Maria Chikina, University of Pittsburgh Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to CuriousKidsUS@theconversation.com.

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Why don’t humans have hair all over their bodies like other animals? – Murilo, age 5, Brazil

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Have you ever wondered why you don’t have thick hair covering your whole body like a dog, cat or gorilla does? Humans aren’t the only mammals with sparse hair. Elephants, rhinos and naked mole rats also have very little hair. It’s true for some marine mammals, such as whales and dolphins, too. Scientists think the earliest mammals, which lived at the time of the dinosaurs, were quite hairy. But over hundreds of millions of years, a small handful of mammals, including humans, evolved to have less hair. What’s the advantage of not growing your own fur coat? I’m a biologist who studies the genes that control hairiness in mammals. Why humans and a small number of other mammals are relatively hairless is an interesting question. It all comes down to whether certain genes are turned on or off.

Hair benefits

Hair and fur have many important jobs. They keep animals warm, protect their skin from the sun and injuries and help them blend into their surroundings. They even assist animals in sensing their environment. Ever felt a tickle when something almost touches you? That’s your hair helping you detect things nearby. Humans do have hair all over their bodies, but it is generally sparser and finer than that of our hairier relatives. A notable exception is the hair on our heads, which likely serves to protect the scalp from the sun. In human adults, the thicker hair that develops under the arms and between the legs likely reduces skin friction and aids in cooling by dispersing sweat. So hair can be pretty beneficial. There must have been a strong evolutionary reason for people to lose so much of it.

Why humans lost their hair

The story begins about 7 million years ago, when humans and chimpanzees took different evolutionary paths. Although scientists can’t be sure why humans became less hairy, we have some strong theories that involve sweat. Humans have far more sweat glands than chimps and other mammals do. Sweating keeps you cool. As sweat evaporates from your skin, heat energy is carried away from your body. This cooling system was likely crucial for early human ancestors, who lived in the hot African savanna. Of course, there are plenty of mammals living in hot climates right now that are covered with fur. Early humans were able to hunt those kinds of animals by tiring them out over long chases in the heat – a strategy known as persistence hunting. Humans didn’t need to be faster than the animals they hunted. They just needed to keep going until their prey got too hot and tired to flee. Being able to sweat a lot, without a thick coat of hair, made this endurance possible.

Genes that control hairiness

To better understand hairiness in mammals, my research team compared the genetic information of 62 different mammals, from humans to armadillos to dogs and squirrels. By lining up the DNA of all these different species, we were able to zero in on the genes linked to keeping or losing body hair. Among the many discoveries we made, we learned humans still carry all the genes needed for a full coat of hair – they are just muted or switched off. In the story of “Beauty and the Beast,” the Beast is covered in thick fur, which might seem like pure fantasy. But in real life some rare conditions can cause people to grow a lot of hair all over their bodies. This condition, called hypertrichosis, is very unusual and has been called “werewolf syndrome” because of how people who have it look.

In the 1500s, a Spanish man named Petrus Gonsalvus was born with hypertrichosis. As a child he was sent in an iron cage like an animal to Henry II of France as a gift. It wasn’t long before the king realized Petrus was like any other person and could be educated. In time, he married a lady, forming the inspiration for the “Beauty and the Beast” story. While you will probably never meet someone with this rare trait, it shows how genes can lead to unique and surprising changes in hair growth.

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Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to CuriousKidsUS@theconversation.com. Please tell us your name, age and the city where you live. And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best. Maria Chikina, Assistant Professor of Computational and Systems Biology, University of Pittsburgh This article is republished from The Conversation under a Creative Commons license. Read the original article.

Orit Peleg, University of Colorado Boulder and Owen Martin, University of Colorado Boulder The Colorado June air was thick with summer heat. Mosquitoes rose in clouds around us, testing our resolve while we gathered our cameras and sensors. We walked into the wetland, down the unmarked path until the cattails rose shoulder-high. The sounds of frogs and crickets filled the air as we set up our cameras and waited. Then we spotted them: tiny lights lifting from the grasses, blinking in slow rhythms. Bioluminescent lampyrid beetles, commonly known as fireflies or lightning bugs, are widespread throughout the Eastern United States but far more scarce west of Kansas. Even though many are stargazers and hikers, most Colorado residents don’t know that fireflies share their state. We are an associate professor of computer science and a Ph.D. candidate who are working to shed light on Colorado’s hidden fireflies. In the past few years, we have observed and filmed elusive bioluminescent fireflies all over Colorado, racing each summer against their brief and unpredictable flashing season.

