Kinship—which can be initially described as the study of the links between people established on the basis of descent, marriage, or adoption—has been a defining domain of anthropological investigation since the inception of this discipline in the last twenty years of the nineteenth century. The detailed description of the complexities of kinship systems was for many decades considered essential to the understanding of non-Western societies. This field went through an intense phase of restructuring from the end of the 1970s to the late 1990s as a result of major paradigmatic shifts within the discipline of anthropology, such as the cultural turn, feminism, and political economy. In the early twenty-first century kinship studies, profoundly redefined, have experienced a revival, also in light of tremendous technological changes, such as the emergence of new reproductive technologies, the development of genetics, new family forms, the gay and lesbian movement, immigration, globalization and such correlated phenomena as transnational adoption that have opened new frontiers to anthropological investigation.
The publication of Systems of Consanguinity and Affinity (1870) and Ancient Society (1877) by Lewis Henry Morgan have traditionally been recognized as steppingstones in the history of anthropological kinship. In line with his evolutionary thinking, Morgan saw kinship as a social institution identifying the earlier steps of societal organization. In other words, kinship was presented as the epicenter of so-called primitive societies' social organization. According to this line of reasoning, kinship was less central in modern societies. Territoriality, the social contract, and the state dominated modern society. As a result, politics and the economy, as distinct fields of social action, regulated important aspects of modern women's and men's lives. Morgan's work is representative of a certain understanding of what were then called primitive societies. He saw them as societies based on blood (kinship), a view that dominated anthropology until the early 1970s. Morgan also established the approach that would characterize anthropological studies of kinship for several decades; that is, the emphasis on kinship terminology and the partition of kinship as a field in a number of constitutive "blocks"—that is, descent, marriage, postmarital residence, inheritance, and so on.
Kinship maintained its centrality in the history of the discipline until the cultural turn in anthropology in the 1970s. Kinship was indeed a central theme of investigation within functionalist and structuralist paradigms. Kinship allowed scholars to answer some fundamental sociological questions. It offered a plausible explanation of the problem of the maintenance of social order in the absence of state-based organizations. Indeed, anthropological knowledge came to question a well-established tradition of Western political thought that had identified in the state the only viable solution for the maintenance of social order and discipline.
One major systematic trend within the traditions of kinship studies is represented by descent theory, the dominant paradigm until the mid-1960s (Kuper, 1982). Classic examples of this approach are African Political Systems, The Nuer, and The Political System of the Anuak. Proponents of descent theory presented non-Western societies as based on their kinship organization. According to this view, a person's place in society was largely determined by his or her position within the kinship system. Crucial was the determination of an individual's position within the line of filiation privileged by a given society (descent). Anthropologists singled out various principles of descent—unilineal with its patrilineal (through the father's line) and matrilineal (through the mother's line) variants and double (through both lines of descent). Non-Western societies were seen as emphasizing one particular line of descent whose analysis was believed to unpack their social mechanisms and account for the maintenance/reproduction of the social order. Thus in the classic studies of the Tallensi (e.g., Fortes, 1949) or the Nuer (Evans-Pritchard, The Nuer, 1940), the modalities of kinship organization and the functioning of descent as a structuring principle were presented as central to understanding these societies, their boundaries, and their internal equilibrium.
Key within functionalist and structural-functionalist approaches was the distinction between de facto descent (biological descent) and de jure descent (the lines of descent a society effectively recognized). In other words, anthropologists distinguished between facts of nature and the selection or play with natural facts of which each kinship system was the recognized expression. Each society was seen as characterized by an emphasis on certain genealogical links and a disregard for others. Thus in a matrilineal society a father's position was generally perceived as marginal. Meanwhile a mother and her relatives, in particular the mother's brother, were seen as the center of a child's social life and largely determine his or her future prospects.
