Angiers, Natalie. "Not Just Genes: Moving Beyond Nature vs. Nature," New York Times, 15

 

Angiers, Natalie. "Not Just Genes: Moving Beyond Nature vs. Nature," New York Times, 15
August 2003, pp. F1, F11.

This year, the genetic revolution that James D. Watson and Francis Crick ushered in with their
discovery of the structure of DNA celebrates its 50th birthday.

The molecule that for so long exemplified youthful bravado, vast promise and vaster self-regard
has become another aging, pot-bellied baby boomer.

In the view of some biologists, nothing would better suit the DNA industry than a genuine
midlife crisis, a realization that this most mythologized of bio-abbreviations may not, after all, be
the fulcrum around which the Milky Way wheels. As these biologists see it, DNA may be
elegant, but it often has been accorded far greater powers than it possesses.

With all the breathless talk of human DNA as a grand epic written in three biollion runes, the
scientists complain that an essential point is forgotten: DNA, on its own, does nothing. It can't
make eyes blue, livers bilious or brains bulging.

It holds bare-boned information - suggestions, really - for the construction of the proteins of
which all life forms are built, but that's it. DNA can't read those instructions, it can't divide, it
can't keep itself clean or sit up properly - proteins that surround it do all those tasks. Stripped of
context within the body's cells, those haggling florid ecosystems of then of thousands of
protenaceous fauna, DNA is helpless, speechless - DOA. By the same token, cells need their
looping lanyards of genes and would grow as dull as hairballs without them.

Nowhere is an appreciation for the perpetual cross talk between gene and scene more important,
these scientists say, than in understanding human nature.

Loose talk about genes "for" neurotic or novelty-seeking behavior, sexual orientation or
schizophrenia is misguided not only because such language neglects the surely multigenic nature
of nearly all characteristics worth studying, but because the phrase puts genes at the command
post and ignores the ineluctably packaged, interactive deal that is DNA and its setting at every
stage of life.

The researchers are desperate to demolish what they see as a false yet obdurate dichotomy,
various rendered as nature versus nurture, genes versus the environment, culture versus biology
or evolution versus social construction.

However it is phrased, said Dr. Peter J. Richerson, an expert in cultural evolution at the
University of California at Davis, "The whole dichotomy makes no sense, and it should be
pitched out." You might as well speak of a rectangle's having a length versus a width, he said.

Yet, while virtually all scientists and academicians profess a commitment to interactionism, and
acknowledge that yes, of course, everyone knows that nature and nurture need each other, only
some are willing to explore what they means in real time.

"Everyone calls themselves and interactionist," said Dr. David Sloan Wilson, an evolutionary
biologist at Binghamton University in New York. "Yet often, when you scratch below the
surface, you find a sociologist who marginalizes the importance of culture, or a social
constructivist who hates the very idea of sociobiology, and they end up painting caricatures of
each other. True integrative thinking is in the veery early states.

In his recent book, "The Dependent Gene," Dr. David S. Moore, a professor of psychology at
Pitzer College and Claremont Graduate University in California, offers a multitude of examples
that challenge a reader's assumptions about what is innate and what isn't, and what it means to
call something a "genetically" determined trait.

He cites the disease phenylketonuria, or PKU. As a result of a defect in a single gene, children
with the condition are unable to produce a protein that breaks down the amino acid phenlalanine,
a common component of foods like milk, eggs, meat and bread. That unmetabolized
phenylalanine can built up in the body, leading to tremors, seizures, and brain damage.

The condition was once a major cause of mental retardation, but in the 1950s doctors devised a
simple treatment for it: dietary intervention. If young children with PKU are kept away from
foods with phenylalaurine, the amino acid doesn't clog their bodies and brains, and they do find.

So is this disease "really" genetic, or "really" environmental? Both, Dr. Moore argues.

No matter how seemingly hardwired a trait, Dr. Moore says, the outside finds its way in, and the
inside responds.

For example, the attraction of baby mallards to their mother's call was long thought to be
"instinctive," caused by genetic factors operating independent of the environment. After all, even
ducklings that developed in an inclbator, with no prenatal exposure to mother's quacks,
immediately prefer upon hatching the sound of a mallard call over that of any other bird.

However, Dr. Gilbert Gottleib, a developmental psychobiologist, wnt beyond the usual knee-jerk
assumptions to ask: could the ducklings' own prehatching peeps be the priming factor here,
teaching their development brains key aspects of the proper mallard melody?

