Strange Tooth Discovery Prompts Rethink of Human Evolution

Koshima Island Macaque and Neandertal Teeth

Koshima Island macaque (left) and Neandertal (right), both upper central incisors showing large vertical scratches. Credit: Ian Towle and John C. Willman.

A study into tooth wear in a group of wild Japanese macaques has significant implications for the study of human evolution, a University of Otago study has shown.

Lead author Dr. Ian Towle and Dr. Carolina Loch, of the Sir John Walsh Research Institute, in collaboration with colleagues from Japan, studied root grooves and large uniform scratches in the macaques’ teeth, which had previously only been described in fossil humans.

“Unusual wear on our fossil ancestors’ teeth is thought to be unique to humans and demonstrates specific types of tool use. These types of wear have also been considered some of the earliest evidence of cultural habits for our ancestors,” Dr. Towle says.

“However, our research suggests this idea may need reconsidering, since we describe identical tooth wear in a group of wild monkeys that do not use tools.

“This research raises questions for our understanding of cultural changes during human evolution and suggests we may need to reassess early evidence of cultural habits.”

Koshima Island Macaques Removing Limpets

Koshima Island macaque removing limpets.
Credit: Cecile Sarabian

The study, published in the American Journal of Biological Anthropology, concluded the ‘toothpick’-like grooves on back teeth and large uniform scratches on the macaques’ front teeth were actually caused by something more mundane, yet still surprising – eating shellfish from rocks and accidentally chewing grit and sand with their food.

This macaque group is well-known for undertaking remarkable behaviors, including washing foods in water, and consuming fish. They have been studied for more than 70 years and have not been seen using tools or other items that could cause the unusual tooth wear observed.

Dr. Towle has been studying tooth wear and pathologies in a wide variety of primate species and was “extremely surprised” to find this type of tooth wear in a group of wild monkeys.

Koshima Island Macaques Eating Limpets

Koshima Island macaque eating limpets. Credit: Takafumi Suzumura

“Up until now, the large scratches in the front teeth of fossil humans have been considered to be caused by a behavior called ‘stuff and cut’, in which an item such as an animal hide is held between the front teeth and a stone tool is used for slicing. Similarly, ‘toothpick’ grooves are thought to be caused by tools being placed between back teeth to remove food debris or relieve pain.

“Although this does not mean hominins were not placing tools in their mouths, our study suggests the accidental ingestion of grit and/or normal food processing behaviors could also be responsible for these atypical wear patterns.”

Dr. Towle believes the findings provide insight into how researchers interpret cultural changes through the course of human evolution.

“We are so used to trying to prove that humans are unique, that similarities with other primates are often neglected. Studying living primates today may offer crucial clues that have been overlooked in the past.”

Reference: “Atypical tooth wear found in fossil hominins also present in a Japanese macaque population” by Ian Towle, Andrew J. J. MacIntosh, Kazuha Hirata, Mugino O. Kubo and Carolina Loch, 1 March 2022, American Journal of Biological Anthropology.
DOI: 10.1002/ajpa.24500

17 Comments on "Strange Tooth Discovery Prompts Rethink of Human Evolution"

  1. We are ‘just’ animals. Religious belief has been a stumbling block to honest science, especially archaeology, geology, cosmology and all of the humanities. It makes objective reason impossible.

  2. Lol,
    I’ve seen a lot of so-called rethinking on The evolutionary theory. So, what is it? All this rethinking seems to make it obvious science is not sure about evolution! I’ve read many articles in the past couple of years about rethinking The evolutionary tree, the origin of man, reconstruction of human skulls from a few pieces, claiming to be able to extrapolate an entire skull from three or four fragments is a joke. Extrapolation is nowhere close to an exact science! How many times have whales lost their legs and walked on land? The same with sea lions, or manatees, or any creature? It’s like a theoretical physicist, you can make anything believable in your mind! But reality is something much different. How many skulls or skeletal remains found are part of a deformed human or a deformed animal? Humans with pointy heads? Humans with small craniums? Humans with expanded craniums from water on the brain? All claim to be these amazing earth-shattering finds, but, nothing can be proven. Theory is not fact, theory is not law, law is law!

    • A scientific theory is a model that explains the evidence. The theory of evolution is the model which explains the change in allele frequency, for any given life form, over time….that’s it. Because there isn’t consensus concerning particular behavioral details, doesn’t impede the model.

  3. Michael p robinson | March 7, 2022 at 10:23 am | Reply

    I so agree. We have an historical account in the bible. It’s funny how any other knowledge of historical events passed down or written from any other culture is considered valid. But yet, when it comes to biblical account its fiction. Even with the evidence being uncovered weekly in the Middke East that proves the bible is a historical document so far to date. Not one thing has been proven beyond a doubt to be false yet. Science still holds out hope that they are right, and the account from witnesses is wrong.

