Sur­vival of the gen­er­ous

An alternative look at evo­lu­tion and com­pe­ti­tion

The McGill Daily - - Contents - Laura Bren­nan

Bac­te­ria are mi­cro­scopic, sin­gle-celled or­gan­isms. Most bac­te­ria have one large cir­cu­lar chro­mo­some in­side of them, and many other smaller cir­cu­lar pieces of DNA called plas­mids. The DNA con­tained within these plas­mids en­code for the ex­pres­sion of pro­teins that are not es­sen­tial to the growth of bac­te­ria. How­ever, they of­ten pro­vide an ad­van­tage to the bac­te­ria, help­ing them to over­come ob­sta­cles in the en­vi­ron­ment, such as the abil­ity to me­tab­o­lize a dif­fer­ent source of food or to syn­the­size a mem­brane pro­tein that al­lows it to re­sist an­tibi­otics. Bac­te­ria can ac­quire and ex­change these plas­mids in many dif­fer­ent ways, such as up­take from the en­vi­ron­ment or, more com­pellingly, through a process called bac­te­rial con­ju­ga­tion.

Bac­te­rial con­ju­ga­tion oc­curs when a donor cell bac­terium that has a cer­tain plas- mid ex­tends a long “arm” called a pilus. In do­ing so, the bac­terium is able to find an­other bac­terium that does not have that spe­cific plas­mid, mak­ing it the re­cip­i­ent. Once the donor finds the re­cip­i­ent, it repli­cates its own plas­mid so the re­cip­i­ent can have a copy of it as well, hope­fully giv­ing it an ad­van­tage that al­lows it to over­come any num­ber of pos­si­ble en­vi­ron­men­tal chal­lenges.

Many peo­ple would, in­cor­rectly, con­sider this a form of bac­te­rial sex. Sci­en­tif­i­cally, this is un­true, be­cause this process does not re­sult in the pro­duc­tion of a daugh­ter cell (The Daily rec­og­nizes that sex does not nec­es­sar­ily re­sult in a child in hu­mans – how­ever, this is the def­i­ni­tion that is used for micro­organ­isms). This process can be thought of more as a bac­terium shar­ing crit­i­cal in­for­ma­tion with its good friend, to help said friend lead a more suc­cess­ful life. An anal­ogy that comes to mind is one per­son teach­ing their friend how to swim. It is easy to get through “every­day life” with­out need­ing to swim, how­ever, if this per­son was ever in a ship­wreck, the ac­tions of their friend will have sin­gle-hand­edly saved their life.

What’s in­ter­est­ing about this en­tire process is that there seems to be no ob­vi­ous ben­e­fit to the donor cell. De­spite this, the donor ex­pends sig­nif­i­cant en­ergy in search­ing for a re­cip­i­ent and in copy­ing its DNA, po­ten­tially putting it­self at a dis­ad­van­tage. So why do bac­te­ria do this? Well – bac­te­ria have been on earth for a very long time. For about three bil­lion years, most or­gan­isms were mi­cro­scopic, and bac­te­ria and ar­chaea (an­other type of mi­cro­scopic or­gan­ism) were the dom­i­nant forms of life. So, bac­te­ria have been ex­chang­ing ge­netic in­for­ma­tion with each other for a very long time, lead­ing us to as­sume there is a log­i­cal ex­pla­na­tion for the process. And yet, con­ju­ga­tion seems to ben­e­fit only the re­cip­i­ent.

Evo­lu­tion over time is un­der­stood by most bi­ol­o­gists as the “sur­vival of the fittest.” This can of­ten be in­ter­preted as, ul­ti­mately, ev­ery or­gan­ism is look­ing out for it­self, and must com­pete with ev­ery­thing else in its en­vi­ron­ment in or­der to sur­vive. How­ever, in my opin­ion, the ex­is­tence of bac­te­rial con­ju­ga­tion demon­strates other­wise. When a bac­terium do­nates its ge­netic in­for­ma­tion to an­other bac­terium, the re­cip­i­ent of this self­less act will have the same ad­van­tages as the donor. Fur­ther­more, this re­cip­i­ent bac­terium will likely go on to do­nate the copied plas­mid to even more bac­te­ria.

This sug­gests the the­ory of evo­lu­tion isn’t so black and white. Per­haps bac­te­ria have been such suc­cess­ful or­gan­isms on this planet in al­most ev­ery en­vi­ron­ment for so long, not only be­cause they are competitive, but also be­cause they are gen­er­ous. In times of trou­ble, they reach out to each other and give each other in­for­ma­tion that is some­times crit­i­cal to sur­vival. Maybe, we could learn some­thing from bac­te­ria. Through­out my en­tire life I have been taught that in or­der to suc­ceed I must com­pete with oth­ers. I must be bet­ter than oth­ers, even if that means leav­ing oth­ers behind in the dust. In competitive en­vi­ron­ments such as Mcgill, I do not think my ex­pe­ri­ence is unique.

How­ever, I do not think that com­pe­ti­tion is im­per­a­tive to success. De­spite all that has been said about sur­vival of the fittest, gen­eros­ity has still pro­lif­er­ated through­out mil­lions of years. Maybe, com­pe­ti­tion isn’t im­per­a­tive to progress; in­stead, in or­der to bet­ter ourselves, we must give to oth­ers. Per­haps there is some­thing in­nate about gen­eros­ity. If bac­te­ria can look out for each other, so can we.

De­spite all that has been said about sur­vival of the fittest, gen­eros­ity has still pro­lif­er­ated through­out mil­lions of years.

What’s in­ter­est­ing about this en­tire process is that there seems to be no ob­vi­ous ben­e­fit to the donor cell.

Maybe, com­pe­ti­tion isn’t im­per­a­tive to progress; in­stead, in or­der to bet­ter ourselves, we must give to oth­ers.

Laura Bren­nan | The Mcgill Daily

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