23 May 2013

All lobsters are mortal

This appeared earlier today on the Facebook feed I Fucking Love Science:


Argh!


I remember seeing a shark documentary as a kid, hosted by Burgess Meredith, if I remember correctly. It made the same basic claim about great white sharks: too big to have predators, nobody had ever seen them die except by accident or by human hands, blah blah blah, therefore “some have suggested” they are immortal.

That I can remember the end of the show all these years later shows you what a terrific close the “immortal” idea makes. But it only sounds plausible because of our disconnect with that natural environment. It plays on our lack of knowledge about the natural world, and that we have a hard time tracking these sorts of things. It’s like asking most city dwellers, “Have you ever seen a baby pigeon?” “No, I haven’t. And you know what, I’ve never seen a dead pigeon, either! Oh my goodness, pigeons must be immortal!”

Sharks and lobsters have a few things in common, too, that makes the “immortality” claim easy to make. They live in the oceans, which means they are hard to track, and few people have first hand experience with them. They are long lived species, and it’s not easy to look at one and know how old it is. Wolff (1978) says of lobsters:

The scanty data presented above demonstrate the great difficulty in estimating the age of the very large lobsters.

When you add in “they only die from external causes,” you have a huge out. Most animals, including humans, die from external causes, broadly construed. Sure, a predator is an external cause. A bacterial or viral infection is an external cause. What would not count as an “external cause”? The definition is so loose that you can make exceptions for almost every possible counter-example.

And, of course, it links out, not to an actual scientific paper, which would be the sort of action you might expect from a group that proclaims to love science, but to a radio interview.

This is not a slap against the participants in the interview. Jelle Atema is a good scientist with real bona fides. But this radio interview is a long way from the sort of careful science you would need to do to show lobsters are “functionally immortal.”

There is some interesting science to this. Many decapod crustaceans have indeterminate growth (mentioned by Vogt 2008, 2010, who cites others). This means that they keep growing throughout their life, and do not have a set upper limit for size. It’s not just lobsters that do this, as far as I know; crayfish do, too. Lobsters are probably in this meme because they get so much larger than crayfish. It’s easier to people to believe a big animal like a lobster could be so much older than a small animal like a crayfish.

There is about one paper that I have been able to find on lobster longevity by Klapper and colleagues (1998). The introduction says:

Lobsters grow continuously throughout their lifespan, only decreasing growth rates with age. Furthermore, and again in contrast to humans, they are able to regenerate whole limbs even at a high age.

This cites a book chapter by Govind, on... muscle innervation?! The chapter talks a little bit about sarcomeres being added throughout life, but that’s about it. It’s not a chapter on aging and senescence.

More provocatively, the abstract of the Klapper and colleagues says (my emphasis):

Lobsters (Homarus americanus) grow throughout their life and the occurrence of senescence is slow.

But there is no citation for the “slow senescence” claim. And there is no original empirical data supporting that in the Klapper paper (e.g., longevity and activity and health and mortality data). The paper shows that adult lobsters still make an enzyme called telomerase, but it does not show that lobsters are long lived because of it.

How old does this “functionally immortal” lobster get? If lobsters really were “functionally immortal,” why would you not expect them to live for centuries?

Wolff (1978) wrote:

I also believe that Herrick gets pretty close to the truth in his poetic conclusion (1911: 199): “Giants weighing from 25 to 35 pounds [11.5-16 kg] have possibly weathered the storms of life half a century or more”.

More recently, Sheehy and colleagues wrote (1999; my emphasis):

The exceptional ages attained by some of the largest lobsters (males: average 31 years, maximum 42 ± 5 years; females: average 54 years, maximum 72 ± 9 years) are explained by ageing theory, indicate natural mortality rates, M, of 0.15 and 0.08 for males and females, respectively, and point to the existence of an offshore refuge.

Bodnar (2009) has a table that puts the oldest lobster on record in the 50-100 range; a bit more liberal than Wolff or Sheehy and company. Bodnar cites Finch (1990), which again does not seem to have much more than a table with an estimated maximum lifespan, connected to another reference I haven’t been able to track down. Nobody seems to define what “slow senescence” is, or how it has been measured in lobsters.

And to make things more complicated, “lobster” covers a lot of not very closely related species, and they have different maximum lifespans. Caribbean spiny lobsters (Panulirus argus) probably live around 20 years, maximum (Maxwell et al. 2007).

