Dietary Proofs

**Introduction****Logical and structural limitations**- Comparative "proofs" of diet are subjective and indeterminate; i.e., they do not provide actual proof
of diet

- Four "proofs"--but what do they prove?

- Four "proofs"--but what do they prove?
- There is no logical validation for the implicit assumption that comparing two or more species via a list of features constitutes proof that a particular diet is natural or optimal

- How are features chosen for a comparison list?
- Once a feature is selected, how to measure?
- What is the definition of a "match"?
- How many matches are required for "proof"?

- The comparative "proofs" focus only on similarities while ignoring differences

- The comparative "proofs" ignore the fossil record and evolution

- The comparative "proofs" are dated and do not reflect current knowledge of
ape diets

- The comparative "proofs" assume dietary categories are discrete (distinct), while in nature diets form a continuum

- The comparative "proofs" ignore the important features that make humans unique in nature

- Comparative "proofs" assume the form/
function connection is strict and necessary

- Similar functions can be served by dissimilar forms

- The form/function relationship can be dissimilar even in closely related species

- Overall systemic constraints as important as individual functions/forms

- Similar functions can be served by dissimilar forms
- Research on the form/function linkage
- Early research

- Gut morphology

- Mastication

- More reliable insights by limiting complexity and narrowly defining features to be studied

- Early research
- The same form can serve multiple/
different functions

- Canine teeth

- Primate teeth

- Teeth of hominids

- Canine teeth
- Subtle changes in form can produce or support significant changes in the function of organs or body systems

- The function served by a particular form can vary dramatically according to specific feeding behavior

- Coprophagy

- The surface area of the digestive system may be less important than the retention time of food in the gut

- Coprophagy
- Analysis of dietary adaptations is non-trivial

- Evolutionary adaptations are compromise solutions that reflect the effect of multiple selection pressures, applied simultaneously
- Diets can temporarily change with habitat in the same species

- Staple foods vs. critical but more rare foods

- Phylogenetic (structural) challenges in comparative studies

- The form of digestive features can be affected by non-diet factors

- Difficulty of untangling cause and effect

- The form of digestive features can be affected by non-diet factors

- Comparative "proofs" of diet are subjective and indeterminate; i.e., they do not provide actual proof
**Counterexamples to the paradigm of comparative proofs**of diet

- Polar bears: an example of semi-aquatic feeding behavior

- The giant panda: a "carnivore" on a
bamboo diet

- Polar bears: an example of semi-aquatic feeding behavior
**Section summary**

*Back to Research-Based Appraisals of Alternative Diet Lore*