Nutrition in Hominidae: Skills (SL IB Biology)

• Humans are part of the Hominidae family, along with chimps, gorillas, orangutans, and gibbons
  • The evolutionary tree below shows the Primate order, which contains the Hominidae family on the left hand side

The Primate order (above) contains the Hominidae family

• Most existing hominids are omnivores, meaning that their nutrition comes from a combination of animal and plant material, e.g.
  • Chimps are mainly frugivores, meaning that their main diet consists of fruit, though they do eat other plant matter and some small mammals
  • Gorillas are mainly herbivores, feeding primarily on leafy vegetation, though they do sometimes eat insects
• The study of the skulls of existing hominid species shows that the jaw and dentition, or teeth, of each species are specialised for their particular diet, e.g.
  • Chimps have relatively small jaw muscles which are only strong enough to chew softer fruit and animal tissue, while gorillas have very strong jaw muscles for biting and grinding tough vegetation
  • Chimps have small incisor teeth and long canine teeth, enabling them to bite and tear meat, while gorillas have large molar and premolar teeth for grinding vegetation
    • Incisor teeth are chisel shaped for cutting and biting
    • Canine teeth are pointed for holding and tearing
    • Premolars and molars are flat and ridged for grinding

Types of teeth diagram

Species will often have different combinations of teeth types and sizes to enable them to better chew and digest their diet

• We know that there is a relationship between diet and the dentition in currently existing hominid species, and it is possible to apply this principle to extinct hominid species
  • The skulls and jaws of extinct species are often well preserved and can be studied
  • This allows scientists to find out about the diets of these extinct species, as well as the ecosystem structures in which they lived
    • It is worth noting that while dentition can sometimes be clearly linked to diet, teeth don't always give a perfect indication of what a species eats, e.g.
      • Existing humans eat quite a lot of meat, but have teeth that are more similar to plant-eaters
      • Orangutans and gorillas have pointed canines but do not eat meat
      • Male chimps have longer canines than females despite not having a different diet
    • Teeth may play a role in other processes, e.g. defending territory, or competing for mates, so are not always a perfect indicator of diet, and other factors would have to be considered when drawing conclusions about the diets of human ancestors
      • E.g. scientists can study fossil teeth under a microscope to look for patterns of abrasion which may indicate diet more clearly
• Examples of extinct hominids include
  • Australopithecus africanus
  • Paranthropus robustus
  • Homo floresiensis
  • Homo neanderthalensis
• E.g. fossil evidence from Paranthrapus robustus suggests that they had a diet of tough plant material
  • Their skull shape was similar to that of modern gorillas; robust in shape, and with attachment points for large jaw muscles for chewing tough vegetation
  • Large molars and premolars for grinding vegetation
  • Thick tooth enamel to protect the tooth from being damaged by tough plant matter
• E.g. fossil evidence from Homo floresiensis suggests that they were primarily plant eaters, but that they may have eaten some meat
  • They had large premolar teeth and small canines
  • Their jaws were square and robust; a feature that is similar to plant-eating gorillas
  • Tooth abrasion suggests a fibrous, plant-based diet
  • Their skulls are more similar in shape to humans that to other human ancestors, suggesting a reduction in the biting forces used
  • Evidence of hunting/cutting tools provides additional evidence of meat eating behaviour
• Some fossils are available to view as part of digital collections, e.g. from the Smithsonian Institution, the Paleontological Research Institution, and the North Carolina School of Science and Mathematics
  • Consider examining 3D specimens of Homo sapiens, Homo floresiensis, and Paranthrapus robustus to infer diet from anatomical features

CC BY-SA 4.0, via Wikimedia Commons

CC0, via Wikimedia Commons

Paranthropus robustus (left) had a skull ridge for the attachment of large jaw muscles and a robust skull shape similar to modern gorillas, while Homo floresiensis (right) had small canine teeth and a skull similar in shape to modern humans

NOS: Deductions can be made from theories

• Scientists begin their work by making observations, e.g. observing how the teeth of existing Hominids relates to their diet
• Observations can then be used to develop theories, e.g. that the diet of extinct Hominids can be deduced by looking at their dentition
• While such theories and deductions are a valuable part of the scientific process, it is important that new evidence is taken into account as it arises, e.g. discrepancies between the dentition and diets of modern hominids tell scientists that their deductions about extinct species may be flawed, and that additional sources of evidence may be needed