Why did feathers evolve

Many of these extraordinary feather structures had already developed in their late ancestor dinosaurs. This was necessarily the case, because the complex, strong, asymmetrical feathers that are necessary for powered or even gliding flight in birds, existed at in the very first known bird ancestor, archaeopteryx, and all modern birds descended from a flying ancestor. But flight was just one highly successful experiment with feathers. Modern feathers involve a range of different genes working together and being expressed at the right time and in the right space during the embryo's development.

This new work helps to establish how feathers initially evolved, around to million years ago, but hints at five separate genetic processes active in birds that needed to work together to create modern feathers. Today his research is opening the door to understand how such a great achievement came about.

There are practical implications of Prof Chuong's work. His team is working with plastic surgeons to help understand why skin structures don't develop well on scar tissue.

This research informs our understanding of the process of how skin creates the structures that interact with the outside environment. With a better understanding of this, regenerative therapies could help people get better after accidents. Airplane wings exploit some of the same aerodynamic tricks. But a bird wing is vastly more sophisticated than anything composed of sheet metal and rivets. From a central feather shaft extends a series of slender barbs, each sprouting smaller barbules, like branches from a bough, lined with tiny hooks.

When these grasp on to the hooklets of neighboring barbules, they create a structural network that's featherlight but remarkably strong. When a bird preens its feathers to clean them, the barbs effortlessly separate, then slip back into place. The origin of this wonderful mechanism is one of evolution's most durable mysteries. In , just two years after Darwin published Origin of Species , quarry workers in Germany unearthed spectacular fossils of a crow-size bird, dubbed Archaeopteryx , that lived about million years ago.

It had feathers and other traits of living birds but also vestiges of a reptilian past, such as teeth in its mouth, claws on its wings, and a long, bony tail. Like fossils of whales with legs, Archaeopteryx seemed to capture a moment in a critical evolutionary metamorphosis.

The case would have been even grander if paleontologists could have found a more ancient creature endowed with more primitive feathers—something they searched for in vain for most of the next century and a half. In the meantime, other scientists sought to illuminate the origin of feathers by examining the scales of modern reptiles, the closest living relatives of birds.

Both scales and feathers are flat. So perhaps the scales of the birds' ancestors had stretched out, generation after generation. Later their edges could have frayed and split, turning them into the first true feathers. It made sense too that this change occurred as an adaptation for flight. Imagine the ancestors of birds as small, scaly, four-legged reptiles living in forest canopies, leaping from tree to tree.

If their scales had grown longer, they would have provided more and more lift, which would have allowed the protobirds to glide a little farther, then a little farther still. Only later might their arms have evolved into wings they could push up and down, transforming them from gliders to true powered fliers. In short, the evolution of feathers would have happened along with the evolution of flight. This feathers-led-to-flight notion began to unravel in the s, when Yale University paleontologist John Ostrom noted striking similarities between the skeletons of birds and terrestrial dinosaurs called theropods, a group that includes marquee monsters like Tyrannosaurus rex and Velociraptor.

Clearly, Ostrom argued, birds were the living descendants of theropods. Still, many known theropods had big legs, short arms, and stout, long tails—hardly the anatomy one would expect on a creature leaping from trees. Other paleontologists argued that birds did not evolve from dinosaurs—rather, their similarities derived from a shared common ancestor deeper in the past. In Chinese paleontologists delivered startling support for Ostrom's hypothesis. It was the fossil of a small, short-armed million-year-old theropod, Sinosauropteryx , which had one extraordinary feature: a layer of thin, hollow filaments covering its back and tail.

At last there was evidence of truly primitive feathers—found on a ground-running theropod. In short, the origin of feathers may have had nothing to do with the origin of flight.

Soon paleontologists were finding hundreds of feathered theropods. With so many fossils to compare, they began piecing together a more detailed history of the feather. First came simple filaments. Later, different lineages of theropods evolved various kinds of feathers, some resembling the fluffy down on birds today, some having symmetrically arranged barbs.

Other theropods sported long, stiff ribbons or broad filaments, unlike the feathers on any living birds. The long, hollow filaments on theropods posed a puzzle. If they were early feathers, how had they evolved from flat scales? The most distant feathered relatives of birds had straight feathers that looked like wires. Then these wires split apart, producing simple branches. In many dinosaur lineages, these simple feathers evolved into more intricate ones, including some that we see today on birds.

At the same time, the feathers spread across the bodies of dinosaurs, turning from sparse patches of fuzz into dense plumage, which even extended down to their legs. A few fossils even preserved some of the molecules that give feathers color. They reveal a beautiful range of colors: glossy, dark plumage, reminiscent of crows, alternating strips of black and white, or splashes of bright red.

Some dinosaurs had high crests on their heads, and others had long, dramatic tail feathers. Now, none of these dinosaurs could use their feathers to fly - their arms were too short and the rest of their bodies were far too heavy.

But, birds don't just use feathers to fly. Similarly, feathers can help keep things cool by providing shade again, eggs and babies in particular might benefit , but it's also possible that they aided cooling since feather vanes have a blood supply, this could be used to shed some heat by bringing blood up to the surface of the animal.

The second big issue is one of colour and pattern. You can only make scales a certain size and they do seem to have limits to their colour patterns and colour types. Feathers on the other hand can be absolutely huge even on some very small animals and the range of colours and patterns do seem to exceed what can be done with scales alone. Certainly some structures and shapes are possible with feathers that are not with scales, and the way they can be fanned out or folded up out of the way is a clear advantage over big bony crests or elongate scales, and they were probably lighter that either of the other options as well.

Related to this, the ability to moult feathers may have been very useful — you can change colour at different times of year be camouflaged in winter, and brightly coloured in summer which is possible with skin colours, but not apparently so easy.

Moreover, one can change the type of feathers too shed large display feather when they are not needed, or gain smaller ones with rough edges to help break up outlines etc.

At least one dinosaur apparently used its feathers for defence, and this may have been a viable strategy for other. Still bristles on the animal may have made them harder to attack or eat and provided a useful defence against some predators, or even parasites if also making them more vulnerable to others like fleas. Some birds use feathers for a variety of odd purposes that are certainly possible and plausible that these were used this way in some dinosaurs.

Many birds have bristle-like feathers that act as eyelashes to keep the eyes clear of dust and so on, and others use feathers as a sensory apparatus rather like whiskers on mammals.