Global warming could make humans shorter, warn scientists who claim to have found evidence that it caused the world's first horses to shrunk nearly 50 million years ago.

　　In fact, a team from the universities of Florida and Nebraska says it has found a link between the Earth heating up and the size of mammals -- horses, in this case, the last time the world heated up.

　　The scientists used fossils to follow the evolution of horses from their earliest appearance 56 million years ago.

　　As temperatures went up their size went down, and vice versa; at one point they were as small as a house cat, said Dr Jonathan Bloch, curator of the Florida Museum of Natural History, was quoted by the "Daily Mail" as saying.

　　The scientists say that the current warming could have the same effect on mammals -- and could even make humans smaller.

　　"Horses started out small, about the size of a small dog like a miniature schnauzer. What's surprising is that after they first appeared, they then became even smaller and then dramatically increased in size, and that exactly corresponds to the global warming event, followed by cooling.

　　"It had been known that mammals were small during that time and that it was warm, but we hadn't understood that temperature specifically was driving the evolution of body size," Dr Bloch said in the "Science" journal.

　　科學家警告說，全球變暖可能會使人類變矮�？茖W家宣稱已經找到證據：近5000萬年前全球變暖就曾讓世界上最早的馬個頭變小。

　　事實上，來自佛羅里達州和內布拉斯加州的大學的一支研究團隊稱，他們已經找到地球變暖和哺乳動物個頭之間的聯(lián)系。這一案例中馬變矮的現(xiàn)象是上一次全球變暖時發(fā)生的。

　　科學家用化石來追溯馬從5600萬年前誕生至今的進化歷程。

　　隨著氣溫的上升，馬的個頭變小，反之馬的個頭就變大。《每日郵報》援引佛羅里達自然歷史博物館館長喬納森布洛赫博士的話說，它們曾一度像家貓那么小。

　　科學家稱，當前的全球變暖可能也會對哺乳動物產生同樣的影響，甚至可能會讓人類的個子也變小。

　　布洛赫博士在《科學》雜志中寫道：“馬最初的個頭很小，和一只小狗的個頭差不多，大約也就像一只迷你型雪納瑞犬那么大。令人驚訝的是，在馬誕生后過了一段時間，它們的個子變得更小，之后個頭又顯著變大，而這些變化與全球變暖和變冷正好是相對應的。

　　“我們已經知道哺乳動物在那個時期個頭較小，而那個時期氣候也較暖，但我們還未意識到正是溫度驅動著身體大小的進化�！