Mating makes gerbil dads dote
Parents often find that newborn babies are the ultimate contraception. But with
Mongolian gerbils, newly published research shows that newborn sons put their
fathers into a mating mood, and it's only after postpartum sex that fathers
settle down into being devoted dads.
"On the day that the female gerbil gives birth, the male spends hardly
any time in the nest with the pups. He actively avoids contact with them,"
says Dr. Mertice Clark, a McMaster University psychologist. She's the Dr. Ruth
of Mongolian gerbil sex, having spent the past three decades studying the
ins-and-outs of the pop-can-sized rodents' mating and parenting behaviour and in
the process gaining remarkable insights into the forces driving mammalian mating
and parenting activity.
Mongolian gerbil fathers' initial offspring avoidance has been a mystery in that
by day three they're dutiful dads, doing everything the moms do, short of
suckling the young.
However, a recent series of NSERC-funded experiments, published in this
September's scientific journal Animal Behaviour, by Dr. Clark and McMaster
University colleagues Elaine Whiskin and Dr. Bennett Galef, Jr., suggest a basis
for this initial paternal avoidance of their progeny. It's the newborn boys that
send the dads packing.
"As the number of male pups in a litter increases, the amount of time he
spends in the nest decreases," says Dr. Clark.
Her team's results show that just a whiff of their sons puts off the pops. When
the researchers temporarily inhibited the fathers' sense of smell, their
response to male and female pups was identical.
So what's in the air that's getting the guys to turn up their noses and run? Dr.
Clark speculates that it's testosterone, or as those in the business simply call
it, "T." Just after birth, Mongolian gerbil pups, particularly the
boys, experience a postnatal surge in testosterone.
"A baby male pup's T-levels are as high as that of an adult male,"
notes Dr. Clark.
The researchers believe the testosterone puts dads on the defensive and dampens
their parenting drive in favour of a focus on mating. Female Mongolian gerbils
go into oestrus a mere six to 12 hours after giving birth. And in the wild,
these mate-ready new moms will seek out males.
In the experiments, Dr. Clark observed that those gerbil dads that actively
parented newborns took longer to begin mating and mated for a shorter period of
time than those dads that avoided interacting with their newborn pups.
Once they'd successfully mated, all the dads spent about as much time in the
nest as the moms, completing a transformation that Dr. Clark calls from
"cad to dad."
She notes that one of the fascinating aspects of this mammalian mating and
parenting dance is that what repels the dads attracts the mothers. Mongolian
gerbil moms show greater attentiveness to their sons, such as licking and
grooming.
"What we think is happening is that the pups in some sense have to compete
with dad for their mother's attention because the mother's in oestrus so she
wants to mate, but they want her to stay home and look after them,"
explains Dr. Clark.
"So maybe one function of the increased T-levels in pups is to enable the
pups to compete with their dads for their mom's attention. And some would even
argue that's why human males don't get much sleep during the early stages with a
newborn. The sleeplessness interferes with the parents' sex life and makes sure
that nothing happens to distract the mother's focus on the newborn." -
NSERC
More information
Contact: Dr. Mertice Clark mclark@mcmaster.ca.
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