The cave of El Castillo (Puente Viesgo, Spain) was discovered in 1903. It contains one of the earliest instances of human painting, if not the earliest.
Above is one of its many “stencils” of a hand–a partial self-portrait: the artist mixed the pigments in his mouth, spat them over his hand and left its negative shape on the wall. This was approximately 40.000 years before you and I did pretty much the same in kindergarten.
Stencils of the artist’s hand are also found in the relatively more recent cave of Chauvet (Ardèche, France), discovered in 1994. There they appear, impressively, alongside their positive counterpart, handprints (below).
These caves do not contain full representations of the human body (which are typically uncommon of paleolithic art and, according to at least one interpretation, might have been taboo), but at Chauvet a vulva with legs is pictured. This cave, dating approximately 32.000 years back, is the one featured in Werner Herzog’s imposing 3D film Cave of forgotten dreams.