Is the human chin a spandrel? Insights from an evolutionary analysis of ape craniomandibular form

Humans are unique among primates in possessing a chin, yet it is currently unclear whether the form of the symphyseal region of the mandible where the chin is located is the product of direct selection or a by-product of evolutionary pressures on other craniomandibular features. Here, we conduct an evolutionary analysis of hominoid craniomandibular traits to test three hypotheses: symphyseal mandibular traits evolved (1) neutrally due to genetic drift, (2) under direct selection, and (3) as a by-product (or “spandrel”) of selection on other craniomandibular traits. Evolutionary rates of morphological change, via Lande’s generalized genetic distance, were estimated along each branch of a fully-resolved hominoid phylogeny to reveal patterns of neutral, stabilizing, and directional selection. Directional selection was detected along the branch between humans and the last common ancestor of chimpanzees and humans, against a backdrop of pervasive stabilizing selection and neutral evolution i..., , # Data from: Is the human chin a spandrel? Insights from an evolutionary analysis of ape craniomandibular form

Dataset DOI: [10.5061/dryad.ncjsxkt7k](10.5061/dryad.ncjsxkt7k)

\"S3_Table.xlsx\" contains the logged cranial and mandibular traits (interlandmark distances) for all ape taxa used as input data for this study.

## Description of the data and file structure

Logged cranial and mandibular interlandmark distances.

### Files and variables

#### File: S3_Table.xlsx

**Description:** Logged interlandmark distances

##### Variables

* *Taxon*: Current valid scientific taxon name (genus, species, subspecies)
* *Sex*: Male (M) or Female (F)
* *Cranial traits*: These codes represent the logged Euclidean distances between pairs of cranial landmarks labelled using the following codes:

BA: Basion: The point where the anterior margin of the foramen magnum intersects the midsagittal plane

HOR: Hormion: The midline point of attachment of the vomer and sphenoid bones

IS: Intradentale superi...,