十万个为什么·科学启蒙30篇（2）
11 / 30
正在校验访问权限...
Why Do We Have Fingerprints?
人类为什么有指纹？
-
Fingerprints form before birth — around weeks 10 to 24 — as skin layers grow at different rates, causing ridges to buckle under tension.
-
These patterns aren’t random; they’re influenced by genetics, amniotic fluid pressure, and even fetal movement — making each person’s prints unique.
-
Ridges improve grip on rough or wet surfaces by channeling water away and increasing friction, much like tire treads on a car.
-
They also enhance touch sensitivity: ridges amplify vibrations when sliding over textures, helping nerves detect fine details like fabric weave.
-
No two people — not even identical twins — share identical fingerprints, although family members may show similar pattern types like loops or whorls.
-
Forensic analysts compare ridge endings, bifurcations, and other minutiae rather than whole patterns, since partial prints are what crime scenes usually yield.
-
Some rare genetic conditions, like adermatoglyphia, cause people to be born without fingerprints — proving they aren’t essential for survival.
-
Modern biometric systems use infrared or ultrasonic scanning to map ridge depth and sweat pore placement — not just surface images.