A baby's gender could be determined by an ancient virus, according to a recent study led by Yale University researchers. They discovered that the gender of human and other mammalian babies may be regulated by the occurrence of a viral mutation that made its way to the mammalian genomes approximately 1.5 million years ago.
USA Today reports that the said study, published in the March 31 issue of the journal Nature, drew its conclusion by looking at the viral DNA found in the mouse genome. A human or an animal can acquire viral DNA when a retrovirus infects a sperm or an egg cell, and inserts its genes into the DNA of host cells.
According to the researchers, humans and animals today carry remnants from viruses that infected their ancestors million years ago. This is possible because when a sperm or egg cell infected by a retrovirus is involved in fertilization, the viral mutation could be carried on to their descendants.
In the study, the scientists discovered that high levels of a viral remnant were present on the mouse X chromosome, and these helped in determining the gender of the mice. They found that the normal level of the viral DNA allows the X chromosomes to remain active, making males and females to be born at an equal proportion. Moreover, when the marker is overrepresented, the X chromosomes will be deactivated, enabling males to be born twice as often as females.
Senior author Andrew Xiao, a molecular biologist at the Yale School of Medicine, told Live Science that over 40 percent of the human genome may be made up of viral remnants. He said that although most viral remnants are inactive, some of them could influence the health or development of a human.
Aside from helping identify the gender of an offspring, Xiao also added that the viral DNA could potentially be used in suppressing the spread of cancer. He explained that the same viral material is present in tumors and it may play a role in cancer growth.
