Nobody ever watched Paranthropus robustus eat. Everything we think we know about its diet comes from bone and enamel. That makes this topic as much about how confident you are allowed to be as about what the teeth say.
📚 What you need to know
Hominidae is the great ape family: humans, chimpanzees, gorillas and orangutans.
Most living hominids are omnivores, though the balance differs: chimps are mainly frugivores, gorillas mainly herbivores.
The jaw and dentition of each species are specialised for its particular diet.
Incisors cut, canines hold and tear, premolars and molars grind.
Because skulls and jaws fossilise well, the same reasoning can be applied to extinct hominids.
But teeth do not always match diet perfectly, so conclusions must be treated as deductions, not facts.
The family, and what they eat
Humans sit inside the Hominidae, alongside chimpanzees, gorillas and orangutans. Gibbons are close relatives but are usually placed in their own family, the Hylobatidae — worth knowing if a question shows you a primate tree.
Most existing hominids are omnivores, meaning their nutrition comes from a combination of animal and plant material. The interesting part is how differently that balance is struck.
Species
Main diet
What the skull looks like
Chimpanzee
Mainly a frugivore — fruit, with other plant matter and some small mammals
Relatively small jaw muscles, only strong enough for softer fruit and animal tissue; small incisors and long canines
Gorilla
Mainly a herbivore — leafy vegetation, with some insects
Very strong jaw muscles for biting and grinding tough vegetation; large molars and premolars
Human
Omnivore, including a substantial amount of meat
Small jaw and small canines; teeth actually more like those of a plant-eater
Notice that last row already. Humans eat plenty of meat and have the dentition of something that does not. Hold on to that — it is the reason this whole topic ends with a warning rather than a conclusion.
The four tooth types
These four shapes are the alphabet of the whole skill. Learn the shape and the job together.
Species have different combinations and sizes of these four types, matched to what they need to chew.
🧠 Front to back, soft to tough
Work along the jaw from the front: cut (incisor), grip (canine), crush (premolar), grind (molar). Food goes in at the front and gets progressively more destroyed as it moves back.
Reading an extinct hominid’s diet
We know there is a relationship between diet and dentition in living hominids. Skulls and jaws of extinct species are often well preserved, so the same relationship can be applied to them. That is how scientists work out both the diets of extinct species and something about the ecosystems they lived in.
The crest on top of the robust skull is not for protection. It is simply extra bone surface for chewing muscles to attach to.
Two worked cases
Species
Fossil evidence
Deduction
Paranthropus robustus
Robust skull shape similar to a modern gorilla, with attachment points for large jaw muscles; large molars and premolars; thick tooth enamel
A diet of tough plant material, needing heavy grinding and enamel that resists damage
Homo floresiensis
Large premolars and small canines; square, robust jaws like a plant-eating gorilla; tooth abrasion patterns; skull shape closer to modern humans; tools found alongside
Primarily a plant eater on a fibrous diet, with reduced biting forces — but the tools suggest some meat eating too
Other extinct hominids you may meet in a question include Australopithecus africanus and Homo neanderthalensis.
Why the answer is never certain
This is the part that separates a good answer from a full-mark one. Dentition can sometimes be clearly linked to diet, but teeth do not always give a perfect indication of what a species eats.
⚠ Three awkward facts
Existing humans eat quite a lot of meat, but have teeth more similar to those of plant-eaters.
Orangutans and gorillas have pointed canines, yet neither eats meat.
Male chimps have longer canines than females, despite eating the same diet.
The explanation is that teeth do more than one job. They are also used in defending territory and competing for mates, so a large canine may be about display rather than diet. That means other factors have to be considered before drawing conclusions about the diets of human ancestors.
A better line of evidence: studying fossil teeth under a microscope to look at patterns of abrasion. Scratches and pitting on the enamel record what the tooth actually chewed, which is closer to direct evidence than shape alone.
🤔 Nature of Science: deductions can be made from theories
The reasoning runs in a clear sequence. Scientists start by making observations — noticing how the teeth of living hominids relate to their diets. Those observations are used to develop a theory: that the diet of an extinct hominid can be deduced from its dentition. The theory is then applied to fossils to produce deductions.
That is a legitimate and valuable way to work. But it only holds while the evidence supports it. The mismatch between human diet and human teeth is exactly the kind of new evidence that must be taken into account: it warns scientists that deductions about extinct species may be flawed, and that additional sources of evidence are needed.
Worked examples
WORKED EXAMPLE
A fossil skull has a pronounced ridge along the top, widely flared cheek arches, and very large molars with thick enamel. Deduce its likely diet and explain your reasoning. [3 marks]
Step 1: read the ridge and the cheek arches
Both provide attachment points and space for large jaw muscles, so this species could generate very strong biting and chewing forces.
Step 2: read the teeth
Large molars are for grinding, and thick enamel protects the tooth from damage by abrasive material.
Step 3: put it togetherstrong chewing muscles + large grinding surfaces + tough enamel → tough, fibrous plant materialA diet of tough vegetation, requiring prolonged grindingSay “deduce” or “suggests”, not “proves”. The command word itself is telling you how confident to be.
WORKED EXAMPLE
Evaluate the use of dentition to determine the diet of an extinct hominid. [4 marks]
Strength 1
Skulls and jaws preserve well as fossils, so dentition is often the best evidence available for a species nobody can observe.
Strength 2
There is a demonstrated relationship between diet and dentition in living hominids, so applying it to extinct species is a reasonable deduction.
Limitation 1
Teeth do not always match diet. Humans eat meat but have plant-eater dentition, and gorillas have pointed canines without eating meat.
Limitation 2
Teeth also serve other functions such as defending territory and competing for mates, so size may reflect display rather than food.
Useful and often the only evidence available, but not conclusive on its own“Evaluate” needs both sides plus a judgement. Two strengths and two limitations is a safe structure.
WORKED EXAMPLE
Suggest one additional source of evidence that could support a conclusion about an extinct hominid’s diet. [2 marks]
Name the evidence
Examining the fossil teeth under a microscope to look at patterns of abrasion on the enamel.
Say why it helps
Scratches and pitting record what the tooth actually chewed rather than what it was shaped to chew, so it gives a more direct indication of diet than tooth shape alone.
Microscopic abrasion patterns; a record of use, not just of formTools found at the same site would also be credited, as evidence of hunting or cutting behaviour.
💡 Exam tip
Always pair a feature with the force or action it implies: “large crest → large jaw muscles → strong chewing”.
Use the tooth names correctly. “Back teeth” will not be credited where molars is expected.
Match your confidence to the command word: deduce and suggest mean “reason it out”, not “prove it”.
In any evaluation, include at least one of the three awkward facts about teeth not matching diet.
Mention thick enamel for abrasive diets — it is a quick, specific mark.
If a question mentions tools found at the site, use them. They are separate evidence of behaviour.
⚠ Common mix-up
“Sharp canines mean it ate meat.” Gorillas and orangutans disprove this on their own.
Confusing premolars and molars with canines when describing grinding. Grinding is the flat, ridged teeth.
Stating a deduction as a fact. Fossil diet conclusions are inferences and should be worded as such.
Forgetting the crest is a muscle attachment, not armour or a display structure.
Placing gibbons in Hominidae. They are close relatives, but usually in their own family.
Giving only strengths in an “evaluate” question. Half the marks are in the limitations.
Up next: Nutritional Adaptations — teeth were just one example. Now we look at the full arms race between eaters and eaten, in animals and in plants.
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