Last Updated on April 17, 2026 by Daily News Staff

Earth Day is celebrated annually on April 22nd, and it serves as a reminder of the importance of taking care of our planet. It’s a day to reflect on our impact on the environment and to take action to create a better future for our planet.

The first Earth Day was celebrated in 1970, and it marked the beginning of the environmental movement. Since then, Earth Day has grown into an international event, with millions of people around the world participating in activities and events to raise awareness about environmental issues.

One of the main goals of Earth Day is to encourage people to take action to reduce their impact on the environment. This can include simple actions like recycling, conserving energy, and reducing waste. It can also involve more significant actions like advocating for environmental policies and supporting sustainable businesses.

Another important aspect of Earth Day is education. It’s a time to learn about environmental issues and to understand how our actions can impact the planet. Many schools and organizations use Earth Day as an opportunity to teach children about the importance of taking care of the environment.

This year’s Earth Day theme is “Restore Our Earth”, and it focuses on the idea that we can all play a role in restoring the planet’s ecosystems. This can include actions like planting trees, reducing plastic waste, and supporting sustainable agriculture.

Earth Day is an important reminder of the impact that we have on the environment and the importance of taking action to create a better future for our planet. By working together and taking small steps, we can make a big difference in protecting the planet and ensuring that it remains healthy and beautiful for generations to come.

Earth Day – April 22

https://nationaltoday.com/earth-day/

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Jacob A Tennessen, Harvard University

The fight against infectious disease is a race against evolution. Bacteria become resistant to antibiotics. Viruses adapt to spread more quickly. Diseases transmitted by insects present another evolutionary front: Insects themselves can evolve resistance to the poisons that people use to kill them.

In particular, the mosquito-borne disease malaria kills over 600,000 people annually. Since World War II, people have battled malaria with insecticides – chemical weapons intended to kill Anopheles mosquitoes infected with the Plasmodium parasites that cause the disease.

However, mosquitoes are quickly evolving counterstrategies that make these insecticides ineffective, putting millions of people at greater risk of deadly infection. My colleagues and I have newly published research showing how.

Insecticide resistance threatens public health

As an evolutionary geneticist, I study natural selection – the basis for adaptive evolution. Genetic variants that best promote survival can replace less advantageous versions, causing species to change. Anopheles mosquitoes are frustratingly adept at evolving.

In the mid-1990s, most African Anopheles were susceptible to pyrethroids, a popular type of insecticide originally derived from chrysanthemums. Anopheles control relies on two pyrethroid-based methods: insecticide-treated bed nets to protect sleepers, and indoor residual spraying of insecticide against the walls of homes. These two methods alone likely prevented over a half-billion cases of malaria between 2000 and 2015.

However, mosquitoes today from Ghana to Malawi are often able to survive insecticide concentrations 10 times the previously lethal dose. Along with Anopheles control efforts, agriculture also inadvertently exposes mosquitoes to pyrethroids and contributes to insecticide resistance.

In some African locales, Anopheles is already showing resistance to all four main classes of insecticide used for malaria control.

Adaptation in Latin American mosquitoes

Anopheles mosquitoes and the malaria-causing Plasmodium also occur outside Africa, where insecticide resistance is less well-researched.

In much of South America, the main malaria vector is Anopheles darlingi. This mosquito species has diverged evolutionarily from the African vectors so extensively that it might be a different genus, Nyssorhynchus. Along with colleagues from eight countries, I analyzed over 1,000 Anopheles darlingi genomes to understand its genetic diversity, including any recent changes due to human activity. My collaborators collected these mosquitoes at 16 locations ranging from the Atlantic coast of Brazil to the Pacific side of the Andes in Colombia.

We found that, like its African counterparts, Anopheles darlingi shows extremely high genetic diversity – more than 20 times that of humans – indicating that very large populations of this insect exist. A species with such a vast gene pool is well poised to adapt to new challenges. The right mutation giving it the advantage it needs is more likely to pop up when there are so many individuals. And once that mutation starts to spread, it’s protected by numbers since it won’t be wiped out if a few mosquitoes die by chance.

In contrast, bald eagles in the contiguous U.S. were never able to evolve resistance against the insecticide DDT and approached extinction. Evolution is more efficient among millions of insects than mere thousands of birds. And indeed, we saw signals of adaptive evolution in the resistance-related genes of Anopheles darlingi occurring over the past few decades.

