skinned Africans inferior to the other three. Wrongly so, Euro-

pean scientists during this period were not aware of their own biases skewing their

interpretations of biological diversity. The conclusions and claims they came to,

consciously or subconsciously, often �t such an age when the superiority of Euro-

pean cultures over others was a pervasive idea throughout these scientists’ social

and political lives.

Occurring alongside this Scien-

ti�c Revolution was also the “

Age of Discovery.” Although

much of Eurasia was linked by

spice and silk trading routes,

the European colonial period

between the 1400s and 1700s

was marked by many new and

intentionally violent encounters

overseas (Figure 13.6). When

Europeans arrived by ship on

the shores of continents that

were already inhabited, it was

their �rst meeting with the indigenous peoples of the Americas and Australasia, who

looked, spoke, and behaved differently from peoples with whom they were familiar.

Building on the idea of species and “subspecies,” natural historians of this time in-

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vented the term race, from the French rasse meaning “local strain.” The idea behind

this terminology was rooted in the observation that geography plays a signi�cant

role in producing the biological traits we observe today. Naturalists like Comte de

Buffon and Johann Blumenbach did believe that all people have a single origin, but

they also believed that differences in environment could lead to biological changes

between different groups of people (i.e., races). However, as they had no under-

standing of genetics, they were incorrect in assuming that factors such as skin color

could change in a single lifetime depending on climate and diet and, essentially, be-

havior. Again, while drawing links between external physical characteristics and be-

havior is not scienti�c, differences in both were used to justify the Othering of

“nonwhite” cultures. Establishing “otherness” and “inferiority” in other people’s cul-

tures was necessary at the time for colonialists to enforce European domination and

the subordination of non-European people. Without genetic technologies, little was

known at the time about the hereditary or evolutionary basis of skin color having lit-

tle to do with innate differences between various “races.”

Another such scientist at the time, Johann Friedrich Blumenbach (1752‒1840), classi- �ed humans into �ve races based on his observations of cranial form variation as

well as skin color. He thus dubbed the “original” form of the human cranium the

“Caucasian” form, with the idea that the ideal climate conditions for early humans

would have been in the Caucasus region near the Caspian Sea. The key insight Blu-

menbach presented was that human variation in any particular trait should be more

accurately viewed as falling along a gradation (Figure 13.7). While some of his theo-

ries were correct according to what we observe today with more knowledge in ge-

netics, workers like him and Buffon believed erroneously that human “subspecies”

were “degenerated” or “transformed” varieties of an ancestral Caucasian or Euro-

pean race. According to them, the Caucasian cranial dimensions were the least

changed over human evolutionary time, while the other skull forms represented ge-

ographic variants of this “original.” As will be discussed in greater detail later in this

chapter, we have genetic and craniometric evidence for sub-Saharan Africa being

the origin of the human species instead. Based on work that shows how most bio-

logical characteristics are coded for by nonassociated genes, it is not reasonable to

draw links between individuals’ personalities and their skull shapes.

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Figure 13.7 Five skull drawings representing specimens for Blumenbach’s “Mongolian,” “American,” “Caucasian,” “Malayan,” and “Aethiopian” races.

“Race” and the Dawn of Scienti�c Racism

Between the 1800s and mid-1900s, and contrary to what you might expect, an in-

creased use of scienti�c methods to justify racial schemes developed in scholarship.

Differing from Blumenbach and Buffon’s views in earlier centuries, which saw all hu-

mans as environmentally deviated from one “original” humankind, classi�cation sys-

tems after 1800 became more polygenetic (viewing all people as having separate

origins) rather than monogenetic (viewing all people as having a single origin). In-

stead of moving closer to our modern-day understandings of human diversity, there

was increased support for the notion that each race was created separately and with

different attributes (intelligence, temperament, and appearance).

The 1800s were an important precursor to modern biological anthropology as we

know it, given that the scienti�c measurement of human physical features (anthro-

pometry) truly became popularized then. However, whether it was skin color, skull

shape, or observations of behavior being analyzed as the data, empirical studies in

the 1800s pushed the idea even further that Europeans were culturally and biologi-

cally superior. The leading �gures in craniometry at this time, focusing on measure-

ments of the skull, were also linked heavily with powerful individuals and wealthy

sociopolitical institutions and �nancial bodies. Therefore, polygenetic ways of think-

ing were particularly in�uenced by sociohistorical and economic factors at the time.

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Theories in support of hierarchical racial schemes certainly helped continue the ex-

ploitative and unethical transatlantic slave trade between the 1500s and 1800s by

justifying the transport and enslavement of African people on a “scienti�c” basis.

While considered one of the pioneers of American “physical” anthropology, Samuel

George Morton (1799‒1851) was a scholar who had a large role in 1800s scienti�c racism. By measuring cranial size and shape, he calculated that “Caucasians,” on av-

erage, have greater cranial volumes than other groups, such as the Native Americans

and “Negros.” Today, we know that cranial size variation depends on such factors as

Allen’s and Bergmann’s rules, which give the more likely explanation for the largest

heads being found in people living among colder regions (i.e., Europeans) being cli-

matic adaptation (Beals et al. 1984). In colder environments, it is advantageous for

those living there to have larger and rounder heads because they conserve heat

more effectively than slenderer heads (Beals et al. 1984).

Morton went on to write in his publication Crania Americana (1839) a number of

views that �t with a concept called biological determinism. The idea behind biolog-

ical determinism is that an association exists between people’s physical characteris-

tics and their behavior, intelligence, ability, values, and morals. If the idea is that

some groups of people are essentially superior to others in cognitive ability and

temperament, then it is easier to justify the unequal treatment of certain groups

based on outward appearances. Based on his cranial measurements and observa-

tions of human nature, Morton claimed that Europeans were the most intelligent

and “well-proportioned,” while Asians were not �t for leadership and had short at-

tention spans, Native Americans were slow in acquiring knowledge and fond of war,

and Africans were superstitious, uninventive, and “barbarous.”

Another such problematic thinker was Paul Broca (1824‒1880), after which a region of the frontal lobe related to language use is named (Broca’s area). In�uenced by

Morton, he likewise claimed that internal skull capacities could be linked with skin

color and cognitive ability. Considering his data taken from different parts of the

globe, Broca thought that factors such as gender, education, and social status could

have an in�uence on brain size for different groups, purporting that men had larger

brains than women and that “eminent” men were superior to men of “mediocre tal-

ent.” He went on to justify the European colonization of other global territories by

purporting it was noble for a biologically more “civilized” population to improve the

“humanity” of more “barbaric” populations. Today, these theories of Morton, Broca,

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Figure 13.8 Aleš Hrdlička (1869 ‒ 1943), a Czech anthropologist who founded the American Journal of Physical Anthropology.

and others like them are known to have no scienti�c basis. If we could speak with

them today, they would likely try to emphasize that their conclusions were based on

empirical evidence and not a priori reasoning. However, we now can clearly see that

their reasoning was biased and affected by prevailing societal views at the time.

