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- Scientists have transformed promiscuous male mice into
more faithful partners and doting dads by inserting a single gene from
a prairie vole.
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- It is the first time that one gene has proven sufficient
to change complex social behaviors so dramatically, the US researchers
believe.
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- Tom Insel and Larry Young, at Emory University, have
also recently done related studies in non-human primates and now plan to
focus on humans.
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- Progress for mental illness
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- Virtually every kind of human mental illness is characterised
by abnormal social attachments, but very little is known about the role
that genetics has on forming social partnerships.
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- The team think their research could lead to greater understanding
of this area, for example in in learning how social isolation can result
from brain dysfunction.
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- "In psychopathologic disorders, there is a severe
deficit in social behaviour and there could be genetic factors involved,"
Dr Young said.
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- "But it takes a lot of time to move from animal
research into humans," Young warned. "And in human cultures we
may find that experience and values have a lot more to do with behaviour."
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- Partners for life
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- The experiments, published in Nature magazine, used a
gene from the prairie vole. Males of this rodent are faithful partners
and attentive fathers.
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- "After mating, the male prairie vole forms a strong
social bond. He prefers to be with that mate to the exclusion of all others,"
said Dr Young. "That pair nests together. When she has her babies
he spends as much time with those babies as she does. He also defends the
nest and they stay together for the next litter and the next and the next."
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- By contrast, the male mice used normally abandon the
female immediately after mating and have no role in raising their offspring.
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- But by transferring a gene from the voles to the mice,
the male mice became much more sociable to their mates, although occasional
"extra-marital" affairs did still occur.
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- Patterns of the brain
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- The gene determines the pattern of particular hormone
receptors in the rodent's brain. The hormone here is called vasopressin
and was already known to have an effect on male social behaviours such
as aggression and communication.
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- Dr Insel said: "What is really intriguing is that
a change in a single gene can lead to a new pattern of receptors in the
brain and then result in this profound difference in something as complex
as social behavior."
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- Although a multitude of genes are likely to be involved
in the evolution of monogamy, this work begins to identify the links between
DNA sequences, brain chemistry and social behavior.
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- "Perhaps it will turn out that mutations in this
same gene have occurred many times in evolution, leading to alterations
in patterns of social interaction and facilitating monogamy under special
socio-ecological conditions," Dr Insel added.
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