Our Ancestral Mind in the Modern World: An Interview with Satoshi Kanazawa

Human behav­ior is noto­ri­ous­ly com­plex, and there’s been no short­age of psy­chol­o­gists and psy­cho­log­i­cal the­o­ries ven­tur­ing to explain what makes us tick. Why do we get irra­tional­ly jeal­ous? Or have midlife crises? Why do we overeat to our own detri­ment? Why do we find our­selves often strong­ly attract­ed to cer­tain phys­i­cal traits? Numer­ous the­o­ries abound, but few are per­haps as nov­el and thought-pro­vok­ing as those sug­gest­ed by a new book with a long title: Why Beau­ti­ful Peo­ple Have More Daugh­ters: From Dat­ing, Shop­ping, and Pray­ing to Going to War and Becom­ing a Bil­lion­aire — Two Evo­lu­tion­ary Psy­chol­o­gists Explain Why We Do What We Do. Writ­ten by Satoshi Kanaza­wa and Alan S. Miller, the book finds answers not in ids, egos and super­egos, but in the evo­lu­tion of the human brain. Writ­ten in snap­py prose, their argu­ment is essen­tial­ly that our behav­ior — our wants, desires and impuls­es — are over­whelm­ing­ly shaped by the way our brain evolved 10,000+ years ago, and one con­se­quence is that our ances­tral brain is often respond­ing to a world long ago dis­ap­peared, not the mod­ern, fast-chang­ing world in which we live. This dis­con­nect can lead us to be out of sync, to act in ways that seem inex­plic­a­ble or counter-pro­duc­tive, even to our­selves. These argu­ments belong to new field called “evo­lu­tion­ary psy­chol­o­gy,” and we were for­tu­nate to inter­view Satoshi Kanaza­wa (Lon­don School of Eco­nom­ics) and delve fur­ther into evo­lu­tion­ary psy­chol­o­gy and the (some­times dispir­it­ing) issues it rais­es. Have a read, check out the book, and also see the relat­ed piece that the Freako­nom­ics folks recent­ly did on this book. Please note that the full inter­view con­tin­ues after the jump.

DC: In a nut­shell, what is “evo­lu­tion­ary psy­chol­o­gy”? (e.g. when did the field emerge? what are the basic tenets/principles of this school of think­ing?)

SK: Evo­lu­tion­ary psy­chol­o­gy is the appli­ca­tion of evo­lu­tion­ary biol­o­gy to human cog­ni­tion and behav­ior. For more than a cen­tu­ry, zool­o­gists have suc­cess­ful­ly used the uni­fy­ing prin­ci­ples of evo­lu­tion to explain the body and behav­ior of all ani­mal species in nature, except for humans. Sci­en­tists held a spe­cial place for humans and made an excep­tion for them.

In 1992, a group of psy­chol­o­gists and anthro­pol­o­gists sim­ply asked, “Why not? Why can’t we use the prin­ci­ples of evo­lu­tion to explain human behav­ior as well?” And the new sci­ence of evo­lu­tion­ary psy­chol­o­gy was born. It is premised on two grand gen­er­al­iza­tions. First, all the laws of evo­lu­tion by nat­ur­al and sex­u­al selec­tion hold for humans as much as they do for all species in nature. Sec­ond, the con­tents of the human brain have been shaped by the forces of evo­lu­tion just as much as every oth­er part of human body. In oth­er words, humans are ani­mals, and as such they have been shaped by evo­lu­tion­ary forces just as oth­er ani­mals have been.

DC: Evo­lu­tion­ary psy­chol­o­gy por­trays us as hav­ing impuls­es that took form long ago, in a very pre-mod­ern con­text (say, 10,000 years ago), and now these impuls­es are some­times rather ill-adapt­ed to our con­tem­po­rary world. For exam­ple, in a food-scarce envi­ron­ment, we became pro­grammed to eat when­ev­er we can; now, with food abound­ing in many parts of the world, this impulse cre­ates the con­di­tions for an obe­si­ty epi­dem­ic. Giv­en that our world will like­ly con­tin­ue chang­ing at a rapid pace, are we doomed to have our impuls­es con­stant­ly play­ing catch up with our envi­ron­ment, and does that poten­tial­ly doom us as a species?

