Greenland shark found to be at least 272 years old | Hacker News Reader

Greenland shark found to be at least 272 years old

nature.com

151 pointsokket25 comments

The study also shows that Greenland shark females don’t reach sexual maturity until around 150 years old — suggesting that a century of heavy fishing could wipe out the entire species, says Bushnell. But climate change is a greater threat, says Aaron MacNeil, a marine biologist at the Australian Institute of Marine Science near Townsville, Queensland.

Fascinating that the reproductive timeline can be so long. I'd always thought evolution was heavily biased in favor of rapid reproduction.

r/K selection theory[1] can help explain why some creatures favor longer reproductive timelines.

[1] - https://en.wikipedia.org/wiki/R/K_selection_theory

Yes, but even the blue whale, the largest animal ever existed (as far as we know), reaches sexual maturity after 5-10 years. Elephants need 10-13 years. Humans are roughly the same. An age for reaching puberty of ten times that, over a century, is a whole other definition of "long".

I'd always thought evolution was heavily biased in favor of rapid reproduction.

It's an arctic scavenger that grows both massive and very old without any natural predators worth mentioning. It doesn't make any sense for it to have a high reproductive rate.

The Greenland shark is pretty unusual.

* Eating it has a deleterious effect on sobriety [1].

* It's also the most toxic shark meat out there. [ibid]

* Female Greenland sharks take 150 years to reach sexual maturity (no word on the gestation period).

[1] https://en.wikipedia.org/wiki/Greenland_shark#Greenland_shar...

> It's also the most toxic shark meat out there.

Is that innate or related to the longevity? Other species could just die for they get to that level of toxicity.

Some turtles can live in excess of a hundred years. If they were toxic, surely some tribal community in the South Pacific would've figured that out by now.

Some quick googling didn't turn up much on turtle toxicity other than we seem to be more concerned about us poisoning turtles than them poisoning us. Probably with good reason.

The toxicity comes from trimethylamine oxide (TMAO) which decomposes to trimethylamine (TMA), a neurotoxin. TMA is the compound that produces the odor most associated with rotten fish and it's a very common metabolite found in many different animals (human gut and surface bacteria can produce it too).

The Greenland shark and other ocean life have nervous systems and livers that are better adapted to handling higher concentrations of TMA because it plays an important role in regulating cellular osmosis, which is critical for both salt and fresh water animals. While this may be loosely related to their extraordinary lifespan, it's much more likely that this is an old adaptation from an ancestor species that is irrelevant to their longevity.

It also tastes really really horrible. Thus you eat it with copious amounts of vodka to clear the taste.

https://en.wikipedia.org/wiki/Greenland_shark#Greenland_shar...

Amazing that there are animals as complex as this living out there today born in 1744 or earlier. Older than the United States.

I like that the number in the headline is the bottom range of their estimate.

"Because radiocarbon dating does not produce exact dates, they believe that she could have been as "young" as 272 or as old as 512. But she was most likely somewhere in the middle, so about 400 years old."

BBC went with 400 in the title :) [0]

[0] http://www.bbc.com/news/science-environment-37047168

The test is performed on a dead shark - a little sad that something so old is no longer with us.

    > The shark's longevity probably arises because 
    > it expends very little energy, owing to its cold 
    > body temperature and enormous size, Bushnell says.

Why would either a low body temperature or a large body size contribute to expanding less energy?

Bergmann's rule https://en.wikipedia.org/wiki/Bergmann%27s_rule

The earliest explanation, given by Bergmann when originally formulating the rule, is that larger animals have a lower surface area to volume ratio than smaller animals, so they radiate less body heat per unit of mass, and therefore stay warmer in cold climates. Warmer climates impose the opposite problem: body heat generated by metabolism needs to be dissipated quickly rather than stored within.

Yes. Since the volume of an organism increases with size faster than the surface area, larger animals are far more effective at retaining their body heat (greater volume stores more heat while a small surface area dissipates less heat). This in turn means less metabolic activity which means a longer lifespan based on our research of caloric restriction and it's impact on human longevity.

However, there are much bigger animals that don't live anywhere near as long so this is unlikely to be a significant contributing factor.

> Instead, the team decided to measure levels of radioactive carbon-14 in fibres in the centre of the shark’s eye lens. Such measurements reflect levels of radiocarbon in the ocean when the lens was first formed. Measurements of 28 female Greenland sharks, made during surveys in 2010–13, suggested that the largest of them (at 5.02 metres long) must have been between 272 and 512 years old at the time.

>levels of radiocarbon in the ocean when the lens was first formed

But wouldn't that tell you the age of the rocks/minerals that were used to make the lens? Or is the lens living tissue that dies after formation?

It's a pretty cool experiment. C14 is formed continuously in the upper atmosphere and enters the carbon cycle via CO2 absorption by plants. Since the ratio of C12 to C14 in the environment is known to be reasonably stable over time, the C12:C14 ratio in a given biological sample can be used to infer how long it's been since the organism stopped participating in the carbon cycle (i.e., died.)

The basic idea is simple enough, but the dating process is complicated by various factors that have to be calibrated out. The environmental C14:C12 ratio got a lot lower when we started burning fossil fuels in the 1800s. Later, setting off a bunch of massive nukes in the 1950s had the opposite effect.

The lens of the eye is living tissue, so it can be carbon-dated. In this study, the researchers actually took advantage of the nuclear contamination problem. They noted that only the smallest, most immature specimens exhibited the unnaturally high C14:C12 ratio characteristic of items from the period before the test ban treaties took effect. Bigger sharks had clearly absorbed most of the carbon in their lenses over a much longer period of time[1]. Since they have a good idea of the rate at which the sharks grow, they could infer that the larger specimens must have been growing for hundreds of years before the nuclear tests.

[1] Things get a bit hand-wavy here; the article suggests that the shark lens stops absorbing carbon after it's formed. Meanwhile, Wikipedia says that the human lens continues to grow.

They need a control to make sure their science is good.

Measure C-14 in other aquatic animals with known ages to make sure the technique actually works.

(Maybe they actually did it.)

interesting, maybe by studying these animals we will discover new tricks to live longer

Definitely. Some say lobsters can live forever since they don't age, others up to about 500 years due to telomerase and jelly fish potentially forever from being able to rejuvenate.

If we can slow down our aging we could live much longer and better lives.

I'm a firm believer that nature has the secret answers to everything.

Relevant discussion: https://news.ycombinator.com/item?id=12271109

Live like a jellyfish.

bloop bloop

Right? What a pointless life. Who could possibly enjoy it?

Now excuse me for the brevity, I have an awesome game of Candy Crush to finish. I think I'll get a new high score. Bloop bloop!

Only a few species of hydrozoan from genus Turritopsis. They are able to just revert between polyp and jellyfish so technically never die, but is a little like a species of embrio growing inside the body so could be said also that they clone itselves and their clon takes the place. In that sense much more vegetables are inmortal, with a little help from humans. We can trace easily some cultivars to several thousand years and a few historically relevant specimens to 2000 years ago or so. I'm talking of a single individual, not of the species.

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