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I've found research that suggests that the reason we develop fingerprints is because they aid us with feeling surfaces (Scheibert, et al. 2008) and not to increase friction and help with the gripping of smooth objects (Warman and Ennos 2009).

One thing I am still curious about is at what stage of growth the pattern is formed and why a unique pattern is created in the fingerprint of each person (including identical twins). I assume it has something to do with the mechanism by which the patterns form, but I couldn't find any detailed research into this. Any insight would be very welcome.

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  • $\begingroup$ We can expect this uniqueness in foot[toe] prints as well. I suppose, all derivatives of germ layers should have their identity and heritability. Many forensic literature have explored these areas for personal identification. $\endgroup$
    – S.Sunil
    Commented Sep 21, 2013 at 4:42

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I would say genetic diversity is the primary reason which results in other reasons that you are looking for. At the lowest level, random crossing over at prophase I, random separation of homologous chromosomes at anaphase I, random separation of sister chromatids at anaphase II, and random fertilization: one sperm fertilizes one egg randomly.

The skin is developed from ectoderm so need to look at the formation of embryonic disc and specifically to the genesis of germ layers: ectoderm.

However, I would stick to the primary reasons, since it is extremely difficult to visualize the given formation - actually we do not have resources for it at the moment.

Very good question the last part. I have an intuition that skin develops randomly because of the above reasons. You would also need a lot of memory to make identical skins for twins! It has not been useful to have identical fingerprints between two people so evolution has not resulted into it.

Feeling surfaces and gripping are movements - not much space taken things, in contrast to the memory needed in storing the exact surfaces of skin from one generation to another. - Learning is a way to save resources here and it is a lot more efficient and than storing static information to species from one generation to another.

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Answer

Fingerprint pattern formation has two components to it: developmental and genetic.

Firstly, this article's abstract describes how fingerprints are physically formed in the womb.

[...] fingerprint patterns are created as the result of a buckling instability in the basal cell layer of the fetal epidermis. Analysis of the well-known von Karman equations informs us that the buckling direction is perpendicular to the direction of greatest stress in the basal layer. We propose that this stress is induced by resistance of furrows and creases to the differential growth of the basal layer and regression of the volar pads during the time of ridge formation.

Also, this OMIM entry describes a study which suggests the function of genes directly related to fingerprint formation.

An assumption is that the basic pattern is all ulnar loops and that a variety of genes cause deviations from the basic pattern. These include (1) a semidominant gene for whorls on the thumbs (one homozygote has whorls on both thumbs, the other homozygote has ulnar loops on both thumbs, and the heterozygote has two ulnar loops or one ulnar loop and one whorl); (2) a semidominant gene for whorls on the ring fingers that acts like the gene for whorls on the thumbs; (3) a dominant gene for arches on the thumbs and often on other fingers; (4) one or more dominant genes for arches on the fingers; (5) a dominant gene for whorls on all fingers except for an ulnar loop on the middle finger; (6) a dominant gene for radial loops on the index fingers, frequently associated with an arch on the middle fingers; and (7) a recessive gene for radial loops on the ring and little fingers. They suggested that these genes may act independently or epistatically.

The first source explains why everyone has different fingerprints, but the second explains why family members and identical twins have increasingly similar patterns.

References

  • Kücken, M, and A. C Newell. “A Model for Fingerprint Formation.” Europhysics Letters (EPL) 68, no. 1 (October 2004): 141–146.

  • Slatis, H M, M B Katznelson, and B Bonné-Tamir. “The Inheritance of Fingerprint Patterns.” American Journal of Human Genetics 28, no. 3 (May 1976): 280–289.

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