Uranium thorium radiometric dating
They were too busy trying to stay alive to create art.
This period used to end 2.5 million years ago when humans first started making tools, but geologists extended it to 1.6 million BCE, trapping the early Lower Paleolithic period in it.
(c.1.6m - 10,000 BCE) This is a geologic period that covers the earth's most recent glaciations.
It includes the later part of the Lower Paleolithic as well as the Middle and Upper Paleolithic periods.
The term pleistocene comes from Greek words (pleistos "most") and (kainos "new").
(The discovery of a hominid skull [Sahelanthropus tchadensis] dated about 7 million years ago, may indicate an earlier divergence).
The very early hominids included species like Australopithecus afarensis and Paranthropus robustus (brain capacity 350-500 cc).
About 2.5 million years BCE, some humans began to make stone tools (like very crude choppers and hand-axes), and newer species like Homo habilis and Homo rudolfensis emerged (brain capacity 590-690 cc).
By 2 million years BCE more species of humans appeared, such as Homo erectus (brain capacity 800-1250 cc).
Dating and Chronology of Prehistoric Art A number of highly sophisticated techniques - such as radiometric testing, Uranium/Thorium dating and thermoluminescence - are now available to help establish the date of ancient artifacts from the Paleolithic era and later.