Caitlin S., PhD
@paleophile.bsky.social
992 followers 351 following 3.5K posts
Research Dev't & #SciPol | doing my best for science | Evolutionary Anthropology PhD | #celiac | 🐶 #DogRescue | #FosterCare | Personal account.
Research Dev't & #SciPol | doing my best for science | Evolutionary Anthropology PhD | #celiac | 🐶 #DogRescue | #FosterCare | Personal account.
![Conference poster with graphs, images of brain endocasts, and some text. Title: What can small apes teach us about the evolution of big brains? Text: Gibbons (Hylobatidae) have many parallels with fossil hominins including variable brain and body size, and taxonomic diversity originating in the Pliocene [1]. Comparison with gibbons can illuminate potential causes and consequences of hominin endocranial (i.e., brain) diversity. Gibbon craniofacial variation is low, consistent with genetic drift or stabilizing selection [2-3], yet their brains and endocasts are under-explored.
Between-group principal component analysis of endocranial shape in gibbons and hominins. Hylobates is most similar to Nomascus and Hoolock to Symphalangus, despite size differences in these dyads. Among hominins, smaller-brained Homo is relatively ‘intermediate’ in shape between H. erectus and sapiens. These patterns suggest there is not a simple relationship between endocast size and shape.
Encephalization characterizes hominin evolution while gibbons (especially Hylobates) may be phyletic dwarves. Variation in size-shape space (3D plots, above) suggests different pathways to brain size change (PC1), with larger hylobatids and smaller hominin taxa separated on PCs 2-3. Each PC is associated with different shape changes among gibbons versus hominins (endocast meshes, above).
Gray shading above highlights the majority of within- and between-genus variation in gibbons, against which to compare hominin variation. KNM-ER 1470 and especially KNM-ER 1813 are more different from other fossil Homo than most members of the same gibbon genus are from one another. Most human and Homo erectus endocast shape differences are beyond the majority of intergeneric gibbon comparisons.
Hominins underwent substantial endocranial size and shape evolution compared to a gibbon baseline. More research into gibbon endocasts, brains, and cognition will be illuminating: “Overlooked small apes need more attention!” [8]](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:cxuewbna4w3ny7h46z4ghcqa/bafkreih6vtyrsecfs3u2cmf4ppg4kfjsja4kaxi2lb4t4or2cla2drjcpa)
