Evolutionary Theories for Everyday Life

On this morning, Seattle’s skyand surrounding waters aregray, and even the blue eyes

and sweater of Margie Profet seem gray.The evolutionary biologist is explainingthat she loves the rain and its flat tonesbecause they make the world look morethree-dimensional, and she points to herpanoramic view of Portage Bay and theUniversity of Washington to demon-strate: “That glass one over there is mybuilding, the astronomy building.”

It is true that a planet that may sup-port life has just been found, but itseems a little premature for an evolu-tionary biologist to be turning to as-tronomy. Profet, however, says she isjust doing what she has always done:trying to come at a subject that shedoesn’t know so she can get excited andperhaps find a different perspective—“Ijust wanted a new adventure in life,and I wanted back that math part ofmy brain that had died.”

Profet is also, at least for now, remov-ing herself from a discipline that shehelped to popularize—and from astorm of criticism over her recent book,Protecting Your Baby-to-Be. Renownedfor three evolutionary theories, Profetappears to have crossed a line in theeyes of some of her colleagues in thefield of Darwinian medicine, and ofmany in the medical establishment,when she recommended that pregnantwomen follow her advice: don’t eatpungent vegetables.

In pared-down form, her pregnancytheory posits that the nausea or foodaversions many women experience inthe first trimester are adaptations de-signed to protect embryos. Profet arguesthat some toxins in plants—including,for instance, allyl isothiocyanate, a car-cinogen found in cabbage, cauliflowerand brussels sprouts—evolved to wardoff herbivores and that some of thesecompounds could, even in tiny amounts,cause defects during the critical stagewhen organs are forming. In general, thePleistocene plants that constituted thediet of our hunter-gatherer ancestors—and, hence, those that would have beenthe force behind the adaptation—were

even more likely to contain toxins, Prof-et explains, because agriculturists hadnot yet selectively bred for crops thatwere less bitter (that is, less poisonous).

Therefore, her theory contends, weevolved mechanisms to deal with thesedietary threats. Hormonal changes makethe olfactory systems of pregnant wom-en hypersensitive, able to detect spoilageor teratogens in a single whiff. A wom-an can thus avoid dangerous foods, re-lying instead on nutrients that her bodystored up before conception. Once theembryonic organs are more or lessformed, hormones allow nausea to sub-side, and women can eat less discrimi-natingly. Profet correlates the period ofpregnancy sickness (from about thethird week after conception, when theplacenta forms, to 14 weeks after con-ception) with the periodof organ creation. Andalthough there are nodirect studies on the top-ic, Profet extensively re-views the literature onplant toxins as well ason birth defects.

So, according to Prof-et, a pregnant woman fleeing the sceneof boiling broccoli or brewing coffee isprotecting her embryo and should payattention to her instincts. Which is whyProfet says she took her message out ofthe realm of theoretical biology and aca-demic papers to the realm of the massesand national book tours. But her di-etary proscriptions have brought herinto often rancorous conflict with ob-stetricians and nutritionists, as well aswith the March of Dimes. Her criticscontend that she herself may very wellcause birth defects by warning womento stay away from greens.

Others embrace her theory—if nother approach. “I was critical of thestance that she has taken. But I was alsovery supportive of the idea, because Ithink it is fascinating,” says CassandraE. Henderson of the Montefiore Medi-cal Center, who intends to study planttoxins and to determine whether thecompounds cause birth defects in ani-mals. “But I cannot go to the next stepand say, ‘Don’t eat this because it maycause birth defects.’ I have no evidence.”

For her part, Profet believes there isample reason for concern. Even if thereare no direct data, she says that no onehas come up with a criticism that her

theory cannot handle. She maintainsthat her goal was to get women to “erron the side of caution until we have bet-ter information” and to stimulate scien-tific study. “I like looking for solutionsto things. And for that you need goodtheory, and you need good experiments,”Profet explains, adding that doing theseexperiments is not where her talents lie.But she is adamant to the point of self-righteousness about speaking out. “Weare talking about life and death. This isnot some kind of intellectual fun, youknow,” Profet states. “People are get-ting birth defects.”

She pauses and rolls her hands up in-side her sweater, taking in the room, itswall of windows and wide vista, the bi-noculars on the table. A view of the wa-ter is very important, Profet says, because

she did her best thinkingin the mid-1980s in SanFrancisco, in a house withsuch a view. She had justcompleted her secondbachelor’s degree—thistime in physics at theUniversity of Californiaat Berkeley; she had stud-

ied political philosophy at HarvardUniversity for the first one—and “I justwanted some time to think about what-ever I wanted to think about.”

