Ed Yong: Suicidal wasps, zombie roaches and other parasite tales

Translator: Matej Divjak Reviewer: Sergej Žižek

A herd of wildebeests, a shoal of fish,

Čreda gnujev, jata rib, jata ptic.

a flock of birds.

Many animals gather in large groups

Mnoge živali se zbirajo v velikih skupinah,

that are among the most wonderful spectacles

ki so med najčudovitejšimi prizori naravnega sveta.

in the natural world.

But why do these groups form?

A zakaj se te skupine oblikujejo?

The common answers include things like

Običajni odgovori vključujejo stvari, kot so iskanje varnosti v množičnosti,

seeking safety in numbers or hunting in packs

ali lov v krdelih, ali zbiranje zaradi parjenja ali razmnoževanja,

or gathering to mate or breed,

and all of these explanations,

in vse te razlage, čeprav pogosto držijo,

while often true,

make a huge assumption about animal behavior,

vsebujejo veliko predpostavko o obnašanju živali,

that the animals are in control of their own actions,

in sicer, da živali nadzirajo svoja dejanja,

that they are in charge of their bodies.

da imajo nadzor nad svojimi telesi.

And that is often not the case.

A temu pogosto ni tako.

This is Artemia, a brine shrimp.

To je artemija, solinski rakec.

You probably know it better as a sea monkey.

Verjetno ga bolj poznate pod imenom morska opica.

It's small, and it typically lives alone,

Je majhen in navadno živi sam, a se lahko zbira tudi v takšnih velikih rdečih rojih,

but it can gather in these large red swarms

that span for meters,

ki se raztezajo več metrov.

and these form because of a parasite.

Ti pa se oblikujejo zaradi zajedavca.

These shrimp are infected with a tapeworm.

Ti rakci so okuženi s trakuljo.

A tapeworm is effectively a long, living gut

Trakulja je v bistvu dolgo, živo črevesje,

with genitals at one end and a hooked mouth at the other.

z genitalijami na enem koncu in kljukastimi usti na drugem.

As a freelance journalist, I sympathize.

Kot samostojni novinar, sočustvujem.

(Laughter)

(smeh)

The tapeworm drains nutrients from Artemia's body,

Trakulja srka hranljive snovi iz artemijinega telesa,

but it also does other things.

a počne tudi druge stvari.

It castrates them,

Kastrira jih, njihovo barvo spremeni iz prosojne v svetlo rdečo,

it changes their color from transparent to bright red,

it makes them live longer,

podaljša jim življenje,

and as biologist Nicolas Rode has found,

in, kot je odkril biolog Nicolas Rode, jih pripravi do plavanja v skupinah.

it makes them swim in groups.

Why? Because the tapeworm, like many other parasites,

Zakaj? Zato ker ima trakulja, tako kot mnogi drugi zajedavci,

has a complicated life cycle

kompliciran življenjski cikel, ki vključuje mnogo različnih gostiteljev.

involving many different hosts.

The shrimp are just one step on its journey.

Rakci so samo en korak na njeni poti.

Its ultimate destination is this,

Njen končni cilj je ta,

the greater flamingo.

veliki flamingo.

Only in a flamingo can the tapeworm reproduce,

Trakulja se lahko razmnožuje samo v flamingu,

so to get there, it manipulates its shrimp hosts

zato, da bi prišla do njega, zmanipulira svoje gostitelje rakce,

into forming these conspicuous colored swarms

da oblikujejo te roje vpadljive barve, ki jih flamingo lažje opazi in požre,

that are easier for a flamingo to spot

and to devour,

and that is the secret of the Artemia swarm.

in to je skrivnost rojev artemij.

They aren't sociable through their own volition,

Niso družabni po lastni volji, ampak ker jih nadzirajo.

but because they are being controlled.

It's not safety in numbers.

Ni varnost v množičnosti. Dejansko je ravno nasprotno.

It's actually the exact opposite.

The tapeworm hijacks their brains and their bodies,

Trakulja ugrabi njihove možgane in njihova telesa

turning them into vehicles

ter jih spremeni v vozilo, s katerim pride do flaminga.

for getting itself into a flamingo.