Sure enough, Dr. Gottleib discovered that embryonic ducklings deprived of the ability of
vocalize in the egg would, on hatching, respond as readily to a chicken cluck as to a mallard call.
The budding duck brain learns by listening to the song of itself.

The developmental biologists are learning, genes and tissues engage in astonishing calls and
responses during fetal growth. Dr. Jill A. Helms, an orthopedic surgeon and researcher at the
University of California at San Francisco, and her colleagues reported in the Jan. 24 isue of the
journal Nature the results of some rather bizarre transplant experiments.

Working with early embryonic ducks and quails, the scientists exchanged nubs of cells destined
to be the birds' beaks, placing the bill-to-be clump in the quail and the beak-to-be cell ball in the
duck. As a result, the quail sprouted a duck's bill, while the duck grew a quail's much shorter,
pointier beak. This happened not simply because the implanted cells carried genetic information
from the donor embryo and grew into what they were "programmed" to be, but because the
installed cells released molecular signals and persuaded the neighboring host tissues to override
their resident genes, and switch species.

Behind the capacity of the birds to by nasally modified like some many feathered Nicole
Kidmans is their shared genetic heritage. What the transplanted tissue did was to speed up or
slow down the timing of embryonic events to assume a more duck-like or quail-like schedule.
The genetic and temporal aspects of development, it seems, are intertwined like the snakes of the
doctor's caduceus - health, the integrity of structure and pattern, life itself, depend on their union.

The importance of timing is by no means limited to fetal development.

Dr. Martha McClintock, a professor of biopsychology at the University of Chicago, and her
colleagues recently showed that the timing of a rat's mating determines one of the most
fundamental "genetic" facts" of all: whether she hears sons or daughters.

A female rat that ventures out before sundown to solicit partners will give birth to mostly sons,
while a female who prefers her matings after dark ends up bearing a little rich with daughters.
The very hormones thatr bind to the female's brain and prod her to mate early or late, said Dr.
McClintock, in turn affect her uterus and its relative hospitality to the implanation of male or
female embryos.

"There's a constant back and forth between genes and the environment," Dr. McClintock said.
"It's important to remember that genes came to be what they are solely because of their capacity
to interact with the environment, and make the right products in response to the environment."

As. Dr. Wilson sees it, genes exist, not to call the shots or delimit the possivilities, but to create
"miniature evolutionary processes" that continue throughout life, he said.

Consider the immune system, he said, which relies on a very limited number of genes for
constructing the building blocks of immune cells and imm7une proteins. But it is a blast from the
outside, the invasion of a new pathogenic threat, that determines what shapes, sizes and bumbers
of immune components will be slapped together on any given day.

Dr. Richerson proposes that many human behaviors may have a kind of immune-system dynamic
to them, with a minimum number of genetically influenced algorithms, or set of multipurpose
rules, giving rise to a huge diversity of behavior.

He points out that one big difference between chimpanzees and humans is that humans are far
more docile, more susceptible to social reinforcement than chimpanzees are. People have tried to
raise chimpanzees as they would children, he said, and the chimpanzees are clever and they do a
lot of humanlike things, but they are not nearly as responsive as children are to praise and
scolding. "They're rougher back," said Dr. Richerson. "They're the terrible twos gone berserk."

So what does our docility and social responsiveness get us? It makes humans quite good at living
in a group, learning from the group, and adapting to ever-shifting group dynamics.

"In ambiguous or novel situations, you can apply the conformist rule and imitate other people,"
Dr. Richerson said. "The community is a source of good information about what the best local
adaptations may be, and it's been shown with mathematical models that it's otern advantageous
to do with the majority is doing."

The tendency to ape the group as no ape can do may even shift the contours of our brains as we
move from tribe to tribe. Dr. Richard E. Nisbett, a professor of psychology at the University of
Michigan, has found that Asians and Westerners think differently from each other in significant
and measurable ways, as he describes in his new book, "The Geography of Thought."

"Westerners focus on some kind of central object," he said in an interview. "They attend to its
attributes and try to find out what rules apply to its behavior, with the goal of categorizing it."

By contrast, he said, Asians tend to see an object in much broader field. "They're not as
interested in categorizing objects," Dr. Nisbett said, "and they don't have as many linear
deterministic rules of behavior."

These differences are revealed even in tests of perceptual and visual skills: Westerners score
higher on the ability to remember the absolute size of an object; Easterners do better with
recalling its dimensions relative to something else.

Significantly, the cognitive styles are not fixed, but shift after a person has spent only a few
months living on the other side of the globe. Whether it must tilt holistic or dualistic, defend
nature, nurture or neither, the human brain will find a way to fit in with the crowd.