“Race” and the Beginnings of Physical Anthropology

In the early 20th century, we saw a number of new �gures coming into the science

of human variation and shifting the theoretical focuses within. Most notably, these

included Aleš Hrdlička and Franz Boas.

Aleš Hrdlička (1869 ‒1943) was a Czech anthropologist who moved to the United States. In 1903, he estab-

lished the physical anthropology section of the Na-

tional Museum of Natural History (Figure 13.8). In

1918, he founded the American Journal of Physical An-

thropology, one of the foremost scienti�c journals dis-

seminating bioanthropological research still today. As

part of his work and the scope of the journal, he dif-

ferentiated “physical anthropology” from other kinds

of anthropology—he wrote that physical anthropology

is “the study of racial anatomy, physiology, and

pathology” and “the study of man’s variation”

(Hrdlička 1918). In some ways, although the scope and

technological capabilities of biological anthropolo-

gists have changed signi�cantly, Hrdlička established

an area of inquiry that has continued and prospered

for over a hundred years.

Franz Boas (1858‒1942) was a German American anthropologist who established the four-�eld anthropology system in the United States and founded the American An-

thropological Association in 1902. He argued that the scienti�c method should be

used in the study of human cultures and the comparative method for looking at hu-

man biology worldwide. Boas’s specialization was in the study of skull dimensions

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Figure 13.9 Logo of the Second International Exhibition of Eugenics held in 1921.

with respect to race. After a long-term research project, he demonstrated how cra-

nial form was highly dependent on cultural and environmental factors and that hu-

man behaviors were in�uenced primarily not by genes but by social learning. He

wrote in one essay for the journal Science: “While individuals differ, biological differ-

ences between races are small. There is no reason to believe that one race is by na-

ture so much more intelligent, endowed with great willpower, or emotionally more

stable than another, that the difference would materially in�uence its culture” (Boas

1931�6). This conclusion directly contrasted with the theories of the past that relied

on biological determinism. Biological anthropologists today have found evidence

that corroborates Boas’s explanations: societies do not exist on a hierarchy or grada-

tion of “civilizedness” but instead are shaped by the world around them, their demo-

graphic histories, and the interactions they have with other groups.

The �rst half of the

1900s still involved

some research that

was essentialist and

focused on proving

racial determinism.

Anthropologists like

Francis Galton (1822‒ 1911) and Earnest A.

Hooton (1887‒1954) created the �eld of

eugenics as an at-

tempt to formalize the

social scienti�c study

of “�tness” and “supe-

riority” among mem-

bers of 19th-century

Europe. As a way of “dealing with” criminals, diseased individuals, and “uncivilized”

people, eugenicists recommended prohibiting parts of the population from being

married and sterilizing these members of society so they could no longer procreate

(Figure 13.9). They instead encouraged “reproduction in individual families with

sound physiques, good mental endowments, and demonstrable social and economic

capability” (Hooton 1936). In the 1930s, Nazi Germany used this false idea of there

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being “pure races” to highly destructive effect. The need to be protected against ad-

mixture from “un�t” groups was their justi�cation for their blatant racism and purg-

ing of citizens that fell under their subjective criteria.

Shortly after World War II and the Nazi Holocaust, the full extent of essentialist, eu-

genicist thinking became clear. Social constructions of race, and the notion that you

could predict psychological or behavioral traits based on external appearance, had

become unpopular both within and outside the discipline. It was up to those in the

�eld of physical anthropology at the time to separate physical anthropology from

race concepts that supported unscienti�c and socially damaging agendas. This does

not mean that there are no physiological or behavioral differences between different

members of the human species. However, going forward, a number of physical an-

thropologists saw human biological variation as more complicated than simple

typologies could describe.

HUMAN VARIATION IN BIOLOGICAL ANTHROPOLOGY TODAY

“Populations” Instead of “Races”

After 1950, replacing the concept of “race” as a unit of diversity was the “population

.” This was outlined by those pioneering the “new physical anthropology,” such as

Sherwood Washburn, Theodosius Dobzhansky, and Julian Huxley, who borrowed this

way of framing human groups from contemporary population geneticists (Figure

13.10). “Races” were then de�ned simply as populations that differ in the frequency

of some gene or genes. And, on the other hand, a “population” is a group of individu-

als potentially capable of or actually interbreeding due to shared geographic prox-

imity, language, ethnicity, culture, and/or values. Put another way, a population is a

local interbreeding group with reduced gene �ow between themselves and other

groups of humans. Members of the same population may be expected to share many

genetic traits (and, as a result, many phenotypic traits that may or may not be visible

outwardly).

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Figure 13.10 Theodosius Dobzhansky, an important scientist who formulated the 20th-century “modern synthesis” reconciling Charles Darwin’s theory of evolution and Gregor Mendel’s ideas on heredity.

Figure 13.11 Julian Huxley (1942).

Thinking of humans in terms of popula-

tions was part of Julian Huxley’s (1942)

“Modern Synthesis”—so named because it

helped to reconcile two fundamental prin-

ciples about evolution that had not been

made sense of together before (Figure

13.11). As discussed in Chapter 3, Gregor

Mendel (1822‒1884) was able to show that inheritance was mediated by discrete par-

ticles (or genes) and not blended in the

offspring. However, it was dif�cult for some 19th-century sci-

entists to accept this model of genetic inheritance at the time

because much of biological variation appeared to be continu-

ous and not particulate (take skin color or height as examples).

In the 1930s, it was demonstrated that traits could be polygenic

and that multiple alleles could be responsible for any one phe-

notypic trait, thus producing the continuous variation in traits

such as eye color that we see today. Thus, Huxley’s “Modern

Synthesis” outlines not only how human populations are capable of exchanging

genes at the microevolutionary level but also how multiple alleles for one trait (poly-

genic exchanges) can cause gradual macroevolutionary changes.

Human Variation Is Clinal/Continuous (Not Discrete)

Human diversity cannot be broken into discrete “races,” because most physical traits

vary on a continuous or “clinal” basis. One obvious example of this is how human

height does not only come in three values (“short,” “medium,” and “tall”) but instead

varies across a spectrum of vertical heights achievable by humans all over the world.

(However, this is with the only difference being the huge divergence in how factors

like body size and traits such as skin color have been viewed and used sociopoliti-

cally as a way of separating people throughout history.) The need to shift from typo-

logical “race” categories to a more nuanced understanding of continuously variable

populations was realized by anthropologists working in the 1960s and 1970s who

shifted their focus toward the study of individual traits rather than the study of

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groups (populations, races). Systematic evaluations of global biological variation in

humans only began then, when large numbers of genetic loci for large numbers of

samples were sampled from human populations distributed worldwide. It was during

the 1960s that “clines” in human genetic variation were �rst identi�ed.