And here is another example

Tu pa je še en primer zajedavske manipulacije.

of a parasitic manipulation.

This is a suicidal cricket.

To je samomorilski čriček.

This cricket swallowed the larvae of a Gordian worm,

Ta čriček je pogoltnil ličinke gordijskega črva ali žive niti.

or horsehair worm.

The worm grew to adult size within it,

Črv je v njem zrastel do odrasle velikosti,

but it needs to get into water in order to mate,

vendar mora za parjenje priti do vode,

and it does that by releasing proteins

to pa naredi z izločanjem beljakovin, ki zmedejo čričkove možgane,

that addle the cricket's brain,

causing it to behave erratically.

da se začne obnašati neobičajno.

When the cricket nears a body of water,

Ko se čriček približa vodi, kot je ta bazen,

such as this swimming pool,

it jumps in and drowns,

skoči vanjo in se utopi,

and the worm wriggles out

črv pa privijuga ven iz njegovega samomorilskega trupelca.

of its suicidal corpse.

Crickets are really roomy. Who knew?

Črički so res prostorni. Kdo bi si mislil?

The tapeworm and the Gordian worm are not alone.

Trakulja in živa nit nista edina.

They are part of an entire cavalcade

Sta del celotne kavalkade zajedavcev, ki nadzirajo um,

of mind-controlling parasites,

of fungi, viruses, and worms and insects and more

glivic, virusov, črvov in žuželk ter drugih,

that all specialize in subverting and overriding

ki so vsi specializirani za spodkopavanje in nadvladovanje

the wills of their hosts.

volje njihovih gostiteljev.

Now, I first learned about this way of life

Za ta način življenja sem prvič slišal

through David Attenborough's "Trials of Life"

v "Preizkusih življenja" Davida Attenbourgha

about 20 years ago,

pred približno 20 leti,

and then later through a wonderful book called

kasneje pa še v čudoviti knjigi

"Parasite Rex" by my friend Carl Zimmer.

"Zajedavec Reks", ki jo je napisal moj prijatelj Carl Zimmer.

And I've been writing about these creatures ever since.

In od takrat naprej pišem o teh bitjih.

Few topics in biology enthrall me more.

Ni veliko tem v biologiji, ki bi me bolj očarale.

It's like the parasites have subverted my own brain.

Kot da bi zajedavci sprevrgli tudi moje možgane.

Because after all, they are always compelling

Konec koncev so vedno neustavljivo privlačni in čudovito strašljivi.

and they are delightfully macabre.

When you write about parasites,

Ko pišete o zajedavcih, je vaše besedišče polno fraz,

your lexicon swells with phrases like

"devoured alive" and "bursts out of its body."

kot so "živ pojeden" in "izbruhne iz njegovega telesa."

(Laughter)

(smeh)

But there's more to it than that.

A gre za več kot zgolj to.

I'm a writer, and fellow writers in the audience

Sem pisec in kolegi pisci v občinstvu bodo vedeli, da imamo radi zgodbe.

will know that we love stories.

Parasites invite us to resist the allure

Zajedavci nas vabijo, da se upremo privlačnosti očitnih zgodb.

of obvious stories.

Their world is one of plot twists

Njihov svet je poln zasukov v zgodbi in nepričakovanih razlag.

and unexpected explanations.

Why, for example,

Zakaj, na primer, ta gosenica

does this caterpillar

start violently thrashing about

začne nasilno mlatiti naokrog, ko se katera druga žuželka približa njej

when another insect gets close to it

and those white cocoons that it seems

in tistim belim kokonom, ki jih očitno straži?

to be standing guard over?

Is it maybe protecting its siblings?

Ali morda ščiti svoje brate in sestre?

No.

Ne.

This caterpillar was attacked

To gosenico je napadla zajedavska osa in vanjo izlegla jajčeca.

by a parasitic wasp which laid eggs inside it.

The eggs hatched and the young wasps

Mlade osice so se izlegle in gosenico živo pojedle,

devoured the caterpillar alive

before bursting out of its body.

preden so izbruhnile iz njenega telesa. Vidite, kaj mislim?

