Fundamentals
With increasing age, skin relief, wrinkle and furrow patterns, soft-tissue contours, and individual facial regions change. Such changes become forensically relevant as soon as image material from different phases of life is compared or where the evidential value of individual features recognisably shifts over time.
What matters here is the distinction between observable change and change that is professionally sustainable in an expert context. Not every visible wrinkle, contour shift, or soft-tissue change is recognisable in the available material in a way that permits a clean conclusion. For practical classification, the main issues are therefore wrinkle and furrow patterns, soft-tissue changes, contour shifts, and the question whether these can be assessed reliably on both sides of the image comparison at all.
Relevance for image comparison
In image comparisons across larger time intervals, morphological ageing is above all a corrective against over-interpretation. It helps to separate changes that are usual for age from findings that actually carry weight for the identity question. Precisely for that reason it is important in practice: it does not reduce evidential value, but stabilises it by limiting premature conclusions.
This field becomes particularly relevant where older reference images, biographically widely separated recording dates, or pronounced changes in the soft-tissue profile have to be assessed.
For practice, morphological ageing is therefore above all a corrective against over-interpretation. It helps to separate age-typical changes from those findings that actually carry weight for the identity question and limits premature conclusions drawn from apparently striking changes. Especially where there are larger time intervals between questioned image and comparison image, this step may be decisive for whether deviations are to be classified as age-typical, technically caused, or actually relevant to identification.
Relation to age estimation
In the context of age estimation, attention to visible facial changes may be useful as a supplement. It does not, however, replace an independent age estimation. The specialist literature points out expressly that in adulthood visible age estimations are possible only very roughly and rely more strongly on typical age changes such as wrinkle formation, soft-tissue changes, and contour shifts. Visible facial features can therefore be used only as a supplement; the main expert conclusion must rest on a methodologically more sustainable framework of findings.
Limits
Age-related change is strongly influenced by image quality, lighting, facial expression, body weight, health status, and the time interval between the recordings. Precisely for that reason a cautious classification is mandatory. What in everyday life appears to be a clear age difference is, in expert terms, often usable only to a limited degree. This very limit shows that morphological ageing remains an important, but methodologically limited component within a larger overall assessment.