Frank B. Livingstone (1928‒2005) wrote: “There are no races, only clines” (1962). A cline is a gradation in the frequency of an allele/trait between populations living in

different geographic regions. In order to study human traits that are clinally distrib-

uted, it is often required to perform genetic testing to uncover the true frequencies

of an allele or trait across a certain geographic space. One easily visible example of a

clinal distribution seen worldwide is the patterning of human variation in skin color.

Whether in southern Asia, sub-Saharan Africa, or Australia, dark brown skin is

found. Paler skin tones are found in higher-latitude populations such as those who

have lived in areas like Europe, Siberia, and Alaska for millennia. Skin color is easily

observable as a phenotypic trait exhibiting continuous variation.

A clinal distribution still derives from genetic inheritance, but clines often corre-

spond to some gradually changing environmental factor. Clinal patterns arise when

selective pressures in one geographic area differ from those in another as well as

when people procreate and pass on genes together with their most immediate

neighbors. There are several mechanisms, selective and neutral, that can lead to the

clinal distribution of an allele or a biological trait. Natural selection is the mecha-

nism that produced a global cline of skin color, whereby darker skin color protects

equatorial populations from high amounts of UV radiation; there is a transition of

lessening pigmentation in individuals that reside further and further away from the

tropics (Jablonski 2004; Jablonski and Chaplin 2000) (Figure 13.12). The ability and

inability to digest lactose (milk sugar) among different world communities varies ac-

cording to differential practices and histories of milk and dairy product consump-

tion (Gerbault et al. 2011; Ingram et al. 2009). Where malaria seems to be most

prevalent as a disease stressor on human populations, a clinal gradient of increasing

sickle cell anemia experience toward these regions has been studied extensively by

genetic anthropologists (Luzzatto 2012). Sometimes culturally de�ned mate selec-

tion based on some observable trait can lead to clinal variation between populations

as well.

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Figure 13.12 Global map of indigenous skin colors.

Two neutral microevolutionary processes that may produce a cline in a human allele

or trait are gene �ow and genetic drift. The ways in which neutral processes can

produce clinal distributions is seen clearly when looking at clinal maps for different

blood groups in the human ABO blood group system (Figure 13.13). For instance, sci-

entists have identi�ed an east-to-west cline in the distribution of the blood type B

allele across Eurasia. The frequency of B allele carriers decreases gradually west-

ward when we compare the blood groups of East and Southeast Asian populations

with those in Europe. This shows how populations residing nearer to one another

are more likely to interbreed and share genetic material (i.e., undergo gene �ow). We

also see 90%‒100% of native South American individuals, as well as between 70%‒ 90% of Aboriginal Australian groups, carrying the O allele (Mourant et al. 1976).

These high frequencies are likely due to random genetic drift and founder effects, in

which population sizes were severely reduced by the earliest O allele-carrying indi-

viduals migrating into those areas. Over time, the O blood type has remained

predominant.

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Figure 13.13a Global distribution of blood group A.

Figure 13.13b Global distribution of blood type B.

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Figure 13.13c Global distribution of blood type O.

�e Apportionment of Human Variation: Genetic Diversity Is Greater Within-Group �an Between-Groups

One problem with race-based classi�cations is they relied on an erroneous idea that

people within a typological category were more similar to each other than they were

to people in other groups. In other words, “race” concepts were predicated on the

notion that individuals with particular characteristics would share more similar

genes with each other within a particular “race” and share less with individuals of

other “races” possessing different traits and genetic makeups. However, since

around 50 years ago, scienti�c studies have shown that the majority of human ge-

netic differences worldwide exist within groups (or “races”) individually rather than

between groups.

Richard Lewontin (1929‒) is a biologist and evolutionary geneticist who authored a paper evaluating where the total genetic variation in humans lies. This article, titled

“The Apportionment of Human Diversity” (Lewontin 1972), addressed the following

question: On average, how genetically similar are two randomly chosen people from

the same group when compared to two randomly chosen people from different

groups? Lewontin studied this problem by using genetic data. He obtained data for a

large number of different human populations worldwide using 17 genetic markers

(including alleles that code for various important enzymes and proteins, such as

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blood-group proteins). The statistical analysis he ran used a measure of human ge-

netic differences in and among populations known as the �xation index (F ). Tech-

nically, F can be de�ned as the proportion of total genetic variance within a sub-

population relative to the total genetic variance from an entire population. There-

fore, F values range from 0 to 1 (or, sometimes you will see this stated as a per-

centage between 0% and 100%). The closer the F value of a population (e.g., the

world’s population) approaches 1, the higher the degree of genetic differentiation

among subpopulations relative to the overall population. In his paper, Lewontin

(1972) identi�ed that most of human genetic differences (85.4%) were found within

local subpopulations (e.g., the Germans or Easter Islanders), whereas 8.3% were

found between populations within continental human groups, and 6.3% were attrib-

utable to traditional “race” groups (e.g., “Caucasian” or “Amerind”). These �ndings

have been important for scienti�cally rejecting the existence of biological races

(Long and Kittles 2008).

In 2002, another landmark article by Noah Rosenberg and colleagues (2002) ex-

plored worldwide human genetic variation using an even-greater genetic data set.

They used 377 highly variable markers in the human genome and sampled from 1,056

individuals representative of 52 populations. The markers chosen for study were not

ones that code for any expressed genes. Because these regions of the human

genome were made of unexpressed genes, we may understand these markers as

neutrally derived (as opposed to selectively derived) as they do not code for func-

tional advantages or disadvantages. These neutral genetic markers likely re�ect an

intricate combination of regional founder effects and population histories. Analyses

of these neutral markers allowed scientists to identify that a majority of global ge-

netic variance (93%‒95%) can be accounted for by within-population differences at the 377 genetic loci, while only a small proportion of genetic variance (3%‒5%) can be attributed to differences among major groups (Rosenberg et al. 2002). Like

Lewontin’s (1972) �ndings, this lends support to the theory that distinct biological

races do not exist, even though misguided concepts of race may still have real social

and political consequences.

Biological Data Fit Isolation-By-Distance and Out-of-Africa Models

ST

ST

ST

ST

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Figure 13.14 Sub-Saharan Africa (shaded dark/green).

One further note is that while the world’s population may be genetically divided into

“groups,” “subsets,” “clumps,” or “clusters” that re�ect some degree of genetic simi-

larity, it is more likely that these identi�able clusters re�ect genetic or geographic

distances—either with gene �ow facilitated by proximity between populations or

impeded by obstacles like oceans or environmentally challenging habitats (Rosen-

berg et al. 2005). Sometimes, inferred clusters using multiple genetic loci are inter-

preted by non-geneticists literally as “ancestral populations.” However, it would be

wrong to assume from these genetic results that highly differentiated and “pure” an-

cestral groups ever existed. These groupings re�ect differences that have arisen

over time due to clinal patterning, genetic drift, and/or restricted or unrestricted

gene �ow (Weiss and Long 2009). The clusters identi�ed by scientists are arbitrary

and the parameters used to split up the global population into groups is subjective

and dependent on the particular questions or distinctions being brought into focus

(Relethford 2009).

