A smaller world

Ambling along the cobblestone paths of a Hindu Kush village, it is not uncommon to chance upon cattle that stand just a metre tall at the shoulder, or sheep that barely measure up to the height of man's knee. Inured to the hard winters of Pakistan's Chitral district and the limited resources on the mountain plateaus, livestock has adapted, along with shaggy coats and sure-footedness, towards smaller specimens of the species.

Examples abound of animals adapting to privation. A species of fox on the California Channel Islands is no larger than a house cat; a species of pygmy mammoth evolved on the same islands, shrinking in size to accommodate the habitat, although it is of course long extinct. Environmental constraints are a hard fact of life.

And now it appears that the world as a whole is becoming a more challenging habitat. A study published on Sunday in the journal Nature Climate Change concluded in a survey of 85 plants and animals that there is a decades-long trend towards smaller species, including everything from polar bears to iguanas to strawberries. As the journal's name suggests, the blame falls on climate change putting the squeeze on larger animals.

Whether that analysis is true or not, the trend is worth watching. A pint-size sheep might be cute to look at, but a full plate of mutton biryani is eminently more satisfying.