See what I mean?

Now, the caterpillar didn't die.

Gosenica ni umrla.

Some of the wasps seemed to stay behind

Nekaj os je očitno ostalo

and controlled it into defending their siblings

in so jo nadzirale, da je branila njihove brate in sestre,

which are metamorphosing

ki gredo skozi preobrazbo v odrasle v tistih kokonih.

into adults within those cocoons.

This caterpillar is a head-banging zombie bodyguard

Ta gosenica je z glavo udarjajoč zombi telesni stražar,

defending the offspring

ki brani potomce bitja, ki jo je ubilo.

of the creature that killed it.

(Applause)

(aplavz)

We have a lot to get through. I only have 13 minutes. (Laughter)

Veliko snovi imamo za predelat. Imam pa samo 13 minut. (smeh)

Now, some of you are probably just

Najbrž nekateri od vas sedaj obupno iščete nekaj tolažbe

desperately clawing for some solace

in the idea that these things are oddities

v ideji, da so te stvari nenavadnosti naravnega sveta, da so osamelci,

of the natural world, that they are outliers,

and that point of view is understandable,

in takšno stališče je razumljivo, saj so zajedavci po svoji naravi precej majhni

because by their nature, parasites are quite small

and they spend a lot of their time

in veliko svojega časa prebijejo v telesih drugih stvari.

inside the bodies of other things.

They're easy to overlook,

Z lahkoto jih spregledamo, vendar to ne pomeni, da niso pomembni.

but that doesn't mean that they aren't important.

A few years back, a man called Kevin Lafferty

Pred nekaj leti je Kevin Lafferty

took a group of scientists into three Californian estuaries

skupino znanstvenikov odpeljal v tri kalifornijske estuarije

and they pretty much weighed and dissected

in stehtali, secirali in zabeležili so vse, kar so lahko našli,

and recorded everything they could find,

and what they found

in kar so našli, je bilo skrajno izobilje zajedavcev.

were parasites in extreme abundance.

Especially common were trematodes,

Še posebej pogosti so bili metljaji, majhni črvi,

tiny worms that specialize in castrating their hosts

ki so specializirani za kastriranje svojih gostiteljev, kot je ta nesrečni polž.

like this unfortunate snail.

Now, a single trematode is tiny, microscopic,

Posamezen metljaj je mikroskopsko majhen,

but collectively they weighed as much

vendar pa so vsi skupaj tehtali toliko, kot vse ribe v estuarijih

as all the fish in the estuaries

and three to nine times more than all the birds.

in tri- do devetkrat več kot vse ptice.

And remember the Gordian worm that I showed you,

In se spomnite žive niti, ki sem vam jo pokazal, tisto s čričkom?

the cricket thing?

One Japanese scientist called Takuya Sato

Japonski znanstvenik, Takuya Sato, je odkril, da v nekem potoku,

found that in one stream,

these things drive so many crickets

te stvari poženejo toliko čričkov in kobilic v vodo,

and grasshoppers into the water

that the drowned insects

da utopljene žuželke predstavljajo 60 odstotkov prehrane lokalnih postrvi.

make up some 60 percent of the diet of local trout.

Manipulation is not an oddity.

Manipulacija ni nenavadnost. Je ključen in običajen del sveta okoli nas

It is a critical and common part

of the world around us,

and scientists have now found

in znanstveniki so odkrili že na stotine primerov takšnih manipulatorjev,

hundreds of examples of such manipulators,

and more excitingly, they're starting to understand

kar pa je še bolj razburljivo, začenjajo razumeti,

exactly how these creatures control their hosts.

točno kako ta bitja nadzirajo svoje gostitelje.

And this is one of my favorite examples.

In to je en od mojih najljubših primerov.

This is Ampulex compressa,

To je Ampulex compressa, smaragdna osa, in univerzalno sprejeta resnica je,

the emerald cockroach wasp,

and it is a truth universally acknowledged

that an emerald cockroach wasp in possession

da si smaragdna osa, ki ima oplojena jajčeca, mora želeti ščurka.

of some fertilized eggs

must be in want of a cockroach.

