Here's an excerpt from an article I read yesterday in New Scientist (in my opinion, the best science magazine out there):
Beastly tales: Rewriting human history
by Bob Holmes, 19 January 2008
ACCORDING to the history books, the Madeira archipelago 600 kilometres west of Africa was discovered in 1419 when Portuguese mariners were blown off-course by a storm. In Roman times Pliny and Plutarch wrote about islands that might be Madeira, but there is no definite account of the islands, nor any signs of people, prior to the arrival of the Portuguese. The mice of Madeira Island, however, tell a different and unexpected story.
The mice are not native to the island and must have arrived on European ships. Genetically, they most closely resemble the mice of Portugal. However, some of their DNA has strong similarities to that of mice found in Scandinavia - a strong hint that Viking ships found Madeira long before the Portuguese. "It might have been a temporary occupation, or just a few boats landing for a short period of time," says Jeremy Searle, an evolutionary biologist at the University of York in the UK and an author of the study (Heredity, vol 99, p 432). "But the mice are telling us something that no artefact so far has told us."
What this piece is saying is that human history can be uncovered by looking at the plants and animals that accompany us, either as stowaways or as sources of food. Those commensal mice that have been a part of our lives since humans first started storing grain, have been following humans on their migrations around the world.
It's not just lab mice that have been teaching us about ourselves.
Here's a link to the original paper. Here's more about Archaezoology.
BTW, "kilometres" and "artefact" are explained by the London address on the masthead.