Development of human palmar and digital flexion creases

Development of human palmar and digital flexion creases, by Cathy A. Stevens, John C. Carey, Manish Shah and G. P. Bagley, published in The Journal of Pediatrics in 1988, is a peer reviewed developmental biology study examining one hundred fetal hands between seven and nineteen weeks gestation, establishing that digital creases are well defined by ten weeks and palmar creases consistently present by thirteen weeks. Its strength is that it is a direct anatomical study with a stated sample and method, the kind of primary evidence a claim about prenatal hand development should rest on. Its limit is precisely the narrowness that makes it reliable, it documents when these creases form and nothing about their folk or divinatory interpretation, so it is cited here only for the developmental timeline itself; any claim connecting palm creases to palmistry or fortune telling practice needs a source on that tradition, not this study, which makes no such claim.