By Jon Stewart, Science Desk, BBC

媒體英語會帶大家一起學習BBC撰稿人在報道世界大事時常用到的單詞和短語。

Background:最近，科學家們稱馬達加斯加島上的獨有動物的祖先，當年是乘坐天然的“木筏”來到了這座位于印度洋的島嶼上。馬達加斯加島位于非洲東海岸300英里處，是世界上少有的生物多種類島嶼。它擁有很多全球其他地方找不到的生物種類，如哺乳類動物還有很多植物。

Madagascar's unique lemurs, flying foxes, and mongooses first started to appear about 60 million years ago, but it's been separated from the mainland, and isolated, for at least 100 million years.

The mystery has been, how did they get there, and why are there no giraffes, elephants and big cats?

Professor Matthew Huber from Perdue University in the US:

"The mammals that appear on Madagascar today may have come over on rafts, and by rafts what we mean are trees that may have fallen into a river and been swept out to sea or a large floating mass of matted vegetation that broke off the coast and headed out to sea."

The ocean currents today go the wrong way - from Madagascar to mainland Africa, but Professor Huber used a climate model - the same type we use to predict the future, and effectively ran it backwards to look at the distant past.

He found that the ocean currents used to go the other way, and were strong enough that the animals would have reached the island without dying of thirst.