Last year in early June it was too early, we thought, for fireflies in Colorado. For weeks we had been checking weather forecasts, comparing them to previous years, waiting for warmer nights and rising temperatures − the signs that would tell us it’s firefly time. Then we got a tip. A friend mentioned seeing one or two flashes near their property. The next morning we packed our gear, rearranged our schedules and contacted our volunteer network. The field season began in a literal flash. As adults, fireflies live and flash for only about two weeks a year − and even then, just for a few hours each night. It’s easy to blink and miss the entire season. The next generation overwinters underground as larvae, emerging as adults the following year, though development may take up to two years in arid climates. Making the most of that narrow window is one of the many reasons we rely on volunteers who help us spot the first flashes and record observations across Colorado.

Western fireflies face unique environmental challenges

Our work joins a growing chorus of scientific observation focused on western fireflies, which pop up across the arid landscape near temporary wetlands, marshes, drainages, desert rivers and other water sources. Because of the dry landscape, these populations tend to be fragmented, isolated to where the water is and nowhere in between. This strong tie to small, unstable habitat spells vulnerability for the fireflies. If the water runs out, or their habitats are damaged by water or light pollution, the flashing populations could vanish. Pesticides in water are toxic to firefly larvae and their prey, and artificial light inhibits the flash courtship between males and females, preventing successful reproduction. Many populations and species of fireflies are threatened with extinction in the United States due to these factors.

Organizations such as our lab at the University of Colorado and the Xerces Society for Inverteberate Conservation are studying the distribution of and direct threats to western firefly populations. Many of the species are either endangered or not yet described. The fireflies of the Photuris genus along the Front Range, for example, still do not have a species name and appear to be genetically distinct from other Photuris around the country. Preliminary genetic results suggest at least one new species might be found here. The genetic data also suggests at least five different bioluminescent species of fireflies are present in Colorado.

How flash patterns help fireflies (and us) tell species apart

During their short mating season, fireflies use their flash patterns as mating calls. Males produce a series of flash-on, flash-off events, each with specific durations and pauses. These Morse code-like signals communicate what type and how fit the fireflies are to potential mates in the darkness. When females detect a suitable male, they respond with their own unique flash pattern. Our work piggybacks on this evolutionary adaptation. We first recorded populations from around the U.S. using two video cameras, which allowed us to accurately track individual fireflies in three dimensions and separate their flash patterns. We used the data on the flash behavior from different species to train a neural network that can classify the firefly’s flash pattern with a high degree of accuracy. Our algorithm learns the unique flash patterns from our data and can identify the species of firefly that is present in a video. This is a powerful tool for firefly conservation efforts. The camera footage can cover more time and ground than field surveys conducted by humans, and our algorithm can more quickly identify species that might be threatened.

Fostering community engagement with citizen science

Based on our success with community science data collection across other states, including Tennessee, South Carolina and Massachusetts, we wanted to apply the same principles to Colorado’s firefly populations. This is a big undertaking: There are dozens of fragmented sites where fireflies are active across Colorado, and more are reported by volunteers every season. Our team of two cannot visit and survey every site during the short firefly season. In 2023 we put out our first call for volunteers in Colorado. Since that time, 18 community members in Boulder, Fort Collins, Divide and Loveland joined the filming effort. We provide cameras for the volunteers, who bring them to their nearby wetlands and set them up in the fading light. Last summer we partnered with local land management agencies in Boulder, Fort Collins and Loveland to host informative community events, where we spoke about firefly biology and conservation to audiences of all ages. On many of those nights, as the flashes began, we heard the excitement build: quiet gasps, hushed enthusiasm and a whisper such as, “Look at that beautiful streak of light!” Fireflies have an important story to tell, and here in Colorado that story is just beginning. Their brief flashes each summer help us learn about communication, ecology and how these delicate insects respond to an ever-changing world. If you’d like to help us find and study fireflies in Colorado, you can sign up to join our community science project. Orit Peleg, Associate Professor of Computer Science, University of Colorado Boulder and Owen Martin, Ph.D. Candidate in Computer Science, University of Colorado Boulder This article is republished from The Conversation under a Creative Commons license. Read the original article.