Additionally, research on worldwide genetic diver-

sity has shown that human variation decreases with

increasing distance from sub-Saharan Africa, where

there is evidence for this vast region being the geo-

graphical origin of anatomically modern humans (

Liu et al. 2006; Prugnolle et al. 2005) (Figure 13.14).

Genetic differentiation decreases in human groups

the further you sample data from relative to sub-

Saharan Africa because of serial founder effects

(Relethford 2004). Over the course of human colo-

nization of the rest of the world outside Africa,

populations broke away in expanding waves across

continents into western Asia, then Europe and eastern Asia, followed by Oceania and

the Americas. As a result, founder events occurred whereby genetic variation was

lost, as the colonization of each new geographical region involved a smaller number

of individuals moving from the original larger population to establish a new one

(Relethford 2004). The most genetic variation is found across populations residing in

different parts of sub-Saharan Africa, while other current populations in places like

northern Europe and the southern tip of South America exhibit some of the least

genetic differentiation relative to all global populations. Previous: Modern Homo sapiens

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Besides �tting nicely into the Out-of-Africa model , worldwide human genetic varia-

tion conforms to an isolation-by-distance model, which predicts that genetic simi-

larity between groups will decrease exponentially as the geographic distance be-

tween them increases. This is because of the greater and greater restrictions to

gene �ow presented by geographic distance, as well as cultural and linguistic differ-

ences that occur as a result of certain degrees of isolation. Since genetic data con-

form to isolation-by-distance and Out-of-Africa models, these �ndings support the

abolishment of “race” groupings. This research demonstrates that human variation is

continuous and cannot be differentiated into geographically discrete categories.

There are no “inherent” or “innate” differences between human groups; instead,

variation derives from some degree of natural selection, as well as neutral processes

like population bottlenecking (Figure 13.15), random mutations in the DNA, genetic

drift, and gene �ow through between-mate interbreeding.

Figure 13.15 The founder effect is a change in a small population’s gene pool due to a limited number of individuals breaking away from a parent population.

Humans Have Higher Homogeneity Compared to Many Other Species

An important fact to bear in mind is that humans are 99.9% identical to one another.

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Figure 13.16 Chimpanzee (Pan troglodytes).

This means that the apportionments of human diversity discussed above only con-

cern that tiny 0.1% of difference that exists between all humans globally. Compared

to other mammalian species, including the other great apes, human diversity is re-

markably lower. This may be surprising given that the worldwide human population

has already exceeded seven billion, and, at least on the surface level, we appear to be

quite phenotypically diverse. Molecular approaches to human and primate genetics

tells us that external differences are merely super�cial. For a proper appreciation of

human diversity, we have to look at our closest relatives in the primate order and

mammalian class. Compared to chimpanzees, gibbons, and even gray wolves and gi-

ant pandas, humans have remarkably low average genome-wide heterogeneity.

When we look at chimpanzee genetic diversity, it is

fascinating that western, central, eastern, and

Cameroonian chimpanzee groups have substantially

more genetic diversity between them than large

global samples of human DNA (Bowden et al. 2012)

(Figure 13.16). This is surprising given that all of these

chimpanzee groups live relatively near one another in

Africa, while measurements of human genetic diver-

sity have been conducted using samples from en-

tirely different continents. First, geneticists suppose that this could re�ect differen-

tial experiences of the founder effect between humans and chimpanzees. Because

all non-African human populations descended from a small number of anatomically

modern humans who left Africa, it would be expected that all groups descended

from that smaller ancestral group would be similar genetically. Second, our species

is really young, given that we have only existed on the planet for around 150,000 to

300,000 years. This gave humans little time for random genetic mutations to occur

as genes get passed down through genetic interbreeding and meiosis. Chimpanzees,

however, have inhabited different ecological niches, and less interbreeding has oc-

curred between the four chimpanzee groups over the past six to eight million years

compared to the amount of gene �ow that occurred between worldwide human

populations (Bowden et al. 2012).

Recent advances have now enabled the attainment of genetic samples from the

larger family of great apes and the evaluation of genetic diversity among bonobos,

orangutans, and gorillas alongside that of chimpanzees and humans (Prado-Mar-

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tinez et al. 2013). Collecting such data and analyzing primate genetic diversity has

been important not only to elucidate how different ecological, demographic, and cli-

matic factors have shaped our evolution but also to inform upon conservation ef-

forts and medical research. Genes that may code for genetic susceptibilities to trop-

ical diseases that affect multiple primates can be studied through genome-wide

methods. Species differences in the genomes associated with speech, behavior, or

cognition could tell us more about how human individuals may be affected by genet-

ically derived neurological or speech-related disorders and conditions (Prado-Mar-

tinez et al. 2013; Staes et al. 2017). In 2018, a great ape genomic study also reported

genetic differences between chimpanzees and humans related to brain cell divisions

(Kronenberg et al. 2018). From these results, it may be inferred that cognitive or be-

havioral variation between humans and the great apes might relate to an increased

number of cortical neurons being formed during human brain development (Kro-

nenberg et al. 2018). Comparative studies of human and nonhuman great ape genetic

variation highlight the complex interactions of population histories, environmental

changes, and natural selection between and within species. When viewed in the

context of overall great ape diversity, we may reconsider how variable the human

species is relatively and how unjusti�ed previous “race” concepts really were.

Phenotypic Traits �at Re�ect Neutral Evolution

Most human traits are non-concordant. “Non-concordance” is a term used to de-

scribe how biological traits vary independent of each other—that is, they don’t get

inherited in a correlative manner with other genetically controlled traits. For exam-

ple, if you knew an individual had genes that coded for tall height, you would not be

able to predict if they are lighter-skinned or have red hair. Depending on the trait

being observed, different patterns of phenotypic variation may be found within and

among groups worldwide. In this subsection, some phenotypic traits that re�ect the

aforementioned patterns of genetic variation will be discussed.

Looking beyond genetic variation brie�y, recent studies have revisited biological

anthropology’s earlier themes of externally observable traits, such as skull shape

(Figure 13.17). In the last 20 or so years, anthropologists have evaluated the level to

which human cranial shape diversity re�ects the results from genetic markers, such

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Figure 13.17 Human skulls in Tana Toraja (Indonesia), common scenery in public graves.

Figure 13.18 Diagram of the bony labyrinth in the inner ear.

as those used previously to �t against

Out-of-Africa models (Relethford 2004)

or those used in the apportionment of

human diversity between and within

groups (Lewontin 1972; Rosenberg et al.