SK: In fact, we’re not play­ing catch up; we’re stuck. For any evo­lu­tion­ary change to take place, the envi­ron­ment has to remain more or less con­stant for many gen­er­a­tions, so that evo­lu­tion can select the traits that are adap­tive and elim­i­nate those that are not. When the envi­ron­ment under­goes rapid change with­in the space of a gen­er­a­tion or two, as it has been for the last cou­ple of mil­len­nia, if not more, then evo­lu­tion can’t hap­pen because nature can’t deter­mine which traits to select and which to elim­i­nate. So they remain at a stand­still. Our brain (and the rest of our body) are essen­tial­ly frozen in time — stuck in the Stone Age.

One exam­ple of this is that when we watch a scary movie, we get scared, and when we watch porn we get turned on. We cry when some­one dies in a movie. Our brain can­not tell the dif­fer­ence between what’s sim­u­lat­ed and what’s real, because this dis­tinc­tion didn’t exist in the Stone Age.

DC: One con­clu­sion from your book is that we’re some­thing of a pris­on­er to our hard-wiring. Yes, there is some room for us to maneu­ver. But, in the end, our evolved nature takes over. If all of this holds true, is there room in our world for utopi­an (or even mild­ly opti­mistic) polit­i­cal move­ments that look to refash­ion how humans behave and inter­act with one anoth­er? Or does this sci­ence sug­gest that Edmund Burke was on to some­thing?

SK: Steven Pinker, in his 2002 book The Blank Slate, makes a very con­vinc­ing argu­ment that all Utopi­an visions, whether they be moti­vat­ed by left-wing ide­ol­o­gy or right-wing ide­ol­o­gy, are doomed to fail­ure, because they all assume that human nature is mal­leable. Evo­lu­tion­ary psy­chol­o­gists have dis­cov­ered that the human mind is not a blank slate, a tab­u­la rasa; humans have innate bio­log­i­cal nature as much as any oth­er species does, and it is not mal­leable. Paul H. Rubin’s 2002 book Dar­win­ian Pol­i­tics: The Evo­lu­tion­ary Ori­gin of Free­dom gives an evo­lu­tion­ary psy­cho­log­i­cal account of why Burke and clas­si­cal lib­er­als (who are today called lib­er­tar­i­ans) may have been right.

As a sci­en­tist, I am not inter­est­ed in Utopi­an visions (or any oth­er visions for soci­ety). But it seems to me that, if you want to change the world suc­cess­ful­ly, you can­not start from false premis­es. Any such attempt is bound to fail. If you build a house on top of a lake on the assump­tion that water is sol­id, it will inevitably col­lapse and sink to the bot­tom of the lake, but if you rec­og­nize the flu­id nature of water, you can build a suc­cess­ful house­boat. A house­boat may not be as good as a gen­uine house built on ground, but it’s bet­ter than a col­lapsed house on the bot­tom of the lake. A vision for soci­ety based on an evo­lu­tion­ary psy­cho­log­i­cal under­stand­ing of human nature at least has a fight­ing chance, which is a much bet­ter than any Utopi­an vision based on the assump­tion that human nature is infi­nite­ly mal­leable.

DC: So give us a hint. Why do beau­ti­ful peo­ple actu­al­ly have more daugh­ters?

SK: The basic idea is this: When­ev­er par­ents have genet­ic traits they can pass on to their chil­dren that are more valu­able for boys than for girls, then they have more sons than daugh­ters. Con­verse­ly, when­ev­er par­ents have genet­ic traits they can pass on to their chil­dren that are more valu­able for girls than for boys, then they have more daugh­ters than sons. Phys­i­cal attrac­tive­ness — being beau­ti­ful — is good for both boys and girls, but it’s much more advan­ta­geous for girls. Phys­i­cal attrac­tive­ness of a woman is one of the most impor­tant con­sid­er­a­tions for men when they select both long-term and short-term mates, but a man’s phys­i­cal attrac­tive­ness is impor­tant for women only when she’s look­ing for short-term mates. Women like to have affairs with good-look­ing men, but they don’t nec­es­sar­i­ly want to mar­ry them, unless of course they are also rich and pow­er­ful.