Many functionalists and structural-functionalists claimed to investigate the domain of the social as separate from other domains of social analysis, namely the biological and the psychological. Building on the work of French sociologist Émile Durkheim, they were concerned with the delimitation of objects and methods of enquiry exclusive to the social sciences (with some notable exceptions, of course, such as Bronislaw Malinowski and his theory of needs and corresponding cultural institutions). Despite their intentions, later research has demonstrated that they were often unaware of the biologism that tainted some of their own theoretical constructions. As David Schneider and other anthropologists after him have highlighted, the realm of nature (natural kinship) was left out from traditional anthropological accounts. Yet each kinship system, with varying degrees of adherence, was seen as reflecting certain aspects of the natural order, but the latter was taken as a given and thus unquestioned realm. However, conceptions of nature and its relations to culture vary and change over time, across and within societies. An important contribution in this direction was constituted by the publication of Nature, Culture, and Gender by Carol MacCormack and Marilyn Strathern in 1980, which showed the inapplicability of Western dichotomies between culture and nature, men and women cross-culturally, and the historical variation of such constructs within the West.
As Janet Carsten (2004) has highlighted, anthropologists' study of kinship did not entail an interest in domestic life or other forms of connectedness aside from genealogical links, thus excluding the study of women, children, alternative forms of solidarity, or the more intimate aspects of sexuality from anthropological accounts. This gap can also partly be explained by the belief that non-Western people were deemed not to have an individualized Western sense of self but were seen as identifying with the collectivities they belonged to (read descent groups), with the latter seen as corporate entities (which found collective expression in their male elders). In addition, only the more public aspects of kinship (the so-called politico-jural aspects) were of privileged interests to anthropologists. Within kin-based societies, kinship defined people's economic, religious, and political rights and obligations.
Claude Lévi-Strauss, the leading proponent of the structuralist turn in French anthropology and beyond, introduced in the 1960s a conflicting paradigm known as alliance theory. Influenced by structural linguistics, Lévi-Strauss turned his attention not to descent but to marriage, the latter interpreted as a system of exchange and communication. In his theoretical constructs marriage is presented as the matrix of the kinship social order. Marriage produces at once two fundamental classes of kin, consanguineal kin (blood relatives) and affinal kin (in-laws). In the course of marriage transactions, women "serve" as the vectors via which social alliances are established (a perspective whose androcentric bias feminist anthropologists will readily point out). By renouncing to marry their own sisters (via the imposition of the incest rule) and by agreeing to marry other men's sisters outside of their own biological family, men establish the foundations of human society.
According to Lévi-Strauss, kinship marks the overcoming of the state of nature (determined by the rule of the biological) and the imposition of the cultural order by humans. In this sense kinship is a cultural universal—that is, something shared by all societies—although its content varies across cultures. By unpacking the systems of marriage and unveiling their deeper logic, Lévi-Strauss came to complement British anthropologists' privileged attention on descent. However, his reliance on linguistic structuralism enabled him to further capture the symbolic quality of human life and distance himself further from the biologism of functionalist and structural–functionalist accounts.
An important turn in kinship studies was marked by the publication of David Schneider's work. In American Kinship: A Cultural Account (1968) and A Critique of the Study of Kinship (1984), Schneider developed an important critique of the study of kinship, one that ultimately laid the foundations for contemporary approaches to the study of kinship. According to Schneider, kinship studies were mostly the expression of anthropologists' ethnocentric biases and disciplinary preoccupations. The centrality of biological reproduction was indeed a character identifying Western perspectives on kinship. Indeed, within a number of other societies, such as the Yap of the West Caroline Islands, it is "hard work" that cements what we would call kinship ties, not biology. It followed that kinship as a field of study was the outcome of the biases of Western scientists who once carved out a predefined interpretive scheme based on their own experience of kinship and then proceeded to investigate other societies, thus missing local understandings of kinship and the relationship between social and natural aspects of kinship (as well as the usefulness of such categories in the analysis of a specific society/culture).
