From three to four chambers
Scientists identify gene that may shape the heart
Lizards and turtles are not warm and cuddly, but they do have hearts — and interesting ones, at that. One molecular difference in reptile hearts may have divided single ventricles into two, creating four-chambered hearts from three-chambered ones as species evolved, a study published in the Sept. 3 Nature finds.
“The major question has been, what drove the evolution of the four-chambered heart?” comments James Hicks, an evolutionary biologist at the University of California, Irvine. Results from the new study “could lead to a deeper understanding of the fundamental factors involved in heart development,” he says.
Amphibians have three-chambered hearts made up of two top chambers, atria, and one bottom chamber, the ventricle. Mammals and birds have two atria and two ventricles, with ventricles separated by a muscular ridge called a septum.