2002). Using larger sample sizes of cra-

nial data collected from thousands of

skulls worldwide and a long list of cranial

measurements, studies demonstrate a

similar decrease in diversity with dis-

tance from Africa and show that a major-

ity of cranial variation occurs within populations rather than between populations

(Betti et al. 2009; Betti et al. 2010; Manica et al. 2007; Relethford 2001; von Cramon-

Taubadel and Lycett 2008). The greatest cranial diversity is found among skulls of

sub-Saharan African origin, while the least variation is found among populations in-

habiting places like Tierra del Fuego at the southern tip of Argentina and Chile.

While ancient and historical thinkers previously thought “race” categories could rea-

sonably be determined based on skull dimensions, modern-day analyses using more

informative sets of cranial traits simply show that migrations out of Africa and the

relative distances between populations can explain a majority of worldwide cranial

diversity (Betti et al. 2009).

This same patterning in phenotypic variation has even

been found in studies examining shape variation of the

pelvis (Betti et al. 2013; Betti et al. 2014), the teeth (Rath-

mann et al. 2017), and the human bony labyrinth of the ear

(Ponce de León et al. 2018) (Figure 13.18). The skeletal mor-

phology of these bones still varies worldwide, but a greater

proportion of that variation can still be attributed to the

ways in which human populations migrated across the

world and exchanged genes with those closer to them

rather than those further away. Human skeletal variation in these parts of the body

is continuous and non-discrete. Given the important functions of the cranium and

these other skeletal parts, we may infer that the genes that underpin their develop-

ment have been relatively conserved by neutral evolutionary processes such as ge-

netic drift and gene �ow. It is also important to note that while some traits such as

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height, weight, cranial dimensions, and body composition are determined, in part,

by genes, the underlying developmental processes behind these traits are under-

pinned by complex polygenic mechanisms that have led to the continuous spectrum

of variation in such variables among modern-day human populations.

Phenotypic Traits �at Re�ect Natural Selection

Even though 99.9% of our DNA is the same between all humans worldwide, and

many traits re�ect neutral processes, there are parts of that remaining 0.1% of the

human genome that code for individual and regional differences. Similarly to cranio-

metric analyses that have been conducted in recent decades, human variation in

skin color has also been reassessed using new methods and in light of greater

knowledge of biological evolution.

New technologies allow scientists to use color photometry to sample and quantify

the visible wavelength of skin color, in a way 19th- and 20th-century readers could

not. In one report, it was found that 87.9% of global skin color variation can be at-

tributed to genetic differences between groups, 3.2% to those among local popula-

tions within regions, and 8.9% within local populations (Relethford 2002). This ap-

portionment differs signi�cantly and is the reverse situation found in the distribu-

tion of genetic differences we see when we examine genetic markers such as blood

type–related alleles. However, this pattern of human skin color worldwide is not

surprising, given that we now understand that past selection has occurred for

darker skin near the equator and lighter skin at higher latitudes (Jablonski 2004;

Jablonski and Chaplin 2000). While most genetic diversity re�ects neutral variation

due to population migrations, geographic isolation, and restricted gene �ow dynam-

ics, some human genetic/phenotypic diversity is best explained as local adaptation

to environmental conditions (i.e., selection). Given that skin color variation is atypi-

cal compared to other genetic markers and biological traits, this, in fact, goes

against earlier “race” typologies. This is because recent studies ironically show how

so much of genetic variation relates to neutral processes, while skin color does not.

It follows that skin color cannot be viewed as useful in making inferences about

other human traits. Previous: Modern Homo sapiens

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Figure 13.19 The Forensic Anthropology Lab at the National Museum of Natural History, Smithsonian Institute, Washington, D.C.

On top of social implications, the quanti�cation and interpretation of human varia-

tion has important medical and clinical applications (National Research Council

Committee on Human Genome Diversity 1997). For instance, large-scale genomic

studies sampling from human populations distributed worldwide have produced de-

tailed knowledge on variation in disease resistance or susceptibility between and

within populations. If we think about drug companies who develop medicines for

African American patients particularly, the genetic diversity in predispositions to

disease and/or good health is likely higher among people of African descent than

these pharmaceutical businesses have taken into account. Through targeted sam-

pling of various world groups, clinical geneticists may also identify genetic risk fac-

tors of certain common disorders such as chronic heart disease, asthma, diabetes,

autoimmune diseases, and behavioral disorders. Having an understanding of popula-

tion-speci�c biology is crucial in the development of therapies, medicines, and vac-

cinations, as not all treatments may be suitable for for every human, depending on

their genotype. During diagnosis and treatment, it is important to have an evolu-

tionary perspective on gene-environment relationships in patients. Typological con-

cepts of “race” are not useful, given that most racial groups (whether self-identi�ed

or not) popularly recognized lack homogeneity and are, in fact, variable.

Cystic �brosis, for instance, occurs in all world populations but can often be under-

diagnosed in populations of African ancestry because it is thought of as a “white”

disease (Yudell et al. 2016).

Lastly, assignments of

“race” to human remains

is a common practice in

forensic anthropology,

especially in the United

States and other world-

wide contexts where

bones are recovered and

associated with criminal

investigations (Figure

13.19). Forensic anthro-

pologists have ascribed

“race” or ancestry to

sets of skeletons thanks

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to scienti�c research that has attempted to divide up different human groups into

culturally constructed categories based on biologically “discrete” assortments (Sauer

1992). Rather than focusing on the neutral or selective causes of human biological

variation, the concentration in forensic anthropology centers upon how probabilistic

it may be to assign bones of certain dimensions to one of several identi�ed racial

categories. Forensic anthropologists do not agree with the typological “race” con-

cepts of the past but, instead, root their racial categorization in methods of proba-

bility estimation (Sauer 1992). Based on many samples of skeletons from different

world regions, statistical tests (such as discriminant function analysis) allow them to

distinguish how likely certain skeletal dimensions may predict geographic ancestry.

It is important to remember that while it is possible to determine geographic origin

(or ancestry) based on skull morphology, again, the amount of craniometric distinc-

tiveness required to distinguish whether a cranium belongs to one group or another

will make for arbitrary decisions (Relethford 2009). Individuals can vary in their

skeletal dimensions by continental origin, country origin, regional origin, sex, age,

environmental factors, and the time period in which they lived, making it dif�cult to

assign individuals to particular categories in a completely meaningful way (Ousley et

al. 2009). When forensic reports and scienti�c journal articles give an estimation of

ancestry, it is crucial to keep in mind that responsible assignments of ancestry will

be done through robust statistical testing and stated as a probability estimate. To-

day, we also live in a more globalized world where a skeletal individual may have

been born originally to parents of two separate traditional racial categories. In con-

texts of great heterogeneity within populations, this de�nitely adds dif�culty to the

work of forensic scientists and anthropologists preparing results for the courtroom.