  4. Ricky Henager | March 7, 2022 at 11:52 pm | Reply

    There are things we are not suppossed to fully understand. We are here to grow in character and be the best that we can be at being good to one another. The size and scope of the universe and all of its mysteries are evident that we are to be humbled by its immense complexity and size and goes to show that we nothing but a grain of sand in comparison. You can spend your entire life speculating about what is this and what is that and for sone theres nothing wrong with that because it does help humanity to gain knowledge and be able to use it to progress our society. But it is what it is and we will never know the answer to questions of our exact origin or anything. We were not meant to know that and it will always be speculation. What isnt speculation is that someone or something created us and placed here inside this box called the earth and we are here only a short time,and to chase phantoms for most of ones life to me is of disinterest. I am humbled by my existence and am also grateful for the gift of life and where it comes from is from a source of powert beyond what we can comprehend. We are bound by physics in this realm and whomever cretaed us is not bound by those same physics. They have physics that we dont know about and to try and compare anything here to there is futile. There is a God and that God gave us the gift of life and that is all i know and its all i have. I dont care if im from a alienbreed for being O-negative or if i came from the recess Monkey. Al i know is that God put me here and will take me from here one day as he will everyone else. Enjoy your life while your here and dont rack your brain over things that you will never know the answer too. JUst be as humble as possible and grow in chracter. Love your life and Love the Lord who gave it to you.

  5. I have a problem with the west, why is the evolution a theory and its a big thing.
    And god existence fact is not a big thing?
    Allah and his messengers on earth from Adam to Mohamed to know are only the true knowledge about us and the world in the Quran the book even arabs and Muslims and non muslims still can’t understand it because of how magical it says leaving us shocked, and no one have ever found a mistake in Quran too.
    Evolution is a joke

    • Because gods are, in fact, Bronze age myths. There is zero evidence for them. Any of them, all of them. Please stop believing in imaginary beings.

    • Brenna Stoppiello | March 8, 2022 at 8:06 pm | Reply

      Good reply!
      I am a Christian, and agree totally. God and His creation and His ways are not meant to be fully known, but to be awed and glorified !

    • Religion is for sheeple indoctrinated by previous generations. You do not question your surroundings, your existence. You resight what a book tells you written by humans 1000s of years ago who thought the earth flat and comets crossing the night sky dangerous omens. What hasn’t changed over the past 1000s of years is human nature. The fact that all civilizations had some form of gods or spiritual creatures to explain existence and death is pretty clear evidence of why it’s all make believe. Fear of the unknown. In most of these civilizations who held the power? Those closest to the “gods”, kings queens, priests, etc. There are always humans who seek power over others and knowledge is power, even if that “knowledge” is a bunch of stories that the people of that time easily fell for given their limited understanding of the world. Today religion dwindles as people look for the real answers. I expect religion will hang on for a while longer as some cultures are more closed minded than others or have built most of their society norms around religion. To believe one religion is superior to another is comical as they are relics of the past and were simply used as tools by the powerful to keep the peasants in their place. Who do you want to believe, the religion that tells you when you die your consciousness goes to a lovely place that will allow you to hang out with other dead people or science that says you die and then you’re gone, no consciousness. Obviously believing religion is a much nicer way to go out, but you and I both know we’re lying to ourselves out of fear of death. So given that this life is really all we have, we should be nice to each other and try to live good lives. See we can have morals without religion too. The more you know.

      • Chris R. Courter | March 9, 2022 at 8:44 am | Reply

        I have studied a lot of science. Have always been fascinated with how things work. Evolution is Proven to happen within a species to adapt to changes they encounter such as environment or food source. Science can accurately account for those types of evolution. Yet evolution from one species to another has never had evidence of occurring. When considering this theory, the animal kingdom is the only discussion, but what of plant life? Are those who believe all live evolved from single cell organisms, also saying that every form of vegetation also evolved from the same single cell organisms? Everything from poison ivy to pineapple, from bananas to bamboo? How did such a wide variety of edible and poisonous plants evolve from the same source as all animals? Is this easier to believe than some architect designed this garden of a planet?

  6. Mr. Rickey well said. Thank you.

  7. Simon Paramor | March 9, 2022 at 10:57 am | Reply

    How embarrassing reading some of these replies

  8. Paul Allen Sudduth | March 9, 2022 at 4:38 pm | Reply

    As far as I can tell man has devolved not evolved.

  9. James kolbeck | March 12, 2022 at 6:27 pm | Reply

    The known fact of it all is all of us live on this planet called Earth and to argue about who’s right and who’s wrong is why we are killing each other.freedom of speech and religion is a right and does not matter who is right or wrong. What does matter is no matter the color of your be skin or your beliefs there are people suffering and needlessly dieing due to these different ways of thinking when we should be helping each other no matter who it is to live a decent life. No one is better than another and could all be living like Kings if we treat each other as we would want to be treated. Sorry about the book I just wrote.

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