Also called: Sydney Crease

Where on the hand: The Head line extends all the way across the palm to the percussion (ulnar edge), while a separate normal Heart line remains present. So: two creases, but the lower one runs the full width.

What it looks like: A normal Heart line above, and below it a Head line that does not stop mid-palm but continues right off the outer edge.

Read as over-analysis of both thought and emotion — a mind that will not stop processing. Subjects make excellent researchers, because of an unusual capacity to absorb and retain information. It is also read as mental restlessness and difficulty switching off.

Read with care: CLINICAL FACTS. The Sydney crease is studied in the same dermatoglyphic literature as the STPC; higher prevalence has been reported in some clinical populations, but as with the simian crease it occurs commonly in healthy people. It is not diagnostic of anything. Naming correction: there was no 'Sydney cohort study'. Purvis-Smith's 1972 paper (Aust Paediatr J 8:198–200) was a clinical report on children with Down syndrome in Sydney. Note also that the trait reading given here — good researcher, strong retention — points in the opposite direction from the weak clinical literature it borrows credibility from, which reports the crease slightly more often in children with developmental delay.