TALKING ABOUT HUMAN BIOLOGICAL VARIATION GOING FORWARD

To conclude, utilizing races to describe human biological variation is not accurate or

productive. Using a select few hundred genetic loci, or perhaps a number of pheno-

typic traits, it may be possible to assign individuals to a geographic ancestry. How-

ever, what constitutes a bounded genetic or geographical grouping is both arbitrary

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and potentially harmful owing to ethical and historical reasons  (see Chapter 3 for

more on the issues with commercial ancestry tests, for example). The discipline of

biological anthropology has moved past typological frameworks that shoehorn con-

tinuously variable human populations into discrete and socially constructed subsets.

Improvements in the number of markers, the genetic technologies used to study

variation, and the number of worldwide populations sampled have led to more nu-

anced understandings of human diversity. It is of utmost importance that scientists

and non-scientists, in theory, have each of the following clari�ed:

���Today, we refer to different local human groups as “populations.” What consti-

tutes a population is carefully de�ned in scienti�c reports based on some geo-

graphical, linguistic, or cultural criteria and some degree of relativity to other

closely or distantly related human groups.

���Humans have signi�cantly less genetic diversity than other primates and mam-

mals, and all human beings on Earth share 99.9% of their overall DNA. Some of

the remaining 0.1% of human variation varies on a clinal or continuous basis,

such as can be seen when looking at ABO blood type polymorphisms

worldwide.

���Many biological characteristics in humans are actually determined non-concor-

dantly and/or polygenically. Therefore, superiority or inferiority in human be-

havior or body form cannot justi�ably be linked to �xed and innate differences

between groups.

���Genetic distances are correlated with geographic distances among the global

human population. This is especially apparent when we consider that genetic

diversity is highest in sub-Saharan Africa, and average genetic heterogeneity

decreases in populations further away from the African continent in accordance

with the migratory history of anatomically modern Homo sapiens.

���The effects of gene �ow, genetic drift, and population bottlenecking are re-

�ected in some phenotypic traits, such as cranial shape.

���Other traits, like skin color and lactase persistence, we recognize to be the

product of many millennia of natural selective pressures in�uencing human bi-

ology from the external environment.

When taken altogether, genetic analyses of human diversity do not support 20th-

century (or even earlier) concepts of race. In discussions about human diversity,

each of these genomic results help clarify for all conversationalists how biological

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variation is distributed across the human population today. Taking care to think

about and debate the nature of human variation is important, because although the

effects and events that produced genetic differences among groups occurred in the

ancient past, sociocultural concepts about race and ethnicity continue to have real

social, economic, and political consequences in the modern era.

Beyond talking about diversity in the university setting, it is important that teachers,

researchers, and students of anthropology recognize and assume the responsibility

of in�uencing public perspectives of human diversity. Race-based classi�cation sys-

tems were developed during the colonial era, transatlantic slave trade, and Scienti�c

Revolution by some of the earliest scholars whom we may call the �rst “anthropolo-

gists” and students of humankind’s variation. Unfortunately, some of their ideas put

forward have persisted and evolved into present-day lived realities. Some of today’s

politicians and socioeconomic bodies have racially charged agendas that promote

racism or certain kinds of economic or racial inequalities. As anthropologists, we

must acknowledge that while human “races” are not a biological reality, their status

as a (misguided) social construction does have real consequences for many people

(Antrosio 2011). In other words, while “race” is a sociocultural invention in some

people’s minds, the treatment different individuals receive due to their perceived

“race” can have signi�cant �nancial, emotional, sociopolitical, and physiological

costs. But assuming a “color-blind” position when it comes to the topics of “race”

and ethnicity (especially in political discussions) is actually counterproductive since

the negative social consequences of modern “race” ideas could be ignored, making it

harder to examine and address instances of discrimination properly (Wise 2010).

Rather than shy away from these topics, we can use our scienti�c �ndings to estab-

lish socially relevant and biologically accurate ideas concerning human diversity. To-

day, research into genetic and phenotypic differentiation among and within various

human populations continues to expand in its scope, its technological capabilities,

its sample sizes, and its ethical concerns. It is thanks to such scienti�c work done in

the past few decades that we now have a deeper understanding not only of how hu-

mans vary but also of how we are biologically a rather homogenous, intermixing

world population.

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Figure 13.20 Michael B. C. Rivera in Hong Kong.

SPECIAL TOPIC: MY EXPERIENCES AS A MINORITY ACADEMIC OF COLOR

My name is Michael, and I am a re-

searcher in biological anthropology

(Figure 13.20). What strikes me as

most interesting to investigate is

human biological diversity today

and the study of past human evolu-

tion. What I am really curious about

is how we can use human skeletons

to infer how people adapt to coastal

environments. Relying on aquatic

foods near rivers, lakes, and the sea

is interesting because we have

found evidence for positive effects

of coastal living on dietary health

and many unique adaptations in

bones and teeth when living near

rivers and beaches. I also really en-

joy talking to students and non-scientists about our work, through teach-

ing, science communication events, and writing book chapters like this

one! I grew up in Hong Kong, a city in southern China. My father is from

the Philippines and my mother is from Hong Kong, which makes me a

mixed Filipino-Chinese academic. When I attended international schools

in my youth, I saw that kids my age came in all shapes, sizes, and colors.

It was not until I left Hong Kong that I realized people with my skin tone

were somewhat rarer in British universities I attended.

Biological anthropology is not taught extensively back home in Hong

Kong, but my initial motivation to enter this �eld was a great TV show

called Bones. This TV series was about a brilliant anthropologist who ex-

amined human remains for the Smithsonian Institute in Washington,

D.C., identi�ed the individuals they belonged to through scienti�c analy-

ses of bones and teeth, and told the stories of the deceased who could

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not tell their own. I went to the United Kingdom to earn my bachelor’s,

master’s, and doctorate degrees. During my studies, I was taught about

human genetics, apes and monkeys, forensics, human cultural and behav-

ioral diversity, and the story of human evolution that began six million to

eight million years ago. It was fascinating to me that we could answer im-

portant questions about human variation and history using scienti�c

methods. While I was at university, I did not have many minority aca-

demic role models to look up to. Today, I look around and see other aca-

demics of color during conferences and perhaps one or two others

around the places at which I work. I am inspired by all my colleagues who

advocate for greater representation and diversity in universities (whether

they are minority academics or not). I admire many of my fellow re-

searchers who are underrepresented and do a great job of representing

minority groups through their cutting-edge research and quality teach-

ing at the undergraduate and graduate levels. The study of anthropology

has really highlighted for me that we share a common humanity and his-

tory. Being somebody who is “mixed race” and Asian likely played a key

role in steering me toward a discipline that studies human diversity. As

this chapter hopefully shows, there is a lot about race and ethnicity to

discuss in terms of the discipline’s history and current understandings of

human biological diversity. Some scienti�c and technological advance-

ments today are unfortunately misused for reasons to do with money,

politics, or the continuation of fairly antiquated ideas. It is my belief,

alongside many of my friends and fellow anthropologists, that science

should be more about empathy toward all members of our species and

contributing to the intellectual and technological nourishment of society.

