Brain’s Cortex Evolved from a Lamprey-like Ancestor

A team of researchers conducted a study at the Karolinska Institutet in Sweden on a lamprey brain which revealed that the cortex of our brain is over 500 million years old and revealed many new insights on brain evolution. As a starting point a lamprey is a fishlike jawless vertebrae. They live in coastal and fresh waters. According to Britannica, “they have well- developed eyes, one or two dorsal fins, a tail fin, a single nostril on top of the head, and seven gill openings on each side of the body.” It is astonishing to think that a part of the human brain has evolved from a fish.

According to Science Daily, “most of the forebrain evolution took place in mammals and that the brains of simpler, pre-mammalian animal groups such as fish and amphibians lack a functional cortex.” Our brain consists of many regions that control a variety of functions, some major parts of our brain would include the frontal lobe, temporal lobe, parietal lobe, occipital lobe, cerebellum, and brain stem. The front part of our brain is called the frontal lobe which entails the cortex. The frontal lobe of our brain consists mainly of decision making, memory, language, and other cognitive functions. The cerebral cortex also helps with cognitive functions like memory, attention, awareness and many more. Researchers at the Karolinska Institutet spent a long time studying the evolution of the lampreys brain, it is one of the oldest extant vertebrates. Sten Grillner, last author of the study and professor of neurophysiology at the Department of Neuroscience, Karolinska Institutet says “..here we’ve made detailed studies of the lamprey brain, combining neurophysiological analyses with histochemical techniques.” According to the Karolinska Institutet, “researchers show that even the lamprey, which existed hundreds of millions of years before mammals, possesses a detailed blue-pring for the development of the cortex, the basal ganglia and the dopamine system– all the vital ingredients of integrative cerebral function.”  Not only that but it was found that the lamprey’s cortex has a visual area and the sensory and motor areas have also been discovered. Professor Grullner says “ this shows that the birth of the cortex has to be pushed back about 300 million years ago. This, in turn, means that the basic plan of the human brain was defined already over 500 million years ago, that’s to say before the lamprey branched off from the evolutionary line that led to mammals and humans.” Overall the study revealed that the main components of the human brain have been found in the lamprey. All of these findings are crucial to understanding how the brain has evolved.

The discovery of the cerebral cortex of a human brain evolving from a lamprey brain is related to our unit about evolution. Evolution is the scientific theory that different types of organisms have developed from earlier forms. This relates to the cladograms and the phylogenetic trees that we examined. For example primates, rodents and rabbits have hair, four limbs, bony skeleton, and are vertebrae. Since they have all of these traits in common, they also share a common ancestor. Although each animal has evolved into its own species they share common traits due to evolution. Similar to the cerebral cortex of the lamprey and the human brain, discovering that both share common aspects such as the motor and sensory areas very similar to the human brain. Although they share common aspects due to evolution the human brain functions differently. This new discovery allowed researchers to discover that the human brain has been evolving for over 500 million years ago.

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Biology Teacher

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