Regardless, a “functionally immortal” animal that has a shorter recorded maximum lifespan than a human? Colour me unimpressed.

For such a bold claim, it has been disappointingly hard to track down the real science. It’s also disappointing to see such a credulous claim come from a source that contends it fucking loves science. I think it is fair to call this one:


Sadly, I suspect this myth might have a longer lifespan than many lobsters.

Additional, 24 May 2013: Fighting fire with fire. Fire, and frickin’ awesome big crustaceans.


Additional, 26 May 2013: Welcome Redditors who found this post though this thread.

I also found this meme, made three days ago, apparently in response to the I Fucking Love Science post.


I got criticized a bit on I Fucking Love Science for promoting this post by characterizing the original IFLS picture as saying lobsters “live forever,” when the original picture said, “functionally immortal.” This meme shows that people are not picking up on the nuance. “Functionally immortal” became “biologically immortal,” which, I think, shows people are just going to remember “immortal.”

So, at this point, the original picture on I Fucking Love Science was probably seen by a few million people (over five million have liked it, and over four million are talking about it, says Facebook). The meme above has 689,321 views to far. This post has about 5,000 views so far.

I am going to have to put up with people asking me about immortal lobsters for years, aren’t I?

Additional, 27 May 2013: More evidence that people are seeing lobsters as pretty much straight-up immortal:

Is it true Lobsters can’t die from old age, are they immortal apart from sickness and injury?

I also finally turned to what may have been the source of the claim. Wikipedia. A section on biological immortality contained (until I edited):

Some scientists have claimed that (lobsters) could effectively live indefinitely, barring injury, disease, or capture.

The good bit was that it had a reference. To a journal article. With a relevant looking title:

Guerin JC. 2004. Emerging area of aging research: long-lived animals with “negligible senescence”. Annals of the New York Academy of Sciences 1019(1): 518-520. http://dx.doi.org/10.1196/annals.1297.096

Aha! Maybe this would be the source of the claim that lobsters are slow to undergo senescence! Maybe there is actual data!

I got it, and searched for “lobster.” It was fast; there are only two pages in the paper besides the references. It cites Finch (1990), again, with the reference that I haven’t yet been able to track down. Guerin notes that Finch listed several animals that might have negligible senescence, “including rockfish, sturgeon, turtles, bivalves, and possibly lobsters.” My emphasis: possibly.

That’s all. That’s weak stuff compared to “some scientist claim” lobsters could live indefinitely. Instead, lobsters might have little senescence. Maybe.

It seems that the source of all these “immortal lobsters” factoids are whatever research Finch is citing. I’ll continue to try to track it down, and report back on what I find.

Additional, 3 June 2013: The Surprising Science blog also tackles this story. That post is not just a repeat of information here (though this post does make a cameo). There are excellent comments from several other lobster biologists. For instance:

According to Carl Wilson, lead lobster biologist with the Maine Department of Marine Resources, between 10 and 15 percent of lobsters die naturally each year as they shed their exoskeletons because the exertion proves to be too much. Each molting process requires more and more energy than the one before it as lobsters grow in size.

Finally, older crustaceans stop shedding their exoskeletons altogether—a clue that they’re near the end of their lifespans. They run out of metabolic energy to molt, and their worn-and-torn shells contract bacterial infections that weaken them. Shell disease, in which bacteria seeps into lobster shells and forms scar tissue, adheres the crustaceans’ bodies to their shells. The lobster, attempting to molt, gets stuck and dies. The disease also makes lobsters susceptible to other ailments, and in extreme cases, the entire shell can rot, killing the animal inside.

Additional, 30 June 2013: Discovered this version of the meme circulating on Google Plus:


As someone pointed out in the response thread, it’s ironic that a picture of a cooked lobster is used to support the idea of their longevity.

Additional, 4 August 2013: David Shiffman informs me that this claim has resurfaced again on Discovery Channel’s Shark Week programming. Argh... I’ll take this moment to plug the Science... Sort Of podcast, where I will be discussing the “immortal lobsters” claim soon (episode 178, I think).

Additional, 9 August 2013: The Science... Sort Of podcast is now available!

Additional, 25 August 2013: Buzzfeed perpetuates the lobster myth with a video “6 almost immortal animals” (spotted by David Shiffman). Of lobsters, it claims:

They don’t age. They just continue to grow until they are killed. Yum.

