Scientists at the Gladstone Institute of Cardiovascular Disease (GICD) have traced the evolution of the four-chambered human heart to a common genetic factor linked to the development of hearts in turtles and other reptiles.
The research, published in the September 3 issue of the journal Nature, shows how a specific protein that turns on genes is involved in heart formation in turtles, lizards and humans.
"This is the first genetic link to the evolution of two, rather than one, pumping chamber in the heart, which is a key event in the evolution of becoming warm-blooded," said Gladstone investigator Benoit Bruneau, PhD, who led the study. "The gene involved, Tbx5, is also implicated in human congenital heart disease, so our results also bring insight into human disease."
From an evolutionary standpoint, the reptiles occupy a critical point in heart evolution.
While bird and mammalian hearts have four chambers, frogs and other amphibians have three. "How did hearts evolve from three to four chambers?" Bruneau said. "The different reptiles offer a sort of continuum from three to four chambers. By examining them, we learned a lot about how the human heart chambers normally form."
He explained that with four chambers—two atria and two ventricles—humans and all other mammals have completely separate blood flows to the lungs and to the rest of the body, which is essential for us to be warm-blooded.
http://www.sciencedaily.com/releases/2009/09/090902133629.htm
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