Social and human capital (SHC) has become an important research topic. The aim of this study is to analyze the leading trends on sustainability, specifically the literature that has connected SHC with sustainability in recent decades. Social capital was initially defined as “the aggregate of the actual or potential resources which are linked to possession of a durable network of more or less institutionalized relationships of mutual acquaintance or recognition” [1
] (p. 248). The concept is also defined as “a resource that actors derive from specific social structures and then use to pursue their interests; it is created by changes in the relationship among actors” [2
] (p. 619), and as “the ability of actors to secure benefits by virtue of membership in social networks or other social structures” [3
] (p. 6). More recently, Falk and Kilpatrick (2000) defined the concept as “an accumulation of the knowledge and identity resources drawn on by communities-of-common-purpose” [4
] (p. 87). Despite the wide variety of definitions, social capital’s concern is clear: the benefits of social connectedness in diverse communities and the relevance of social networks for the development of resources and skills. Social capital also includes the idea that social bonds and social norms are the basis of sustainable livelihoods [5
], hence its importance as a template for personal and collective evaluation of changes [6
]. Furthermore, social capital may have a relevant role in the management of resources such as natural resources in diverse socio-economic and cultural contexts [7
On the other hand, human capital refers to the capital provided by employees or individuals. Coleman (1988) states that “human capital is created by changes in persons that bring about skills and capabilities that enable them to act in new ways” [8
] (p. 100). Similarly, human capital also refers to the know-how, information, relationships, and general capabilities that individuals provide to the firm through the employment relationship [9
], or to “a set of abilities and skills obtained because of training, as well as the scientific activities of workers necessary for the effective operation of the enterprise” [10
] (p. 121). This type of capital “comprises all the knowledge assets (tacit and explicit) placed in individuals” [11
] (p. 333). In sum, human capital is necessary to apply and develop knowledge in the firm [12
The relevance of both concepts is reflected in a significant increase of research on these topics. This is explained by sustainability’s generally positive effect on social, human, and natural capital. In contrast, unsustainable behaviors tend to deplete these assets, leaving fewer for future generations [13
]; on the other hand, several authors, such as Bebbington and Perreault [14
], conceptualize sustainable development in terms of some types of capital, and explore ways in which social and human capital (and also financial, physical or natural capital) contribute to theoretical frameworks in sustainable development. Specifically, these authors draw out some of the links among social capital formation, the access to other capitals, or the development of livelihood, political change, and the transformation of the landscape. However, the particulars of the research on SHC are unknown, especially in the case of research related to sustainability. Following the structure of the Special Issue, which considers human capital as a part of the broad term of social capital, and which could in turn include “societal capital”, and due to the lack of enough data to analyze them separately, we analyze both terms together. In addition, and following the structure of the Special Issue, we compare financial and economic capital, social and human capital, and natural capital.
A common technique to analyze research output is bibliometrics, a cross-disciplinary science that studies the bibliographic data through mathematical and statistical tools [15
]. The technique is recognized because of its potential to use objective information [17
] and the possibility to analyze specific research areas and obtain relevant conclusions [18
]. Some studies analyze the structure of research on sustainability. For instance, Garrigós et al. (2018) offer a review of diverse bibliometric analyses regarding sustainability and management, marketing, and fields related to innovation, information technology, logistics, and economics.
Other bibliometric studies analyze research on social capital related to management [19
], communication [20
], sociology [21
], or academic careers [22
]. In addition, some bibliometric studies focus on human capital [23
] or related areas such as non-financial information [24
] and human capital in university research centers [25
]. Additionally, some bibliometric analyses focus on the combination of social and human capital [26
] in academic research on science and engineering [27
]. In fact, bibliometric research has even analyzed social capital related to sustainable forest management [28
]. However, there is a lack of bibliometric or visualization analyses on SHC in general, or on SHC’s relationship to sustainability despite their relevance for practitioners and researchers. This analysis provides an overview of the study of SHC and sustainability and a visualization of the structure and development of this kind of research. On the one hand, researchers can identify key ideas for future research. On the other hand, managers can understand better the situation of SHC and its relationship with sustainability issues.
