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This individual has a double whorl. The dominant whorl is on the right side and is counter-clockwise. I call it dominant because it affects the majority of the crown and it overwhelms the left side whorl. The left side whorl is clockwise. The patient is left handed for writing and right handed for throwing. A counterclockwise whorl is more common with left handedness in my experience while ambidextrous individuals commonly have a double whorl. This individual plays soccer with both feel equally well.
In an article by Klar, he discussed theories concerning the cause of right- or left-hand preference in humans, which vary from purely learned behavior, to solely genetics, to a combination of the two mechanisms. The cause of handedness and its relation to the biologically specified scalp hair-whorl rotation is discussed in his article, Gene Regulation and Chromosome Biology Laboratory, National Cancer Institute, Frederick, Maryland 21702-1201, USA.. The general public, consisting of mostly right-handers (RH), shows counterclockwise whorl rotation infrequently in 8.4% of individuals. Interestingly, according to his study non-right-handers (NRH, i.e., left-handers and ambidextrous) display a random mixture of clockwise and counterclockwise swirling patterns. Confirming this finding, in another independent sample of individuals chosen because of their counterclockwise rotation, one-half of them are NRH. These findings of coupling in RH and uncoupling in NRH unequivocally establish that these traits develop from a common genetic mechanism. Another result concerning handedness of the progeny of discordant monozygotic twins suggests that lefties are one gene apart from righties. Together, these results suggest (1) that a single gene controls handedness, whorl orientation, and twin concordance and discordance and (2) that neuronal and visceral (internal organs) forms of bilateral asymmetry are coded by separate sets of genetic pathways. |
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