Darwin’s adult neuroplasticity

Charles Dar­win (1809–1882)‘s auto­bi­og­ra­phy (full text free online) includes some very insight­ful refec­tions on the evo­lu­tion of his own mind dur­ing his mid­dle-age, show­cas­ing the pow­er of the brain to rewire itself through expe­ri­ence (neu­ro­plas­tic­i­ty) dur­ing our whole life­times-not just when we are youngest.

He wrote these paragraphs at the age of 72 (I have bold­ed some key sen­tences for empha­sis, the whole text makes great reading):

“I have said that in one respect my mind has changed dur­ing the last twen­ty or thir­ty years. Up to the age of thir­ty, or beyond it, poet­ry of many kinds, such as the works of Mil­ton, Gray, Byron, Wordsworth, Coleridge, and Shel­ley, gave me great plea­sure, and even as a school­boy I took intense delight in Shake­speare, espe­cial­ly in the his­tor­i­cal plays. I have also said that for­mer­ly pic­tures gave me con­sid­er­able, and music very great delight. But now for many years I can­not endure to read a line of poet­ry: I have tried late­ly to read Shake­speare, and found it so intol­er­a­bly dull that it nau­se­at­ed me. I have also almost lost my taste for pic­tures or music. Music gen­er­al­ly sets me think­ing too ener­get­i­cal­ly on what I have been at work on, instead of giv­ing me plea­sure. I retain some taste for fine scenery, but it does not cause me the exquis­ite delight which it for­mer­ly did. On the oth­er hand, nov­els which are works of the imag­i­na­tion, though not of a very high order, have been for years a won­der­ful relief and plea­sure to me, and I often bless all nov­el­ists. A sur­pris­ing num­ber have been read aloud to me, and I like all if mod­er­ate­ly good, and if they do not end unhap­pi­ly– against which a law ought to be passed. A nov­el, accord­ing to my taste, does not come into the first class unless it con­tains some per­son whom one can thor­ough­ly love, and if a pret­ty woman all the better.

This curi­ous and lam­en­ta­ble loss of the high­er aes­thet­ic tastes is all the odd­er, as books on his­to­ry, biogra­phies, and trav­els (inde­pen­dent­ly of any sci­en­tif­ic facts which they may con­tain), and essays on all sorts of sub­jects inter­est me as much as ever they did. My mind seems to have become a kind of machine for grind­ing gen­er­al laws out of large col­lec­tions of facts, but why this should have caused the atro­phy of that part of the brain alone, on which the high­er tastes depend, I can­not con­ceive. A man with a mind more high­ly organ­ised or bet­ter con­sti­tut­ed than mine, would not, I sup­pose, have thus suf­fered; and if I had to live my life again, I would have made a rule to read some poet­ry and lis­ten to some music at least once every week; for per­haps the parts of my brain now atro­phied would thus have been kept active through use. The loss of these tastes is a loss of hap­pi­ness, and may pos­si­bly be inju­ri­ous to the intel­lect, and more prob­a­bly to the moral char­ac­ter, by enfee­bling the emo­tion­al part of our nature.”

 

 

We have already dis­cussed how “cells that fire togeth­er wire togeth­er”. The neu­rons and synaps­es that we use often grow over time; the ones we don’t use get weakened.  As it seems, Dar­win implic­it­ly trained him­self to devel­op a high­ly method­i­cal and ana­lyt­i­cal mindset, while, as he posits, not devot­ing enough time to oth­er inter­ests. Check out this para­graph (which pre­cedes the pre­vi­ous two in the orig­i­nal text):

“Hav­ing said thus much about my man­ner of writ­ing, I will add that with my large books I spend a good deal of time over the gen­er­al arrange­ment of the mat­ter. I first make the rud­est out­line in two or three pages, and then a larg­er one in sev­er­al pages, a few words or one word stand­ing for a whole dis­cus­sion or series of facts. Each one of these head­ings is again enlarged and often trans­ferred before I begin to write in exten­so. As in sev­er­al of my books facts observed by oth­ers have been very exten­sive­ly used, and as I have always had sev­er­al quite dis­tinct sub­jects in hand at the same time, I may men­tion that I keep from thir­ty to forty large port­fo­lios, in cab­i­nets with labelled shelves, into which I can at once put a detached ref­er­ence or mem­o­ran­dum. I have bought many books, and at their ends I make an index of all the facts that con­cern my work; or, if the book is not my own, write out a sep­a­rate abstract, and of such abstracts I have a large draw­er full. Before begin­ning on any sub­ject I look to all the short index­es and make a gen­er­al and clas­si­fied index, and by tak­ing the one or more prop­er port­fo­lios I have all the infor­ma­tion col­lect­ed dur­ing my life ready for use.”

Lit­tle by lit­tle, he cre­at­ed his own, per­son­al­ized Yahoo direc­to­ry and pre­dic­tion algorithm…and his “mind seems to have become a kind of machine for grind­ing gen­er­al laws out of large col­lec­tions of facts”. 

Some final remarks by this amaz­ing sci­en­tist and man:

“There­fore my suc­cess as a man of sci­ence, what­ev­er this may have amount­ed to, has been deter­mined, as far as I can judge, by com­plex and diver­si­fied men­tal qual­i­ties and con­di­tions. Of these, the most impor­tant have been–the love of sci­ence– unbound­ed patience in long reflect­ing over any subject–industry in observ­ing and col­lect­ing facts–and a fair share of inven­tion as well as of com­mon sense. With such mod­er­ate abil­i­ties as I pos­sess, it is tru­ly sur­pris­ing that I should have influ­enced to a con­sid­er­able extent the belief of sci­en­tif­ic men on some impor­tant points.”