An intriguing new study suggests children may indeed resemble a mother’s previous sexual partner.
The idea that the physical traits of
previous sexual partners could be passed on to future children was first hypothesised by Aristotle and formed part of the reason that kings were banned from marrying divorcees.
The science of genetics supposedly put an end to the theory of 'telegony'. But advanced scientific research techniques may be proving that Aristotle may have been right afterall.
Now scientists at the University of New South Wales discovered that, for fruit flies at least, the size of the young was determined by the size of the first male the mother mated with, rather than the second male that sired the offspring.
It is the first time that telegony has been proved in the animal kingdom.
The researchers propose that the effect is due to molecules in the semen of the first mate being absorbed by the female's immature eggs where they influence future offspring.
“Just as we think we have things figured out, nature throws us a curve ball and shows us how much we still have to learn," says lead author Dr Angela Crean.
"We know that features that run in families are not just influenced by the genes that are passed down from parents to their children.
“Various non-genetic inheritance mechanisms make it possible for environmental factors to influence characteristics of a child.
"Our new findings take this to a whole new level – showing a male can also transmit some of his acquired features to offspring sired by other males," she says.
"But we don't know yet whether this applies to other species."
Telegony was first hypothesised by Aristotle and was a widely held belief in the Middle Ages and up until the 19th century.
In Greek mythology many heroes, such as Theseus, were born through two fathers, one human and one divine.
It was partly why there was much resistance to the 14th century marriage of Edward, the Black Prince, heir to the throne of Edward III and Joan, who had been previously married as it was feared their children would not be completely Plantagenet. But the theory was discredited by the advent of genetics.
To study whether telegony was possible, the team produced large and small male flies by feeding them diets as larvae that were high or low in nutrients. They then mated the immature females with either a large or a small male.
Once the females had matured, they were mated again with either a big or a small male, and their offspring were studied.
Those who had originally mated with a larger male continued to produce larger offspring even when mated with a small male.
However experts said it was too early to say whether the same effect could occur in humans.
“I think it’s impossible to say whether this could apply to humans without further studies in a more related species like a mouse,” said Associate Professor John Parrington, Lecturer in Cellular & Molecular Pharmacology at Oxford University.
“Certainly until recently it would have been thought impossible because the DNA genome of the sperm was thought to be the only thing passed down to future generations by the male.
“However, there is now evidence that so-called ‘epigenetic’ changes, can be passed down at least one or two generations, and such changes can be influenced by diet and other lifestyle differences.
“With such findings, things that were thought impossible previously might indeed turn out to be not so far-fetched after all, but in the case of telegony, there would need to be studies in a more similar animal to ourselves like a mouse, before we could start speculating about whether there is any potential relevance for humans.”
Dr Stuart Wigby of the Department of Zoology at Oxford University added: "The principle of telegony is theoretically possible for pretty much any internally fertilising animal, but these hasn't historically been much evidence for it.
"I'm aware of Crean et al's work, and it seems to be a neat demonstration of the phenomenon in insects. The mechanism they propose – molecules in the seminal fluid of the first mate being absorbed by the female's immature eggs – is indeed a possibility, and it would be revealing to test this.
This particular mechanism would be unlikely to apply to mammals such as humans because of differences in reproductive physiology compared to insects. However, other researchers have suggest that mechanisms exist that could in principle result in telegony in humans; for example because mothers carry fetal DNA in their blood during pregnancy."
PHD student Jolle Jolles of Cambridge University's Zoology Department said: "I would expect telegony to be possible to a certain extent via behavioural effects, i.e. women who were previously in a relationship with a wealthier man might have a better body condition and therefore might be able to invest more in their offspring."
The study is published in the journal Ecology Letters.
This post based on an an original article by
No comments:
Post a Comment