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Mosquitoes evolve to detoxify poisons

Insecticides like pyrethroids and DDT share the same molecular target: channels in nerve cells that can open and close. When open, the nerve cell stimulates other cells. These insecticides force the channels to remain open and continuously fire, causing paralysis and death. However, insects can evolve resistance by changing the shape of the channel itself.

Earlier genetic scans performed by other researchers had not detected this type of resistance in Anopheles darlingi, and neither did ours. Instead, we found that resistance is evolving in another way: a group of genes encoding enzymes that break down toxic compounds. High activity of these enzymes, called P450, frequently underlies resistance to insecticides in other mosquitoes. The same cluster of P450 genes has changed independently at least seven times across South America since insecticide use began in the mid-20th century.

In French Guiana, a different set of P450 genes exhibits a similar evolutionary pattern, cementing the clear connection between these enzymes and adaptation. Moreover, when we exposed mosquitoes to pyrethroids in sealed bottles, differences among the P450 genes of individual mosquitoes were linked to the length of time they stayed alive.

Insecticide-heavy campaigns against malaria have been only sporadic in South America and may not be the main driver behind this evolution. Instead, it’s possible that mosquitoes are being exposed indirectly to agricultural insecticides. Intriguingly, we saw the strongest signs of evolution in places where farming is prevalent.

Toward more sophisticated vector control

Despite new vaccines and other recent advances against malaria, mosquito control remains essential for reducing disease.

Some countries are launching trials of gene drives to control malaria, which involve forcing a genetic modification into a mosquito population to reduce their numbers or their tolerance for Plasmodium. Such prospects are exciting, though the relentless adaptability of mosquitoes could be an obstacle.

I and others are revising methods to efficiently test for emerging insecticide resistance. Genome-scale sequencing remains important to detect new or unexpected evolutionary responses. The risk of adaptation is highest under a continuous, strong selection pressure, so minimizing, switching and staggering pesticides can help thwart resistance.

Success in the fight against evolving resistance will require a coordinated effort of monitoring, and reacting accordingly. Unlike evolution, humans can think ahead.

Jacob A Tennessen, Research Scientist in Immunology and Infectious Diseases, Harvard University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Laela Sayigh, Woods Hole Oceanographic Institution

Human fascination with bottlenose dolphins goes back thousands of years, at least as early as Greek mythology.

But it wasn’t until the 1960s that methodical research into dolphin communication began. Scientists like John Lilly and the husband-and-wife team of Melba and David Caldwell tried various experiments to decipher the sounds dolphins can make.

The Caldwells figured out a way to record isolated animals in human care. They discovered that each individual dolphin communicated mostly with one unique whistle, which they called the “signature whistle.” Researchers now know that these whistles convey identities much like human names do. Dolphins use them to stay in touch with each other in their murky habitat, where vision is limited. It’s like announcing “I’m over here!” when someone can’t see you.

This discovery is foundational to my own research. I’ve been studying communication in wild dolphins since the mid-1980s, when I joined my mentor Peter Tyack in documenting signature whistles in wild dolphins for the first time. Our team’s research focused on a resident community of free-ranging bottlenose dolphins in waters near Sarasota, Florida, where I continue to work today.

This collaborative study, led by Randall Wells of Brookfield Zoo Chicago’s Sarasota Dolphin Research Program, involves numerous researchers from a variety of institutions, who study different aspects of dolphin biology, health, ecology and behavior. Begun in 1970, this is the longest-running research project on a population of wild cetaceans – whales, dolphins and porpoises – in the world.

Recording and observing

Researchers know the age, sex and maternal relatedness of almost all of the approximately 170 dolphins in the Sarasota community. This depth of knowledge provides an unprecedented opportunity to study communication in a wild cetacean species.

The dolphins in the Sarasota project are periodically subject to brief catch-and-release health assessments, during which researchers, including me, briefly handle individual dolphins.

Our team attaches suction-cup hydrophones directly onto each dolphin’s melon – that is, its forehead. We then record the dolphins continuously throughout the health assessments, taking notes on who is being recorded when, and what is happening at the time.

