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Anthropology

<OpenstaxParagraph>
	The true nature of inheritance was not really understood until the beginning of the 20th century, when the 19th-century work of Gregor <OpenstaxTerm>Mendel</OpenstaxTerm>, a Catholic priest from Slovakia, was rediscovered. While in college, Gregor Mendel was introduced to <OpenstaxTerm>cell theory</OpenstaxTerm>, which states that all organisms are composed of cells and that cells are the fundamental unit of all living things. Cell theory raised many questions in Mendel’s mind, including whether both parents contribute equally to the cells in their offspring. In 1854, Mendel began a series of experiments with pea plants to help resolve this question and better understand how traits are inherited from generation to generation.
</OpenstaxParagraph>
<OpenstaxFigure id="fig-00002" src="https://openstax.org/apps/archive/20240226.174525/resources/7dc8fa2801c929b3ca03ed2fc7fc71de8fb8cc36" alt="Black and white portrait of a man in a monk’s robe wearing a large cross around his neck." mediaType="image/jpeg" width="610" height="800" />
<OpenstaxFigureText width="610">
	Figure 4.7 Gregor Mendel was a Catholic priest whose experiments with selective breeding of pea plants established many of the rules of heredity. (credit: “Gregor Mendel Monk” by William Bateson, Mendel’s Principles of Heredity: A Defence/Wikimedia Commons, Public Domain)
</OpenstaxFigureText>
<OpenstaxParagraph>
	The first stage of Mendel’s experiments was identifying plants that breed true, meaning that each parent only produces one kind of offspring when self-crossed. A self-cross is essentially a self-mating; some plants, such as peas, have both male and female parts and can self-fertilize. Not all self-crosses are the same as the parent plant, however. For example, self-crossed pea plants that have yellow pods sometimes produce offspring with yellow pods and sometimes produce offspring with green pods. Mendel continued to selectively breed only those pea plants that produced offspring that were the same as the parents. He called them purebreds and referred to them as the P1 generation. It took him more than two years to establish plants that always bred true.
</OpenstaxParagraph>
<OpenstaxParagraph>
	Then Mendel selected seven traits of his pea plants that each had two distinct phenotypes, or observable expressions of the trait. For example, seed shape can be either round or wrinkled, while pod color can be either yellow or green. Over the next eight years, Mendel studied the mating and resulting traits of more than 28,000 plants. Mendel’s first round of experiments used his purebred pea plants to create what is known as a <OpenstaxTerm>monohybrid cross</OpenstaxTerm>. A monohybrid cross is a mating between two purebred individuals who differ in a single characteristic. In Mendel’s monohybrid crosses, the parent pea plants differed from one another in terms of whether the pods of the parental pea plants were yellow or green or whether the seeds of the parental pea plant were wrinkled or round.
</OpenstaxParagraph>
<OpenstaxFigure id="fig-00003" src="https://openstax.org/apps/archive/20240226.174525/resources/c810f022f8c704f699d0310fde65a79a1825bc89" alt="Chart of different traits of pea plants. Under the category “Seeds” appear the characteristics “round or roundish” and “wrinkled”; as well as “yellow” and “green”. Under the category “flower color,” options are “white” or “violet-red”. Pods are described as either “full” or “constricted between the seeds”, as well as either “yellow” or “green.” Stem options are “axial” or “terminal”, “long” or “short.&amp;# 8221;" mediaType="image/png" width="1200" height="588" />
<OpenstaxFigureText width="1200">
	Figure 4.8 Mendel identified a number of distinct characteristics observable in the seeds, flowers, pods, and stems of pea plants. He used these observable traits as the basis for his breeding experiments, taking note of which traits were dominant and which unexpressed (or recessive) in offspring. (credit: “Mendel Genetics” by LadyofHats/Wikimedia Commons, Public Domain)
</OpenstaxFigureText>
<OpenstaxParagraph>
	In his first monohybrid crosses, Mendel mated a purebred yellow pea plant with a purebred green pea plant. He found that all the offspring resulting from this monohybrid cross were yellow, even though when the green peas self-crossed, all their offspring were green. In other words, all the <OpenstaxEm>hybrid</OpenstaxEm> offspring were yellow in color. A <OpenstaxTerm>hybrid</OpenstaxTerm> plant is one in whose parents differ in a term of a specific characteristic, such as pod color or seed shape. The trait that was expressed (yellow) Mendel referred to as <OpenstaxTerm>dominant</OpenstaxTerm>, and the trait that disappeared (green) he referred to as <OpenstaxTerm>recessive</OpenstaxTerm>. Mendel’s next set of experiments involved mating two hybrid plants—in other words, those that resulted from the monohybrid cross. In these experiments, he found that the recessive traits reappeared in a ratio of three dominant to one recessive.
