Predicting body mass of bonobos (Pan paniscus) with human-based morphometric equations

Area of Science:

• Paleoanthropology
• Primate Anatomy
• Biometrics

Background:

• Primate body mass is a key indicator of ecological, physiological, and behavioral traits.
• Body mass prediction equations (BMPEs) are crucial in paleoanthropology, but accuracy can be compromised by extrapolating beyond reference sample limits.
• Existing human-based morphometric BMPEs may not accurately predict non-human primate body mass due to skeletal differences.

Purpose of the Study:

• To evaluate the predictive accuracy of human-based morphometric BMPEs for bonobos (Pan paniscus).
• To develop a novel BMPE for bonobos by addressing systemic differences in stature and bi-iliac breadth between humans and bonobos.
• To assess the potential application of the novel BMPE to fossil hominins.

Main Methods:

• Utilized a test sample of 56 bonobos from the Lola ya Bonobo sanctuary.
• Assessed systemic differences in stature and bi-iliac breadth between humans and bonobos.
• Employed panel regression to generate a novel BMPE based on living bi-iliac breadth, and compared its accuracy against two existing morphometric equations.

Main Results:

• The novel BMPE demonstrated superior predictive accuracy for bonobo body mass compared to previously published human-based equations, with 41 of 56 bonobos predicted within 20% of their observed mass.
• The novel equation showed particular accuracy for bonobos weighing between 25 and 45 kg.
• Significant differences in scaling relationships between body mass and stature, limb proportions, pelvic morphology, and body tissue composition were noted between humans and bonobos.

Conclusions:

• The novel BMPE, derived from bonobo skeletal data, offers a more accurate prediction of bonobo body mass than human-based equations.
• The promising results suggest potential applicability of this novel BMPE for estimating body mass in fossil hominins, accounting for species-specific anatomical variations.
• Further research is warranted to refine BMPEs for diverse primate taxa and fossil hominins.