When she finds one,

Ko ga najde, ga zabode z želom, ki je tudi čutni organ.

she stabs it with a stinger

that is also a sense organ.

This discovery came out three weeks ago.

Do tega odkritja smo prišli pred tremi tedni.

She stabs it with a stinger that is a sense organ

Zabode ga z želom, ki je čutni organ,

equipped with small sensory bumps

opremljen z majhnimi zaznavnimi izboklinami,

that allow her to feel the distinctive texture

ki ji omogočijo, da otipa značilno teksturo ščurkovih možganov.

of a roach's brain.

So like a person blindly rooting about in a bag,

Tako kot oseba, ki na slepo tipa po vreči,

she finds the brain, and she injects it with venom

najde možgane in jim vbrizga strup v dva točno določena skupka nevronov.

into two very specific clusters of neurons.

Israeli scientists Frederic Libersat and Ram Gal

Izraelska znanstvenika, Frederic Libersat in Ram Gal,

found that the venom is a very specific chemical weapon.

sta odkrila, da je strup zelo specifično kemično orožje.

It doesn't kill the roach, nor does it sedate it.

Ščurka niti ne ubije, niti ga ne uspava.

The roach could walk away

Ščurek bi lahko odkorakal ali odletel ali stekel, če bi se tako odločil,

or fly or run if it chose to,

but it doesn't choose to,

a se ne odloči za to, ker strup uniči njegovo motivacijo za hojo

because the venom nixes its motivation to walk,

and only that.

in samo to.

The wasp basically un-checks the escape-from-danger box

Osa v bistvu odstrani kljukico iz kvadratka pobegni-pred-nevarnostjo

in the roach's operating system,

v operacijskem sistemu ščurka, kar ji omogoči, da svojo nemočno žrtev vodi

allowing her to lead her helpless victim

back to her lair by its antennae

nazaj do svojega brloga s svojimi antenami kot človek, ki sprehaja psa.

like a person walking a dog.

And once there, she lays an egg on it,

Ko sta enkrat tam, nanj izleže jajčece,

egg hatches, devoured alive, bursts out of body,

jajčece se izleže, živega poje, izbruhne iz telesa,

yadda yadda yadda, you know the drill.

bla, bla, bla, zdaj že veste, kako to gre.

(Laughter) (Applause)

(smeh) (aplavz)

Now I would argue that, once stung,

Trdil bi, da ko ga osa enkrat piči, ščurek ni več ščurek.

the cockroach isn't a roach anymore.

It's more of an extension of the wasp,

Je bolj kot podaljšek ose, kot je bil čriček podaljšek žive niti.

just like the cricket was an extension of the Gordian worm.

These hosts won't get to survive or reproduce.

Ti gostitelji ne bodo preživeli ali se razmnoževali.

They have as much control over their own fates

Nad svojimi usodami imajo toliko nadzora kot moj avto.

as my car.

Once the parasites get in,

Ko zajedavec enkrat vstopi, gostitelji nimajo več besede.

the hosts don't get a say.

Now humans, of course,

Seveda tudi ljudem manipulacija ni tuja.

are no stranger to manipulation.

We take drugs to shift the chemistries of our brains

Jemljemo zdravila, da bi spremenili kemijo v svojih možganih in svoje razpoloženje,

and to change our moods,

and what are arguments or advertising or big ideas

in kaj so argumenti ali oglaševanje ali velike ideje,

if not an attempt to influence someone else's mind?

če ne poskus vplivanja na um nekoga drugega?

But our attempts at doing this

Toda naši poskusi tega so preprosti in nedodelani v primerjavi

are crude and blundering compared

to the fine-grained specificity of the parasites.

s fino specifičnostjo zajedavcev.

Don Draper only wishes he was as elegant

Don Draper si lahko le želi, da bi bil tako eleganten in natančen kot smaragdna osa.

and precise as the emerald cockroach wasp.

Now, I think this is part of what makes parasites

Mislim, da je to tisti del, ki dela zajedavce

so sinister and so compelling.

tako zlovešče in tako neustavljivo privlačne.