</OpenstaxParagraph>
<OpenstaxFigure id="fig-00004" src="https://openstax.org/apps/archive/20240226.174525/resources/45cdc0796246c2ed0bdeafdf21b23173107b564e" alt="Top chart shows a cross between a plant represented by two green y’s, indicating purebred green, and a plant represented by one green and one yellow y, indicating hybrid yellow. Crosses result in two plants represented by two green y’s (purebred green) and two represented by a yellow and green y (hybrid yellow). Bottom chart shows a cross between a plant represented by two green y’s (purebred green) and a plant represented by two yellow y’s (purebred yellow). All four offspring are represented by one green and one yellow y (hybrid yellow)." mediaType="image/png" width="896" height="737" />
<OpenstaxFigureText width="896">
	Figure 4.9 These diagrams are examples of Punnett squares, a simple method for predicting the observable results of breeding experiments. In the top square, a purebred green plant (yy) is crossed with a hybrid yellow plant (Yy). The four possibilities for offspring appear in the four interior squares of the diagram. In this case, half of the offspring will be hybrid yellow and half will be purebred green. The bottom diagram shows the results of a cross between a purebred green and a purebred yellow plant – in this case, all offspring are hybrid yellow. (credit: Copyright Rice University/OpenStax, under CC BY 4.0 license)
</OpenstaxFigureText>
<OpenstaxParagraph>
	Mendel’s experiments suggested two very important facts. First, Mendel noted that various expressions of a trait (such as pea color) were controlled by discrete units that occur in pairs and that offspring inherited one unit of each pair from each parent. This observation became <OpenstaxTerm>Mendel’s first law of inheritance</OpenstaxTerm>, the <OpenstaxTerm>law of segregation</OpenstaxTerm>, which states that the two alleles for each trait segregate, or separate, during the formation of gametes (eggs and sperm) and that during the reproductive process, the alleles combine at random with other alleles. Today, we know that the process of meiosis—division of sex cells—explains Mendel’s law of segregation. Each of the seven traits identified by Mendel is controlled by a pair of genes in the plant, one on each chromosome. During the reproductive cycle, the chromosomes separate from one another so that each gamete has only one allele for each trait. During fertilization, the alleles combine, and the two-gene state is restored.
</OpenstaxParagraph>
<OpenstaxParagraph>
	After Mendel established his first law of inheritance, he extended his studies to more complex situations. He began performing experiments with two set of traits, using <OpenstaxTerm>dihybrid crosses</OpenstaxTerm>. A dihybrid cross is a cross between individuals who differ with respect to two gene pairs—for example, a cross between a plant with a round yellow pea and a plant with a wrinkled green pea. Because yellow and round are both dominant traits and wrinkled and green are both recessive, all the offspring resulting from the first-generation mating were 100% yellow and round. The green color and the wrinkled pea shape had disappeared. However, these recessive traits reappeared in a ratio of three dominant to one recessive when two round yellow individuals from the first-generation dihybrid cross were mated. The green color and the wrinkled pea shape had not truly disappeared. In the second generation of the dihybrid cross, Mendel found that 9/16 of the offspring were round and yellow, 3/16 were wrinkled and yellow, 3/16 were round and green, and 1/16 were wrinkled and green. The results of these dihybrid crosses indicate that the two characteristics—pea color and pea shape—segregate independently. The expression of one trait is not influenced by the expression of the other trait. This is known as the <OpenstaxTerm>law of independent assortment</OpenstaxTerm>, which is <OpenstaxTerm>Mendel’s second law of inheritance</OpenstaxTerm>. There is nothing to dictate that round peas will be yellow or that wrinkled peas will be green. The alleles that code for different traits sort independently of one another during sex cell division (meiosis).
</OpenstaxParagraph>

