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I've heard (multiple times) that your finger is as easy to bite through as a carrot.

Here are some places I've seen it proposed:

Additionally, it is a popular question on Yahoo! answers. None of these have particularly definitive, well-referenced answers.

I've heard stories of people biting off fingers/toes of other people. I've also heard your brain knows it would hurt and won't let you do it to yourself.

Is it true that fingers and carrots are relatively equivalent when it comes to biting force?

Sunishtha Singh
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SSumner
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  • "I've heard" is a bit bad claim. Where have you heard it? What locality? Any references or bigger claims? – Wertilq Mar 04 '13 at 18:17
  • Seems to be a common "Urban Legend", but I don't know the veracity of it – SSumner Mar 04 '13 at 18:38
  • If you have heard of people biting off other people's fingers, what is left to answer? – Oddthinking Mar 04 '13 at 22:27
  • @Oddthinking: We would still need to know if it is as easy as biting through a carrot. – Saturn Mar 04 '13 at 22:59
  • Omega, I looked closer at the references. I'm updating the question to match those claims, and dropping the issue of what "easy" means, whether the brain "known" and other guff. – Oddthinking Mar 04 '13 at 23:56
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    With the updated question, would it be valid to wonder whether the carrot is cooked or not (if so, the cooking method)? – Saturn Mar 05 '13 at 00:39
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    Someone just try it! :) – 0xC0000022L Mar 05 '13 at 03:34
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    I believe the equivalency was dependent on an uncooked carrot. A cooked carrot is extremely easy to bite through. – SSumner Mar 05 '13 at 03:47
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    @0xC0000022L: My brain didn't let me :( – Saturn Mar 05 '13 at 04:45
  • Where on the finger? - at a joint (between the bones) will be much easier than through the bone – Rory Alsop Mar 05 '13 at 09:03
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    I we talking about breaking or severing? I'd imagine that severing is substantially harder. Try it on a raw chicken leg... – Benjol Mar 05 '13 at 09:18
  • Is it sufficient to show you can chop through a carrot with a whip of a school cane, not chop through a finger with the same force? – Oddthinking Mar 05 '13 at 10:16
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    Biting through a chicken wing / leg isn't as easy as a carrot, and birds have weaker bones than mammals. This is one of those annoying questions where the answer is obvious (we can all break a carrot with our fingers without any fear of our fingers shattering), yet it's going to be a pain to provide a well referenced answer (unless there's a reputable Cannibalism journal I'm not aware of). – Ian Mar 05 '13 at 10:45
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    @Ian - There might be physiology journals out there that show you tensile strength of the finger bones and then you should show that based upon the human bite strength that it would be comparable. Mythbusters has done some work with human bite strength so it should be possible to do the research but I doubt it will be a quick answer. – rjzii Mar 05 '13 at 12:41
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    My two year old bites through carrots. My two year old also bites her twin brother's fingers as hard as she can when she's angry. He still has all his fingers. He also has no carrots – jdstankosky Mar 07 '13 at 19:33
  • Also, both your sources say it isn't possible. Do you have any sources saying that it IS? – jdstankosky Mar 07 '13 at 19:45
  • No, but I'm not sure how well-sourced they are. And it's a very common question, so I'm curious about an authoritative answer saying it's not. – SSumner Mar 07 '13 at 22:09
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    As I was trying to find an answer to this question, I found various references of food studies on the force needed to cut or shear a carrot in various conditions (frozen, cooked, old, ecc) with various cutting instrument. I found various references to the biting and shearing force of teeths. The difficult thing was finding references to the shearing force needed to cut a finger. – Duralumin Mar 28 '13 at 08:21
  • I would assume human flesh is roughly comparable to animal flesh in terms of difficulty to bite through. At any rate, the flesh is not the determining factor, but the bone. Is there any way to determine the force needed to break the bone (obviously it would be different than the blunt-force trauma required to break a bone)? – SSumner Mar 28 '13 at 13:16
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    Bite through a carrot. It's quite easy. Now bite down on your finger. You probably won't even break the skin. – James Christopher Oct 10 '13 at 22:59
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    @JamesChristopher - that's the point of the original question-you're brain won't let you – SSumner Oct 10 '13 at 23:26
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    @SSumner - of course it will. Even the average person can cause themselves a fair amount of pain with little effort. The brain doesn't prevent you from doing a significant amount of damage to yourself, even with average willpower. In any case, common sense should make it obvious that a bone is far stronger than a carrot. – James Christopher Oct 11 '13 at 02:19
  • @James Christopher-I know. My original question was seeking to debunk this. I just wanted to be sure,for curiosity's sake – SSumner Oct 11 '13 at 03:16
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    Years ago, I remember reading an article online about a pair of young lovers who, instead of exchanging wedding rings, decided to bite off each others' ring fingers and mount the bones on matching necklaces. I don't care to Google for the link because the images were graphic and I'd rather not revisit it. But the act turned out to be much harder than they anticipated, and I seem to recall that at least one of them needed to resort to a knife and/or kitchen shears. They were careful to bite directly on a joint. – ESultanik Jan 04 '16 at 18:43
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    @ESultanik Aww, that's sweet. Who says romance is dead? – Reinstate Monica -- notmaynard Jan 04 '16 at 22:49
  • [Here's the link](http://news.bme.com/2005/04/01/love-at-first-bite-the-publishers-ring/) [warning: graphic images]. Their teeth were unable to cut through all of the skin and connective tissue, so they had to use a knife to complete the job. – ESultanik Jan 05 '16 at 17:54

