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ratio of the index finger (2D) to the ring finger (4D) (2D:4D; Manning, Scutt, Wilson, & Lewis-Jones, 1998), along with a hypothesis about the origin of these, has spurred ongoing research interest in psychology and adjacent disciplines. Because this sex effect is determined in utero and 2D:4D shows little plasticity thereafter, 2D:4D has been suggested as an indirect marker for the organizational (permanent) masculinizing effects of prenatal androgens on the brain, behavior, and physique (Manning, 2002). Given this hypothesis is correct, it would straightforwardly allow for comfortable (non-invasive) tests of the biological bases of behavior, cognition, personality, and other individual difference variables that show sex differences and therefore conceivably are partly influenced by prenatal sex-hormone action. Unsurprisingly, this idea has attracted wide interest, resulting in a sizeable literature now approaching 250 reports (partial reviews: Manning, 2002; Putz, Gaulin, Sporter, & McBurney, 2004). 2D:4D research also has a number of problems, including usually modest effects, preponderantly unreplicated findings, statistically underpowered (and thus type I error-prone) studies reporting positive findings, a spate of recently published nonreplications, and singlesample studies (without replication attempts) still being the norm. Replicated nil associations of digit ratio (2D:4D) and absolute finger lengths with implicit and explicit measures of aggression