Climate Crisis Could Make Humans Shrink In Size，Says Fossil Expert

潘紅華

The climate crisis may lead the human race to shrink in size，as mammals with smaller frames appear better able to deal with rising global temperatures，a leading fossil expert has said.

Prof Steve Brusatte，a palaeontologist at the University of Edinburgh，suggested that the way in which other mammals have previously responded to periods of climate change could offer an insight into humans future.

He likened the potential plight of people as similar to that of early horses，which became smaller in body size as temperatures rose around 55m years ago，a period called the Paleocene Eocene Thermal Maximum.

Writing in The Rise and Reign of the Mammals，Brusatte notes that animals in warmer parts of the world today are often smaller than those in colder areas，an ecological principle known as Bergmanns rule. “The reasons are not entirely understood，but it is probably，in part，because smaller animals have a higher surface area relative to their volume than plumper animals and can thus better shed excess heat，”he writes.

Brusatte said that becoming smaller was “a common way that mammals deal with climate change”. He added：“Thats not to say every species of mammal would get smaller，but it seems to be a common survival trick of mammals when temperatures spike pretty quickly. Which does raise the question：if temperatures do spike really quickly might humans dwarf，might humans get smaller？And I think that s certainly plausible.”

一位頂尖化石專家表示，氣候危機可能導致人類體型縮小，因為體型較小的哺乳動物似乎能夠更好地適應全球氣候變暖。

愛丁堡大學古生物學家史蒂夫·布魯薩特教授認為，其他哺乳動物此前在氣候變化時期的反應可以預示人類的未來。

他將人類的潛在困境比作早期馬的困境，早期馬的體型隨著5500萬年前氣溫的升高而變小，這一時期被稱為古新世-始新世極熱事件時期。

布魯薩特在《哺乳動物的崛起和統治》一書中指出，當今世界較溫暖地區的動物通常比寒冷地區的動物小，這一生態學原理被稱為伯格曼法則。他寫道：“我們還不清楚為什么，但部分原因可能是與大型動物相比，體型越小的動物，其體表面積與體積的比率則越大，因此可以更好地排出多余的熱量。”

布魯薩特表示，變小是“哺乳動物應對氣候變化的常見方式”。他還表示：“這并不是說每一種哺乳動物都會變小，但當溫度迅速升高時，這似乎是哺乳動物常見的生存技巧。這確實提出了一個問題：如果溫度真的迅速升高，人類會變小嗎？我想這是很有可能的?！?/p>

In a recent study，researchers studying human remains over the past million years have also suggested that temperature is a major predictor of body size variation，while scientists studying red deer have said that warmer winters in northern Europe and Scandinavia may lead to the body size of these animals becoming smaller.

However，not all experts agree that rising temperature causes mammals to shrink. Prof Adrian Lister，of the Natural History Museum in London，said the relationship shown by the recent human remains study is weak，while the strong correlations between temperature and mammal body size may often be down to the availability of food and resources.

Lister is also sceptical that humans will shrink as the climate heats. “We are not really controlled by natural selection，”he said. “If that was going to happen，you'd need to find large people dying before they could reproduce because of climate warming. That is not happening in today's world. We wear clothes，we have got heating，we have got air conditioning if it is too hot.”

研究數百萬年前人類遺骸的研究人員在最近的一項研究中指出，溫度是體型變化的主要預測因素，而研究馬鹿的科學家則表示，北歐和斯堪的納維亞地區的暖冬可能會導致馬鹿的體型變小。

然而，并非所有專家都同意溫度升高會導致哺乳動物體型縮小的觀點。倫敦自然歷史博物館的阿德里安·利斯特教授表示，最近的人類遺骸研究顯示兩者之間的關聯很弱，而溫度與哺乳動物體型之間的密切關系可能往往取決于食物和資源的可獲得性?！?br>