Why Some Animals Can’t Feel Pain

Animal rights activists, scientists, and biological ethicists debated this for years, and still do today: Can animals, insects, and other living beings feel pain?

It’s an interesting topic, both from a scientific reasoning perspective and a moral perspective. After all, there are various sports and activities around the world that involve animals and may be painful for them.

There are two main problems when determining if animals feel pain:

1. Most animals, especially wild animals, are very good at hiding pain and injuries. If something injures them in the wild, they can’t show vulnerability or a predator will take advantage of them.
2. They can’t tell us if they are in pain.

Sure, most animals will react to something that should be painful. If you have domestic pets, you likely experience this and feel sympathetic toward them.

But does this mean they experience pain in the same way we do?

There are some interesting studies on this topic that revealed more than we could know on the surface by studying the physiological makeup of different species.

Here’s what we know now:

How Do We Feel Pain?

The ISAP (International Association for the Study of Pain) defines pain as follows:

“An unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage.”

The interesting thing about pain is that it’s subjective. Everyone has a different tolerance for pain and finds different experiences more painful than others. Even pain awareness differs from person to person.

One of the things that is consistent is how the human body processes pain. When we hurt ourselves, pain receptors (nociceptors) in that area send electric signals through our spinal cords to our brains.

Our brains then direct these signals to the cortex, which is an area within our brains that perceives and processes pain. Signals also go to our limbic system, an area of our brain that controls emotional responses to pain.

We then feel pain based on how our brains interpret the signals. It’s a way of letting us know we have an injury to attend to, and to recognize the same dangers in the future.

Here’s Why Some Animals Can’t Feel Pain

If an animal lacks the pain receptors and parts of the brain we use to process pain, it’s a good indication that they do not feel pain. Here are some examples of organisms that lack some of these key pieces of anatomy:

Why Fish Can’t Feel Pain

Studies into the anatomy and physiology of some fish discovered that fish do not possess a neocortex, the part of our brains that is responsible for sensory perception. This is a strong indication that fish do not feel pain, or at least not in the same way we do.

In addition, almost all the fish studied lacked the nerve fibers we have that send pain signals to our brains. The study concluded that the fish lack these two parts in their anatomy and do not feel pain.

The study explains that some bony fish do possess simple nociceptors. So, there is a possibility that these fish are aware of some kind of pain. However, scientists don’t fully understand how they process pain and what it feels like.

Why Insects Can’t Feel Pain

Insects – like spiders, flies, butterflies, bees, etc. – also lack the neurological structures and parts of the brain that process pain.

From an observational standpoint, insects also lack the ability to learn from doing something that would be painful. For example, if we touched something sharp and it hurt, we would know to avoid doing it again. Insects, on the other hand, repeat actions that should cause pain, showing they are not feeling pain and learning from the experience.

Do Mammals Feel Pain?

Other mammals are a lot closer to us genetically and share a lot of the same features. They share the same nervous system, emotions, perceptions, and neurochemicals as us. Despite some mammals not showing it, we believe they do feel pain.

It’s still not clear exactly how they interpret pain and what they feel. Whether or not it’s similar to what we would feel if we had the same experience, we can’t be completely sure. Read more about how animals function to discover how their senses differ from ours.