Links between life history traits and neuroanatomy of wild Canidae using cranial endocasts

Abstract

The Caninae subfamily (dogs, foxes, jackals, wolves) is a prolific taxon with 36 extant species displaying a wide variety of behavioural and physical adaptations to wildly different environments. 3D brain moulds generated from CT-scans of skulls, called digital endocasts, are used to study the brain and its shape in a non-invasive or destructive manner. My work aimed to investigate links between wild Canid brain shape and the following life-history traits: activity patterns, eating habits, and social levels. I used a semi-automated landmarking pipeline to capture shape variation and an extended phylogenetic generalized least squares to test whether life-history traits are linked to brain shape. I found a strong significant phylogenetic signal in brain size and a moderate signal in brain shape, and no significant relationship between brain shape and the aforementioned life-history traits. This indicates that brain size is highly conserved throughout the family and that brain shape is driven by evolutionary processes beyond phylogeny but ultimately not connected to their lifestyles. To investigate further, future studies should address subsetting the brain into representations of functional lobes, improving endocast quality, and increasing sample size.

Popular Abstract

From Foxes to Wolves: Discovering How Lifestyle Shapes the Wild Canid Brain

Arising 40 million years ago, the dog family (known as Canidae) has had over 214 species in its history. Today, the 36 wild members of the family such as wild dogs, foxes, jackals, and wolves, have incredibly diverse lives all across the world except for Antarctica. They vary in colour and size, and in lifestyles. Some species, like the tiny social desert-dwelling fennec fox thrive in the nighttime, whereas others, like the solitary south american Darwin’s fox, are active at all hours of the day. This striking behavioural diversity is ideal for studying how different environments shape species over time.

Scientists use bones commonly accessible in museum collections, such as the skull, to answer questions about species' lives and origins. Inside the mammal skull, the brain leaves impressions of its many folds and grooves. These imprints can be digitally extracted to reproduce the exterior surface of the brain in 3D, known as a digital endocast. Getting brains this way offers a non-destructive technique, useful for rare, delicate, or extinct skull specimens and species.

Since dog brains have been studied as models for human disorders, scientists have studied their brain in great detail. This means we have access to labelled maps of the dog brain that show which regions process different senses and emotions. Researchers create them by locating neural activity in the brain during reactions to specific stimuli. For example, the sound-processing region of the brain is found by playing sound and identifying which brain areas react. Since dogs are descended from wolves, we can use the dog map to infer brain function in other species in the family.

Do the lifestyle differences of wild Canids show up in the shape of their brains? Can we see changes in brain shape that are connected to their activity patterns, their diets, or their social lives? For example, do nocturnal species have larger visual regions of the brain?

To explore these questions, I recreated 89 endocasts from CT scans (3D x-rays taken in 360°) of wild Canid skulls, representing 29 out of the 36 species alive today. Then, I digitally applied pseudo-landmarks: dots placed on the surface of a 3D model that help computers compare shapes that don’t have the same obvious features. Using these pseudo-landmarks, I could look at brain shape across species and identify differences between them, especially when comparing their lifestyles.

Does the lifestyle of wild Canids influence their brain shape? My analyses suggest that behavioural habits don’t influence brain shape. Activity patterns (day vs night), social structure, and diet showed no strong relationship with brain shape across wild canids. That doesn’t necessarily mean behaviour has no influence. Wild canids are highly behaviourally flexible and quickly adapt to changing conditions, making it difficult to define a single “typical” lifestyle for a species. Also, we rarely know how individual animals actually behaved: it could've had a lifestyle more typical for the species, or behaved quite differently. This makes studying the relationship between behaviour and brain shape challenging.

Interestingly, brain size told a different story. Size was strongly linked to evolutionary relationships: species that are closely related tended to have more similar brain sizes. But brain shape was less tied to the canid family tree, and since I didn’t find any links between behavioural habits and brain shape, it suggests that it may be influenced by other factors beyond ancestry such as the environment, climate, or resource availability.

Further research must dive deeper into how brain shape changes in the wild Canid family, because doing so will help us understand what role brain anatomy plays in the wide variety of behaviours in the animal kingdom. Ultimately, understanding how brains evolve in a diverse mammal group such as canids can help reveal broader rules of brain evolution, including the forces that shaped the human brain.

• author: Wawro, Matylda Anna
• supervisor: Masahito Tsuboi; Christy Anna Hipsley; Sarah Jane Du Plessis
• organization: Degree Projects in Biology
• course: BION03 20242
• year: 2026
• type: H2 - Master's Degree (Two Years)
• subject: Biology and Life Sciences
• language: English
• id: 9222113
• date added to LUP: 2026-02-05 09:29:55
• date last changed: 2026-02-05 09:29:55