1 Answers1

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A “newton” is the international unit of force. A human adult’s maximum biting force ranges from 520-1,178 newtons depending on factors such as age and gender. It requires less than 200 newtons to bite through a raw carrot. This is well within the normal limits of the average person. Biting through a finger requires so much force that attempts often lead to partial-amputation; a bite that doesn't completely sever the finger. There are cases of fingers being bitten entirely off, but such an act requires extraordinary force, far greater than 200 newtons of carrot-cutting power.

You'll still have to bite through skin, tendons, and some flesh. Skin, unlike "meat", is very elastic. It's similar to trying to bite a rubber band instead of a carrot. There are a lot of factors that contribute to mechanical failure, applied force is only one :)

[EDIT] According to this study done in 1956 (Jamming of fingers: an experimental study to determine force and deflection in participants and human cadaver specimens for development of a new bionic test device for validation of power-operated motor vehicle side door windows) cadavers bones were tested at maximum applied force of 1886 N for the index finger and 1833 N for the little finger. In 200 jam positions, 25 fractures were observed on radiographs; fractures occurred at an average force of 1485 N.

So if it takes 1485 newtons to cause fractures (obviously greater force is required to completely sever through the entire fingers) then it does not take the same force to bite through a finger as a carrot. [/EDIT]

[EDIT 2] Was wondering if you were waiting to mark this as the answer. I re-read your comment and realized you may have been waiting on a hard number for human bite force as well as the force required to sever the finger.

For human bite force: the Wikipedia article on Orders of Magnitude tells us that human bite force, measured at the molars is averaged at 720 N. As far as understanding what it would take to sever a finger you must understand how measurements of hardness are taken (and the different scales used, but I won't go into that.)

According to the Wikipedia article on Hardness: Hardness is a measure of how resistant solid matter is to various kinds of permanent shape change when a force is applied. Hardness is dependent on ductility, elastic stiffness, plasticity, strain, strength, toughness, viscoelasticity, and viscosity. There are three main types of hardness measurements: scratch, indentation, and rebound. Within each of these classes of measurement there are individual measurement scales.

Scratch hardness is the measure of how resistant a sample is to fracture or permanent plastic deformation due to friction from a sharp object.

Indentation hardness measures the resistance of a sample to material deformation due to a constant compression load from a sharp object.

Rebound hardness, also known as dynamic hardness, measures the height of the "bounce" of a diamond-tipped hammer dropped from a fixed height onto a material. This type of hardness is related to elasticity.

All that being said, the manner in which the finger is severed, be it stripping of the flesh from the bone vs. a clean cut vs. blunt force crushing/obliterating, makes answering the question of 'how much' force is required to 'sever' a finger from the body difficult. I hope this answers your question in enough detail to dispel any skepticism that the human finger can be severed as easily as a carrot by the human mouth.

(For purposes of this answer I have not researched specific data regarding macroscopic molecular bonding of the biological materials that make up the human finger. Perhaps a thesis is in order?)

[/EDIT 2]

Kristopher
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    Good answer. Can you provide a hard number on human biting force and the force required to sever the finger? – SSumner Apr 04 '13 at 16:40
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    Where did you get 200N from for the carrot? Also, there is an assumption in the answer the bite is through bone. I just assumed without much thought that the joints would be less strong than the bones, and that the bite would have to be through a joint to get close to a carrot. – Oddthinking Apr 05 '13 at 02:49
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    I just re-checked this and noticed the edit. Good answer! I think this dispels the myth in my mind completely – SSumner Apr 05 '13 at 17:28
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    @Oddthinking - Good question! I found that first and didn't challenge it. However, page 156 of the Oxford Handbook of Applied Dental Sciences, (2002), by Crispian Scully, Oxford University Press, tells us that we generate about 70N - 150N of force during routine mastication of food like carrots or meat. The book also tells us that we have around 500N to 700N of mastication force. Regarding biting through a knuckle, you still have the required amount of force to sever the synovial sac, muscle, tendon, ligament, bone, articular cartilage and bursa. The knuckles aren't just floating in there (O; – Kristopher Apr 08 '13 at 18:47
  • Oxford Handbook of Applied Dental Sciences, (2002), by Crispian Scully, Oxford University Press ISBN: 9780198510963 – Kristopher Apr 08 '13 at 18:52