We humans have been around for about 2.5 million years, but the beating of our hearts is controlled by something much older than Homo sapiens -- an ancient molecular pathway that, according to Huck Institutes faculty researcher Tim Jegla, may be on the order of 700 million to a billion years old.
The Jegla Lab studies the evolution of the nervous and muscular systems, using model organisms such as the cnidarian Nematostella vectensis -- also known as the starlet sea anemone -- to investigate conserved traits and the molecular pathways and genes that underpin them.
Cnidarians -- comprising an ancient phylum that, in addition to sea anemones, includes animals such as jellyfish and corals -- have nervous systems that allow them to coordinate movement and respond to their surroundings, but do not have a brain or any other analogous organs.
In a study recently published in Proceedings of the National Academy of Sciences, the Jegla Lab identified in the Nematostella sea anemone the same gene family (Erg) that is responsible for the slow-wave contractions of the human heart. After cloning the genes for further investigation, the researchers found that the ion channel it encodes has retained its function relatively unchanged since the time of humans' and cnidarians' divergence from their common ancestor almost a billion years ago.
“This discovery,” says Jegla, “shows that at least some of the molecular mechanisms through which we control electrical activity in things like the heart evolved in some of the earliest animals, long before the existence of hearts or even cardiac tissue.”
“This fits a broad pattern we're finding,” Jegla continues, “that almost all the major signaling systems used in our brains and muscles evolved hundreds of millions of years ago in an ancestor of bilaterians which seems to have had a very versatile and molecularly complete set of tools for neuronal function that has been conserved throughout subsequent animal evolution and tuned to the specific needs of the major animal phyla. It appears that a lot of the signaling that we do in our complex neuromuscular systems is based on pre-existing programs that are just adapted to our specific physiological needs.”