I recently applied to the Cultural Evolution Society’s Advancing Cultural Evolution (ACE) grant scheme. I narrowly missed out on the funding, but was listed as an honourable mention.

For wider interest, I reproduced the project description I submitted below. If you are interested in helping progress this project - please get in touch.

Research Question

What causes kinship terminology to change? Kinship terminology are the system of words we use for family members, such as aunt or cousin in English. These words divide kin into categories that reflect the communicative needs of a society, which are in turn thought to reflect behavioural norms. The assumed connection between language and behaviour has been leveraged by researchers to make inferences on the social organisations of past societies, but is this assumption supported? And can we make specific predictions about this relationship?

Hypotheses

This project takes on two levels. First, we test the general claim that kinship terminology changes track significant changes in society, through the proximate measure of population size. Larger populations usually contain more levels of social hierarchy, more social institutions, and less dependence on kin for support, resulting in a change in kinship system. There is direct evidence that decreases in population size causes changes in kinship organisation, resulting in kinship terminology change.¹ Kinship terminology change will be measured through kinship terminology complexity, calculated using the number of kinterms and types of categories.

Second, we identify whether specific changes in parts of kinship organisation (e.g. changes in cousin marriage patterns) result in specific changes in kinship terminology (e.g. changes in kinterms for cousins). We test three specific hypotheses: 1) Changes in cross-cousin marriage practices result in changes in cross-cousin distinctions, 2) Changes to extended family systems result in the extension of kinterms from siblings to cousins 3) Changes in intergenerational kinterms indicate changes in descent patterns. Each of these hypotheses identifies kinship system changes that influence the movement of people.

Predictions: Kinship terminology change will show significant correlations to population size. However, the specific hypotheses only show relationships within some language families.

Data & Methods

This project will use phylogenetic sister-pair analyses to identify changes in kinship terminology.² Sister-pair languages are the closest relatives to each other on a model of linguistic history. Within a sister-pair we know there have been no branching events since their most recent split, and this implies that any differences in kinship terminology must have occurred since that split. We can correlate terminology differences with changes to our hypothesised drivers, population size and kinship system change.

Sister-pairs will be identified from the taxonomic models of language evolution held in Glottolog. Data on kinship terminology will be drawn from Kinbank, a database of kinship terminology. Population sizes are drawn from Ethnologue but will be bolstered with ethnographic sources where available. Information on kinship system organisation will be drawn from D-PLACE. Languages will be sampled from the Austronesian (209 languages in Kinbank), Bantu (113), Indo-European (73), and Uto-Aztecan (37) language families. The sister-pair sampling approach will require these datasets to be enriched with further data collection to maximise the total pairs.

Project Impact

Kinship systems are central systems to models of cultural evolution. For individuals, kinship norms guide our daily-lives, e.g. in the construction of social-networks,³ and informing where we live.⁴ Individual-level processes accumulate to create macro-channels of human and cultural movement, directing the paths of language⁵ and technology.⁶ However, kinship systems are not stable through time. The macroevolutionary impact of kinship systems means a change in kinship systems produces a change in the channels of cultural evolution. Models of human and cultural history must understand the varying impact of kinship system change.

Inferring the kinship systems of the past is challenging. Behaviour does not fossilize, and although genetics may reveal the movements of some people, they ultimately only reveal part of the story. For example, genetics might reveal the presence of cross-cousin marriage practices, it cannot reveal anything about the relationships between men and their sibling’s children or the level of interdependence between cousins and siblings.

Anthropologists have often relied on kinship terminology as a proximate tool for understanding societal kinship organisation. Notably, linguistic reconstruction of kinship terminology has been used to reconstruct the social organisation of societies in the past.⁷

The assumption used in kinship terminology reconstruction is that kinship terminology structure is caused by other parts of society. Simply, language structure reflects behaviour. Evidence for this assumption comes from the Kuikuru (Brazil), who saw a rapid population decline, meaning communities merged to consolidate resources. This also caused a shift from a kinship system of exogamy to endogamy, and a change in kinship terminology.⁸ The language-behaviour assumption is often extended to make inferences in the deep past. Reconstructions of cross-cousin kinterms in Nilo-Saharic languages inferred that cross-cousin marriage occurred in the past.⁷ In Proto-Oceanic societies, kinterms for mother’s brother and wife’s father were reconstructed to be the same, inferring the historic presence of the generalized exchange of women.⁹

Large-scale comparative models of kinship terminology across three language families have questioned that the assumption of a universal relationship between kinship terminology and behaviour is not supported.¹⁰ However, it was unclear whether the absence of correlation was due to data granularity or a genuine separation of language and behaviour. The release of Kinbank a database of over 1,000 kinship terminology, means we can assess the relationship between language and behaviour in a more granular and systematic fashion.

By identifying which changes in kinship behaviour are most likely to be reflected in changes to kinship terminology, we can more confidently paint pictures of our ancestors' social lives and how their social norms influenced cultural change.