A number of lines of research emerged from this initially seemingly devastating critique. This of course happened after a critical reassessment of Schneider's symbolic theory. Indeed, several aspects of this have been questioned by successive generations of anthropologists. Schneider's view of culture as an integrated whole and his exclusive focus on symbols are now seen as too schematic and limited (Stone, 2004). Twenty-first century anthropologists typically share a more complex and less bounded understanding of culture, an attention to practice and processes in addition to meanings, and a keen interest in the social construction of science (a topic left unresolved in Schneider's writings as Carsten  clarifies). Post-Schneiderian kinship is characterized by the inclusion of the study of Western kinship systems. This is partly due to the realization that an increased understanding of a researcher's own cultural assumptions and social practices is a powerful strategy to come to terms with researchers' biases, as well as changes in the object and methods of anthropological studies. In addition, nature is no longer taken for granted. Indeed, changing conceptions of nature and the varying relationships between culture and nature are regarded as central topics in order to understand kinship within Western and non-Western societies.
Post-Schneiderian kinship studies are often characterized by the insertion of kinship into a wider analytic field. Indeed, kinship studies have benefited from the insights of feminist anthropology, historical anthropology, and postmodern anthropology.
The feminist turn in anthropology in the mid-1970s (that is, the study of the much-neglected study of gender in a cross-cultural perspective) brought new life to anthropology as a discipline and to kinship studies in particular. The relationship between gender and kinship was the topic of Jane Collier and Sylvia Yanagisako's edited collection Gender and Kinship: Essays Towards a Unified Analysis (1987). These authors argued for a unified theory of gender and kinship. Indeed, they suggested that gender relations and gender asymmetries are central to the understanding of kinship systems cross-culturally (see also Yanagisako and Delaney). For instance, how would one understand, within the patrilineal Bamana families of Mali, women's differential positions and their limits and possibilities as mothers, daughters, and sisters if gender and kinship are not taken into consideration. The coupling of studies of gender, kinship, power, and inequality has contributed much to a renewed interest in anthropology. These studies also reflect the decline of the traditional separation between social studies and social activism, disclosing indeed a well-formulated agenda for the expansion of human rights. (See, for instance, the 2004 statement by the American Anthropological Association in support of gay and lesbian marriage at http://www.aaanet.org/press/ma_stmt_marriage.htm.)
Particularly rich is the study of new reproductive technology (NRT) (Strathern, After Nature, 1992 and Reproducing the Future, 1992; Ginsburg and Rapp; Ragone and Winddance Twine). The study of NRT has led people in Western societies to begin to deconstruct traditional distinctions between nature and culture/choice, given that NRTs have widened human possibilities of intervention and modification of what were once believed unchangeable biological phenomena. Similarly, the growing body of literature on gays and lesbians cross-culturally has led to a more complex understanding of the complexity of gender, which once were viewed more simplistically (see, for instance, Weston). It has also promoted new understanding of people's mediations with Western dictates of kinship.
Political economy and later developments (for example, historical anthropology) have added an important dimension to the study of kinship. From the path-breaking work by Jack Goody (1958) that included attention to the temporal dimension in the study of kinship, as well as the work of Esther Goody on marriage as a process (1962), the work of Claude Meillassoux on kinship and the formation of social inequalities (1981) to more recent accounts of political and economic processes that look for more satisfactory mediations between neo-Marxist and interpretive analyses (for example, work by McClintock; Cooper and Stoler), that kinship phenomena do not stand in a vacuum; instead they simultaneously reflect and affect wider societal trends. Kinship is indeed a privileged site for societal reproduction and the construction of local, ethnic, and national identities. (See, for instance, Kahn on NRT in Israel or De Jorio on kinship and politics in postcolonial Mali.)
In sum, early-twenty-first-century studies highlight the importance of local conception of kinship and the impact of such constructs on people's identity formation. Some anthropologists look at kinship as conceived in the West as a specific network of relatedness whose generality and interest should be ascertained in the course of open-ended fieldwork. Other trends also consist of broader approaches to the study of kinship (e.g., in the context of larger paradigms such as political economy), the inclusion of relatively recent developments (NRT), or traditionally excluded phenomena such as sexuality and third genders, thus contributing to new understandings of different lifestyles and cultural traditions.
Rosa De Jorio