The significance of dermatoglyphic whorl patterns in relation to fetal pad regression

In the area of digital dermatoglyphics little is known about the way in which fetal fingertip pads regress. Do these pads regress radially, ulnarly, uniformly, or a combination of these three? Do these pads regress differently for different fingers or populations? These questions were investigated in 1986 by Thomas Dwight Hargreaves at The University of Tennessee, Knoxville.

Ridge-count data were obtained from Dr. Richard Jantz for all ten digits of seven populations: U.S. Whites, Armenian, U.S. Blacks, African, Mixtec, New Guinea, and Cashinahua. Whorls were the only pattern type looked at since they occur during all stages of fingertip pad regression (early-late) and are "transitional" between radial and ulnar loops in their level of pad asymmetry (radial-ulnar).

An Index measurement of fingertip pad asymmetry was used in this research instead of traditional methods of measuring pad asymmetry. It was created in an attempt to get a more accurate R-U measurement of fingertip pad tilt (R-U/R+U).

A regression and scatterplot analysis of this Index and a measurement of pad size (R+U) showed that the type of fingertip pad regression that occurs is different for each digit and population sample. Populational differences, however, overlap and are not as significant as the differences among digits. Pad asymmetry was concluded to be more influenced by environmental than genetic factors.

The Index was also used to investigate developmental field theory. Traditional finger groupings were not obtained using the Index, instead it was found that fingers group most closely with their ulnarly adjacent finger.