Python meat, unique bird songs, & invisibility cloaks | Last Week in Science (24th Mar 2024)

The symphony of birds

All bird songs sound sweet to our human ears, but it is not the same for birds. While a lot of song birds sing many different songs, some like zebra finch sing only a single song throughout their life. The female birds, wherein males sing a variety of songs, use this variety as a criteria to select male birds, the more variety would mean greater fitness of the bird thereby increasing its chances of selection by the female. We do not know how a single song in zebra finch can help them decide the fitness of their mate.

Male zebra finches sing the songs that they have learnt in their childhood from their tutor - their father. So, each bird song is going to be unique and male birds sing this song in their adulthood to attract mates. The female birds choose their mate by listening to their song. Until now, we have classified bird songs based on pitch, duration, and loudness - factors that are perceptible to human ears. We do not know how and what features of the song the female birds use to select their mate.

In an attempt to understand this complex communication between birds, scientists recorded songs sung repeatedly, 1000 times, by 49 different male birds. They then used machine learning and artificial intelligence to make sense of this complex data. The different sounds or syllables of the songs were used to understand the complexity of the songs. The researchers found that male birds which produced more distinct sounds - that can be considered as high quality, were chosen by the females. Also, such songs were more difficult to learn as compared to the ones that did not have highly distinct sounds or syllables.

This study needs to be repeated to understand whether the female birds indeed use distinctness of syllables. And also what does the distinctness of syllables, estimated by machine learning, mean in terms of how we classify and understand sound.

Reference: Birds convey complex signals in simple songs

Will you eat snake meat?

One of the major arguments of vegetarians, excluding religious reasons, is the impact of raising animals for meat on the environment. With deforestation and 10% of greenhouse gases being coming from the cows raised for beef, water pollution caused by pork and poultry, it sure is better to become a vegetarian. But one cannot even deny the nutritional benefits - proteins and certain vitamins- that come from animal sources. So why not look for alternative sources of protein?

Snake scientists propose that pythons may have the answer to eating meat without harming the environment. For one they are better at converting their food into protein than other animals that are consumed by humans, thereby leading to more protein production. And second they can survive without food for long durations and not lose much of their body mass. Thus, they would need much lesser to be a better source of protein than the existing animals used for meat production for human consumption.

Many parts of the world already consume snakes, so let us wait and see if switching to pythons for our protein requirements is a possibility or not.

Reference: Snake Steak Could Be a Climate-Friendly Source of Protein

Invisibility cloaks

Credit: Lin Wang and Tak-Sing Wong / Penn State. Creative Commons

We see objects because they absorb certain wavelengths of light and reflect others. The color of the object is decided by the wavelength that it reflects. A material that will not reflect any visible light will be invisible to human eyes. Such anti reflective material coatings are used to coat glass screens and lenses to reduce glare. But the materials that are used to create anti reflective coating isn't suitable to make other surfaces invisible.

Researchers at Penn State University have now synthetically created a material that may someday lead to the creation of cloaking devices - that can make objects or individuals invisible. This synthetic material mimics a naturally occuring substance present on the body surface of leaf hoppers. Leaf hoppers cover themselves with particles called as brochosomes that are football shaped hollow structures with holes evenly distributed on their spherical surface. The function of brochosomes is not fully understood but it is known that their structure, which is of the same dimension in all the insects irrespective of the insects' size, absorbs UV and visible light completely. It is thought that the absorption of UV light makes them invisible to their predators that have UV vision. 

Scientists synthesized a scaled up version of brochosomes by 3D printing which was shown to absorb 94% of the visible light. Studies are underway on improving the production of brochosomes and also manufacturing much smaller versions that will be same in size as the ones in leaf hopper. The potential applications range from better anti reflective coatings for devices like solar cells, encryption technology with the possibility of decoding a message only under a specific wavelength and of course invisibility cloaks.

Reference: Backyard insect inspires invisibility devices, next gen tech