What: "About half of the current X chromosome is like a fossil, having remained the same through the evolution of all mammals, even the relatively primitive marsupials. Genes on the remainder of the X in placental mammals, on the other hand, were more recently acquired from other chromosomes." Common point, they both old and have not changed for a long time. They are both "preserved" as they were in the past.

Writer: Sharon Guynup

LCC:

Where:

Date: Dec 11 2012 2:32 PM