Media Releases

University of Toronto study demonstrates impact of adversity on early life development

October 25, 2012

Study part of growing body of knowledge surrounding gene-environment interplay

TORONTO, ON – It is time to put the nature ver­sus nur­ture debate to rest and embrace grow­ing evi­dence that it is the inter­ac­tion between biol­o­gy and envi­ron­ment in ear­ly life that influ­ences human devel­op­ment, accord­ing to a series of stud­ies recent­ly pub­lished in a spe­cial edi­tion of the Pro­ceed­ings of the Nation­al Acad­e­my of Sci­ences (PNAS).

“Biol­o­gists used to think that our dif­fer­ences are pre-pro­grammed in our genes, while psy­chol­o­gists argued that babies are born with a blank slate and their expe­ri­ence writes on it to shape them into the adults they become. Instead, the impor­tant ques­tion to be ask­ing is, ‘How is our expe­ri­ence in ear­ly life get­ting embed­ded in our biol­o­gy?’” says Uni­ver­si­ty of Toron­to behav­iour­al geneti­cist Mar­la Sokolows­ki. She is co-edi­tor of the PNAS spe­cial edi­tion titled “Bio­log­i­cal Embed­ding of Ear­ly Social Adver­si­ty: From Fruit Flies to Kinder­garten­ers” along with pro­fes­sors Tom Boyce (Uni­ver­si­ty of British Colum­bia) and Gene Robin­son (Uni­ver­si­ty of Illi­nois).

Sokolows­ki, who is a Uni­ver­si­ty Pro­fes­sor in the Depart­ment of Ecol­o­gy & Evo­lu­tion­ary Biol­o­gy (EEB), the inau­gur­al aca­d­e­m­ic direc­tor of U of T’s Fras­er Mus­tard Insti­tute for Human Devel­op­ment and co-direc­tor of the Expe­ri­ence-based Brain and Bio­log­i­cal Devel­op­ment Pro­gram (EBBD) at the Cana­di­an Insti­tute for Advanced Research (CIFAR) says that rel­a­tive­ly lit­tle is known about the gene-envi­ron­ment inter­play that under­lies the impact of ear­ly life adver­si­ty on adult health and behav­iour.

In one of the stud­ies in the series, Sokolows­ki and her col­leagues found that chron­ic food depri­va­tion and lack of ade­quate nutri­tion in the ear­ly life of the fruit fly Drosophi­la melanogaster had sig­nif­i­cant impact on adult behav­iour and qual­i­ty of life. Fruit flies are espe­cial­ly use­ful for genet­ic stud­ies because they share a sur­pris­ing num­ber of qual­i­ties with humans, are inex­pen­sive to care for and repro­duce rapid­ly, allow­ing for sev­er­al gen­er­a­tions to be stud­ied in just a few months.

The researchers exam­ined two types of fruit flies with vari­ants in the for­ag­ing gene (for) known as rovers and sit­ters because of their dif­fer­ent behav­iours in the pres­ence of food.

When well fed as lar­vae, rover adults exhib­it dart­ing explo­ration into open areas as they move about in search of food, while sit­ters show lit­tle of this behav­iour. When nutri­tion­al­ly deprived as lar­vae, both rover and sit­ter adults exhib­it dart­ing explo­ration. Fur­ther, the sit­ters that faced nutri­tion­al adver­si­ty in ear­ly life dis­played a reduc­tion in their abil­i­ty to repro­duce. Rovers exhib­it­ed no effect on their repro­duc­tive fit­ness.

“The for­ag­ing gene makes an enzyme called PKG, which is found in the fly as well as in most oth­er organ­isms, includ­ing humans. When faced with a nutri­tion­al­ly adverse envi­ron­ment while grow­ing up, the lev­els of the enzyme dropped in flies,” says Sokolows­ki. “This told us that the for­ag­ing gene lis­tens to its envi­ron­ment.” Trans­genic manip­u­la­tions of PKG lev­els altered dart­ing explo­ration in well fed but not nutri­tion­al­ly deprived flies.

The research team includ­ed James Burns, a CIFAR junior fel­low in Sokolowski’s lab, U of T EEB pro­fes­sor Locke Rowe and EEB post-doc­tor­al fel­low Nico­las Svetec, as well as col­leagues from the Uni­ver­si­ty of British Colum­bia and the Uni­ver­sité Paris-Sud. The find­ings are report­ed in the paper “Chron­ic food depri­va­tion in ear­ly life affects adult explorato­ry and fit­ness traits” in the Octo­ber 16, 2012 issue of the Pro­ceed­ings of the Nation­al Acad­e­my of Sci­ence.

The papers in the vol­ume are authored large­ly by CIFAR researchers, and com­prise a mul­ti­dis­ci­pli­nary col­lec­tion of research into fields from mol­e­c­u­lar genet­ics, evo­lu­tion­ary biol­o­gy and neu­ro­science, to social and behav­iour­al sci­ence, epi­demi­ol­o­gy and social pol­i­cy – as well as the emerg­ing field of epi­ge­net­ics, which inves­ti­gates devi­a­tions in a gene’s abil­i­ty to pro­duce its prod­ucts (e.g. RNA, pro­tein) caused by mech­a­nisms oth­er than changes in an organism’s under­ly­ing DNA sequence.

The col­lec­tion of papers in the vol­ume sets out an emerg­ing new field of the devel­op­men­tal sci­ence of child­hood adver­si­ty, and changes con­ven­tion­al under­stand­ing of the ear­ly years of human life.

“This is the first vol­ume of col­lect­ed research to pro­vide a sub­stan­tial and com­pre­hen­sive pic­ture of the inter­ac­tion between expe­ri­ence and biol­o­gy in the ear­ly years,” says Sokolows­ki.

“Devel­op­men­tal neu­ro­science is extra­or­di­nar­i­ly intri­cate and com­plex, and so by approach­ing this ques­tion from mul­ti­ple angles we’re able to reveal a con­ver­gence on a num­ber of themes and set a clear­er direc­tion for future research.”

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Note to media: Vis­it for an image and the research paper asso­ci­at­ed with this media release.

For  more infor­ma­tion, con­tact:

Mar­la B. Sokolows­ki
Depart­ment of Ecol­o­gy and Evo­lu­tion­ary Biol­o­gy
Uni­ver­si­ty of Toron­to
Tel: 416–978-8325

Sean Bet­tam
Com­mu­ni­ca­tions, Fac­ul­ty of Arts & Sci­ence
Uni­ver­si­ty of Toron­to
Tel: 416–946-7950