What’s the News: A new analysis finds that many of the genes
behind the development of modern mammalian pregnancy are
controlled by mysterious genetic elements called transposons,
long referred to as “junk DNA.” The results suggest that the
placental uterus did not evolve gradually but instead arose from
a massive, transposon-driven genetic rewiring. How the Heck: -
The research team looked at the DNA of uterine cells from the
possum, a marsupial that gives birth two weeks after conception
and shelters its developing young in a pouch, and compared them
with cells from armadillos and humans, which both carry their
children to term in a womb lined with a nutrient-rich placenta.
The uterine cells of armadillos and humans shared more than
1,500 active genes that possums lacked. - Looking closer, the
team saw that a number of these genes—about 13%—were very near
on the genome to a particular kind of transposon specific to
placental mammals. The origins of transposons, jumping genetic
elements that copy and insert