Additional, 13 November 2013: Buzzfeed repeats this myth yet again, linking out to the National Public Radio story, via Quora.

Additional, 25 March 2014: A database on ageing includes a list of organisms with “negligible senescence.” It lists eight species, and none of them are lobster species.

References

Bodnar AG. 2009. Marine invertebrates as models for aging research. Experimental Gerontology 44(8): 477-484. DOI:

Govind CK. 1995. Muscles and their innervation. In: Factor, J.R. (Ed.), Biology of the Lobster Homarus americanus, pp. 291–312, Academic Press, San Diego, CA.

Klapper W, K├╝hne K, Singh KK, Heidorn K, Parwaresch R, Krupp G. 1998. Longevity of lobsters is linked to ubiquitous telomerase expression. FEBS Letters 439(1-2): 143-146. DOI:

Maxwell KE, Matthews TR, Sheehy MRJ, Bertelsen RD, Derby CD. 2007. Neurolipofuscin is a measure of age in Panulirus argus, the Caribbean spiny lobster, in Florida. The Biological Bulletin 213(1): 55-66. http://www.biolbull.org/content/213/1/55.short

Sheehy MRJ, Bannister RCA, Wickins JF, Shelton PMJ. 1999. New perspectives on the growth and longevity of the European lobster (Homarus gammarus). Canadian Journal of Fisheries and Aquatic Sciences 56: 1904-1915. DOI: 10.1139/f99-116

Vogt G. 2008. How to minimize formation and growth of tumours: Potential benefits of decapod crustaceans for cancer research. International Journal of Cancer 123: 2727-2734. DOI: 10.1002/ijc.23947

Vogt G. 2008. The marbled crayfish: a new model organism for research on development, epigenetics and evolutionary biology. Journal of Zoology 276: 1-13. DOI: 10.1111/j.1469-7998.2008.00473.x

Vogt G. 2010. Suitability of the clonal marbled crayfish for biogerontological research: A review and perspective, with remarks on some further crustaceans. Biogerontology 11: 643-669. DOI: 10.1007/s10522-010-9291-6

Wolff T. 1978. Maximum size of lobsters (Homarus) (Decapoda, Nephropidae). Crustaceana 34: 1-14. DOI: 10.1163/156854078X00510 http://www.jstor.org/stable/20103244

Hat tip to Chris Vitek for “Someone is wrong” picture.

12 comments:

missmolamola said...

As usual, another great post :) Thanks for the clarification about this, since I was skeptical about it too, but wasn't exactly sure why and had to hazard a guess when I was asked about it.

Christophe L. said...

Big animals are not likely to be immortal. What about the "immortal jellyfish", Turritopsis Nutricula?
http://en.wikipedia.org/wiki/Turritopsis_nutricula

Zen Faulkes said...

Christophe: Yeah, I forgot to add in claims about the jellyfish. The jellyfish story has also been overblown, most notably late last year in the New York Times.

Here's a post about jellyfish similar to mine on lobsters:

First we get proof of heaven; now the secret of immortality.

Two key extracts:

"His contention: the kind of immortality seen in Turritopsis is far from unique. ‘Immortality might be much more common than we think,’ Peterson says. ‘There are sponges out there that we know have been there for decades. Sea-urchin larvae are able to regenerate and continuously give rise to new adults.’ He continues: ‘This might be a general feature of these animals. They never really die.’

"But were we not told that this obscure organism, and its lone scientific pursuer, were our best chance at understanding immortality? Now we learn that Turritopsis is not unique."

And the second:

"Turritopsis, we now find out, is not immortal:

"‘That word ‘immortal’ is distracting,” says James Carlton, [a] professor of marine sciences at Williams. ‘If by ‘immortal’ you mean passing on your genes, then yes, it’s immortal. But those are not the same cells anymore. The cells are immortal, but not necessarily the organism itself.’

"Humans pass on genes, too. Does that mean we are already immortal? That is, in fact, the principal thing organisms do--pass on their genes. (And the quote itself is confusing. Carlton says the regenerated creature does not have ‘the same cells anymore,’ but then he says ‘the cells are immortal.’ Which is it?)

"The disclosure that immortality is being used in some special sense makes everything we've read meaningless. The semantic distinction means we are not talking about immortality at all--merely about reproducing. Far from being a potential medical breakthrough, the 'immortality' of Turritopsis is nothing more than a biological oddity."

