Why do animals have such different lifespans? - Joao Pedro de Magalhaes

Zašto životinje imaju tako različit životni vek? - Žoao Pedro Magaljes ( Joao Pedro de Magalhaes)

Prevodilac: Milenka Okuka Lektor: Mile Živković

For the microscopic lab worm, C. elegans

Za mikroskopskog laboratorijskog crva, C. elegans,

life equates to just a few short weeks on Earth.

život znači nekoliko kratkih nedelja na zemlji.

Compare that with the tortoise, which can age to more than 100 years.

Uporedite to sa kornjačom, koja može da dosegne više od 100 godina.

Mice and rats reach the end of their lives after just four years,

Miševi i pacovi dosegnu kraj života nakon svega četiri godine,

while for the bowhead whale, Earth's longest-lived mammal,

dok grenlandskog kita, najdugovečnijeg sisara na zemlji,

death can come after 200.

smrt može da zatekne nakon 200.

Like most living things,

Poput mnogih živih bića,

the vast majority of animals gradually degenerate after reaching sexual maturity

velika većina životnja postepeno propada nakon što dostignu seksualnu zrelost

in the process known as aging.

u procesu koji je poznat kao starenje.

But what does it really mean to age?

Međutim, šta zaista znači stariti?

The drivers behind this process are varied and complicated,

Pokretači ovog procesa variraju i složeni su,

but aging is ultimately caused by cell death and dysfunction.

ali starenje je naposletku uzrokovano smrću ćelija i disfunkcijom.

When we're young, we constantly regenerate cells

Kada smo mladi, stalno nam se ćelije obnavljaju

in order to replace dead and dying ones.

kako bi se zamenile mrtve i one koje umiru.

But as we age, this process slows down.

Međutim, kako starimo, ovaj proces se usporava.

In addition, older cells don't perform their functions as well as young ones.

Dodatno, starije ćelije ne obavljaju svoje funkcije tako dobro kao mlade.

That makes our bodies go into a decline,

Zbog toga naša tela propadaju,

which eventually results in disease and death.

a ishod toga na kraju je bolest i smrt.

But if that's consistently true,

Međutim, ako je to dosledno tako,

why the huge variance in aging patterns and lifespan within the animal kingdom?

otkud ogromna varijacija u obrascima starenja

i životnog veka u životinjskom carstvu?

The answer lies in several factors,

Odgovor počiva u nekoliko faktora,

including environment

uključujući okolinu

and body size.

i telesnu veličinu.

These can place powerful evolutionary pressures on animals to adapt,

One mogu da stave moćan evolutivni pritisak na životinje da se adaptiraju,

which in turn makes the aging process different across species.

a zbog toga je proces starenja različit širom vrsta.

Consider the cold depths of the Atlantic and Arctic Seas,

Zamislite hladne dubine Atlantika i arktičkih mora,

where Greenland sharks can live to over 400 years,

gde grenlandske ajkule mogu da žive preko 400 godina,

and the Arctic clam known as the quahog can live up to 500.

a arktička školjka može da živi i do 500.

Perhaps the most impressive of these ocean-dwelling ancients

Možda je najimpresivniji, od ovih straca koji žive u okeanu,

is the Antarctic glass sponge,

antarktički staklasti sunđer,

which can survive over 10,000 years in frigid waters.

koji može da živi preko 10,000 godina u ledenim vodama.

In cold environments like these, heartbeats and metabolic rates slow down.

U hladnim sredinama, poput ovih, otkucaji srca i metabolizam usporavaju.

Researchers theorize that this also causes a slowing of the aging process.

Istraživači teoretišu da ovo takođe uzrokuje usporavanje procesa starenja.

In this way, the environment shapes longevity.

Na ovaj način okruženje oblikuje dugovečnost.

When it comes to size, it's often, but not always,

Kada se radi o veličini, često je slučaj, ali ne uvek,

the case that larger species have a longer lifespan than smaller ones.

da veće vrste imaju duži životni vek od manjih.