So beau­ti­ful daugh­ters will be more like­ly to take full advan­tage of their phys­i­cal attrac­tive­ness than beau­ti­ful sons. Beau­ti­ful daugh­ters are more like­ly to pass on their genes suc­cess­ful­ly to the next gen­er­a­tion than beau­ti­ful sons, because they are more like­ly to find them­selves in sta­ble mar­riages to desir­able spous­es. In a rep­re­sen­ta­tive sam­ple of 3,000 young Amer­i­cans, those who are “very attrac­tive” had 36% greater odds of hav­ing a daugh­ter com­pared to every­one else. Sim­i­lar­ly, stud­ies have found that big and tall par­ents are more like­ly to have sons, and short and thin par­ents are more like­ly to have daugh­ters, because body size is more of an advan­tage to men than to women. Women are attract­ed to big and tall men much more than men are attract­ed to big and tall women.

DC: In the book you debunk the notion of “midlife cri­sis.” Why?

SK: We don’t debunk its exis­tence; we believe it exists. But we sug­gest that it might exist for dif­fer­ent rea­sons than peo­ple think. Midlife cri­sis is a mys­tery for evo­lu­tion­ary psy­chol­o­gy, because there is real­ly no rea­son for mid­dle-aged men to change their behav­ior sud­den­ly when they reach mid­dle age. So we spec­u­late in the book that mid­dle-aged men may engage in a con­stel­la­tion of behav­ior which we asso­ciate with the phrase “midlife cri­sis,” not because they are mid­dle-aged, but because their wives are. When their wives reach menopause, it means that, not only is the wife’s repro­duc­tive career over, but so is the husband’s, unless, of course, he can find a younger mate to replace (or, as often hap­pened through­out evo­lu­tion­ary his­to­ry, add to, since humans are nat­u­ral­ly polyg­y­nous) the menopausal wife. We believe that “midlife cri­sis” might be a reflec­tion of mid­dle-aged men’s attempt to attract younger women because their wives are no longer repro­duc­tive. So we hypoth­e­size that a 50-year-old man mar­ried to a 25-year-old wife will not under­go midlife cri­sis, where­as a (very rare) 25-year-old man mar­ried to a 50-year-old wife will. And, of course, evo­lu­tion­ary psy­chol­o­gy can explain why there are very few young men mar­ried to mid­dle-aged women. If you want to know, you have to read the book!

DC: Final­ly, what are some of the remain­ing mys­ter­ies in evo­lu­tion­ary psy­chol­o­gy? Are there things that you still don’t know, ques­tions for which you still don’t have answers?

SK: There are many ques­tions for which we don’t yet have answers. We devote our last chap­ter to dis­cussing some of these ques­tions. For exam­ple, why do most mid­dle-class peo­ple in west­ern indus­tri­al nations have so few chil­dren? Most mid­dle-class Amer­i­cans can eas­i­ly raise five or six chil­dren, and feed, clothe, and shel­ter them all very well. Yet most cou­ples only want (and have) two chil­dren. This is a mys­tery for evo­lu­tion­ary psy­chol­o­gy.

A relat­ed mys­tery is the fact that there seems to be a genet­ic trans­mis­sion of fer­til­i­ty from par­ents to chil­dren, so that par­ents who have many sib­lings tend also to have many chil­dren them­selves. This makes absolute­ly no sense from an evo­lu­tion­ary psy­cho­log­i­cal per­spec­tive. If your par­ents had many chil­dren, that means you have many broth­ers and sis­ters who car­ry some of your genes, so you can afford not to have many chil­dren your­self. Con­verse­ly, if you are an only child, nobody else besides you car­ries half of your genes, so you have to have many chil­dren to spread your genes, to com­pen­sate for your par­ents’ lack of repro­duc­tive suc­cess. So there should real­ly be a neg­a­tive cor­re­la­tion between your par­ents’ fer­til­i­ty and your own, but all the demo­graph­ic stud­ies show that the cor­re­la­tion is pos­i­tive. Only chil­dren tend to beget only chil­dren. This is a mys­tery.