This is how my colleagues and I were able to confirm that wild dolphins, like captive animals, produced large numbers of individually distinctive signature whistles when briefly isolated from other dolphins. Through observations and recordings of known free-swimming dolphins, we were further able to confirm that they produced these same signature whistles in undisturbed contexts.

We have organized these recordings into the Sarasota Dolphin Whistle Database, which now contains nearly 1,000 recording sessions of 324 individual dolphins. More than half of the dolphins in the database have been recorded more than once.

We identify each dolphin’s signature whistle based on its prevalence: In the catch-and-release context, about 85% of the whistles that dolphins produced are signature whistles. We can identify these visually, by viewing plots of frequency vs. time called spectrograms.

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Signature whistles and ‘motherese’

The Sarasota Dolphin Whistle Database has proved to be a rich resource for understanding dolphin communication. For instance, we have discovered that some calves develop signature whistles similar to those of their mothers, but many do not, raising questions about what factors influence signature whistle development.

We have also found that once developed, signature whistles are highly stable over an animal’s lifetime, especially for females. Males often form strong pair bonds with another adult male, and in some instances, their whistles become more similar to one another over time. We are still trying to understand when and why this occurs.

Dolphin mothers modify their signature whistles when communicating with their calves by increasing the maximum frequency, or pitch. This is similar to human caregivers using a higher-pitched voice when communicating with young children – a phenomenon known as “motherese.”

Slowed recording of a bottle-nosed dolphin without her calf, then with her calf. Courtesy of Laela Sayigh of Woods Hole Oceanographic Institution, and Brookfield Zoo Chicago’s Sarasota Dolphin Research Program. These sounds were obtained under a federal scientific research permit issued to R. Wells of SDRP.72 KB (download)

Also similar to humans is how dolphins will initiate contact with another dolphin by imitating their signature whistle – what we call a signature whistle copy. This is similar to how you would use someone’s name to call out to them.

Our team is interested in finding out if dolphins also copy whistles of others who aren’t present, potentially talking about them. We have seen evidence of this in our recordings of dolphins during health assessments, which provide a rare context to document this phenomenon convincingly. But we still have more work to do to confirm that these are more than chance similarities in whistles.

Shared whistle types

Another exciting development has been our recent discovery of shared whistle types — ones that are used by multiple animals and that are not signature whistles. We call these non-signature whistles.

I could hardly believe my ears when I first discovered a repeated, shared non-signature whistle type being produced by multiple dolphins in response to sounds we play back to them through an underwater speaker. We had previously believed that these non-signature whistles were somewhat random, but now I was hearing many different dolphins making a similar whistle type.

Our team originally had been using the playbacks to try to determine whether dolphins use “voice cues” to recognize each other – similar to how you can recognize the voice of someone you know. Although we found that dolphins did not use voice cues, our discovery of shared non-signature whistle types has led to an entirely new research direction.

So far, I’ve identified at least 20 different shared non-signature whistle types, and I am continuing to build our catalog. We are hoping that artificial intelligence methods may help us categorize these whistle types in the future.

To understand how these shared non-signature whistle types function, we are carrying out more playback experiments, filming the dolphins’ responses with drones. We’ve found that one such whistle often leads the dolphins to swim away, suggesting a possible alarm-type function. We have also found that another type might be an expression of surprise, as we have seen animals produce it when they hear unexpected stimuli.

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More difficult, more interesting

So far, the main takeaway from our experiments has been that dolphin communication is complex and that there are not going to be one-size-fits-all responses to any non-signature whistle type. This isn’t surprising, given that, like us, these animals have complicated social relationships that could affect how they respond to different sound types.

For instance, when you hear someone call your name, you may respond differently if you are with a group of people or alone, or if you recently had an argument with someone, or if you’re hungry and on your way to eat.

Our team has a lot more work ahead to sample as many dolphins in as many contexts as possible, such as different ages, sexes, group compositions and activities.

This makes my job more difficult – and far more interesting. I feel lucky every day I am able to spend working on the seemingly infinite number of fascinating research questions about dolphin communication that await answers.

This article has been corrected to better describe how dolphins respond to playback whistles.

Read more stories from The Conversation about Florida.

Laela Sayigh, Senior Research Specialist, Cetacean Communication, Woods Hole Oceanographic Institution

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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