# Osteometric distinctions between domestic reindeer (Rangifer tarandus tarandus), wild mountain reindeer (R.t.t.), wild forest reindeer (R.t. fennicus), and the identification of castrated reindeer bones: Biometric explorations and archaeological methods

## TL;DR

This study uses bone measurements to distinguish between types of reindeer, including domestic, wild, and castrated individuals, aiding in understanding past human-reindeer interactions.

## Contribution

The paper introduces osteometric methods to identify reindeer ecotype, sex, and castration status from bones, enhancing zooarchaeological analysis.

## Key findings

- Ecotype, variety, sex, and castration status influence reindeer bone growth in element- and dimension-dependent ways.
- Scatterplots combining slenderness with other measurements enable independent clustering of reindeer groups.
- A classification model based on isometric size and shape can differentiate ecotype/variety but not sex or castration status due to limited sample sizes.

## Abstract

The types of reindeer hunting, keeping, and herding in Fennoscandia have seen different periods of transformations and have found unique side by side expressions through time. To refine zooarchaeological analysis and scrutinize reindeer domestication and other past ancient human-reindeer relationships in the North, we propose methods for identifying sex, castration status, and ecotype/variety from complete and fragmented reindeer bones. This study examines the leg bones and pelvises of 161 reindeer from the Fennoscandian domestic reindeer (Rangifer tarandus tarandus), Norwegian wild mountain reindeer (Rangifer tarandus tarandus) and Finnish wild forest reindeer (Rangifer tarandus fennicus). We include intact males, castrated males, and females in our study. Ecotype (fennicus versus tarandus), variety (wild versus domestic tarandus), sex, and castration status are shown to influence bone growth in often element- and dimension-dependent ways. We demonstrate that metric variance is highest in fennicus and castrated domestic tarandus. Slenderness as expressed by diaphysis breadth–length index is sex and (albeit less) ecotype dependent, while distal breadth–bone length indices are mostly ecotype dependent. Scatterplots that combine slenderness with other measurement variables result in independent clustering between groups. The combination of two measurement variables facilitates ecotype/variety, sex, and castration status assignment due to independent clustering of groups. Our classification model based on isometric size and shape can be used to differentiate ecotype/variety, but not sex and castration status, due to limitation of group sizes. This study shows that reindeer ecotype, variety, sex, and castration status can be demonstrated through straightforward osteometric methods. We suggest cautious application in archaeological contexts because of (relative) changes in body size of past reindeer populations and our limited sample size, of especially wild male tarandus.

The online version contains supplementary material available at 10.1007/s12520-025-02198-3.