I saw a question on social media today. A parent said their six year old had asked: ‘Why don’t plants have brains?’ What an excellent question. As always, it’s the simple ones that get us thinking and I thought it would make a good topic for a blog post. Especially as it’s more easily answered in the context of how ecosystemsHow ecosystems function An ecosystem is a community of lifeforms that interact in such an optimal way that how ecosystems function best, is when all components (including humans and other animals) can persist and live alongside each other for the longest time possible. Ecosystems are fuelled by the energy created by plants (primary producers) that convert the Sun's heat energy More work and Earth’s energy systems. It is also one of those topics that places animals right at the centre of humanity’s future – it explains why we can’t do without them. Here are my five reasons plants don’t have brains.
#1 – Plants didn’t evolve brains to start with
This is a bit like saying ‘because they don’t’ but it’s a little more interesting than that. Primitive plants came from bacteria and date back almost to the creation of the Earth. Evolution, according to the wonderful work of Jeremy England, is all about pattern forming. At first our planet was energy chaos(Of energy and ecosystems). Ecosystems are thermodynamically driven. Disorder occurs when energy dissipates and becomes more chaotic. For example, the release of hot air into the atmosphere results in that energy is freer to disperse (maximum entropy). The opposite is true when energy is locked into biological processes, when it is stored inside molecules (minimum entropy). Stability in ecosystems occurs More but as molecules connected in ever more complex way, life was formed.
The abundance of Solar energy begets the lifeforms most able to use it … the plants. The ability to photosynthesise was central this. That means using the Sun’s energy to build sugars from carbon and water. Bacteria carried on doing this somewhat simple chemical reaction for billions of years. That didn’t require a brain.
#2 – Animals evolved because plants would kill ecosystems
Left to their devices plants would collapse the world’s ecosystems. This is because they convert so much of the Sun’s energy to sugars, they make a lot of waste. In the Devonian, they contributed a mass extinction, because there were no land animals to feed on their excess. Land plants eroded the continents and polluted the sea.
For any ‘pattern’ of life to form it has to be stable. Plants couldn’t stabilise the Earth so among the next most likeliest survivors were animals. This extraordinary sophistication was created not by forcing evolution to happen. It was the result of lots of failures caused by the Sun’s energy eroding life, so only the most sophisticated patterns of life would ever make it. Plants couldn’t create lasting patterns alone, as they created too much waste. So animals formed.
#3 – Plants don’t have mitochondria
The very first plants were a symbiosis between two bacteria. The ancestors of those early life forms still exist today inside every plant as ‘organelles.’ These are cells inside the cells, that act as factories for energy transfer(of nutrients) the thing that sets animals apart from plants, is that they can move. Some of the biggest migrations on Earth every day, are the movement of insects like caterpillars, from the stem of a plant to a leaf and back, before turning into butterflies and transferring the energy elsewhere. Large-scale migration of grazing animals and migratory songbirds moves More. They provide fuel for the plant to build itself. There are THREE original bacteria that did this. Three types of plant.
The same thing happened to make animals but these bacteria became mitochondria and only ONE of these survives (identical in every cell of your body, and of every other animal on Earth). Their role is to use oxygen (a very powerful fuel) and make Adenosine Triphosphate, to fuel the growth of your cells. There is only one type of animal, and we are among them.
It is this combination of oxygen, mitochondria and powerful enzymes, that creates sufficient fuel for you to move. Movement is the defining factor that separates animals and plants.
#4 – Plants don’t need interior brains to connect to the Earth
The most complex plants today are towering trees. You’d think if there was ever a plant-based life form that would need a brain, it would be a tree. In a way they do have brains but not ones that are housed inside themselves. Plants are rooted to the spot and communicate via fungal and microbial networks. They are intimately connected to the world around them in ways we are only just beginning to understand. Their brains are an extension of their being.
Fungal networks connect trees together so they can ‘talk’ to each other and act cooperatively when under insect attack. We tend to forget that ecosystems are extensions of intelligence, with all their operators functioning as one unit.
Animals can move about though. We have to, in order to transfer, amplifyAmplification (of nutrients and energy). Animals consume plants and other animals and in doing so, reintroduce important energy-containing nutrients back into the environment, at even higher concentrations and in patches. Amplification of energy is driven by migration and happens at every scale, from insects moving daily in and out of your vegetable patch, to African wildebeest herds and the seasonal More and concentrate nutrientsEnergy and nutrients are the same thing. Plants capture energy from the Sun and store it in chemicals, via the process of photosynthesis. The excess greenery and waste that plants create, contain chemicals that animals can eat, in order to build their own bodies and reproduce. When a chemical is used this way, we call it a nutrient. As we More (energy). Otherwise we would never have become the most likely beings to create stability on Earth. But means we have to consume an extraordinary amount of energy. Mobility requires a brain to coordinate sensory organs and make sense of the surrounding world so we can have the motor skills to do what plants cannot. The brain uses more energy than any other organ.
#5 – The animal brain is the way it connects to ecosystems
Plants connect to ecosystems by roots, fungal networks and so on. Animals can jump up in the air and create a space between themselves and the Earth. To reconnect with it – to be part of the ecosystem – animals literally have to move from place to place, meet it physically and consume parts of it.
That is why coordination is needed. A big brain helps in moving around but it does another important thing. It acts as a storage device for knowing where and how to find food. Feeding is the very behaviour that maintains healthy ecosystems … that balances nature. That storage device needs a code-base to store and retrieve knowledge and that is called ‘culture’ and ‘language’.
The ability to transfer nutrients (and then amplify and concentrate them) was the final step in Earth stabilising over the last few hundred million years.
Summary
Here is a quick summary of these five reasons plants don’t have brains.
Animals evolved brains to store information for a mobile body. Mobile bodies were needed to save us from the degrading of the Earth by surplus energy. Plants create this surplus energy and are immobile, but communicate instead, through associations with soil and microbes. It’s like they have brains outside themselves.
Plants need animals to have interior brains but not the other way around. The Earth would be bare rock (like Mars) without ecosystems. But ecosystems containing plants cannot exist unless animals are there to move stuff around and keep things in order – and that requires a brain to connect any independently-moving organism (animal) back to the Earth’s processes.
This is ultimately why plants don’t have brains.