We place such a premium on our free will

Takšno težo dajemo svoji svobodni volji in svoji neodvisnosti,

and our independence

that the prospect of losing those qualities

da možnost izgube teh lastnosti zaradi nevidnih sil

to forces unseen

informs many of our deepest societal fears.

naslavlja naše najgloblje družbene strahove.

Orwellian dystopias and shadowy cabals

Orwellovske distopije in senčne spletke in super zlobneži, ki nadzirajo ume -

and mind-controlling supervillains --

these are tropes that fill our darkest fiction,

to so stvari, ki polnijo našo najtemnejšo fikcijo,

but in nature, they happen all the time.

v naravi pa se to kar naprej dogaja.

Which leads me to an obvious

Kar me vodi do očitnega in zaskrbljujočega vprašanja:

and disquieting question:

Are there dark, sinister parasites

Ali obstajajo temačni, zlovešči zajedavci, ki vplivajo na naše obnašanje,

that are influencing our behavior

without us knowing about it,

ne da bi mi za to vedeli,

besides the NSA?

poleg NSA (nacionalni urad za varnost, op. p.)?

If there are any —

Če obstajajo -

(Laughter) (Applause)

(smeh) (aplavz)

I've got a red dot on my forehead now, don't I?

Zdaj imam na čelu rdečo pikico, kajne?

(Laughter)

(smeh)

If there are any, this is a good candidate for them.

Če obstajajo, je to dober kandidat za njih.

This is Toxoplasma gondii, or Toxo, for short,

To je Toxoplasma gondii, ali na kratko, Toxo,

because the terrifying creature

ker si strašljivo bitje vedno zasluži ljubek vzdevek.

always deserves a cute nickname.

Toxo infects mammals,

Toxo lahko okuži sesalce, mnogo različnih vrst sesalcev,

a wide variety of mammals,

but it can only sexually reproduce in a cat.

spolno razmnožuje pa se lahko samo v mačkah.

And scientists like Joanne Webster have shown that

Znanstveniki kot Joanne Webster so pokazali,

if Toxo gets into a rat or a mouse,

da če Toxo pride v podgano ali miš, tega glodavca spremeni v raketo, ki išče mačke.

it turns the rodent into a cat-seeking missile.

If the infected rat smells the delightful odor

Če okužena podgana zavoha prekrasen vonj mačjega scanja,

of cat piss,

it runs towards the source of the smell

steče proti viru tega vonja, namesto v bolj razumno smer, stran.

rather than the more sensible direction of away.

The cat eats the rat. Toxo gets to have sex.

Mačka poje podgano. Toxo lahko seksa. Klasična zgodba Jej, moli, ljubi.

It's a classic tale of Eat, Prey, Love.

(Laughter) (Applause)

(smeh) (aplavz)

You're very charitable, generous people.

Ste zelo velikodušni, radodarni ljudje.

Hi, Elizabeth, I loved your talk.

Zdravo, Elizabeth, tvoj govor mi je bil všeč.

How does the parasite control its host

Kako zajedavec svojega gostitelja tako nadzira?

in this way?

We don't really know.

V bistvu ne vemo. Vemo, da Toxo izloča encim,

We know that Toxo releases an enzyme

that makes dopamine, a substance involved

ki tvori dopamin, snov, ki je povezana z nagrajevanjem in motivacijo.

in reward and motivation.

We know it targets certain parts of a rodent's brain,

Vemo, da cilja določene dele glodavčevih možganov,

including those involved in sexual arousal.

v ključno s tistimi, ki so povezani s spolno vzburjenostjo.

But how those puzzle pieces fit together

Toda, kako se ti koščki sestavljanke sestavijo, ni takoj jasno.

is not immediately clear.

What is clear is that this thing

Kar je jasno je, da je ta stvar ena sama celica.

is a single cell.

This has no nervous system.

Nima živčnega sistema. Nima zavesti. Celo telesa nima.

It has no consciousness.

It doesn't even have a body.

But it's manipulating a mammal?

A manipulira s sesalcem?