Given the relevance of bibliometric analyses and SHC related to sustainability, and the lack of appropriate bibliometric and visualization studies, this study provides an in-depth and updated bibliometric analysis of the evolution of SHC literature related to sustainability. The research comprises 635 documents, drawn from the Web of Science (WoS) database, and the use of the visualization of similarities (VOS) viewer software to graphically map the data. Co-occurrence of keywords, co-citation and co-authorship tools are employed.
The results indicate the important development of the literature on sustainability and on SHC related to sustainability in recent decades. Furthermore, although the literature about financial and economic capital, and natural capital related to sustainability has been growing significantly over the last few years, its development is still incipient. Focusing on SHC related to sustainability, the study shows that the main studies on the topic, led by Folke et al. (2005), are highly cited, which confirms the relevance of the topic [29
]. The journals that have published the most on these topics are Sustainability
, Ecological Economics
, and Journal of Cleaner Production
; the most-cited documents among the 635 works are authored by Putnam, Coleman, and Pretty; and the journal whose documents are cited the most is World Development
. The study shows that there are some prevailing approaches to the topic, such as managerial, economic, tourism, and sociological perspectives, although the multidisciplinarity of some clusters indicates the growing potential of this area.
According to the results, the main institutions that published documents on the topic are from Anglo-Saxon countries such as the USA, England, and Australia. Conversely, studies from India or China are very sparse. The results are especially important for practitioners and policymakers, since the results identify important topics of the literature on the subject and the main trends. The indicators used in the study allow identifying the goals of the studies, such as the development of appropriate polices, or sustainable management of institutions. The reason is that they have to incorporate not only the main research findings, but also the incipient trends if their aim is to develop sustainable policies. The study also suggests the incorporation of diverse perspectives related to information and communication technologies, collaborative economy, or ethical and socially responsible corporate policies in the development of managerial policies. As for research, the study stresses the knowledge about SHC related to sustainability and plots the connections among the diverse authors, institutions and perspectives, being also a source of new ideas for the development of future research. These ideas can be developed after considering the state of the art, the pioneer trends, the perspectives that have not been analyzed yet in the literature, the trends that are showing a more rapid expansion, or the explanation offered for the development of the diverse trends.
The structure of the article is as follows. Section 2
explains the data sources and bibliometric methods used, Section 3
provides the bibliometric and graphic results, and Section 4
comprises the discussion and main conclusions.
4. Discussion and Conclusions
This study analyzes the relevance of SHC and the research that combines SHC with sustainability through the use of bibliometrics. In addition, it overviews previous bibliometric analyses related to social capital and human capital, or the combination of both concepts. Nevertheless, this study covers a research gap by addressing the evolution of social capital and human capital in areas related to sustainability and by presenting the results visually.
The results lead to the following conclusions. Firstly, the analysis of the definition of social capital and human capital evinces not only the debate about the terms, due to their complexity, but also the relevance of both concepts, especially for the topic of sustainability. The relevance of SHC capital does not reside only in its role for knowledge creation and development for firms, but also in its crucial effect on the promotion of sustainable policies (economic, social, or even environmental) that can affect organizations and diverse environments. Understanding these mechanisms is essential for managers and practitioners, but also for researchers.
Research on sustainability has experienced huge growth in recent years, with over 10,000 documents published annually since 2015. This increase is reflected in the literature on SHC. However, this study shows that the literature on SHC is scarce, but very diverse, and that diversity of perspectives defines its high potential. This study represents the first attempt to analyze SHC research related to sustainability. The results show that the scarcity of research on SHC related to sustainability is even more significant regarding research on financial capital, economic capital and natural capital, which impeded an analysis through bibliometric techniques to compare its intrinsic features. Moreover, the different approaches to SHC (and natural, financial and economic capital) are essential to develop sustainable policies that contemplate the diversity of the process. Although the lack of enough literature can be an obstacle for a proper management of diverse situations, it also offers an opportunity to develop the literature. In this vein, this study is the starting point for further analyses about these topics.
