You may think the title of this article has something to do with Carnival but this story is seriously true!

According to some European scientists who study house mice patterns of genetic diversity, house mice may tell us other history than that written by humans... Here is an excerpt taken from New Scientist magazine about Madeira and its introduced house mice:

"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." (in Beastly tales: Rewriting human history by Bob Holmes, 19 January 2008 - Magazine issue 2639)

So what this article means is that maybe the Portuguese João Gonçalves Zarco, Tristão Vaz Teixeira and Bartolomeu Dias were not the first ones to discover Madeira. House mice are part of human history since we started to store grain, this way if we study their history we might find some new facts to our history.

Madeira mice "populations were more closely related to those of Portugal than to other continental regions, in agreement with the documented human colonization of the island. Such a Portuguese origin contrasts with a study indicating a north European source of the mitochondrial haplotypes present in the Madeira mice. This apparent discrepancy may be resolved if not one but two colonization events took place, an initial north European introduction followed by a later one from Portugal. Asymmetrical reproduction between these mice would have resulted in a maternal north European signature with a nuclear Portuguese genome." (in Heredity (2007) 99, 432–442; doi:10.1038/sj.hdy.6801021; published online 4 July 2007")

So now mices are telling us that Vikings were in Madeira long before Portuguese did though it seems the only marks they left were themselves, mices...