Beavers, asides from being the largest rodent in North America and making rather fetching hats, also have iron compounds within their teeth enamel which allows said tooth handle higher amounts of mechanical strength.

It also makes their teeth orange.
enter image description here

Now, if humans had iron within their bones they would become stronger, right?

What I'm wondering is that would introducing iron to our skeleton make our bones stronger? Or is this a bad idea with unforeseen consequences, asides from an expanded appetite.


2 Answers 2



The Iron compounds in a beaver's teeth are not there to make its teeth stronger, they make the front layer of its teeth harder. This means that the beaver can gnaw tough, abrasive material such as wood without its teeth wearing down so fast. Additionally, the differential in hardness between the front and the back of the teeth means that the higher rate of wear at the back of the teeth makes them self-sharpening.

This has little or nothing to do with strength.

Bones wouldn't be made stronger by adding these iron compounds... if anything, it would make the bones more brittle.


Probably not

Teeth and bones are different. Their structures are different. Their formation processes are different. They mostly share the same minerals but bones have collagen unlike teeth. Collagen provides the flexible framework of bones and heals bone fractures as well. Dental homeostasis and bone homeostasis are different and affected by different factors. Dental homeostasis depends on the whole oral homeostasis as teeth are exposed to outside world unlike bones.

The iron in beaver teeth makes their teeth both mechanically stronger and more acid-resistant than fluoride-treated enamel.1 Iron can theoretically strengthen human teeth too. Nevertheless, studying beaver teeth helped us find a way to improve on enamel.2 It will probably not work for bones though, as bone homeostasis requires optimal iron levels in the system.

Iron overload as well as iron deficiency disrupt the delicate balance between bone destruction and production, via influencing osteoclast and osteoblast differentiation as well as activity. Iron overload as well as iron deficiency are accompanied by weakened bones, suggesting that balanced bone homeostasis requires optimal—not too low, not too high—iron levels

Balogh E, Paragh G, Jeney V. Influence of Iron on Bone Homeostasis. Pharmaceuticals (Basel). 2018;11(4):107. Published 2018 Oct 18. doi:10.3390/ph11040107

A possibility

It happened in nature. Chrysomallon squamiferum, commonly known as the scaly-foot gastropod, is the only known animal that has iron in its skeleton. Iron sulfites are found on dermal sclerites on its foot and in its shell.3 Again, their skeletal system is different than ours and exposed to outside world. They live in deep-sea hydrothermal vent ecosystems in the Indian Ocean.

However, studying snail's iron armor could help scientists and engineers design bioinspired materials and structures in many different fields. Each of the layers of its shell contributes differently to the armor's effectiveness. Their shell provides both mechanical and thermal protection.

In addition to the mechanical advantages, the OL and ML were experimentally determined to resist low pH dissolution, and the ML was also predicted to be beneficial for protection against brief thermal impulses (SI Text). Hence, the shell of C. squamiferum is a multifunctional design providing protection against numerous environmental threats found in the deep-sea hydrothermal vent environment to maximize survivability.

enter image description here

Yao H, Dao M, Imholt T, et al. Protection mechanisms of the iron-plated armor of a deep-sea hydrothermal vent gastropod. Proc Natl Acad Sci U S A. 2010;107(3):987-992. doi:10.1073/pnas.0912988107

1 Beaver Teeth Have Iron Advantage Author: Christopher Intagliata Publication: Scientific American Publisher: SCIENTIFIC AMERICAN, a Division of Springer Nature America, Inc. Date: Feb 23, 2015 Copyright © 2015, Scientific American, Inc. https://www.scientificamerican.com/podcast/episode/beaver-teeth-have-iron-advantage/

2 https://source.wustl.edu/2015/02/making-teeth-tough-beavers-show-way-to-improve-our-enamel/

3 Chong Chen, Katrin Linse, Jonathan T. Copley, Alex D. Rogers, The ‘scaly-foot gastropod’: a new genus and species of hydrothermal vent-endemic gastropod (Neomphalina: Peltospiridae) from the Indian Ocean, Journal of Molluscan Studies, Volume 81, Issue 3, August 2015, Pages 322–334, https://doi.org/10.1093/mollus/eyv013

Additional details

In my answer, I used to terms "stronger" and "strengthen" when talking about teeth/enamel. I said: "The iron in beaver teeth makes their teeth both mechanically stronger and more acid-resistant than fluoride-treated enamel. Iron can theoretically strengthen human teeth too". I stand by this statement.

Strength and Hardness can have different definitions in physics. However, it wouldn't be wrong to say teeth or enamel gets stronger. Enamel is part of the teeth. When enamel gets harder it makes teeth stronger against mechanical stress and and makes them more resistant to acid. "Strong teeth", "strong enamel", "strong gums" are used in dental context even it can have details in biology, chemistry and physics.

Whether "strong" or "strength" is used as an all-encompassing term to make it easier to understand, it has accuracy in physics/chemistry as well.

The difference of strength and hardness in summary:

Strength measures how much stress can be applied to an element before it deforms permanently or fractures. Hardness measures a material's resistance to surface deformation.


Enamel fractions can happen too beside enamel erosion. Enamel can have both strength and hardness. Beaver teeth are strong/resistant against both fractions and erosion.

There is even a scientific article that talks about "enamel strength" and the term "strength" is used by a materials chemist. Here are the relevant quotes from the article:

Enamel’s strength comes from how the hydroxyapatite is arranged, which scientists think reduces the risk of having a catastrophic crack propagate through enamel, Joester says.

In the inner enamel, the rods are organized in decussated layers, meaning the rods in each layer are at a different angle relative to the ones above and below, somewhat like the arrangement of wood fibers in plywood layers—but at alternating specific angles. This decussation makes the enamel stronger, Joester says, just as it does in plywood.

Brushing with fluoride toothpaste can strengthen your teeth after ion loss and protect your teeth against further decay.

Chemical & Engineering News ISSN 0009-2347 Copyright © 2022 American Chemical Society https://cen.acs.org/materials/biomaterials/dental-enamel-does-protect-teeth/98/i41

And surprise! Human enamel has iron in it too but it is very low compared to beaver teeth. Here is a comparison between human and beaver tooth enamel and the term "stronger" is used here also:

After the comparative evaluation of human and beaver tooth enamel, the following data were obtained. The chemical composition of beaver enamel has an increased content of magnesium, sodium, potassium, and silicium and a decreased content of sulfur and chlorine. The beaver enamel microhardness is 1.53 times higher than that of humans. These figures indicate that beaver tooth enamel is functionally stronger [49]. That is how the extremely rare carious teeth in these animals can be explained. It also proves that fluorine is only needed in childhood as in the newborn beavers’ teeth (it is known that they are born with teeth), the F content is 10 times higher than in humans, and in adult beavers’ teeth, despite the absence of caries, only traces of fluoride are found [41].

Kunin AA, Evdokimova AY, Moiseeva NS. Age-related differences of tooth enamel morphochemistry in health and dental caries. EPMA J. 2015;6(1):3. Published 2015 Jan 29. doi:10.1186/s13167-014-0025-8 https://pubmed.ncbi.nlm.nih.gov/3857315/


You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .