Giving octopuses ecstasy

Nobody told me it was “Drug an invertebrate week.” But not only has a story of lobsters getting pot rather than going into pots made the round, now we have octopuses getting another recreational human drug. The story, according to headlines, is that giving ecstasy (MDMA) to octopuses makes them act more socially. And everyone’s comparing octopuses to ecstasy fueled partygoers at a rave.

It’s a nice narrative, but there isn’t enough evidence to conclude that.

There is some genetic analyses of MDMA receptors in this paper, but all of the interest in the press is about the behaviour experiments. The authors gave the octopuses the drug. The octopuses’ behaviour changed. The popular press is interpreting that behaviour in a cutesy way, using terms like “hug” and “cuddle” in headlines. (Even publications like Nature who should know better.)

That’s a problem. Octopuses hunt prey by enveloping them with their web and tentacles — effectively “hugging” them, if you will. Being eaten is rather different than cuddling. The authors provide no videos in the paper, just two still images (below), so you can’t see the behaviour in detail.

The sample size for the behavioural experiments is 4 or 5, as far as I can see. That’s tiny.

It’s worth noting that the behavioural changes were not always the same.

In addition, pilot studies in 3 animals indicated that higher submersion doses of MDMA (ranging from 10-400 mg/Kg) induced severe behavioral changes (e.g., hyper or depressed ventilation, traveling color waves across the skin or blanching, as well as catatonia or hyper-arousal/vigilance) and these animals were excluded from further analysis.

Dose-dependent responses are not at all unusual, but again, it makes the simple story of “MDMA means social” more complicated.

I do appreciate that this paper has an Easter egg for people who read the methods:

Novel objects consisted of multiple configurations of 4 objects: 1) plastic orchid pot with red weight, 2) plastic bottle with green weight, 3) Galactic Heroes ‘Stormtrooper’ figurine, and 4) Galactic Heroes ‘Chewbacca’ figurine.

But which Stormtrooper, people?

Which Stormtrooper?!

The paper is interesting, but it’s not getting attention from popular press because it’s particularly informative about the evolution of social behaviour. It’s getting attention because of the novelty of giving drugs to animals, and the “Oh look, animals are like us!” narrative.

Additional, 24 September 2018: Another interpretive problem. Normally, in an interview on CBC’s Quirk and Quarks, Gul Dolen notes octopuses overcome their asocial behaviours for mating. Dolen cites this as reason to think that there could be a way to “switch” the octopuses’ behaviour using a drug. So mating behaviour is the natural “social” mode for these animals.

But the octopus under the basket was always male, because the researchers found octopuses avoided males more than females.

Three of the four octopuses tested were male. (I had to dig into the supplemental information for that.) So most of the observations were male-male behaviour. I don’t know that homosexual behaviour has ever been documented in octopuses. A quick Google Scholar search found nothing.

A Washington Post story revealed that the authors’ wouldn’t even talk about some of the behaviours they had seen:

The authors observed even stranger behavior that they did not report in the study, Edsinger said. He was reluctant, even after extensive questioning, to further describe what the octopuses did, because the scientists could not be sure if the MDMA had induced these actions.

This is problematic. This suggests the behaviours in the paper are deeply underdocumented at best. And it seems to be done on purpose, because it doesn’t fit the authors’ narrative. This, combined with the description of behaviours at different doses, it further suggests that rather than “prosocial” behaviour that the authors and headlines are pushing, the exposure to MDMA is making octopuses behave erratically, not socially.

Reference

Edsinger E, Dölen G. A conserved role for serotonergic neurotransmission in mediating social behavior in Octopus. Current Biology 28(3): P3136-3142.e4. https://doi.org/10.1016/j.cub.2018.07.061

External links

Octopuses on ecstasy: The party drug leads to eight-armed hugs
This is what happens to a shy octopus on ecstasy
Octopuses on ecstasy just want a cuddle
Serotonin: octopus love potion?

Picture from here.

The bat signal: Can cricket ears hear their predators?

(This was originally published here in 2005.)

Few events in animal behaviour evoke an observer’s visceral response as interactions between predators and prey, leading to poetic metaphors like, “nature red in tooth and claw.” The mechanisms through which prey avoid being caught and eaten provide some of the best examples of behaviours whose neural basis is reasonably well understood. For example, in fish, the Mauthner cells are key players in generating C-start escape responses (Korn and Faber 2005); in crayfish, the lateral and medial giant interneurons generate escape tailflips (Edwards et al. 1999). Surprisingly, however, our knowledge of when these well studied circuits are triggered by actual predators in the wild is rather limited, though those gaps are beginning to close (Herberholz et al. 2004).

Crickets have neurons that trigger escape responses, named AN2 (also referred to as Int-1). Unlike fishes’ Mauther neurons or crayfish’s giant interneurons, which can be triggered by a wide range of sudden stimuli, AN2 neurons appear to serve as detectors for one particular type of predator, namely echolocating bats (Nolen and Hoy 1984, 1987). While AN2 neurons respond to a wide range of sound frequencies, they are particularly sensitive to ultrasound, that is, sound frequencies that are too high for human ears to hear (Nolen and Hoy 1987). This is the approximately the same range of sound frequencies that echolocating bats use when foraging. But, as a recent paper by Fullard and colleagues (Fullard et al. 2005) notes, the key word is “approximately.” There are many species of bats, which differ in their foraging tactics, and emit a wide range of sounds as they do so. Most lab studies, for understandable reasons of simplicity and convenience, have used pure tones generated by computers to trigger crickets’ auditory neurons.

Fullard and colleagues studied Teleogryllus oceanicus, a cricket species found across much of the western Pacific. They recorded the calls of a half-dozen species of bats that share habitat with this cricket, then recorded AN2 neurons as they played back the bat calls at different sound intensities.

The crickets’ AN2 neurons responded to calls from all six bat species, if the sound intensity was 80 decibels sound pressure level (dB SPL) or more, although they did not react equally to all bat search calls.

Simply firing the AN2 neuron, however, does not determine if the cricket can avoid a foraging bat, because a single spike of AN2 is not sufficient to trigger an escape response (Nolen and Hoy 1984). By examining the pattern of firing in more detail, the authors were able to estimate how far away a bat call might trigger an escape response. Only calls by three of the bat species fired AN2 neurons strongly enough to generate escape responses before the bat would be aware of the cricket's echo.

If the AN2 is indeed a “bat detector,” it is reasonable to hypothesize that it has been shaped by natural selection to detect bat species living in the same habitat. All bat calls tested were from species that live in the same regions as T. oceanicus (i.e., sympatric species), but one might reasonably predict that AN2 should be less responsive to calls of bats that do not live in the same regions (i.e., allopatric species). That T. oceanicus has such a wide distribution, however, might mean that its auditory system has remained a bat “generalist.” Another prediction of the “bat detector” hypothesis would be that the bats that AN2 detects best would be those of species that are the most successful predators of crickets. In this case, the bat species Tadarida australis generated the greatest AN2 responses, raising the question of what the natural ecological interactions are between the cricket and the bat.

The bat species that is arguably the least conspicuous to crickets demonstrates the importance of understanding natural ecology in interpreting patterns of neural activity. Of the six species of bat whose calls were tested, the least conspicuous to crickets was Nyctophilus geoffroyi, because the echolocating calls of this species are too short and too high frequency for the crickets’ ears to detect reliably. The simple hypothesis might be that this bat species is a mammalian “stealth bomber:” by using echolocation calls that are almost undetectable by crickets, the bat would seem to be well equipped to pluck crickets from the air at will. Instead, N. geoffroyi seems to forage primarily by “gleaning,” i.e., locating insects by the sounds they emit and picking them off the ground (Bailey and Haythornthwaite 1998), a tactic that circumvents crickets’ tuned AN2 “bat detector” almost entirely.

References

Bailey WJ & Haythornthwaite S. 1998. Risks of calling by the field cricket Teleogryllus oceanicus; potential predation by Australian long-eared bats. 513. Journal of Zoology 244(4): 505-513

Edwards DH, Heitler WJ, & Krasne FB. 1999. Fifty years of a command neuron: the neurobiology of escape behavior in the crayfish. Trends in Neurosciences 22(4): 153-160.

Fullard JH, Ratcliffe JM, & Guignion C. 2005. Sensory ecology of predator-prey interactions: responses of the AN2 interneuron in the field cricket, Teleogryllus oceanicus to the echolocation calls of sympatric bats. Journal of Comparative Physiology A 191(7): 605-618.

Herberholz J, Sen MM, & Edwards DH. 2004. Escape behavior and escape circuit activation in juvenile crayfish during prey-predator interactions. The Journal of Experimental Biology 207(11): 1855-1863.

Korn H & Faber DS. 2005. The Mauthner Cell half a century later: A neurobiological model for decision-making? Neuron 47(1): 13-28.

Nolen TG & Hoy RR. 1984. Initiation of behavior by single neurons: The role of behavioral context. Science 226(4677): 992-994.

Nolen TG & Hoy RR. 1987. Postsynaptic inhibition mediates high-frequency selectivity in the cricket Teleogryllus oceanicus: implications for flight phonotaxis behavior. The Journal of Neuroscience 7(7): 2081-2096.

Wake up calls for scientific papers

I once called scientific articles “love letters to the future.” I was making the point that just because a paper doesn’t get cited soon after its publication does not mean that it is useless.

A new article by Ho and Hartley bears out that description. It focuses on three papers that were largely uncited for many years, the, for some reason, it was noticed and became widely cited.

The authors don’t use my romantic term. There is another established term for these papers, also with romantic overtones: “sleeping beauties.” They pick out three, from the field of psychology, which hasn’t been studied before. This one has the most dramatic citation shift, really only picking up steam when it reached retirement age (65 years after publication!)

While it is encouraging to know that these reversals of fortune can happen, Ho and Hartley show that they are extremely rare. They found only three cases out of over 300,000 psychology papers (0.001%).

The duo don’t identify who re-popularized these papers. It’s a little frustrating, because the paper is pretty short.

Hat tip to Remi Gau and Neuroskeptic.

Reference

Ho Y-S, Hartley J. 2017. Sleeping beauties in psychology. Scientometrics 110(1): 301-305. http://dx.doi.org/10.1007/s11192-016-2174-0

Related posts

Better a deluge than a drought

Picture from here.

Misunderstanding antibiotic resistance

Even people who try to incorporate evolutionary thinking into their research struggle with the concepts, it seems.

Thomas Wittum was interviewed on Quirks and Quarks about finding bacteria in a pig farm that were resistant to one of the “last resort” antibiotics. He repeatedly put forward the idea that these bacteria must have been introduced there from a human health care facility, like a hospital, where these particular classes of antibiotics are used the most.

This notion come perilously close to the idea that organisms evolve features that they “need.” The thinking seems to go that antibiotic resistant bacteria must come from hospitals, because why would bacteria is someplace without those antiobiotics have resistance to them?


This misses the concept of “standing variation”: that any population can have variation in a trait in the absence of any selection pressure for one version of the trait or the other. If you look at classic cases of dark coloured insects, like peppered moths, flourishing in industrial areas (industrial melanization, for those who know the fancy words), populations always had some dark insects around before industrialization. That’s standing variation. Later, the dark colour provided an advantage as the landscape got darker. But the key point is that the insects didn’t newly evolve dark colouration as regions became industrialized, because they needed it.

Similarly, it is possible that these farm bacteria came had antibiotic resistance “out of the box,” so to speak. The resistance would do very little in the farm setting, but... if those bacteria were in an environment where those antibiotics were released, they would suddenly have a huge advantage.

Having said that, it is entirely possible that the antibiotic resistance did come from a hospital or someplace similar. The manuscript itself (Mollenkopf et al., in press) doesn’t address the source of the bacteria, or the antibiotic resisting gene. But it’s not a good assumption that if we create a new antibiotic, there will be no bacteria that will be able to survive it at the start. Some bacteria might, by chance, already have a way to evade the antibiotics.

References

Mollenkopf DF, Stull JW, Mathys DA, Bowman AS, Feicht SM, Grooters SV, Daniels JB, Wittum TE. Carbapenemase-producing Enterobacteriaceae recovered from the environment of a swine farrow-to-finish operation in the United States. Antimicrobial Agents and Chemotherapy: in press. http://dx.doi.org/10.1128/AAC.01298-16

External links

Drug resistant "superbug" gene found on pig farm

Picture from here.

Emily through the aquarium glass: The Dragon Behind The Glass reviewed

Ahab had a great white whale.

Emily Voigt had a great red fish.

Then a great batik fish.

Then a great silver fish.

In every case, Voigt is pursuing the arowana. She first hears the name from a law enforcement who is talking to her about the exotic pet trade in New York. She learns that the arowana is a large fish prized by a certain kind of aquarium owner: usually Asian, male, and rich. The latter is the most necessary feature for many arowana owners, because single individual arowanas are fetching hundreds of thousands of American dollars.

That’s not a typo. It’s no surprise that you find arowana gracing the landing page of Aquarama, a trade show for the aquarium industry that Voigt visits early in the book.

Even by the time Voigt visits Aquarama, it’s clear that the arowana is the center of an unusual market, often shrouded in secrecy, and both threats and acts of violence. Again and again throughout the book, arowana are stolen, smuggled, and fought over, both in the professional and literal sense of the word.

The strangeness of it all is compelling for the reader and Voigt, who ends up pursuing this fish through multiple countries and jungles. She’s accompanied by a memorable set of other people, who I found myself constantly googling to see by the time I reached the second half of the book.

The Dragon Behind the Glass is not an academic work, but it almost could have been. Voigt’s research on the pet trade and the science is flawless. There is lots of solid biology and scientific history. For instance, we learn one species of arowana was collected and drawn by no less than the co-discoverer of natural selection, Alfred Russel Wallace, on an expedition to the Amazon that was ultimately doomed. (Sean Carroll’s Into the Jungle describes why in more detail than here. It’s about the only example in the book where I felt Voigt missed a good story.)

I came to this book because of my own research on the aquarium industry. But I was an armchair investigator. I was frustrated by my inability to get a handle on much of the supply chain for aquarium animals (crayfish in my case). Voigt provides that inside view of the production and wholesale end of the aquarium trade, and has many thoughtful asides about the pet trade. She considers the pros and cons of collecting from wild populations, CITES listings, and the paradox of the arowana being “a mass produced endangered species” (a term that applies perfectly to some crayfish in the pet trade, too).

While I was originally interested in this book because of its relevance to my own research, I kept reading because it was intertwined with the personal stuff, and her own jungle adventures, in such an entertaining way. Voigt is self aware enough to realize that her interest in this fish is... not normal. There’s a recurring theme of, “Why am I doing this and is it worth it?” that I think anyone deeply invested in a project will recognize.

The Dragon Behind the Glass is part exposé, part travelogue, part scholarship, and part descent into madness. It’s a combination as addictive as a skillfully made desert.

External links

Emily Voigt
The Dragon Behind the Glass (publisher page)
The Dragon Behind the Glass (Amazon page)
The deadly trade around exotic fish
Aquarama trade show
Early evolution pioneers’ artwork now online


Talks at Google:

A handy new Intelligent Design paper

Back on January 5, PLOS ONE published an Intelligent Design paper containing numerous references to “the Creator.” Judging from the consistent use of capitals, this would mean the Judaeo-Christian God.

I have no idea how this went unnoticed by science social media. The paper didn’t bury this, but announced it right in the abstract:

The explicit functional link indicates that the biomechanical characteristic of tendinous connective architecture between muscles and articulations is the proper design by the Creator to perform a multitude of daily tasks in a comfortable way.

The Introduction marks it as an Intelligent Design paper:

Hand coordination should indicate the mystery of the Creator’s invention.

And again in the discussion:

In conclusion, our study can improve the understanding of the human hand and confirm that the mechanical architecture is the proper design by the Creator for dexterous performance of numerous functions following the evolutionary remodeling of the ancestral hand for millions of years.

Judging from the rest of the text,the paper probably has other credible information, which is probably why PLOS ONE published it. PLOS ONE reviews for technical competence, not importance.

From my point of view, these three sentences should have been removed as a condition of publication. Random references to a “Creator” do not advance the argument of the paper. It is not at all clear what predictions flow from the “Creator” hypothesis. The authors do not support the “Creator” hypothesis with relevant literature from the biomechanical field. In short, references to a “Creator” mark the paper as not competent science, and thus unfit for publication under PLOS ONE’s standards.

This might be one of the few times that a peer-reviewed journal has published an Intelligent Design paper. The best known was a paper by Stephen Meyer in the Proceedings of the Biological Society of Washington, over ten years ago. It was much more explicit about its Intelligent Design aspirations than this one, and it got in by... suspect methods of dodging peer review.

PLOS ONE made a mistake. It’s not a big one, as far as mistake go. Reasonable people can disagree over how big a mistake it is. It’s probably not as bad as running an entire journal devoted to homeopathy (say). It’s not surprising that the biggest journal in the world, handling thousands of papers annually, makes mistakes. They’re far from the only journal to have published texts with religious overtones.

It’s an embarrassing mistake because it would have been so easy to fix. Change three sentences, and this paper would be uncontested. Good editing is valuable, not disposable.

Hat tip to James McInerney and Jeffrey Beall.

Update: Oh yeah, this story is now burning up my Twitter feed. PLOS ONE tweeted that they are looking into this paper.

