Could your exes pass on traits to your future children?
New research shows a link between a female fly's former sexual partners and the offspring that result from her current match, TIME reported.
Recently publishing their findings in the journal Ecology Letters, Angela Crean and her colleagues found that male flies don't necessarily have to fertilize the eggs to pass on their traits--they just have to be there first.
"The genetic tests showed that even though the second male fertilized the eggs, the offsprings' size was determine by the condition of the first male," explained Crean, as quoted by TIME. "The cool thing is that the non-genetic effects we are seeing are not necessarily tied to the fertilization itself."
Working with a team at the University of New South Wales in Australia, Crean conducted a series of experiments using female flies while their eggs were still immature to see how eggs respond to the semen of the first male flies the females mated with. The immature eggs can't yet be fertilized and result in baby flies, but they can absorb factors in semen.
The researchers paired the females with larger male flies for mating and then after they grew to maturity, the female flies were allowed to mate with smaller males. Despite being actually fertilized by the smaller males, the resulting offspring was marked by the large size of the first males that the females mated with, physically resembling the former partner while carrying genes from the second.
"This could be seen as a maternal effect [such as diet or smoking] where the mother's environment are her previous mating partners," Crean said. "We have to realize that it's not just DNA that gets passed on. It opens up the opportunity for all these other pathways that we had excluded."
Telegony, the theory of non-genetic inheritance, was first proposed by Aristotle but was discarded after science discovered genetics.
"The entire ejaculate has a whole bunch of other things in it; only 5 percent is the sperm itself," Crean told Popular Science. "The sperm is what fertilizes the egg, but you have all these sugars and proteins and fluid that carry that sperm. And we know it can carry things like STDs and lots of other things like peptides."
Animal breeders have long held that the most pure-bred offspring come from females that have not mated before, but Crean isn't ready to say that the research applies to other species yet. As for people? That's too big a leap for now.
"It's something we definitely don't want to speculate about yet with humans," said Crean. "There is no direct scientific evidence for that at all."
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