Nevertheless, the high number of citations received by the main documents reflects the relevance of the topic. For instance, the most-cited document in sustainability has a little more than 4100 citations, and another document that focuses on SHC aspects related to sustainability has more than 1700 citations [29
]. In addition, two other documents have more than 500 citations, and more than 20 documents have more than 10 citations. The citations per year also indicate the importance of the topic. The study by Folke et al. (2005) is the most influential and cited document according to the citations per year (142.67 citations per year) [29
]. In addition, five of the 10 most influential documents have received over 30 citations per year.
The 635 documents on SHC related to sustainability were published in 436 journals, which indicates the simultaneous development of the topic across different academic disciplines. However, the main category is environmental studies, with more than 20% of the documents published. In addition, the top sources of publication in the field are Sustainability, Ecological Economics, and Journal of Cleaner Production, accumulating more than 9% of publications. However, none of the 20 top journals dedicate to this topic more than 2% of their published articles, the most prolific being the International Journal of Agricultural Sustainability, followed by World Development, with publications on this topic receiving more than 120 citations on average.
The keywords co-occurrence reveals that the main subjects on SHC related to sustainability belong to four main areas, two related to sustainability, and two related to social and human capital. Hence, the most frequent keywords are social capital, sustainability, human capital, and sustainable development. This analysis also stresses the close relationship with other areas, such as natural capital (fourth in the list of co-occurrences), and the importance of resilience, community, or governance and development. Specifically, the main words that are connected to social capital in the same cluster are words like resilience, trust, social entrepreneurship, urban planning, collaboration, or environmental management. This fact, together with the close relationship of “social capital” with “governance” in the Figure 2
, indicates the crucial importance of the social structures or networks, and the relevance of collaboration to secure benefits and enhance sustainability, as mentioned by Portes [3
] in its definition of social capital. In addition, the strong relationship among human capital and words such as “entrepreneurship” and “innovation”, and also the central situation of the words “social entrepreneurship” and “resilience” implicates the need for focusing on entrepreneurial actions related to sustainability, and the need to empower the actions of individual people (mainly women, as shown in the connection between gender and human capital) as essential mechanisms to overcome difficult situations and promote sustainability. On the other hand, the co-citation analysis indicates that two articles by Putnam [41
] lead the ranking of the most-cited documents of the 635 articles related to SHC and sustainability. These articles are followed by two other articles by Coleman [8
]. The four articles are also central in the network of other documents. Another important cluster is led by articles by Pretty and Ward [5
Focusing on the journal co-citation network, the results reveal five clusters of journals. The leader is World Development, which leads a cluster of journals related to ecology, the environment, and the management of natural resources. However, the cluster with the most journals, which is central in the picture, has a multidisciplinary nature. Other important clusters have managerial (with journals such as Academy of Management Review, Academy of Management Journal, Journals of Business Ethics, or Strategic Management Journal), economic (with journals such as Ecological Economics, or American Economic Review) or tourism perspective (with journals such as Annals of Tourism Research, Tourism Management, Journals of Sustainable Tourism, or Journal of Travel Research). This analysis reveals the prominence of economic and managerial areas in this topic, but also this area’s multidisciplinary nature, which can be a source of further research using alternative approaches. The results also stress the relevance of the tourism sector in the literature related to social and human capital
The author co-citation analysis yields five clusters of authors. The main cluster is led by Putnam, the author with the highest number of citations and includes authors such as Coleman or Bourdieu, who follow a sociological perspective. The second cluster, led by Ostrom and some of her co-authors, follows a more economic, strategic planning and an institutional perspective. The cluster led by Pretty has a more environmental perspective. Other clusters include institutional documents coming, for instance, from the World Bank or the OECD.
