About Kin & Number

Kin & Number explains the mathematical and computational ideas that run through anthropology. Some of them are old: the kinship terms collected in the nineteenth century, or the algebra a mathematician wrote for Claude Lévi-Strauss in 1949. Others are newer, such as network analysis, phylogenetic comparison and agent-based simulation. All of them are easier to understand with a pencil in hand, and that is how we try to present them.

What we cover

• Kinship structures and terminologies: how different societies classify relatives, marriage rules, section systems and the algebra used to describe them.
• Genealogy mathematics: cousins, coefficients of relationship, pedigree collapse and the length of a generation.
• Networks: density, centrality, small worlds and kinship networks drawn as graphs.
• Cultural evolution: transmission biases, drift, dual inheritance and simulation.
• Methods: statistics, consensus analysis, cross-cultural comparison and fieldwork sampling.

Alongside the explainers there are interactive models you can run in the browser, a notation guide, a self-study route in the lecture notes and book notes for further reading.

Who it is for

Students meeting these ideas in a course for the first time, teachers looking for examples they can put on a board, family historians who want the arithmetic behind a cousin chart, and readers who simply like seeing mathematics turn up in unexpected places. We assume school algebra and curiosity. Where a piece needs more, it says so and builds up the extra step.

How pieces are written

Every piece is researched from published sources: books, journal articles, university pages and open datasets, named in the piece or listed at the end so you can follow them up. The central idea is then worked through with a small example, using numbers you can check by hand. Hypothetical villages, families and informants are labeled as hypothetical. We write about the societies whose kinship systems we analyze as living communities, using the names they use where scholarship does. The full rules, including how corrections are handled, are in our editorial policy.

The contributors

• Ines Valdera studied social anthropology, reads ethnographies in Spanish and Portuguese, and writes about kinship terminologies and marriage systems with a weakness for a well-drawn diagram.
• Tomasz Wierzba came to anthropology from graph theory and data work, and writes the most mathematical pieces on the site, about networks and the algebra of kinship.
• Ruth Ashdown is a family historian with an actuary's love of tables who covers genealogy mathematics: cousins, relatedness, pedigree collapse and generations.
• Kwame Asante-Boyd is a programmer who reads evolutionary anthropology and writes about cultural evolution, simulation and agent-based models.
• Leila Farzan writes about research methods, statistics and teaching, always with the student meeting an idea for the first time in mind.

Get in touch

Corrections, questions and topic suggestions are welcome through the contact page. A message about a particular piece goes to the contributor who wrote it.