It's about maximizing surface area in a constrained volume, by adding folds and wrinkles you can do that. It's the same reason why a walnut resembles a brain, it's essentially the same solution to the same packing problem. A walnut wants to maximize its surface area to increase the amount of moisture it can draw from the soil, a brain wants to maximize its surface area for more complex reasons, but the result is the same. The two main 'brain tissues' are white matter and gray matter, with gray matter doing the thinking so to speak, and white matter acting as interconnections between regions of gray matter. For a variety of reasons including relative growth rates and the need to place some gray matter regions close to others that in a smooth surface would be more distant, as well as maximizing surface area... the brain gets its folds (or sulci and gyri).
And a brain with more surface area conferred a benefit to the individual in response to selective pressures increasing its fitness and was therefore a trait favored by natural selection.
But why do we need so much surface area? I understand it for lungs (exchanging oxygen and CO2) or skin (exchanging heat). But brains? What's in the surface that's so valuable?
Grey matter is more prevalent on the surface. Grey matter contains the nerve cell bodies. In short, more surface area means more grey matter (for a given volume) therefore more neurons. And natural selection favored more neurons even despite the energy cost of having more.
Surface area vs volume is an important concept in physiology. This ratio explains, in part, why elephants have such large ears. It isn't just for hearing, but also to increase the massive animal's surface area, which is important for cooling the animal.
Most of what you can see when you look at the brain is the cortex. This is the part where high level brain function occurs--conscious thought, decision making, processing input form your senses, etc. All of the neurons that do this work live right at the surface of the cortex. If you want a smarter brain with more neurons, the surface of the brain has to get bigger. But it can only get so big without making the skull enormous. So, the surface is folded up to get a lot more surface area in the same size skull.
If you look at how the brain evolved from reptiles on up you'll see it kept building upward and outward. When space ran out it started to fold up in order to maximize the space w/o making the space bigger. As it is, women have a hard time delivering babies because the head size has maxed out.
It's about maximizing surface area in a constrained volume, by adding folds and wrinkles you can do that. It's the same reason why a walnut resembles a brain, it's essentially the same solution to the same packing problem. A walnut wants to maximize its surface area to increase the amount of moisture it can draw from the soil, a brain wants to maximize its surface area for more complex reasons, but the result is the same. The two main 'brain tissues' are white matter and gray matter, with gray matter doing the thinking so to speak, and white matter acting as interconnections between regions of gray matter. For a variety of reasons including relative growth rates and the need to place some gray matter regions close to others that in a smooth surface would be more distant, as well as maximizing surface area... the brain gets its folds (or sulci and gyri).
And a brain with more surface area conferred a benefit to the individual in response to selective pressures increasing its fitness and was therefore a trait favored by natural selection.
But why do we need so much surface area? I understand it for lungs (exchanging oxygen and CO2) or skin (exchanging heat). But brains? What's in the surface that's so valuable?
See my edit; sorry it took me a minute to organize my thoughts and I had a late edit.
Seems like you could use more walnut folds
Because the surface is where thinky cells live (grey matter), the inner portions of the brain are mostly just cabling connecting different parts.
Grey matter is more prevalent on the surface. Grey matter contains the nerve cell bodies. In short, more surface area means more grey matter (for a given volume) therefore more neurons. And natural selection favored more neurons even despite the energy cost of having more. Surface area vs volume is an important concept in physiology. This ratio explains, in part, why elephants have such large ears. It isn't just for hearing, but also to increase the massive animal's surface area, which is important for cooling the animal.
Most of what you can see when you look at the brain is the cortex. This is the part where high level brain function occurs--conscious thought, decision making, processing input form your senses, etc. All of the neurons that do this work live right at the surface of the cortex. If you want a smarter brain with more neurons, the surface of the brain has to get bigger. But it can only get so big without making the skull enormous. So, the surface is folded up to get a lot more surface area in the same size skull.
If you look at how the brain evolved from reptiles on up you'll see it kept building upward and outward. When space ran out it started to fold up in order to maximize the space w/o making the space bigger. As it is, women have a hard time delivering babies because the head size has maxed out.
How long before C section accelerates our evolution?