The Very First Sculptures

While data sculptures date back from the 1990s, the very first sculptures were Venus figurines:

A Venus figurine is any Upper Paleolithic statuette portraying a woman with exaggerated physical features.

The oldest ones are about 35,000 years old. Right image: modern versions.

Also see V.S. Ramachandran on the peak shift principle in art.

Sources:

1. Wikipedia article on Venus figurines.
2. Left image from ancient-origins.net, right images from Mari Shiranui's flickr page and heldenshop.de.