Our smile identifies us in life and in death

It is becoming increasingly obvious that the smile has an unexpectedly high value in identifying people, both living and dead. To a study that paved the way at the time in terms of the use of smiles to identify living people, there is now another that presents a new forensic technique that allows a corpse to be identified from Instagram or Facebook photos in which the subject leave smiling.

The first study mentioned was carried out by the team of Mila Mileva, from the University of York in the United Kingdom, and its results were made public in 2018.

In that study, the difficulty in identifying in a photo an individual that appears in another photo or that we have in front of us in flesh and blood was explored. It is a fairly common difficulty, verified in previous research and well known by all professionals in whose daily work they must examine identity documents and verify that the person in front of them is the same as the one that appears in the photo of the document.

Mileva and her colleagues found that if the person to be identified has a big smile, that is, showing their teeth, it is easier to recognize the match when it is the same person, and also to notice that the identities do not match when it is a different person. .

Specifically, the analysis of the study showed that those who had to verify the identity of people, improved their percentage of correct answers by 9 percent when comparing two photos of the same person if they both smiled, and by 7 percent when comparing two photos of different people if both appeared smiling.

A wide smile, which leaves teeth exposed, helps to determine whether or not the person smiling is the one who appears, also smiling, in another photo. And it can even be useful for identifying dead bodies. (Photo: University of York)

In the new study, an international team, which includes scientists from the University of Granada (UGR) in Spain, has verified the great utility of analyzing the profile of the anterior teeth, which are the ones seen when a person smiles.

The advantage of this technique, within the framework of forensic anthropology, is that it allows access to antemortem data provided by relatives, such as the photos that the deceased person published on their social networks before they died.

The morphology of the teeth can be an individualizing trait if characteristics such as size, the presence of diastemas, dental torsion, etc. are taken into account. Despite offering less reliable results than those collected in international protocols, this technique has the advantage of being able to use the antemortem data that the deceased person published on their social networks, such as Instagram or Facebook, before they died.

Another aspect addressed in this new research is the analysis of the distortion caused in the images when using objectives of different focal lengths. The results obtained undoubtedly open alternative ways of identifying missing or deceased persons in contexts of violation of International Humanitarian Law collected by the United Nations Organization (UN).

One of the lines of research that is being developed in the Physical Anthropology Area of ​​the UGR aims to develop alternative human identification methods to those included in international protocols. Currently, the only recognized methods are those based on dactyloscopy (fingerprints), dentistry and genetics. However, there are many contexts in which they cannot be used, since on many occasions the missing or deceased persons come from socio-cultural environments and/or countries in which there are no fingerprint databases, or there are no resources. to obtain odontograms or DNA profiles.

As the authors of the new study explain, “to identify is to compare, so it is necessary to have antemortem and postmortem data. In these contexts, alternative methods are being sought that make it possible to analyze resources that are easy to obtain by relatives (antemortem data) with those collected from the persons or corpses of the deceased/disappeared (postmortem).

This work therefore opens up a wide range of possibilities to identify a person, since we live in the age of communication and of sharing our images, for which the use of social networks has transcended globally.

The main author of this research is Melania Mazur, from the Fingerprints and Forensic Anthropology Section of the Criminalistics Department of the Institute of Forensic Research in Krakow (Poland), with the collaboration of Katarzyna Górka, researcher from the Department of Anthropology (Hirszfeld Institute of Immunology and Experimental Therapy of the Polish Academy of Sciences in Breslau) and Inmaculada Alemán, professor at the Department of Legal Medicine, Toxicology and Physical Anthropology at the University of Granada, in Spain. (Source: UGR / NCYT by Amazings)