After speaking to many members of the public, as well as my own under-

graduate students, I have received lovely messages from other individuals

of color expressing thanks and appreciation for my presence and under-

standing as a fellow minority and mentor �gure. This is why anthropol-

ogy needs more diversity and to make room for more personal routes

into the discipline. All paths to anthropology are valuable and valid. I

would encourage anyone to study anthropology as it really is a �eld for

understanding and celebrating the intricacies of human diversity. Previous: Modern Homo sapiens

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Review �uestions

How is the genetic variation of the human species distributed

worldwide?

What evolutionary processes are responsible for producing

genotypic/phenotypic diversity within and between human

populations?

Should we continue to attribute any value in “race” concepts older

than 1950, based on our current understandings of human biologi-

cal diversity?

How should we communicate scienti�c �ndings about human bio-

logical variation more accurately and responsibly to those outside

the anthropological discipline?

Key Terms

Age of Discovery: A period between the late 1400s and late 1700s when European

explorers and ships sailed extensively across the globe in pursuit of new trading

routes and territorial conquest.

Ancestry: Biogeographical information about an individual, traced either through

the study of an individual’s genome, skeletal characteristics, or some other form of

forensic/archaeological evidence. Anthropologists carry out probabilistic estimates

of ancestry. They attribute sets of human remains to distinctive “ancestral” groups

using careful statistical testing and should report ancestry estimations with statisti-

cal probability values. Previous: Modern Homo sapiens

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Binomial nomenclature: A system of naming living things developed by Linnaeus in

the 1700s using a scienti�c name made up of two Latin- or Greek-form words, with

the �rst name capitalized and representative of an organism’s genus and the second

name indicating an organism’s species (e.g., Homo sapiens, Australopithecus

afarensis, Pongo tapanuliensis, etc.).

Biological anthropology: A subdiscipline of anthropology concerned with the bio-

logical origins, ecology, evolution, and diversity of humans and other primates. This

term is increasingly preferred to physical anthropology, as many in the �eld now un-

comfortably associate this original name (coined by Aleš Hrdlička) with the ways in

which questions of human variation were studied in decades past and the sociohis-

torical context that made anthropology problematic before 1950 (see Warren 2018).

Biological determinism: The erroneous concept that an individual’s behavioral char-

acteristics are innate and determined by genes, brain size, or other physiological at-

tributes, and with no in�uence of social learning or the environment around the in-

dividual during development.

Bony labyrinth: A system of interconnected canals within the auditory (ear- or

hearing-related) apparatus, located in the inner ear and responsible for balance and

the reception of sound waves.

Cline: A gradient of physiological or morphological change in a single character or

allele frequency among a group of species across environmental or geographical

lines (e.g., skin color varies clinally, as, over many generations, human groups living

nearer the equator have adapted to have more skin pigmentation).

Continuous/clinal variation: Variation that exists between individuals and cannot

be measured using distinct categories. Instead, differences between individuals

within a population in relation to one particular trait are measurable along a

smooth, continuous gradient.

Cystic �brosis: A genetic disorder in which one defective gene causes overproduc-

tion and buildup of mucus in the lungs and other bodily organs, most common in

northern Europeans (but also in other world populations more rarely).

Ecological niche: The position or status of an organism within its community Previous: Modern Homo sapiens

Next: Human Variation: An Adaptive Signi�cance Approach

and/or ecosystem, resulting from the organism’s structural and functional adapta-

tions (e.g., bipedalism, omnivory, lactose digestion, etc.).

Essentialism: A belief or view that an entity, organism, or human grouping has a

speci�c set of characteristics that are fundamentally necessary to its being and clas-

si�cation into de�nitive categories.

Ethnicity: A complex term used commonly in an interchangeable way with the term

race (see below).

Eugenics: A set of beliefs and practices that involves the controlled selective breed-

ing of human populations with the hope of improving their heritable qualities, espe-

cially through surgical procedures like sterilization and legal rulings that affect mar-

riage rights for interracial couples.

Founder effect: See population bottlenecking below.

Gene �ow: A neutral (or nonselective) evolutionary process that occurs when genes

get shared between populations.

Genetic drift: A neutral evolutionary process in which allele frequencies from gen-

eration to generation due to random chance.

Heterogeneity: The quality of being diverse genetically.

Homogenous: The quality of being uniform genetically.

Human diversity/differentiation/variation: Group differences involving variation

in biology, physiology, body chemistry, behavior, and culture.

Isolation-by-distance model: A model that predicts a positive relationship between

genetic distances and geographical distances between pairs of populations.

Monogenic: Characterized as being controlled by a single gene (or, in other words,

one pair of alleles). Sickle cell anemia and cystic �brosis are examples of disorders

that are monogenically caused.

Monogenetic: Pertaining to the idea that the origin of a species is situated in one

geographic region or time (as opposed to polygenetic). Previous: Modern Homo sapiens

Next: Human Variation: An Adaptive Signi�cance Approach

Mutation: A gene alteration in the DNA sequence of an organism. As a random, neu-

tral evolutionary process that occurs over the course of meiosis and early cell devel-

opment, gene mutations are possible sources of diversity in any given human gene

pool. Genetic mutations that occur in more than 1% of a population are termed poly-

morphisms.

Natural selection: An evolutionary process whereby certain traits are perpetuated

through successive generations, likely owing to the advantages they give organisms

in terms of chances of survival and/or reproduction.

Non-concordance: The fact of genes or traits not varying with one another and in-

stead being inherited independently.

Othering: In postcolonial anthropology, we now understand “othering” to mean any

action by someone or some group that establishes a division between “us” and

“them” in relation to other individuals or populations. This could be based on lin-

guistic or cultural differences, and it has largely been based on external characteris-

tics throughout history.

Out-of-Africa model: A model that suggests that all humans originate from one sin-

gle group of Homo sapiens in (sub-Saharan) Africa who lived between 100,000 and

315,000 years ago and who subsequently diverged and migrated to other regions

across the globe.

Physical anthropology: See biological anthropology above.

Polygenetic: Having many different ancestries, as in older theories about human ori-

gins that involved multiple traditional groupings of humans evolving concurrently in

different parts of the world before they merged into one species through inter-

breeding and/or intergroup warfare. These earlier suggestions have now been over-

whelmed by insurmountable evidence for a single origin of the human species in

Africa (see the “Out-of-Africa model”).

