Sudden discovery. Vampire fish helped scientists figure out a non-obvious fact about human evolution
April 21, 13:51 Share:
Lampreys have demonstrated the presence of a sympathetic nervous system (Photo: Fernando Losada Rodríguez)
A new study of vertebrate evolution has found that humans have more in common with creepy fish called lampreys than previously thought.
Lampreys, with their long, slippery bodies, round mouths and parasitic tendencies, scare people. However, in fact, they have a lot in common with us. These creatures belong to an ancient line of vertebrates known as Agnatha, or jawless fish.. Previous research has shown that lampreys and their relatives represent the most primitive group of vertebrates still in existence, originating approximately 360 million years ago. For the past 150 years, scientists have theorized that lampreys lack jaws because they lack a structure known as a neural crest.. This group of stem cells is unique to vertebrates, and in the womb or egg they develop into a wide range of structures. These structures include both the jaws and the sympathetic nervous system, which controls our involuntary responses. “ fight or flight” triggered in dangerous or stressful situations.
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Creepy. Fossils of lampreys that lived 160 million years ago have been found in China.
However, a new study published in the journal Nature shows that lampreys do have sympathetic nerve cells.. This suggests that life-saving responses in vertebrates evolved much earlier than expected.. According to LiveScience, the new study did not begin as a search for sympathetic nerve cells.. Instead, the work focused on finding similar cells that were precursors to the complex neural crest seen in jawed vertebrates. They thought they might find such cells in lampreys because they are closest to ancient jawless vertebrates that first appeared about 500 million years ago.
But when researchers began dissecting lamprey larvae, they noticed that the immature fish had structures that looked a lot like neurons, running in a chain along the length of their bodies.. This chain of nerve cells is characteristic of the sympathetic nervous system, a system that lampreys are not supposed to have.
When the scientists looked closer, they confirmed through RNA sequencing that these structures were indeed nerves. The team also found that the cells produce a precursor enzyme for norepinephrine, a key chemical messenger that helps control reactions. “ fight or flight.”
The discovery that these jawless fish have a reaction Fight or Flight shows that the evolutionary origins of this system occurred some 50 million years earlier than previously thought.