See also: Twisted tree of life award #14: @nytimes and Nathaniel Rich on Immortal Jellyfish

Christophe L. said...

Thanks for the link about the Turritopsis jellyfish. None of this is relevant for humans (contrary to what is implied in that NYT piece). However, I find these oddities of nature quite fascinating by themselves!

Don said...

If I was going name a creature as being immortal I would be looking at planarians. The asexual species just keep on dividing in half and regenerating. Grow, divide, grow, divide, ad infinitum. You'll note there isn't any "die" involved.

Joel said...

I actually looked at this a few years ago, it turns out that lobsters, over time, accumulate a waste material called "lipofuscin", so they do indeed have a measurable aging process:

http://skeptics.stackexchange.com/questions/6561/is-it-impossible-to-tell-a-lobsters-age/6563#6563

Artem Kaznatcheev said...

If a lobsters are functionally immortal and only subject to external threats of death, wouldn't it be reasonable to assume that these external threats are a constant probability of death? Or maybe even decreasing probability with time (since the lobster gets bigger and thus might more easily defend itself; although I guess the counterpoint is that it gets more tasty...)?

If so, then you would expect a power-law distribution of ages for captured lobsters. I wouldn't be surprised if lobster fishers keep data on the size of lobsters they catch, and if lobsters grow throughout their life (as would be consistent with the functionally immortal view) then couldn't you use that size data to get a reasonable estimate of their age? Looks like a fun stats project.

Zen Faulkes said...

Don: Given the track record of immortality claims so far, I am dubious about planarians. Yes, they can regenerate, but at this instant, if I had to bet, I would wager they still have a definite lifespan.

Joel: References! Thank you! Those help.

Artem: "(C)ouldn't you use that size data to get a reasonable estimate of their age?"

That's exactly what the estimates of the biggest lobsters being fifty year old (maybe more) are based on.

Zen Faulkes said...

2 July 2013: For those wondering about claims of jellyfish immortality, check out Deep Sea News: http://deepseanews.com/2013/07/are-jellyfish-immortal/

Garon-Time said...

You're off your game. Successful lab results in wistar rats regarding removing the telomere cap resulted in increasing the average lifespan from 1y and 7-8months to 2y and 4 months, showing a dramatic increase in lifespan.

I don't know what you consider immortality, but there is a difference between being immortal and eternal life.

When exactly in society did immortal mean "cannot die"?

Immortal has always meant cannot die as a result of ones own biological functions (or lack thereof).

You say there is a lack of evidence to suggest immortality, yet its waving its arma in your face, with data nontheless. Lobsters (and most animals) are not like humans in the sense that they are able to escape all predation and build a food chain topping civilization.

The larger an animal gets, the more likely it is to be killed for food.

Technically humans and im sure many other animals have the same immortal potential, we are just too dam vulnerable to dna damage and degradation.

Your criticism here is unfounded and quite frankly doesn't even make sense.

Eric Weihl said...

Zen, I really think you're overlooking something. Both humans and lobsters die of external causes for the most part, but if placed in the correct environment a lobster could live forever where a human would die of old age. That is the entire idea they are trying to portrait. They aren't trying to say that lobsters never die or that there is any lobsters in the wild that could live forever. They are simply saying that given the correct environment they COULD live forever unlike humans. Besides, I've learned not to trust facts from guys in kilts.

Zen Faulkes said...

Eric: "They are simply saying that given the correct environment they COULD live forever unlike humans."

And that's exactly the claim that bugs me most, because I have found not one single, solitary, lone shred of evidence backing it up.

Zip. Zero. Zilch.

Most people seem to be deferring to the NPR interview I mention in the article, which is not the stuff I want to support the claim. I want a paper in a peer-reviewed journal with numbers and statistics and all that stuff so I can evaluate the claim properly.

I keep crayfish in captivity, with lots of food and no predators. They die. No reason to think lobsters are any different than crayfish in that regard.

The claim “Only die from external causes" or “live indefinitely given right conditions" is virtually unfalsifiable. If I said, “Organism X could live indefinitely in the right environment,” how could you disprove that? You always have the wiggle room of saying, “Of, it was just the wrong environment” or “Oh, there was some undiagnosed infection or ailment.” If there is no way claim can be disproven, it’s probably not a scientific claim.

"I've learned not to trust facts from guys in kilts."

I wasn't wearing a kilt during the interview. Just so ya know.