The Great Brain Size Debate: Is Bigger Really Better?Does Brain Size Matter?

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From a small age, we as children begin to develop an idea based on a natural observation that we make. Animals with bigger brains are more intelligent. As far as children and most adults know, this is true. But not only is it a very general statement, we know that it is, in fact, untrue, and we have examples of it throughout the natural world. It is true that having a large brain, relative to body size, does help in the intelligence department, but the sociocultural aspects of our being, which as social apes, are crucial, may not lay in the cranial capacity of our skulls, but rather the formation and development of our brains themselves. For an organ that takes up 20% of our caloric intake, it must be an impressive act of feats it accomplishes. 

Throughout the history of Paleoanthropology, scientists and researchers have assumed that if the hominin (one of our extinct bipedal ancestors) had a tiny brain, it must mean that said hominin was “lower on the evolutionary tree.” It was less intelligent, capable, and organized as a social animal. But there have been a few essential pointers here that we have to consider if we want to test the hypothesis of “does a bigger brain equal a more advanced, intelligent, and social animal.” 

Of course, there will be hundreds of studies on this, surrounding animals of all kinds, throughout scientific literacy. Being an anthropology page, we will focus on humans and non-human primates. But the basic idea that I will try to prove in this article is that brain size relative to body size is not only critical, but how the brain is formed, the factions of it, and how it is divided up play much more important roles in the creation of the behavior of the animal, than the size of the brain itself. More brain matter does not equal more intelligence, as we will see. 

So with that, let us begin. 

Why is our Brain important? While this may seem like a dumb question, it is much more complicated than one might believe at first thought. Why do we have a center for all our electrical stimuli to originate? Why not other localities around our bodies or some ofter biological formation? While I am no neurologist, I will walk us through the basics of the development and evolution of the human brain and any mammalian brain, as we all share the same structure, despite differences in size and organization. First off, we have the development of the most basic form of our brain, the innermost brain. The deeper you go into the brain, the more ancient the parts of the brain are evolutionary. The Medulla Oblongata, the part of the brain that controls breathing, is believed to be, along with the pons, one of the most ancient parts of the brain. From then on, senses and other items were developed, leading to nerves and the nervous system; the brain became more complex, dividing itself into parts or lobes responsible for different things. For example, the back of our brains, the brains of modern Homo sapiens, is called the Occipital Lobe. This part of the brain is responsible for vision; we know this thanks to MRI scans of brain activity and the good old fact that if you get hit in the back of the head, you “see stars.” An animal with a brain half our size may still have an occipital bun larger than ours, or more importantly, more developed than ours, and thus may have better vision, even though its occipital lobe may be smaller.

So, where does the size of the brain come in? First, I need you to think about and understand an important point. Brain size is relative to the size of the body of the animal. It does not have relevance to the intelligence of the animal. An elephant, while extremely intelligent, with a much larger brain than ours, is not thought to be more self-reflective, intelligent, or social than Homo sapiens. Just because you have a big brain does not make you at the top of the food chain, so to say, What counts more, we have found out through numerous studies, is that the creases in our brain, called fissures, and the amount of them is more relevant to our level of intelligence. So, just because Neanderthals, in some instances, would have had bigger brains than our modern species, it does not mean they were more or less intelligent. When it comes to neanderthals, it is more likely that it comes to the fact that our brains are organized differently. 

We can see from endocasts, which are prints that the brain leaves on the inside of a cranium; we can see and use advanced technology to recreate their brain structure (and those of other species, extant and extinct) and see how they differ from our own. 

So why is this all so important? Especially at this point in the field of Paleoanthropology. Well, as was said for the longest time, we believed that our brains grew as we evolved and became closer to the beings we are today. However, even with this, there is a problem; in the last 20,000 years, we have lost brain mass, but have we become less intelligent? Highly unlikely. So what happened? (Refer to image 1). Even more importantly, there have been numerous discoveries over the last decade, such as the finds on Flores and Luzon. In South Africa, significant finds have challenged the idea that you need a big brain to have a complex and advanced society of what we would recognize as cultures today. 

Here comes Homo naledi. Discovered in 2013 by a team led by Dr. Lee Berger, a mass of remains was found deep inside the Rising Star Cave System, dubbed a new species, and it became more and more apparent that something strange was happening there. There were so many individuals, in situ, laid out, children to adults, and everyone in between. While it was known at the end of 2022, there is evidence of burned charcoal and remains of small animals, soot on the roof of the cave, and even hearths discovered. Now, this may not sound all too impressive when you are talking about a member of the Homo lineage, but let me tell you something about naledi. Their brains were tiny, around 450-600cc, whereas ours are around double that. So now we have a creature performing possible ritual burial, controlling fire, and using it to light its ways to navigate in these insanely complex passageways, all with a brain the size of a chimp. According to Prof. John Hawks, this is because, as we mentioned earlier, the formation of the brain. While we are still piecing together exactly how their brain was formed, we can learn so much from the endocasts we have, archaeology, or the behavior they left behind. 

Here we have a creature, 300,000 years ago, performing what we believe were at least simple burial rites, ritualistically, showing distinct signs of culture, with a brain the size of a modern chimpanzee. This stunned the scientific world and still holds many secrets to be unveiled. One thing is for sure, though, the recent discoveries in Indonesia and South Africa prove that a tiny brain is just as capable of forming a distinct and understandable culture and that a large brain is not needed for the intelligence required to be called “human.” 

For decades, one of the most famous explorers has been wondering, “what makes us? Human” Dr. Louis Leakey started the world on an adventure that came about with “Man the Tool Maker,” thinking that only humans could possess the talent and brains needed to produce tools. How wrong we have been proven since then. Every major paper that comes out these days claims that they have discovered or proven something else that “makes something human or not.” And every other paper proves other animals had the same behavior. We are a part of the animal world, and we need to recognize that. We are all a part of a natural cycle, and by just looking at an animal and assuming its intelligence, consciousness, ability for apathy, etc., by just its brain size. I think we are looking at it the wrong way. 

An animal’s smarts do not come from the size of its brain; while, of course, relevant to the size of its body, the brain does vary in how much of the body’s energy it consumes. Some animals need to be constantly alert, using their senses; others, such as modern humans, can put things on the back burner and relax our minds. This is due to our ability to compartmentalize through abstract thought. A sign of higher thinking that we do not see in other animals. Even with the mirror test, where we place an animal in front of a mirror and see if it can recognize itself as itself, only so few pass the test. Mostly primates, as one might expect. 

In an interview done last week (as of the writing of this), Dr. John Hawks was on a podcast interview. In the interview, he claimed much of what has been said above, that brain size is not as important as an organization or how parts of the brain are connected in terms of the animal’s behavior and what it is capable of. In an interview this week, Dr. Lee Berger says there will be announcements about this species that change how we define and think of what is human (like I said, huh?) We will see what naledi was up to to make Lee think that, but he confirms that it is not the size of the brain that matters. So some big announcements concerning the behavior and activities of Homo naledi are on the horizon. So be sure to stay tuned for all of that juicy news! 

Well, I think that about does it for this article; I hope it makes sense and clears up a few things for people who may be wondering how neanderthals had bigger brains than us in some cases or how such small-brained animals like the hobbit were surviving, even thriving for a while on such a small island with limited resources, yet modern ( for the time) tools. There is so much left for us to learn, and we will do it together at each step! 

Until Next Time! 

Seth Chagi