The Nobel Prize is often awarded not to researchers who made a huge discovery about how the world works, but to those who have developed techniques that improve research itself. The downstream effects of such developments are likely to be dozens or hundreds, even thousands, of discoveries This is the case for the 2026 Nobel Prize in physiology or medicine – awarded to Karl Deisseroth, Peter Hegemann, and Georg Nagel for their work developing optogenetics. This is a powerful tool that allows us to create a functional map of the brain.

The story begins with Hegemann who in the 1990s was studying the free swimming algae, Chlamydomonas. The algae swims towards light, which anyone can reproduce by shining a light on a petri dish full of the green organisms. They have a small eyespot which can detect light, but Hegemann was fascinated with how quickly they were able to respond to a light signal. This lead him to hypothesize that the algae may be using a different method for turning light into a signal that can affect their behavior than vertebrate eyes. When he attached electrodes to Chlamydomonas and shined a light on them, he was able to detect an electrical signal in half a millisecond – incredibly fast. This is simply too fast to conduct any signal, so he thought it must be the same protein that detects the light and creates the resulting electrical pulse. Now all he had to do was identify that protein.

A Japanese group had already mapped the DNA of Chlamydomonas, and of the genes identified, two had properties that might fit the bill. But this was now a bit out of the field of expertise of Hegemann, so he contacted Nagel for help and sent him the code for the two candidate genes. Nagel injected the genes into separate batches of frog eggs, which began to express the proteins. He could then study how the proteins functioned, and was able to confirm Hegemann’s hypothesis. Both proteins, named channelrhodopsin-1 and channelrhodopsin-2, were ion channels that respond to light by opening up, allowing positive ions to flow through,  and creating an electrical potential. Channelrhodopsin-2 was particularly powerful, creating an electrical signal in 0.2 milliseconds. They were able to incorporate the gene for this protein into human and hamster kidney cells and show that they become light sensitive.

Continue Reading »

Stephen J Gould (still my favorite science essayist) wrote an excellent article in 1985 (Red Wings in the Sunset, later published in his book, Bully for Brontosaurus) about artist and naturalist Abbott Handerson Thayer. Thayer wrote about how animals use coloration as camouflage – what he called “cryptic coloration”. His ideas were solid, but he made a classic mistake that scientists sometimes make, overapplying their key discovery. Thayer argued that all animal coloration is cryptic. For example, he argued that flamingos are pink because it hides them in the setting sun (hence the title of the essay). This is a transparently absurd argument, and it shows how Thayer tried to shoehorn all evidence into his preferred and absolute narrative. It is better to assume that nature is complex, and all explanations are at best partial (unless proven otherwise).

Animal coloration, in fact, can serve many different purposes, only one of which is camouflage. Thayer also struggled with the male peacock, for example. Butterflies appear to be another example. Actually, many butterflies are camouflaged on the underside of their wings, so that when they are at rest with their wings up they tend to blend into their surroundings. But the top side of their wings are often very colorful and not camouflaged at all.

One assumption is that the brightly colored part of their wings is to attract mates. This may be true, but that does not mean the coloration does not serve another function. Often animals use visual cues when choosing their mates that are markers for health and success. As evidence that butterfly wing color may be serving a survival benefit, if you look at birds that feed on insects during flight, they target dully-colored moths much more than brightly colored butterflies, even though the butterflies should be easier to see.

A recent study tests the hypothesis that the brightly colored and patterned top side of butterfly wings may have evolved to produce an optical illusion to confuse predators. The idea of using optical illusions as visual protection in animals is not new. For example, zebra stripes allow zebras to hide in the herd, confusing predators as to where one zebra ends and another begins. Stripes on zebras and snakes may also serve to confuses predators about their direction of motion, but this hypothesis has not been tested previously. Continue Reading »