That happened to be evolutionary bi-ology. “I mean, the first month out ofphysics I went and got a standard biol-ogy book. I knew some people in evolu-tionary biology, and I would have someconversations with them, and I wouldread everything, and I just started think-ing about things. I had this wonderfulview and my animals,” recalls Profet inher fast and breathless voice, holdingout pictures of wild foxes and the rac-coon she befriended while living there.“And it was really productive. It wasthe most productive time of my life, thenext three or four years.”

Her pregnancy theory, which she firstbegan to research in 1986, was followedin quick succession by two others thatare essentially variations on the sametheme: ejection. The second one cameto her one night when her allergies hadsuddenly brought on a fit of scratching,and she began to think about peoplewho had fits of coughing and sneezing.“I thought: What do you need thesethings for? It is almost like you are try-ing to expel something immediately.

News and Analysis40 Scientific American April 1996

Evolutionary Theoriesfor Everyday Life

“I think it is goodto try to jump into something new every once

in a while.”

PROFILE: MARGIE PROFET

Copyright 1996 Scientific American, Inc.

And, well, maybe you are trying to ex-pel it immediately, and if so, what wouldcause that?” Out of this came her ideathat certain forms of allergies evolved asa means of expelling nasty things suchas plant toxins and insect venom.

“Every mechanism out there was de-signed by natural selection to solve aproblem, so you have to identify theproblem,” Profet declares. You have toask, “During the Pleistocene, would thisreally have been adaptive?” This rea-soning led her next to an explanation ofmenstruation. She recalls that when shefirst heard about pregnancy sickness andmenstruation as a kid, neither madesense: “I was miffed. No, not miffed.Just puzzled.” Then one night in 1988,she dreamed of black triangles embed-ded in a red background (other aspectsof the dream resembled an educationalcartoon about menstruation that Profethad seen in high school); her cat wokeher up in the middle of the vision, so shewas able to remember it. It became clearto Profet that menstruation is morethan merely a monthly waste of bloodand energy: the process allows the re-

productive tract to rid itself of patho-gens that attach themselves to sperm.

According to her argument, the myri-ad bacteria that are found in and aroundthe genitals of men and women hitchrides on sperm, thereby gaining accessto the uterus and fallopian tubes. Theuterine wall sheds each month so it cancleanse the system, washing away thecontaminants that could cause infectionor infertility. As with the theory of preg-nancy sickness, the menstruation ideaawaits further study—but Profet spe-cifically urges that gynecologists checkwomen with particularly heavy flowsto see if they have active infections. Sheis again outspoken about being proac-tive: “You get bad theories that peopleadhere to, and it is killing people orcausing them a lot of harm.” In the sci-entific community, debate continues.

In an upcoming issue of the Quarter-ly Review of Biology Beverly I. Strass-

mann of the University of Michigan ar-gues, among other things, that there isno evidence that there are more patho-gens in the uterus before menstruationthan there are immediately after. Strass-mann offers instead another explana-tion for such bleeding: the uterine liningsloughs off when implantation does notoccur, because keeping the womb in aconstant state of readiness requires moreenergy than do the cycles of menstrua-tion and renewal.

Despite her rich intellectual life be-tween 1985 and 1988, when she workedout her theoretical trinity, Profet saysher poor economic situation drove herto consider getting a doctorate in anthro-pology at Harvard—she figured thatwith a stipend and a student’s scheduleshe could do the coursework and keepresearching evolutionary biology. “Butit was just not like that at all,” she says.Graduate school was too stifling forProfet’s taste and, she maintains almostwistfully, the wrong place for peoplewho need freedom and who want touse the energy of their twenties and thir-ties to ask naive questions: “You maybe using up a time in life that will justnever come again.”

She left the program, returning toCalifornia and to a part-time job thatshe had held in the Berkeley laboratoryof Bruce Ames, a toxicologist famousfor his work on plant toxins and natu-ral carcinogens. (She still maintains anaffiliation with the lab.) Over time, herideas—two of them published in theQuarterly Review of Biology and one asa chapter in the 1992 book The Adapt-ed Mind—earned Profet a reputation asa maverick. And in 1993 she won oneof the “genius” awards from the Mac-Arthur Foundation.

But Profet seems tired of evolution-ary biology for now. “I love the field asI think the field should be,” she says ina nearly questioning voice. “But as thefield currently is, I don’t.” Profet says toofew of her colleagues make a distinctionbetween a hypothesis and a theory, rush-ing to publish ideas that are not rigor-ously worked out but that may haveimplications for public health. And soshe says it suits her just fine to be a visit-ing scholar in astronomy. “I am here toexplore,” Profet says. “I think it is goodto try to jump into something new everyonce in a while.” As long as her roomhas a view. —Marguerite Holloway

News and Analysis42 Scientific American April 1996

EVOLUTIONARY BIOLOGISTMargie Profet has turned

to the study of stars.

RAY

MO

ND

GEN

DR

EAU

Copyright 1996 Scientific American, Inc.