Brain in all organisms can be simply defined as a mass of nerve tissue that integrates sensory information and directs motor responses and in higher organisms, it is also the center of learning. The evolution of the brain occurred over a time scale of 3.5 billion years. It transformed from simple nerve conduction through ion channels in single-celled bacteria into a complex human brain made up of billions of cells. 

Brain Evolution – Where did our brains come from?

Brains have their origin billions of years ago in simple single-celled organisms such as bacteria.

~3.4 Billion years ago

Bacteria began to develop ion channels, membrane proteins that control the flow of ions, paving the way for nerve conduction. In higher organisms, the flow of ions through ion channels helps in generating a nerve impulse.

~2 billion years ago

Eukaryotic cells (cells with enclosed nuclei) developed the ability to make electrical signals when they swam. Cilia in single-celled eukaryotes respond to environmental stimuli and send electrical signals to the cell body using ion-conducting channels in the ciliary membranes.

Also Read: Mesozoic Era – the Age of Reptiles.

~600 million years ago 

Around this time, sponges and comb jellies developed further features seen in modern nervous systems. Sponges organized their colonies with proteins used in modern synapses and comb jellies evolved one of the first neural networks.

~550 million years ago

Flatworms developed primitive bilaterally symmetric nerve cords and light sensors (eyes), which led to early fishes with complex brains inside a protected spinal cord-like structure.

~350 million years ago

Amphibians developed a brain comprised of a complex forebrain, midbrain, and hindbrain.

~200 million years ago

Mammals entered the scene, further evolving the forebrain. Among all vertebrates, mammals have the biggest and most complex brain for their body size.

200,000 years ago 

Modern humans appeared, with ever more complex brains with highly developed visual systems and reasoning abilities. The human brain weighs around 1.4 kg and is made up of billions of cells called neurons.

Also Read: Sexual Reproduction – An Important Innovation of the Early Protists.

So, now we can say that, in a way, we all have a brain like a sponge. That is all for now and meet you in my next article. Keep Reading, Keep Exploring, and Keep Sharing your Knowledge, and above all BE CURIOUS. 🙂