[Paleopsych] NYT: DNA of Deadbeat Voles May Hint at Why Some Fathers Turn Out to Be Rats

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DNA of Deadbeat Voles May Hint at Why Some Fathers Turn Out to Be Rats
http://www.nytimes.com/2005/06/10/science/10behave.html

    By [3]NICHOLAS WADE

    Some male prairie voles are devoted fathers and faithful partners,
    while others are less satisfactory on both counts. The spectrum of
    behavior is shaped by a genetic mechanism that allows for quick
    evolutionary changes, two researchers from Emory University report in
    today's issue of Science.

    The mechanism depends on a highly variable section of DNA involved in
    controlling a gene. The Emory researchers who found it, Elizabeth A.
    D. Hammock and Larry J. Young, say they have detected the same
    mechanism embedded in the sequence of human DNA but do not yet know
    how it may influence people's behavior.

    Voles, not to be confused with the burrowing, hill-making mole, are
    mouselike rodents with darker coats and fatter tails. The control
    section of their DNA expands and contracts in the course of evolution
    so that members of a wild population of voles, the Emory researchers
    have found, will carry sections of many different lengths. Male voles
    with a long version of the control section are monogamous and devoted
    to their pups, whereas those with shorter versions are less so.

    People have the same variability in their DNA, with a control section
    that comes in at least 17 lengths detected so far, Dr. Young said.

    So should women seek men with the longest possible DNA control region
    in the hope that, like the researchers' voles, they will display
    "increased probability of preferences for a familiar-partner female
    over a novel-stranger female"?

    Dr. Young said he expected that any such genetic effect in men would
    be influenced by culture, and thus hard to predict on an individual
    basis.

    The control mechanism is also present in humans' two closest cousins,
    the chimpanzee and the bonobo, and bears on a controversy as to which
    of the two species humans more closely resemble.

    Chimpanzees operate territorially based societies controlled by males
    who conduct often-lethal raids on neighboring groups. Bonobos, which
    look much like chimps, are governed by female hierarchies and
    facilitate almost every social interaction with copious sex.

    The DNA sequence of humans, chimps and bonobos is generally very
    similar, but in the section that controls response to the hormone
    vasopressin, the Emory researchers have found the human and bonobo
    versions differ significantly from that of the chimp. Though not too
    much can be deduced from a single gene, the result shows that bonobos
    should be taken very seriously as a guide to human behavior and that
    the chimp is not the only model, said Dr. Frans de Waal of the Yerkes
    National Primate Research Center in Atlanta.

    Dr. de Waal, who is writing a book, "The Inner Ape," said the last
    common ancestor of all three species presumably possessed the elements
    of both chimp and bonobo behavior, and that humans also "unite all
    these aspects."

    The effects of vasopressin on the behavior of the three higher
    primates is not well understood, but has been studied in voles for
    many years. The hormone, generated by the pituitary gland at the base
    of the brain, makes male prairie voles form monogamous pair bonds, but
    has no similar effect in the determinedly polygamous montane vole.

    The Emory researchers recently noticed that in their prairie vole
    colony, some fathers spent more time with their pups and some less.
    They traced the source of this variability to its molecular roots, a
    variation in the length of the DNA region that controls a certain
    gene.

    This is the gene for the vasopressin receptor, the device used by
    neurons to respond to vasopressin. Voles with long and short DNA
    segments had different patterns of vasopressin receptors in their
    brains, which presumably changed their response to the hormone.

    The long and short DNA segments differ by only 19 DNA units, mostly
    the same two units repeated over and over. The repeats are notorious
    for confusing the DNA copying apparatus, which every few generations
    or so may insert an extra repeat or delete one. The random changes
    have generated a spectrum of lengths in the voles that in turn
    underlies the variability in behavior, the Emory researchers say.

    They proved the point by separating voles with the shortest length and
    longest length of DNA and showing that their progeny differed in
    behavior.

    Dr. Young said he suspected that many other genes that influenced
    behavior, in voles and other species, might have fallen under similar
    control systems. Because the DNA repeats are so variable, they
    generate diversity more quickly than most other types of mutation. And
    a population whose individuals show a range of behavior is more likely
    to include some who can better adapt to a new situation.

    Dr. Gene Robinson, an expert in social behavior at the University of
    Illinois, said the new finding was "a significant advance in
    sociogenomics," the attempt to explain social life in terms of DNA,
    because it showed how easily behavior could be changed just by
    altering a gene's activity, not the gene itself.

    For a long time, researchers have assumed the genetic control of
    behavior would be too complex a problem to address. "The nice thing
    about this story is that it tells you it's not complex," Dr. Young
    said.