Book Re­view: Life's Edge

by Janie

Life's Edge — The Search for What It Means to Be Alive
By Carl Zim­mer

Ask bi­ol­o­gists what they study and the an­swers will quick­ly home in on liv­ing things, on parti­cular life­forms that they've spent count­less hours think­ing, scru­tiniz­ing, ana­lyz­ing, and toil­ing over. Yet one fur­ther ques­tion – what ex­actly is a liv­ing thing? – is a sure-fire ticket to hesi­ta­tion.

Fig­ure 1. Amer­i­can book cover. Source. Fron­­­tis­piece.

It's a good ques­tion, and it's tack­led by sci­ence writer Carl Zim­mer in Life's Edge: The Search for What It Means to Be Alive. The book com­pels read­ers to con­tem­plate how pos­sibly to de­fine what makes some­thing alive by meld­ing scien­tific snip­pets on di­verse life­forms, his­tori­cal tales, per­sonal anec­dotes, and a bit of philo­sophy. From the begin­ning we are intro­duced to a mena­gerie that perches in the gray area bet­ween alive and not-alive: crea­tures like tardi­grades and nema­todes that can re­emerge from crypto­biosis with the touch of wa­ter, pythons whose basal meta­bolic rates can grind al­most to a halt, slime molds that dis­play a brain­less kind of mem­ory and prob­lem-solv­ing abil­ity, and a girl named Jahi Mc­Math, who was dec­lared brain-dead yet had a beat­ing heart and con­tinued to grow be­fore dy­ing (again) five years later. SARS-CoV‑2 makes an ap­pear­ance, since a book on the def­ini­tion of liv­ing would not be com­plete with­out a look at viruses. We are intro­duced to var­ious def­ini­tions of life, sourced from sci­entists to phil­osoph­ers, and we find that these tele­scope down to five spe­cial hall­marks: meta­bolism, infor­ma­tion gath­er­ing, homeo­stasis, re­pro­duc­tion, and evol­ution. It's through biz­arre and won­drous flora and fauna that the sheer diver­sity with­in these traits is shown, and the elu­sive­ly com­plex na­ture of defin­ing life made pal­pable. As quoted in Life's Edge, biol­ogy is in­deed a "sci­ence in which the most impor­tant ob­ject has no defin­ition."

Bizarre crea­tures have long been invol­ved in defin­ing the fron­tiers of life, as we see with the book's turn to­wards the his­tor­ical. In the 1700s, Swiss nat­uralist Abra­ham Trem­b­ley dis­covered the regen­era­tive abil­ity of Hy­dra as he sliced and diced and re­grew whole organ­isms from those lit­tle "polyp" pieces. We are intro­duced to the mech­anical vis­ion of life propel­led by Descartes' writ­ings, and to the vi­tal­ist move­ment, which op­posed the for­mer and be­lieved that all liv­ing things pos­sess a spe­cial life force. We learn of red her­rings, like the 1800s dis­covery of a "liv­ing jelly" from the ocean, Ba­thy­bius, which turned out to be gyp­sum reac­ting with alco­hol to form a gelat­inous prod­uct, and the 1900s dis­covery of "micro­scopic crea­tures" dub­bed ra­diobes, which turned out to be com­pounds formed when ra­dium encoun­ters bouil­lon. We meet a multi­discip­linary cast of sci­entist prota­gonists who have tried to bot­tle up a def­ini­tion of life, from a physio­logist moon­lighting as a spy, to phy­sicists like Bohr, Del­brück, and Schrödinger tack­ling biol­ogy through the phy­sicist's lens, and all the while, the NASA defin­ition of life – "life is a self-sus­tained chem­ical sys­tem cap­able of under­going Dar­winian evol­ution" – grows increas­ingly flimsy.

I esp­ecially en­joyed the high­lighted con­nec­tion bet­ween biol­ogy and crea­tive writ­ing. We are intro­duced to the grand­father of Charles Dar­win, Eras­mus Dar­win, whose po­etry propel­led the idea of evol­ution into the pub­lic eye (ideas later to be ex­pounded upon by his grand­son). The poet's prop­osal that sim­ple life-forms arose from or­ganic mat­ter in­spired a bevy of writ­ers, includ­ing none other than Mary Woll­stonecraft Shel­ley. From this inter­est in life­forms and the 1800s no­tion that elec­tricity was inti­mately linked to life arose the novel Franken­stein, in which the titu­lar sci­entist brings his mon­ster to life us­ing elec­tricity. This snip­pet was a fascin­ating illus­tra­tion of the syn­ergy bet­ween sci­ence com­muni­cation, sci­ence fic­tion, and sci­entific re­search, at work since one of the ear­li­est sci­ence fic­tion nov­els.

Frankenstein's fic­tional tech­niques were a har­binger of the spark essen­tial to the 1952 Miller-Urey exper­iment, that land­mark in ori­gins-of-life res­earch immor­talized in liter­ature and text­books. Life's Edge con­tains a con­densed sur­vey of histor­ical ori­gins-of-life res­earch, and here it tran­sitions from a nar­rative of scien­tific snip­pets and his­tory into one com­posed more of per­sonal vig­nettes. Un­like Michael Marshall's The Gen­e­sis Quest (a com­prehen­sive read on Ori­gins res­earch that we prev­iously cov­ered⛓️‍💥 on the blog), Life's Edge con­tains a more per­sonal take with anec­dotes and Zimmer's encoun­ters with scien­tists. Feat­ured prom­inently is David Deamer, a ma­jor prop­onent of the hypo­thesis that the ori­gins of life lie in lipo­somes and vol­canic hot spring pools, and a multi­discip­linary bunch of sci­entists whose collab­orative work rev­olves around proto­cells, sim­ple lipid-mem­brane ves­icles remin­iscent of prim­itive cells.

I en­joyed the book. It was a thought-pro­vok­ing pop-sci read that brought the lab environ­ment alive and painted a switch­back path of in­quiry, mis­takes, and dis­coveries. Zimmer's wri­ting is enjoy­able and acces­sible: at times sus­pense­ful, at times lyri­cal, al­ways car­rying an under­current of wonder­ment with the nat­ural world.

The book evokes a pal­pable excite­ment in learn­ing about the div­erse at­tempts at defin­ing life. It rem­inded me of the enjoy­ment found in read­ing old lib­rary books marked up by prev­ious read­ers: in the under­lining of cer­tain sen­tences, or in the brief thoughts scrib­bled along page mar­gins, the next reader can ob­serve a com­munal ef­fort to find mean­ing. To some, it's off-putting van­dal­ism; to oth­ers, it's a peek into other people's minds and his­tory. The value in these mark-ups – and in the quest to delin­eate what is alive – may not be in which ex­act words are high­lighted or cir­cled, but rather in the pro­cess of dis­covery.

I hap­pened to read Life's Edge around the same time I read The Book of Dis­quiet by the Por­tuguese writer Fer­nando Pes­soa. The two books syner­gized. They both read to me as appre­cia­tions of the uncer­tainty of all things and the creat­ivity that arises as a re­sult. In the words of the prota­gonist in the lat­ter book, "the or­a­cles who said 'Know thy­self' prop­osed a task greater than all of Her­cules' labours and an enigma even more obs­cure than that of the Sphinx.'" Undoubt­edly an apt des­crip­tion.

The an­swer to what is life? has under­gone a kind of evol­ution it­self, and Life's Edge is an adept tour guide to that convol­uted path.

 

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