4.3.2 Gregor Mendel and the Laws of Heredity

1 What Is Anthropology?

1.1 The Study of Humanity, or "Anthropology Is Vast"

1.1.1 The Heart of Anthropology: Central Narrative and Commitments

1.1.2 Central Commitment #1: Exploring Sociocultural Diversity

1.1.3 Central Commitment #2: Understanding How Societies Hold Together

1.1.4 Central Commitment #3: Examining the Interdependence of Humans and Nature

1.2 The Four-Field Approach: Four Approaches within the Guiding Narrative

1.2.1 Biological Anthropology

1.2.2 Archaeology

1.2.3 Cultural Anthropology

1.2.4 Linguistic Anthropology

1.2.5 How the Four Fields Work Together: The Example of Race

1.3 Overcoming Ethnocentrism

1.3.1 Enculturation and Ethnocentrism

1.3.2 Primitivism and Orientalism

1.4 Western Bias in Our Assumptions about Humanity

1.4.1 Primitivism and Orientalism in Popular Culture

1.4.2 The Bias of Backwardness

1.5 Holism, Anthropology’s Distinctive Approach

1.5.1 Society as an Integrated Whole

1.5.2 Sources of Contradiction, Conflict, and Change

1.6 Cross-Cultural Comparison and Cultural Relativism

1.6.1 Relativism Is Not “Anything Goes”

1.6.2 Morality, Activism, and Cultural Relativism

1.7 Reaching for an Insider’s Point of View

1.7.1 The Challenge of Representing Others

1.7.2 Collaborative Methods of Representation

1.7.3 Working across Cultures toward Common Goals

1.7.4 Suggested Readings

2 Methods: Cultural and Archaeological

2.1 Archaeological Research Methods

2.1.1 Archaeological Techniques

2.1.2 Archaeological Dating Methods

2.2 Conservation and Naturalism

2.2.1 Early Efforts

2.2.2 Salvage Anthropology

2.2.3 Museum Collections

2.2.4 Interpretation and Voice

2.3 Ethnography and Ethnology

2.3.1 The Development of Ethnography and Ethnology

2.3.2 Perspective and Interpretation in Ethnography

2.4 Participant Observation and Interviewing

2.4.1 Participant Observation

2.4.2 Interviewing Informants

2.4.3 Ethical Considerations

2.5 Quantitative and Qualitative Analysis

2.5.1 Differences between Quantitative and Qualitative Information

2.5.2 Modeling

2.5.3 The Science of Anthropology

2.6 Collections

2.6.1 Archives

2.6.2 Three-Dimensional Collections

2.6.3 Ownership

2.6.4 Suggested Readings

3 Culture Concept Theory: Theories of Cultural Change

3.1 The Homeyness of Culture

3.2 The Winkiness of Culture

3.3 The Elements of Culture

3.3.1 Culture Is What We Make

3.3.2 Culture Is What We Do

3.3.3 Culture Is What We Think

3.4 The Aggregates of Culture

3.4.1 Symbols

3.4.2 Ritual

3.4.3 Social Structure

3.5 Modes of Cultural Analysis

3.5.1 Evolution, Adaptation, and Historical Particularism

3.5.2 Functionalism

3.5.3 Structuralism

3.5.4 Ontology

3.6 The Paradoxes of Culture

3.6.1 Paradox 1: Culture Is Continuous, but It Changes

3.6.2 Paradox 2: Culture Is Bounded but Mobile

3.6.3 Paradox 3: Culture Is Consensual but Contested

3.6.4 Paradox 4: Culture Is Shared, but It Varies

3.6.5 Suggested Readings

4 Biological Evolution and Early Human Evidence

4.1 What Is Biological Anthropology?

4.1.1 Looking to the Deep Past

4.1.2 Exploring What It Means to Be Human

4.2 What’s in a Name? The Science of Taxonomy

4.2.1 Defining the Science of Taxonomy

4.2.2 Defining a Species

4.3 It’s All in the Genes! The Foundation of Evolution

4.3.1 The Units of Life

4.3.3 Mendelian Inheritance in Humans

4.4 Evolution in Action: Past and Present

4.4.1 Early Evolutionists and the Fixity of Species

4.4.2 Charles Darwin’s Role in Changing Views of the Natural World

4.4.3 Understanding Darwin’s Theory of Natural Selection

4.5 What Is a Primate?

4.5.1 What Is a Primate?

4.5.2 Primate Behavioral Variation

4.5.3 Explaining Primate Success

4.5.4 Primate Classification and Taxonomy

4.6 Origin of and Classification of Primates

4.6.1 Understanding Concepts of Time

4.6.2 Fossils and Dating Methods

4.6.3 Making Sense of Fossils

Question	Answer
a law of inheritance stating that different genes and their alleles are inherited independently.	law of independent assortment
a law of inheritance stating that when two alleles for a trait separate during the formation of new zygotes, these alleles will combine at random with other alleles.	law of segregation