We are mammals.

Mi smo sesalci.

We are more intelligent than a mere rat, to be sure,

Seveda smo bolj inteligentni od navadne podgane,

but our brains have the same basic structure,

a naši možgani imajo enako osnovno strukturo,

the same types of cells,

enake vrste celic, enake kemikalije, ki se pretakajo skozi njih,

the same chemicals running through them,

and the same parasites.

in enake zajedavce.

Estimates vary a lot, but some figures suggest

Ocene se precej razlikujejo, a nekatere številke nakazujejo,

that one in three people around the world

da ima en od treh ljudi na svetu v svojih možganih Toxo.

have Toxo in their brains.

Now typically, this doesn't lead to any overt illness.

Običajno to ne vodi v nobeno očitno bolezen.

The parasite holds up in a dormant state

Zajedavec zelo dolgo ostaja v mirujočem stanju.

for a long period of time.

But there's some evidence that those people

Vendar pa je nekaj dokazov, da ljudje,

who are carriers score slightly differently

ki ga prenašajo, dosegajo nekoliko drugačne rezultate

on personality questionnaires than other people,

na vprašalnikih o osebnosti, kot ostali ljudje,

that they have a slightly higher risk of car accidents,

da imajo nekoliko večje tveganje za avtomobilske nesreče,

and there's some evidence that people with schizophrenia

nekaj pa je tudi dokazov, da so ljudje s shizofrenijo bolj verjetno okuženi.

are more likely to be infected.

Now, I think this evidence is still inconclusive,

Mislim, da ti dokazi še ne zadostujejo in celo med raziskovalci Toxo-ja

and even among Toxo researchers,

opinion is divided as to whether the parasite

so deljena mnenja, ali zajedavec resnično vpliva na naše obnašanje.

is truly influencing our behavior.

But given the widespread nature of such manipulations,

Vendar glede na razširjenost narave takšnih manipulacij

it would be completely implausible

bi bilo precej neverjetno, da bi bili ljudje edina vrsta,

for humans to be the only species

that weren't similarly affected.

na katero ne bi imele podobnega vpliva.

And I think that this capacity to constantly

In mislim, da je ta zmožnost,

da nenehno spodkopavajo naš način razmišljanja o svetu,

subvert our way of thinking about the world

makes parasites amazing.

tista, ki dela zajedavce neverjetne.

They're constantly inviting us to look at the natural world sideways,

Nenehno nas vabijo, da naravni svet gledamo postrani,

and to ask if the behaviors we're seeing,

in se sprašujemo, ali obnašanja, ki jih vidimo,

whether they're simple and obvious

naj bodo enostavna in očitna, ali begajoča in zapletena,

or baffling and puzzling,

are not the results of individuals

niso rezultat posameznikov, ki se ravnajo po lastni volji,

acting through their own accord

but because they are being bent

ampak so upognjena zaradi nadzora nečesa drugega.

to the control of something else.

And while that idea may be disquieting,

In čeprav je ta ideja lahko zaskrbljujoča

and while parasites' habits may be very grisly,

in čeprav so navade zajedavcev lahko zelo grozne,

I think that ability to surprise us

mislim, da jih sposobnost, da nas presenetijo, dela čudovite in karizmatične

makes them as wonderful and as charismatic

as any panda or butterfly or dolphin.

kot katerakoli panda ali metulj ali delfin.

At the end of "On the Origin of Species,"

Na koncu knjige "O izvoru vrst"

Charles Darwin writes about the grandeur of life,

Charles Darwin piše o veličastnosti življenja

and of endless forms most beautiful

in o neskončnih oblikah najlepšega in najčudovitejšega

and most wonderful,

and I like to think he could easily have been talking

in rad si mislim, da bi z lahkoto lahko govoril

about a tapeworm that makes shrimp sociable

o trakulji, ki naredi rakca družabnega, ali o osi, ki pelje ščurke na sprehod.

or a wasp that takes cockroaches for walks.

But perhaps, that's just a parasite talking.

Morda pa to govori le zajedavec.

Thank you.

Hvala.

(Applause)

(aplavz)