Friday Weird Science: We need your ID, kiss on the dotted line.

May 14 2010 Published by under Friday Weird Science

Sci watched the new Sherlock Holmes movie the other night. It's cute, and one of the things that she really enjoyed was watching Sherlock Holmes use his amazing power of deduction:

Sherlock Holmes: As to where I am, I was, admittedly, lost for a moment, between Charing Cross and Holborn, but I was saved by the bread shop on Southford Hill. The only baker to use a certain French glaze on their loaves - a Brittany sage. After that, the carriage forked left and right, and then a tell-tale bump at the Fleet conduit. And as to who you are, that took every ounce of my not-inconsiderable experience. The letters on your desk were addressed to a Sir Thomas Rothman, Lord Chief Justice, that would be the official title. Who you *really* are is, of course, another matter entirely. Judging by the sacred ox on your ring, you're the secret head of the Temple of the Four Orders in whose headquarters we now sit, located on the northwest corner of St. James Square, I think. As to the mystery, the only mystery is why you bothered... to blindfold me at all.

And then of course there's this:;

(An excellent reason to enjoy watching a movie if ever I saw one)
And then of course, there was the cool historical methods Holmes and Watson used in their forensic studies. None of the normal fingerprint stuff, though. And it's too bad, fingerprints make great identifiers.
As I'm sure most of you already know, no two people's finger prints are identical. This means that you can identify someone by their finger print (usually the thumb). It also means that a lot of stories talk about robbers who sanded off their fingertips to make them more sensitive and prevent fingerprinting. Which seems pretty cool, though painful and probably rather ineffective.
So Sci always thought that the fringerprints were the only easily accessible thing about people that could be used for identification.
But what about other parts?
What about the lips?

This Friday Weird Science comes to you courtesy of reader Tony, who saw this and thought of Sci! Tsuchihashi, Y. "Studies on personal identification by means of lip prints" Forensic Science, 1974.

Of course, finger prints aren't the only method of ID. There's height and eye color and nose shape and whatall else. There's also teeth, but that's a little...invasive for routine identification ("We need some ID, please hand over a molar." Would people carry molars around?). Of course height and eye color and nose shape are things that can be the same a lot of people. You need something a little more individual sometimes.
But the idea of lips came as a bit of an accident. Apparently another scientist was trying to look at the OUTER shape of the lips by using "lip rouge" and looking at the prints to see if they were individual. They weren't, but they DID notice that the lines and fissures in the lips varied between people. Another scientist proposed a system of lip fissure classification for use in identification. As you probably know, for example, there are several types of fingerprints: the arch, the whorl, and the loop (right or left). They look like this:

Well, the scientists proposed a similar system for lips. At first it was just straight lines vs angled lines vs curved lines, but it's a bit more complex than that. They ended up with 6 types, 1-5 with a 1prime in there.
Type I: Clear-cut grooves running vertically across the lip. Looks like this.

Type I': The grooves are straight but disappear half-way instead of covering the entire
breadth of the lip.

Type II: The grooves fork in their course.

Type III: The grooves intersect.

Type IV: The grooves are reticulate.

Type V: The grooves do not fall into any of the Types I-IV, and cannot be differentiated

And then it gets even more specific than that, because within one pair of lips, you can have some of ALL of these classifications:

Um. Yikes.
Anyway. Are these patterns all specific? To find this out, they took over 1300 people, and got lip prints. They were looking for individuality as well as heritability, and so they looked at groups of people and families between the ages of 3 and 60. And no two people had the same lip print, though identical twins came close.
They also looked at the lip prints over TIME. It's no good to have individuality if the differences don't persist across time;

You can see above a single person's lip print over a period of three years. The lip prints apparently remained pretty well the same.
The study concluded that lip prints might be a good way to ID people, in the same way finger prints are. And it's possible. Keep in mind, though, that this study was from the 70s, and several things have come along since then:
1) Lip plumping chemicals
2) Lip injections
3) Botox.
Sci would not be remotely surprised if any one of these things made some drastic changes to your lip print. In addition, people often get scars or damage to their lips which can change the resulting print, though the same happens for fingers. However, Sci has yet to see (and hopes she never sees) people trying to make the pads of their fingers look younger. So it's probably best to use fingerprints for now.
Still this could be useful. Lipstick on the collar? Check out the print. Who knows, you might recognize someone from more than just that magenta lipstick shade they favor.
Tsuchihashi, Y. (1974). Studies on personal identification by means of lip prints Forensic Science, 3, 233-248 DOI: 10.1016/0300-9432(74)90034-X

4 responses so far

  • Mac says:

    "And then of course, there was the cool historical methods Holmes and Watson used in their forensic studies. None of the normal fingerprint stuff, though"
    Are you sure?
    To quote 'The Adventure of the Norwood Builder' :
    "You are aware that no two thumb marks are alike?"
    "I have heard something of the kind."
    "Well, then, will you please compare that print with this wax impression of young McFarlane's right thumb, taken by my orders this morning?"
    As he held the waxen print close to the blood-stain it did not take a magnifying glass to see that the two were undoubtedly from the same thumb.
    It seems that Mr Holmes did use fingerprints after all ...

  • Scicurious says:

    Mac: oh I know they used fingerprints in the books, just not in this rendition of the movie.

  • Art says:

    My impression is that pretty much any section of skin would have a unique pattern if examined closely. This would need to be tested. But it does open up a opportunity for greater security.
    Presently fingerprints can be lifted and copied. If necessary the finger/s can be removed. Some locks require the fingers to be warm but warming them would be easy. Just keep the severed fingers under your arm and use them immediately.
    If, on the other hand, the skin used was virtually anywhere on the body, examined by a hand-held scanner, there would be far less opportunity to fake them or detach the part. Could be the back of the left hand, or the right nipple or the parch of skin directly over the sternum. Anyone seeking to fool the lock wouldn't know what part to take.
    There would still be ways around it, waterboarding to get you to say what patch of skin you use being one, but it would complicate things.

  • stripey_cat says:

    I've never been more relieved to have chapped, chewed lips every other week!
    I also seem to remember a (possibly apocryphal or entirely fictional) story of a burglar who was identified by the ear-print he left listening to make sure a room was empty.