Gene tweak led to humans’ big toe

Decrease in bone-building protein helped enable upright walking

mouse embryo

TRUE BLUE The blue coloring in this mouse embryo shows that a genetic switch that controls production of a bone- and tissue-building protein turns on genes in the lower half of the embryo’s body. 

V.B. Indjeian et al/Cell 2016

Small tweaks of one gene may have helped humans to walk upright.