Polymorphism: A genetic variant within a population (caused either by a single gene

or multiple genes) that occurs at a rate of over 1% among the population. Polymor-

phisms are responsible for variation in phenotypic traits such as blood type and skin

color. Previous: Modern Homo sapiens

Next: Human Variation: An Adaptive Signi�cance Approach

Population: A group of humans living in a particular geographical area, with more

local interbreeding within-group than interbreeding with other groups. A limited or

restricted amount of gene �ow between populations can occur due to geographical,

cultural, linguistic, or environmental factors.

Population bottlenecking (or founder effect): An event in which genetic diversity is

signi�cantly reduced owing to a sharp reduction in population size. This can occur

when environmental disaster strikes or as a result of human activities (e.g., geno-

cides or group migrations). An important example of this loss in genetic variation

occurred over the �rst human migrations out of Africa and into other continental

regions.

Prejudice: An unjusti�ed attitude toward an individual or group not based on rea-

son, whether that is positive and showing preference for one group of people over

another or negative and resulting in harm or injury to others.

Race: The identi�cation of a group based on a perceived distinctiveness that makes

that group more similar to each other than they are to others outside the group.

This may be based on cultural differences, genetic parentage, physical characteris-

tics, behavioral attributes, or something arbitrarily and socially constructed. As a so-

cial or demographic category, perceptions of “race” can produce effects that have

real and serious consequences for different groups of people. This is despite the fact

that biological anthropologists and geneticists have demonstrated that all humans

are genetically homogenous and that more differences can be found within popula-

tions as opposed to between them in the overall apportionment of human biological

variation.

Racism: Any action or belief that discriminates against someone based on perceived

differences in race or ethnicity, and the characteristics, qualities, or abilities be-

lieved to be speci�c to a race that is inferior to another in some way.

Scienti�c Revolution: A period between the 1400s and 1600s when substantial shifts

occurred in the social, technological, and philosophical sense, when a scienti�c

method based on the collection of empirical evidence through experimentation was

emphasized and inductive reasoning used to test hypotheses and interpret their

results.

Typology: An assortment system that relies on the interpretation of qualitative simi-

Previous: Modern Homo sapiens

Next: Human Variation: An Adaptive Signi�cance Approach

Michael B. C. Rivera

larities or differences in the study of variation among objects or people. The catego-

rization of cultures or human groups according to “race” was performed with a ty-

pological approach in the earliest practice of anthropology, but this practice has

since been discredited and abandoned.

About the Author

Michael B. C. Rivera

University of Cambridge, [email protected]

The Arch and Anth Podcast, [email protected]

Michael B. C. Rivera is a biological anthropologist and hu-

man bioarchaeologist, studying the transition into agricul-

ture in coastal environments. His recently completed doc-

toral thesis brought together human skeletal biology,

palaeopathology, and prehistoric archaeology to investi-

gate the lives of ancient people on the northeastern Euro-

pean coastline. Being from Hong Kong and a student of

human biological variation, Michael is also an advocate for

greater inclusion, diversity, and equality in academia. Ad-

ditionally, as a believer in the value of science communication, and of the value of

the discipline to greater society, he launched The Arch and Anth Podcast in May

2019, which disseminates scienti�c knowledge in a fun, educational, and informal in-

terview-style audio format.

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Figure Attributions

Figure 13.1a Tanzania – Hadzabe hunter (14533536392) by A_Peach from Berlin, Ger-

many, is used under a CC BY 2.0 License.

Figure 13.1b Inuit-Kleidung 1 by Ansgar Walk is used under a CC BY-SA 3.0 License.

Figure 13.1c Andean Man by Cacophony is used under a CC BY-SA 4.0 License.

Figure 13.1d Jane Goodall GM byFloatjon is used under a CC BY-SA 3.0 License.

Figure 13.2 Egyptian races Drawing (1772-1846) by an unknown artist after a mural of

the tomb of Seti I, Copy by Heinrich von Minutoli (1820), is in the public domain.

Figure 13.3 Naturalishistoria from the front page of Pliny the Elder’s Naturalis Histo-

ria is in the public domain.

Figure 13.4 Great Chain of Being 2 by Didacus Valades (Diego Valades) is in the public

domain.

Figure 13.5 Carl von Linné by Alexander Roslin artist QS:P170,Q315102 is in the public

domain. Previous: Modern Homo sapiens

Next: Human Variation: An Adaptive Signi�cance Approach

Figure 13.6 Discovery of the Mississippi by William Henry Powell artist

QS:P170,Q3568696 (photograph courtesy Architect of the Capitol) is in the public

domain.

Figure 13.7 Blumenbach’s �ve races by Johann Friedrich Blumenbach is in the public

domain.

Figure 13.8 (Ales Hrdlicka) SIA2009-4246 by Unknown photographer is in the public

domain.

Figure 13.9 Eugenics congress logo scanned from Harry H. Laughlin, The Second In-

ternational Exhibition of Eugenics held September 22 to October 22, 1921, is in the

public domain.

Figure 13.10 Dobzhansky no Brasil em 1943 by Unknown photographer is in the pub-

lic domain.

Figure 13.11 Julian Huxley 1-2 by Unknown photographer is in the public domain.

Figure 13.12 Skin color by S25454541 is used under a CC BY-SA 4.0 License.

Figure 13.13a Map of blood group a by Muntuwandi at en.wikipedia is used under a

CC BY-SA 3.0 License.

Figure 13.13b Map of blood group b by Muntuwandi at en.wikipedia is used under a

CC BY-SA 3.0 License.

Figure 13.13c Map of blood group o Based on diagrams from

http://anthro.palomar.edu/vary/vary_3.htm reproduced from A. E. Mourant et.al.,

The Distribution of the Human Blood Groups and Other Polymorphisms, 2nd ed.

(1976) is used under a CC BY-SA 3.0 License.

Figure 13.14 Sub-Saharan-Africa by Ezeu has been designated to the public domain

(CC0).

Figure 13.15 Bottleneck effect by Tsaneda is used under a CC BY 3.0 License.

Figure 13.16 Chimpanzee IV (13968482163) by Chi King is used under a CC BY 2.0 Li-

cense. Previous: Modern Homo sapiens

Next: Human Variation: An Adaptive Signi�cance Approach

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Explorations by Beth Shook, Katie

Nelson, Kelsie Aguilera, and Lara Braff,

Eds. is licensed under a Creative

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Figure 13.17 Human skulls by 22Kartika is used under a CC BY-SA 3.0 License.

Figure 13.18 Bony labyrinth by Selket (5 February 2007, UTC) has been designated to

the public domain (CC0).

Figure 13.19 Forensic Anthropology Lab by Pp391 is used under a CC BY-SA 3.0 Li-

cense.

Figure 13.20 Michael B. C. Rivera in Hong Kong original to Explorations: An Open In-

vitation to Biological Anthropology is under a CC BY-NC 4.0 License.

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