These are stone axe heads from Berbice, Guyana (with my watch for scale!). The man who found them couldn't say how old they were, and nor can I. However, they are broadly similar to tools found in Europe and the Middle East, dating from the Stone Age (which ended between 4,500BC and 2,000BC). If these are that old, they could have belonged to some of the earliest inhabitants of South America, who are believed to have arrived about 10,000 years ago. My feeling is that they are not that old, and that stone tools continued to be made on 'The Wild Coast' for many centuries (if not millenia) after that.
Technological change came much later to the indigenous or Amerindian people of this coast (due to the limited resources). With the arrival of Europeans, however, change came fast - too fast - with lethal consequences. In modern times, administrators have tried to slow the pace. The 20th century was the age of the museum; Amerindians lived like specimens, preserved in their own domain. It was made illegal to visit them, and they became wards of the Crown. Sex with an Amerindian was made a crime, like the seduction of a child. It wasn't quite what the tribes had wanted, but at least they began to revive.
There are now 45,000 Amerindians living in nine different groups. In fact, it’s the only section of Guyanese society whose numbers are increasing.