Guidonian hand
In Medieval music, the Guidonian hand was a mnemonic device used to assist singers in learning to sight-sing. Some form of the device may have been used by Guido of Arezzo, a medieval music theorist who wrote a number of treatises, including one instructing singers in sightreading. The hand occurs in some manuscripts before Guido's time as a tool to find the semitone; it does not have the depicted form until the 12th century. Sigebertus Gemblacensis in 1105–10 did describe Guido using the joints of the hand to aid in teaching his hexachord. The Guidonian hand is closely linked with Guido's new ideas about how to learn music, including the use of hexachords, and the first known Western use of solfege.
Hand axe
By 1.8 mya early man was present in Europe. Remains of their activities were excavated in Spain at sites in the Guadix-Baza basin and near Atapuerca. Most early European sites yield "mode 1" or Oldowan assemblages. The earliest Acheulean sites in Europe appear around 0.5 mya. In addition, the Acheulean tradition did not spread to Eastern Asia. In Europe and particularly in France and England, the oldest hand axes appear after the Beestonian Glaciation–Mindel Glaciation, approximately 750,000 years ago, during the so-called "Cromerian complex". They became more widely produced during the Abbevillian tradition.