How/Why did the brain form in the early life forms?

[WaveJumper]

The first brains came about in the precambrian or at the border with the cambrian around 560 million years ago when the first multi-celluar organisms emerged. It has always struck me how/why organisms developed brains. The brain must have emerged together with eyesight, since eyesight would be worthless without a brain. I can see how certain multicellular organisms might have evolved certain photo-sensitive cells into eye-sight, but how did they know, and what gave them information(the blueprint) how and why to construct a brain to make use of the eyesight? Did the brain form before the eyesight and the other senses? If so, what purpose would it serve? If it came about at the same time with the other 6 senses, what made it possible? How does the evolution theory address this question?

 

[Moonbear]

You can actually look at more simple/primitive organisms to get a handle on your question. Development of nervous systems would have preceded vision. If, for example, you look at worms, like the earthworm, they have just ganglia (clumps of cell bodies of neurons). Work your way up to insects, and some very simple brains start forming. The brains of insects have so few neurons that I think every individual neuron has been mapped. Keep working up from there, and you get organisms like lampreys that have basically the equivalent of nothing more than our brainstem. Moving into birds, huge brainstem, and a little bit of cortex stuck on the front (lots of visual processing going on there). Get to mammals, and the cortex starts to get proportionally larger relative to the brainstem, smoother in "lower" mammals, and more folded as it develops more in "higher" mammals.

 

[quicknote]

The development of the brain in early life forms is a complex and fascinating topic that has been studied and debated by scientists for many years. While there is still much to learn and understand about this process, there are several theories that can help us understand how and why the brain formed in early life forms.

One theory is that the brain evolved as a means of survival. As multi-cellular organisms emerged and began to interact with their environment, they needed a way to process and respond to information from their surroundings. This led to the development of basic sensory organs, such as eyes, which allowed for the detection of light and other stimuli. The brain then evolved as a way to process and interpret this sensory information, allowing these organisms to make more complex and adaptive responses.

Another theory suggests that the brain evolved through a process of natural selection. As organisms with more complex brains were better able to survive and reproduce, their genetic traits were passed on to future generations. Over time, this led to the development of increasingly complex and advanced brains in different species.

It is also possible that the brain and eyesight evolved simultaneously, with each one influencing and shaping the development of the other. This could have been driven by the need for organisms to gather and process information from their environment in order to survive and thrive.

The evolution theory does not provide a definitive answer to the question of why and how the brain formed in early life forms, but it does offer some insights and possible explanations. It is a complex and ongoing process that is still being studied and understood by scientists. Through continued research and investigation, we may be able to gain a deeper understanding of the origins and development of the brain in early life forms.