2.10.3Inquiry Process
Nutrition in Hominidae: Skills — IB Biology HL Revision Notes & Topical Questions
5 min read 6 parts Lesson 98 of 160
Part 1 of 6The Hominidae and Their Diets
Diets vary even among close relatives, and body structure reflects what each species eats.
The family
- Hominidae includes humans, chimpanzees, gorillas and orangutans, all primates sharing recent common ancestry.
Chimpanzees
- Mainly frugivores that eat fruit, but they also eat other plant matter and small amounts of meat.
Gorillas
- Mainly herbivores that feed mostly on leafy vegetation, with occasional insects.
Humans
- Omnivores that eat a mixture of plant and animal material and prepare food with fire and tools.
| Species | Main diet | Typical dental feature |
|---|---|---|
| Chimpanzee | Fruit with some meat | Long canines, small incisors |
| Gorilla | Leaves and stems | Large molars and premolars |
| Human | Omnivorous | Small canines, mixed teeth |
Part 2 of 6Teeth and Jaws as Evidence
Dentition and skull shape are well preserved in fossils, which makes them good evidence.
Teeth and Jaws as Evidence
Incisors
- Chisel-shaped teeth used for cutting and biting food, large in species that bite off fruit.
Canines
- Pointed teeth used for gripping and tearing, large in some meat eaters but also used in display.
Premolars and molars
- Broad ridged teeth that grind tough plant material, enlarged in species eating coarse vegetation.
Jaw muscles
- Strong muscles need large attachment areas on the skull, so crests and wide cheekbones suggest hard chewing.
Part 3 of 6Inferring Diets of Extinct Species
1
Study the skull, jaw and teeth of living hominids to link each structure to a known diet.
2
Examine fossil skulls and teeth of an extinct species and compare the same features.
3
Paranthropus robustus has large molars, thick enamel and a robust skull, which fits a diet of tough plant material.
4
Microscopic wear patterns on fossil teeth can give additional evidence of foods such as hard seeds or soft fruit.
5
Combine the lines of evidence to propose a diet and then recognise the uncertainty in the conclusion.
Part 4 of 6Limitations of the Evidence
Humans
- Humans eat a lot of meat yet have teeth more similar to those of plant eaters, so teeth alone mislead.
Other uses
- Canines may serve in defence or display, as in male chimpanzees and in gorillas that do not eat meat.
Preservation
- Fossils are incomplete, so the sample may not represent the whole species.
Diet change
- A species may eat different foods across seasons or between populations, hiding variation.
Part 5 of 6Worked Example
Question
- A fossil hominid skull shows large flat molars, thick enamel, small incisors and a ridge on top of the skull for jaw muscle attachment.
- Suggest its probable diet and one limitation of the inference.
- Large flat molars and thick enamel indicate grinding of tough, abrasive food.
- A skull ridge for strong jaw muscles supports heavy chewing.
- These features match living plant eaters such as gorillas, so a diet of tough vegetation is likely.
Answer
- Probably tough plant material;
- teeth may not reveal occasional meat, so wear patterns or other evidence would be needed.
Part 6 of 6Exam Checklist & Tips
2.10.3 – Key Points for the Exam
- Hominidae The family of primates containing humans, chimpanzees, gorillas and orangutans.
- Frugivore An animal whose diet consists mainly of fruit.
- Herbivore An animal that feeds mainly on plants.
- Dentition The type, number and arrangement of an animal's teeth.
- Omnivore An animal that eats both plant and animal matter.
Common Mistakes
- Treating canine size as proof of meat eating; display and defence also use canines.
- Assuming one fossil gives the diet of the entire species.
- Forgetting to compare fossils with living species before inferring a diet.
- Ignoring other evidence such as wear marks when drawing conclusions.
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