Ancient humans had strong teeth to eat resistant plants, seeds and nuts without damaging the enamel, studies say
- Scientists thought that resistant plants and seeds had been avoided by ancient humans
- But new analysis reveals that hard plant tissue has no harmful effects
- Only minor damage is done and not enough to justify avoiding a food source
- Now I thought hard plant foods could have made up a larger part of the early ancestor’s diet than previously thought
Scientists have long rejected the belief that prehistoric humans avoided eating robust plants because they had damaged their teeth.
It is now believed that hard plant foods may have contributed to a larger part of the early ancestor’s diet than previously thought.
U.S. scientists have found that even the toughest plant tissues just wear out for primate teeth.
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In the photo: a schematic drawing of seeds mechanically protected by lignified woody fabric. (a) The large seeds of some dicotyledon plants are protected by a woody seed shell (b) Even small monocotyledon seeds have lignified pericarps that protect the seed inside, making it difficult to open
“We found that hard plant tissues such as nut and seed shells barely affect the micro-dental textures on the teeth,” said Adam van Casteren, a professor of biological anthropology at Washington University in St Louis.
Scientists studied the molars of the Borneo orangutan to see how hard plants affected the enamel.
They found that microscopic pits were not created from hard plant tissue, such as nuts and seeds, as expected.
“If your teeth don’t show elaborate dimples and scars, that doesn’t necessarily rule out eating hard food,” said Dr. Van Casteren.
The study shed light on a little-known group of ancient humans known as austrolopites with large and powerful jaws.
It is suspected that they also had extremely powerful jaw muscles, similar to some primates of our day.
“All of these morphological attributes seem to indicate that they had the ability to produce large bite forces, and therefore probably cut down on a diet of hard or bulky foods such as nuts, seeds or underground resources such as tubers,” said Dr. Van Casteren.
The researchers attached tiny fragments of seed shells to a probe and repeatedly dragged it over the enamel from a Borneo orangutan molar tooth. Seed fragments did not produce large pits, scratches or fractures in the enamel, the researchers found – only shallow grooves (pictured)
The researchers attached tiny seed shells to a probe and repeatedly dragged it over the enamel from a Borneo orangutan molar tooth.
A total of 16 different tests were conducted to replicate three types of nuts that make up the modern primate diets, each with different levels of hardness.
The researchers also dragged the seeds with the same force that a jaw would have created.
The seed fragments did not produce large holes, scratches or fractures in the enamel, the researchers found.
There were some shallow grooves, but scientists saw nothing that indicated that hard plant tissues could significantly contribute to the dental micro-tooth.
The seed fragments themselves, however, showed signs of degradation caused by rubbing against the enamel.
Researchers now believe that the large australopith jaws could have been used to chew large quantities of seeds and would not have healed the teeth.
“And this makes perfect sense in terms of the shape of their teeth,” said Peter Lucas, co-author of the Smithsonian Tropical Research Institute, “because the blunt and cusp shape of their molars is ideal for this purpose.”
“When consuming many very small hard seeds, large bite forces are likely to be needed to grind all cereals,” said Dr. Van Casteren.
“In light of our new findings, it is plausible that small hard objects such as grass seeds or sedge seeds were a dietary resource for early hominids.”
WHEN DID THE FIRST EMERGENCY OF HUMAN ANCESTORS MAKE?
The chronology of human evolution can be traced back to millions of years. Experts estimate that the family tree goes as such:
55 million years ago – The first primitive primates evolve
15 million years ago – Hominidae (great apes) evolve from the ancestors of the gibbon
7 million years ago – The first gorillas evolve. Later, the chimps and human lineages diverge
A recreation of a Neanderthal man is depicted
5.5 million years ago – Ardipithecus, the first proto-humans share traits with chimpanzees and gorillas
4 million years ago – Monkey like the first humans, Australopithecines appeared. They had a brain no bigger than that of a chimpanzee but other more human characteristics
3.9-2.9 million years ago – Australoipithecus afarensis lived in Africa.
2.7 million years ago – Paranthropus, lived in the woods and had huge jaws for chewing
2.6 million years ago – Manual axes become the first major technological innovation
2.3 million years ago – Homo habilis thought he first appeared in Africa
1.85 million years ago – The first “modern” hand emerges
1.8 million years ago – Homo ergaster begins to appear in fossil records
800,000 years ago – Early humans control fire and create hearths. Brain size increases rapidly
400,000 years agoor – Neanderthals begin to appear and spread in Europe and Asia
300,000 to 200,000 years ago – Homo sapiens – modern humans – appear in Africa
50,000 to 40,000 years ago – Modern humans reach Europe