The co-authorship analysis of SHC documents related to sustainability identifies five nodes of countries, led by the USA, Australia, Canada, Germany and Spain. Finally, the leading universities come from the USA, with Washington State University, University of Kansas and Arizona State in first position; other universities from England and Australia are also well placed. In this vein, the study has mapped the research dimensions of SHC related to sustainability, and their relative importance and the evolution of the different perspectives. These results are important for policymakers and practitioners when considering sustainable polices. The research results indicate the main perspectives that they can take into account when planning to develop sustainable policies focused on organizations, institutions or locations. In addition, policymakers may use the results to develop further policies that take into account the complexity of the topic from a managerial, sociological, or environmental perspective.
On another note, the results show a lack of research on information and communication technologies’ effect on SHC development, the development of new techniques and solutions, and sustainability issues [47
], and their impact on sustainability. The results do not indicate extensive research on collaborative economy, open innovation and crowdsourcing processes [16
] in the development of SHC and their impact on sustainability; however, keywords such as “cooperation”, “collaboration” or “collective action” indicate the relevance of the topic. Finally, regarding ethics and socially responsible polices, or the promotion of social entrepreneurship [48
], incipient keywords such as “community development”, “rural development”, “corporate social responsibility”, “education”, or “empowerment” indicate new questions that can be developed soon, and that must be taken into account by institutions and organizations.
The results are particularly relevant for researchers, who may use the connections between the diverse areas analyzing SHC related to productivity to develop new ideas and studies in areas that are still underdeveloped. Furthermore, the new and growing approaches may open new research avenues. For instance, the most studied approaches (i.e., environmental studies, sociology, management and economics) could be complemented with new areas as indicated by a multidimensional cluster that comprises a plethora of scarcely employed perspectives. This study is also useful for the analysis of financial capital, economic capital, and natural capital related to sustainability, which are areas with great potential.
Future research may use a theoretical approach that combines various perspectives or a methodological approach for the development of indicators to measure the concepts explained. This bibliometric analysis may also offer answers to crucial questions associated with each research area [16
] and help to discover the determinants of the evolution of research. In this vein, new trends of research are motivated by three main reasons [16
]: the expansion of the topic, the development of new sciences or areas of study, and the emergence of fashionable questions in research or society. For instance, the keywords “social entrepreneurship”, or “indicators”, which are quite central in the keyword concurrence analysis, indicate that these questions, although incipient, are especially important in the area of social and human capital related to sustainability. Moreover, the growing evolution of SHC related to sustainability, the important number of citations of the main documents in this area, or the still scarce analysis of diverse perspectives (such as marketing, medicine, computing ethics, or even psychology) indicate an important potential for further research. In this respect, this bibliometric analysis has shown numerous perspectives that are misleading, which can also help researchers for further analysis.
Despite being a pioneer as regards the topic of research, this study is not without limitations, some of which are good opportunities for further research. First of all, the use of a purely objective technique, the collection of keywords, may lead to confusing interpretations if it is not complemented with qualitative analyses. In this case, the relatively small sample of documents analyzed could limit the interpretation of the results. Secondly, this study focuses on the material provided by the WoS Core Collection database, and limits the sample to articles, reviews, letters, and notes. This procedure can help to guarantee the inclusion of the most important and consistent works; however, further research could use other materials, such as conference proceedings, or other reports, such as doctoral theses. This study could be also be extended with the use of other sources such as Scopus, or material in languages other than English. In this respect, the co-authorship of institutions and countries shows the prevalence of USA and Anglo-Saxon countries at a level that indicates the lack of representation of important countries such as Russia, India, or China. The software used in this study and other bibliographic tools, software and methodologies could improve or extend the conclusions. Finally, future research could apply a qualitative approach to the analysis of the identified clusters.