It’s smarter to be born in spring?

Originally published 18 March 1996

Are peo­ple born in the spring smarter than the rest of us?

A flur­ry of let­ters in [1996] issues of the pres­ti­gious sci­ence jour­nal Nature sug­gests that they are. The data are hard­ly sci­en­tif­ic, but I know a mar­ketable idea when I see one. Might as well get on the band­wag­on now.

It start­ed with let­ters link­ing birth date to suc­cess in sports. Then a British psy­chol­o­gist named Michael Holmes set the pot boil­ing by link­ing birth dates to sci­en­tif­ic creativity.

Holmes looked at biogra­phies of sci­en­tists who sup­port­ed the rev­o­lu­tion­ary the­o­ries of Dar­win and Ein­stein, and those who resist­ed the new the­o­ries. He found an appar­ent­ly sig­nif­i­cant major­i­ty of the rev­o­lu­tion­ar­ies were born from Decem­ber to April. The reac­tionar­ies were most­ly sum­mer babies.

Inspired by Holmes, physi­cians on the fac­ul­ty of med­i­cine at the Uni­ver­si­ty of Por­to, Por­tu­gal, exam­ined birth dates of their stu­dents, young peo­ple who were at the top of their high school class­es. A tan­ta­liz­ing bulge in the birth dates occurs in the months April to June. The birth date dis­tri­b­u­tion in the gen­er­al pop­u­la­tion is more or less flat.

Next, doc­tors on the fac­ul­ty of med­i­cine at the Uni­ver­si­ty of Flo­rence, Italy, chimed in. Dit­to. More bright stu­dents born April to June.

What could be the cause of this phe­nom­e­non, assum­ing it is real?

Holmes argues for a sea­son­al effect on ear­ly devel­op­ment, through mater­nal behav­ior or biol­o­gy, before birth or dur­ing the first year of extrauter­ine life. Light-induced hor­mone fluc­tu­a­tions, he sug­gests, might be a potent influ­ence on ear­ly development.

The social envi­ron­ment of the infant might also be influ­enced by the sea­sons, Holmes guess­es: “Ini­tial­ly, the win­ter-born rev­o­lu­tion­ary would have been restric­tive­ly swad­dled but with the com­ing of sum­mer he would have expe­ri­enced more free­dom to explore on his own initiative.”

The doc­tors in Por­to and Flo­rence look to the­o­ries of neu­ro-devel­op­ment. Unlike a com­put­er, the brain must “wire itself,” and this process is strong­ly affect­ed by exter­nal stim­uli. Appar­ent­ly, there are crit­i­cal peri­ods in ear­ly devel­op­ment when “self-wiring” takes place. The spring baby may be favored by sea­son­al dif­fer­ences in the envi­ron­ment, either in the womb or out.

Anoth­er let­ter in Nature, from fac­ul­ty at the School of Med­i­cine of the Uni­ver­si­ty of Rome Tor Ver­ga­ta, offers evi­dence that the sea­son of con­cep­tion may influ­ence intrauter­ine devel­op­ment. They specif­i­cal­ly looked for a cor­re­la­tion of birth date and an enzyme that may have impor­tant func­tions in cel­lu­lar growth reg­u­la­tion and in the mod­u­la­tion of gly­colyt­ic rate. They con­clude: “The effects on neona­tal para­me­ters mea­sur­able at a gen­er­al pop­u­la­tion lev­el seem rather small, but may be far-reach­ing in select­ed groups of tal­ent­ed people.”

Now, don’t get me wrong, we should­n’t take any of this too seri­ous­ly. The data are sparse, and we haven’t heard yet from the south­ern hemi­sphere, where the sea­sons are reversed. Find­ing an Octo­ber bump in the birth dates of smart Aus­tralians will be a cru­cial obser­va­tion. Also, chil­dren gen­er­al­ly start school accord­ing to birth date, and this might con­fer an arti­fi­cial advan­tage on a cer­tain age group.

Nev­er­the­less, now is the time for some­one to move on a hot new book for yup­pie par­ents: “April’s Child: Sea­son­al Influ­ences on Ear­ly Devel­op­ment and Suc­cess in Lat­er Life,” or “Con­ceiv­ing Ein­stein: Opti­miz­ing Your Child’s Intel­li­gence and Creativity.”

There’s a best-sell­er here, I can smell it.

This is the sort of thing that will tor­ment yup­pies who want their off­spring to have every intel­lec­tu­al and cre­ative advan­tage. Play schools, bal­let lessons, gym­nas­tics, ear­ly school starts, and all the rest won’t be enough. Now, par­ents’ respon­si­bil­i­ties to their child’s future will start with the month of conception.

And the guilt! “Oh God, Fran­cis. I’m preg­nant, and the baby will be born in August.”

The mater­ni­ty wards of hos­pi­tals will be jam-packed in the spring and emp­ty in the fall. Obste­tri­cians will be as sea­son­al­ly employed as life­guards and hock­ey players.

The clus­ter­ing of tod­dler birth­day par­ties in a busy spring “sea­son” will mean boom or bust for clowns, sto­ry-tellers, and magicians.

Not only will every kid in class have the same name — Ash­ley or Michael, or what­ev­er is cur­rent­ly fash­ion­able — they will also have the same birthday.

Cou­ples who inad­ver­tent­ly con­ceive in the wrong sea­son will be forced to move to Aus­tralia for the dura­tion of the preg­nan­cy and first year of birth, or face embar­rass­ment at home: “Can you imag­ine, Ellen is giv­ing birth in Sep­tem­ber! I mean, it’s like she does­n’t care.”

If the birth-date/in­tel­li­gence phe­nom­e­non is real, and if sea­son­al dif­fer­ences are the cause, then it may turn out that cer­tain cru­cial stages of neur­al devel­op­ment are influ­enced by ambi­ent light or tem­per­a­ture. This will unleash anoth­er flur­ry of best-sell­ing yup­pie man­u­als: “Cold Smarts: How to Keep Cool Dur­ing Preg­nan­cy and Enhance Your Child’s Poten­tial,” or “Bright Ideas: Turn Up the Lights and Help Your Infant Learn.”