The 'Clovis first' theory proposes that around 14,000 years ago people travelled across a land bridge that existed between Siberia and Alaska. Once in North America, their journey took them through a corridor that opened up between the ice sheets in Western Canada making them the first to be able enter the interior of the continent. It's an elegant and almost biblical explanation, but more recent fossil finds question the theory. Some researchers believe the first people entered North America much earlier - perhaps as long as 20,000-30,000 years ago.

If animals such as bears and foxes lived here then why not people? Fossilised human remains have been found on Alaska's Prince of Wales Island and much further south on the Channel Islands off California. These are thought to be as old as some of the Clovis finds and it may only be a matter of time before older remains are discovered.

If people did travel down the coasts between islands, they must have used boats. Although the coastal route still lacks a lot of hard evidence, the relatively recent discovery of a stone tool off the coast of British Columbia has added support to the idea.

To have come across the sea, they would have needed boats and would have been dependent on marine resources. They were evidently skilled land hunters and had some fearsome weapons, including a wooden handheld stick called an atlatl, used to launch spears over tens of metres. Recent discoveries of 'soft technology' or degradable objects such as clothing, tell us that these first people could sew. They were able to make fitted clothing and boots and probably had outfits for different seasons.

So, whoever and wherever these first arrivals came from, they appear far more advanced and versatile than the cliché of spear-throwing stone-age man would have us believe.