NSOr humanAdaptation to climate change is primarily a technical issue. More air conditioning, better designed homes and greater flood protection may help improve the impact of a warmer world. Animals must rely on changing their bodies and behaviors.In a treatise published in Ecology & Evolution Trends, A team led by Sara Ryding, NSNSNS Candidates at Deakin University in Australia show that it’s already happening. Climate change has already transformed the bodies of many animal species, giving them larger beaks, limbs and ears.

For example, some Australian parrot species have increased their beak size by 4% to 10% since 1871. In another study, another bird found the same pattern, this time in the North American dark-eyed juncoid. A similar trend is seen in mammals, with mouse, shrews, and bat species evolving larger ears, tails, legs, and wings.

All of these are in good harmony with evolution. Named after Joel Asaph Allen, who proposed it in 1877, Allen’s Rule argues that warm-blooded animals in hot regions tend to have larger appendages than animals in temperate regions. Such adaptations increase the surface area relative to the volume of the animal’s body and help dissipate excess heat. The beak is rich in blood vessels and is not covered with insulating feathers, making it an ideal place for birds to handle heat. Fennec foxes, which grow naturally in the Sahara Desert, on the other hand, have surprisingly large ears, especially compared to their Arctic cousins.

Ms. Riding examined museum specimens and compared their bodies to modern ones. She is not the first researcher to take that approach. However, when dealing with individual species, it is difficult to prove that climate change was the cause of anatomical changes. All other types of factors are believed to drive change, from changes in prey to the evolution of male or female reproductive preferences.

The big picture makes the pattern clearer, says Ryding. Her team combined different species of data from different locations. She says climate change is the most plausible explanation, as they have little in common, except that they live on warming planets.

So far, at least the increase is modest and does not exceed 10%. It may change as global warming accelerates. Evolutionary adaptation involves trade-offs, so it is unclear how far the process will go. For example, a large beak can interfere with eating. The larger the wings, the heavier it is, and the larger the legs, the more energy it takes to grow.

And there are other ways to adapt. Researchers have already seen changes in the geographical extent of many species, from insects to fish. Another evolutionary rule of thumb, Bergmann’s rule, believes that animals in hot places tend to be smaller. This is another way to increase the surface area to volume ratio. Other animals can change their behavior and body, such as by looking for shelter during the hot hours of the day.

Studying a wider range of animals will help determine exactly what is happening. Much of Riding’s data is about birds, and little information is available in other taxa. But it is clear that the world of the future will not only get hotter than humans are accustomed to. The animals that live there will look different. ■■

This article was published in the Science and Technology section of the printed version under the heading “My Big Beak You Have”.