A second later, he picked up his book and launched it across the room. The projectile landed squarely on the creature, squashing it neatly into the carpet. The spider was no more. 

Most people who swat at a fly or squash a spider never give their actions a second thought. But what if insects could feel pain? What if the spider felt panic, fear, even sadness as it met its grisly fate? 

For centuries, this idea was dismissed as nonsense. Now, evidence is mounting that some bugs may have feelings. 

Everyday, scientists are learning more about insects. At any one time, there are an incredible ten quintillionA thousand to the power of six; or a million million millions; or a billion billions; or a million trillions; or a thousand quadrillions. bugs living on Earth. Astonishingly, that means that for every one person, there are roughly one billion insects. 

Insects look different to humans. Our last common ancestor was a slug-like creature that lived 600 million years ago. Many insects have no lungs, stomach or blood vessels. Their body contents float in liquid. 

But in other ways, humans and bugs are uncannily similar. Their brains may be smallThe study's participants were given Pleos (baby robots which looked like people). First they were told to interact with them, then to tie them up and beat them., but they have areas for learning and memory. 

According to scientists, bees can count up to four. Cockroaches have social lives. Fruit flies learn from their peers and experience pain long after physical wounds heal.

In 1872, Charles Darwin noted that animals make noise when they are excited and bees hum when they are angry. Now, nearly 150 years later, entomologistsEntomologists are people who study insects. The term comes from the Greek entomon, meaning insect.  have revealed that Asian honey bees scream with a frantic buzzing when murder hornets attack their hive. 

For many evolutionary zoologists, the idea that insects have emotions makes perfect sense. A spider that is hungry is more likely to seek out food. A woodlouse that is delighted to find a fallen tree will not perish in the open. 

"Let's say you're a bee that ends up in a spider web, and a spider is swiftly coming towards you across the web," says one bee cognitionThe mental processes involved in gaining knowledge and understanding.  expert.  "It's not impossible that the escape responses are all triggered without any kind of emotions. But on the other hand, I find it hard to believe that this would happen without some form of fear." 

If the scientists are right, it could have huge implications. Every year, two trillion insects are squashed on Dutch roads alone. 

Of course, not everyone is indifferent to the suffering of insects. JainJainism is an ancient Indian religion. It teaches that the path to liberation is to live a life of harmlessness. monks, who practice nonviolence, wear masks over their mouths to avoid accidentally inhaling flying bugs. 

In 2018, online retailer ASOS banned silk, extracted by boiling the cocoons of silkworms, from its website. As more information about insects' cognition emerges, some think insects rights will become an increasingly prominent part of the animal rights movement. 

"Most people think that insects are like little machines that are just here to annoy us all," says one zoologist. "People just need to get to know them better."

Yes, say some. For years, humans have scorned, crushed, trampled on and eaten insects. They are the most persecuted creatures on this planet. But insects are capable of far more than many realise. From pain to pleasure, the evidence is emerging to suggest many species feel the world around them quite vividly. 

This is ridiculous, say others. Insects may be able to feel states like hunger or pain, but they cannot experience complex emotions in the same way as humans. And until a bumblebee can tell us how it feels, we cannot know for sure how sophisticated insects' emotional capabilities truly are.