For instance, an elephant or whale will live much longer

Na primer, slon ili kit će da žive mnogo duže

than a mouse, rat, or vole,

od miševa, pacova ili poljskih miševa,

which in turn have years on flies and worms.

koji, zauzvrat, imaju godine prednosti u odnosu na muve i crve.

Some small animals, like worms and flies,

Neke male životinje, poput crva i muva,

are also limited by the mechanics of their cell division.

su takođe ograničene mehanikom njhove deobe ćelija.

They're mostly made up of cells that can't divide and be replaced when damaged,

Uglavnom ih sačinjavaju ćelije

koje ne mogu da se dele i menjaju nakon oštećenja,

so their bodies expire more quickly.

te se njihova tela brže troše.

And size is a powerful evolutionary driver in animals.

A veličina je moćan evolutivni pokretač kod životinja.

Smaller creatures are more prone to predators.

Manja bića su podložnija predatorima.

A mouse, for instance, can hardly expect to survive more than a year in the wild.

Miš, na primer, jedva da može da očekuje da preživi više od godinu u divljini.

So, it has evolved to grow and reproduce more rapidly,

Te je evoluirao da mnogo brže raste i razmnožava se,

like an evolutionary defense mechanism against its shorter lifespan.

poput evolutivnog mehanizma odbrane protiv njegovog kraćeg životnog veka.

Larger animals, by contrast, are better at fending off predators,

Veće životinje, nasuprot tome, se uspešnije brane od predatora,

and so they have the luxury of time to grow to large sizes

te imaju dragoceno vreme da više porastu

and reproduce multiple times during their lives.

i da se razmnožavaju više puta tokom njihovog života.

Exceptions to the size rule include bats, birds, moles, and turtles,

Izuzetak pravilu veličine uključuje šišmiše, ptice, krtice i kornjače,

but in each case, these animals have other adaptations

ali u svakom slučaju, ove životinje imaju druge adaptacije

that allow them to escape predators.

koje im omogućuju da izbegnu predatore.

But there are still cases where animals with similar defining features,

Ali i dalje imamo slučajeve gde životinje sličnih određujućih karakteristika,

like size and habitat,

poput veličine i staništa,

age at completely different rates.

stare potpuno različitim stopama.

In these cases, genetic differences,

U ovim slučajevima, genetske razlike,

like how each organism's cells respond to threats,

poput toga kako ćelije svakog organizma odgovaraju na opasnost,

often account for the discrepancies in longevity.

često se odražavaju na raskorak u dugovečnosti.

So it's the combination of all these factors

Dakle, kombinacija svih ovih faktora

playing out to differing degrees in different animals

uzrokuje različite stepene starenja kod različitih životinja,

that explains the variability we see in the animal kingdom.

a to objašnjava varijabilnost koju vidimo u životinjskom carstvu.

So what about us?

Pa, šta je s nama?

Humans currently have an average life expectancy of 71 years,

Kod ljudi je trenutno životni vek 71 godina,

meaning that we're not even close to being the longest living inhabitants on Earth.

što znači da nismo ni blizu najdugovečnijih stanovnika zemlje.

But we are very good at increasing our life expectancy.

Međutim, veoma smo uspešni u produžavanju životnog veka.

In the early 1900s, humans only lived an average of 50 years.

Ranih 1900-ih, ljudi su živeli u proseku svega 50 godina.

Since then, we've learned to adapt by managing many of the factors

Od tada, naučili smo da se prilagodimo uređujući mnoge faktore

that cause deaths,

koji uzrokuju smrti,

like environmental exposure and nutrition.

poput izloženosti okolini i ishrane.

This, and other increases in life expectancy

Ovo i druga uvećanja životnog veka

make us possibly the only species on Earth

nas verovatno čine jedinom vrstom na zemlji

to take control over our natural fate.

koja je preuzela kontrolu nad našom prirodnom sudbinom.