We don’t think it comes as a surprise to anyone that there are major differences between the human brain and the brains of animals. Those that follow Darwin’s Theory of Evolution may say it has to do with the structures of our brains. Then, there are those who believe in the religious view that God created humans in His image and gave us the gift of self-awareness. Since we couldn’t decide on just one key distinction, we’ve compiled a list of the major differences between human and animal brains.
Let’s look at the most basic, obvious difference between animal and human brains. Although our brains all look very similar, there are distinct differences between each species’ brain that set them apart.
The ratio of the brain’s weight to that of the entire body is different in humans and animals. One myth that would have easily answered this question is that since humans are the most intelligent, we have the biggest brains. The independent size of the brain isn’t what’s important. It’s the ratio between brain weight to the entire body weight. Humans have a ratio of about 1-50, whereas most other mammals are closer to 1-180. This means that the brain takes up more weight in a person than it does in other animals.
The Encephalization Quotient (EQ) describes the brain’s size as a ratio of the expected average brain’s size for a given body weight. For example, humans have an EQ of about 7.5, which means that our brains are seven and a half times larger than what you would expect from an animal of our size. A squirrel, on the other hand, has an EQ of 1.1. This is pretty average for an animal of its size.
Another ratio that is worth mentioning in this discussion is that of the size of the cerebral cortex in relation to the size of their brains. The cerebral cortex is where the cerebral hemispheres are found. These areas are responsible for communication, thinking, and memory. Now when it comes to brain size, humans have the largest cerebral cortex of any mammal.
White Matter Really Does Matter
As its name suggests, white matter is white and is the part of the brain that connects the cells together so the nerves can communicate. When comparing human brains with those of our primate cousins, the chimpanzee, the Smithsonian found that a chimp’s temporal cortex is made up of less white matter. This indicates fewer connections between the nerve cells.
Humans, on the other hand, have more white matter in our temporal cortex, which is why we are able to process information more quickly and thoroughly. As similar as we are to primates, this is one area where humans definitely have the advantage.
In most cases, you’d never hear a human say they love their wrinkles. But when it comes to the human cortex, we may have to rethink this. The human cortex is full of wrinkles, which increases its surface area so that a larger cortex can fit inside of our skull. In many animals, including the brown rat, the cortex is smooth. Since the cortex houses many areas responsible for cognition and language, this is believed to be one of the main reasons humans are more intelligent than our animal friends.
The neocortex is the part of the brain that drives higher-order brain functions such as sensory perception, spatial reasoning, cognition, language, and the generation of motor commands. In humans, the neocortex is more developed, as with most mammals.
We’ve looked at the evolutionary approach and found several structural differences. Now it’s time to explore the cognitive differences that cannot be measured as easily through a microscope.
It would be easy to say that self-awareness distinguishes humans from all animals. But this simply isn’t true. It does, however, set humans apart from most other species. Apes, for example, demonstrate metacognition, which is our own awareness of our ability to think. Scientists would argue that since self-awareness and thereby, cognition, are possible due to the prefrontal cortex, those animals that do not demonstrate metacognition and self-awareness, lack this area in their brain.
In testing for self-awareness, scientists have conducted the mirror test. Animals are marked with a colored dye or dot on their forehead and shown their own reflection in the mirror. If they try to remove or get a better view of the spot by moving their body, scientists have concluded they are aware that the reflection is their own.
The attention network of humans was found to have expanded over time as we evolved. During a recent study, scientists used functional magnetic resonance imaging, or fMRI, on humans and macaque monkeys, to observe their brain activity. During this test, it was found that the monkeys lacked the temporal junction found in human brains. This is significant because it helps to pinpoint evolutionary stressors that caused this differentiation.
The study found that since humans are more complex in how we interact socially, we need a better ability to pick up on subtle cues and then use that information to guide our next steps. This finding also indicates that there are some aspects of human cognition that can only be studied using human participants.
There are distinct differences between the brain of a human and that of an animal. While the size and extent of the differences can vary based on whether we are discussing a mammal, a primate, a non-vertebrate, or a crustacean, to name a few, we are just looking at the tip of the iceberg when we think about what separates us from other animals on planet Earth. As scientists learn more about the brain and its functionality, we learn more about ourselves and about animals in general. We learn that for all our differences, we have much more in common than we may have realized.