Baboon feeding ecology informs the dietary niche of Paranthropus boisei.

Gabriele A Macho,Karen Hardy

doi:10.1371/journal.pone.0084942

Abstract

Hominins are generally considered eclectic omnivores like baboons, but recent isotope studies call into question the generalist status of some hominins. Paranthropus boisei and Australopithecus bahrelghazali derived 75%–80% of their tissues’ δ13C from C4 sources, i.e. mainly low-quality foods like grasses and sedges. Here I consider the energetics of P. boisei and the nutritional value of C4 foods, taking into account scaling issues between the volume of food consumed and body mass, and P. boisei’s food preference as inferred from dento-cranial morphology. Underlying the models are empirical data for Papio cynocephalus dietary ecology. Paranthropus boisei only needed to spend some 37%–42% of its daily feeding time (conservative estimate) on C4 sources to meet 80% of its daily requirements of calories, and all its requirements for protein. The energetic requirements of 2–4 times the basal metabolic rate (BMR) common to mammals could therefore have been met within a 6-hour feeding/foraging day. The findings highlight the high nutritional yield of many C4 foods eaten by baboons (and presumably hominins), explain the evolutionary success of P. boisei, and indicate that P. boisei was probably a generalist like other hominins. The diet proposed is consistent with the species’ derived morphology and unique microwear textures. Finally, the results highlight the importance of baboon/hominin hand in food acquisition and preparation.

Highlights

Papio and Theropithecus are considered good analogues for an assessment of the adaptive suite of hominin dento-cranial and manual morphology relating to the lineages’ dietary radiation and the ecological drivers underlying it [1,2,3]
I explore whether the energetic requirements of P. boisei could have been met by a C4 diet, and bearing in mind the limitations of P. boisei dento-cranial morphology
By varying the time allocated to eating various C4 sources, I enquire how many minutes per day a 34–49 kg Paranthropus boisei [22] would have had to feed on C4 sources to meet approximately 80% of its daily energy requirements

Summary

Introduction

Papio and Theropithecus are considered good analogues for an assessment of the adaptive suite of hominin dento-cranial and manual morphology relating to the lineages’ dietary radiation and the ecological drivers underlying it [1,2,3]. The composition of baboon diet differs between groups and individuals as a result of local habitats, seasonal fluctuations in resources and individual preferences [7,10]. This flexibility and selectivity enables baboons to extract the maximum amount of energy and nutrients from the foods available, even when the environments appear resource poor while, concomitantly, limiting the intake of tanins and excessive amounts of fibers; unlike grazers, baboons lack the gut physiology to digest large amounts of fibers [11,12,13]. By employing a selective feeding strategy, short-term, e.g. seasonal, fluctuations in resources can be buffered [7] This is important for a large-brained, slow-growing primate [14,15], as brains are expensive to grow and to maintain and require a constant supply of energy-rich foods [16]. By varying the time allocated to eating various C4 sources, I enquire how many minutes per day a 34–49 kg Paranthropus boisei [22] would have had to feed on C4 sources to meet approximately 80% of its daily energy requirements

Methods

Results

Conclusion