Update: Grant pointed out that even one of the paper’s own authors doesn’t seem to buy into their references to “the Creator”:

Update: Terry McGlynn notes that the lab page of one of the authors doesn’t appear to have any overt religious overtones. Several people are suggesting that this is a mistranslation. I’m not convinced (nor are others). Even if it is “just” a mistranslation, the journal doesn’t come out looking much better, because it highlights weak editing.

The hashtag for this has been deemed #HandOfGod.

Update, 1:12 pm: PLOS ONE writes:

The PLOS ONE editors apologize that this language was not addressed internally or by the Academic Editor during the evaluation of the manuscript.

Reference

Liu M-J, Xiong C-H, Xiong L, Huang X-L. 2016. Biomechanical characteristics of hand coordination in grasping activities of daily living. PLOS ONE 11(1): e0146193. http://dx.doi.org/10.1371/journal.pone.0146193

External links

The shroud of retraction: Virology Journal withdraws paper about whether Christ cured a woman with flu
Hands are the “proper design by the Creator,” PLOS ONE paper suggests

Open access paper, closed data

A new paper in Science Advances by Kicheli-Katz and Regev (2016) is interesting in several ways. It’s a very interesting look at gender bias using eBay auction data.

I’ve used data from eBay myself (Faulkes 2015), and it was hard going. I visited the website roughly daily and pulled auction data into a spreadsheet by hand for each listing. Nothing was automated.

Kicheli-Katz and Rege, however, got data directly from eBay. And they got over one million transactions to analyze. That’s an awesome sample that gives them a lot of statistical power. I was curious to know more, but found this text in several places in the paper.

According to our agreement with eBay, we cannot use, reproduce, or access the data.

I raised my eyebrows at that a bit. All sorts of questions bubbled into my mind. The acknowledgements section provided more detail, however:

eBay has provided written assurance that researchers wishing to replicate the work would be afforded access to the data under the same conditions as the authors.

Okay. That’s more helpful information, and I wish it was in the main body of the text, rather than buried at the end of the acknowledgements. On the Science Advances webpage, it is the second to last thing on the page (the last is the copyright notice).

Clearly, social media companies realize that their data is scientifically valuable and want to use that for their own gain. OKCupid used to write amazing blog posts based on their data that give you a hint of how rich the kinds of questions and answers you can tackle are using large social media datasets. (Although OKCupid also got flak for running unregulated experiments on its users, and rightfully so.)

The eBay disclaimer runs counter to the major trends we are seeing in scientific publication: more transparency, more access to raw data. I am not sure how confident I am with eBay’s promise to share the data with other researchers. From the point of view of reading this paper, eBay is mostly a big black box.

Update, 12 April 2017: I emailed the eBay representative listed as a contact in the paper on 26 February 2016, inquiring about working with eBay’s research lab.

I never got a reply.

References

Kricheli-Katz T, Regev T. 2016. How many cents on the dollar? Women and men in product markets. Science Advances 2(2): e1500599. http://dx.doi.org/10.1126/sciadv.1500599

Faulkes Z. 2015. Marmorkrebs (Procambarus fallax f. virginalis) are the most popular crayfish in the North American pet trade. Knowledge and Management of Aquatic Ecosystems 416: 20. http://dx.doi.org/10.1051/kmae/2015016

Picture from here.

Tuesday Crustie: Down deep

This crustacean isn’t big, but space is in short supply when you’re 1.4 kilometers under the surface of the earth.

This little animal may be a copepod - Borgonie and colleagues (2015) list it as Amphiascoides with a question mark behind it, but provide no more details.

This picture has been contrast enhanced from the original in the journal article.

Reference


Borgonie G, Linage-Alvarez B, Ojo AO, Mundle SOC, Freese LB, Van Rooyen C, Kuloyo O, Albertyn J, Pohl C, Cason ED, Vermeulen J, Pienaar C, Litthauer D, Van Niekerk H, Van Eeden J, Sherwood. Lollar B, Onstott TC, Van Heerden E. 2015. Eukaryotic opportunists dominate the deep-subsurface biosphere in South Africa. Nature Communications 6: 8952. http://dx.doi.org/doi:10.1038/ncomms9952

External link 

Animals found living in rock deep, deep underground

Leader of the pack: fleshing out Velociraptor behaviour in Jurassic World

“Do we know Velociraptors were pack hunters, or did the filmmakers just make that up?”

That question came up on the Nature “Backchat” podcast during discussion of Jurassic World. None of participants had a good answer, so here’s mine.

The first thing you have to understand is that the Velociraptor in Jurassic Park / Jurassic World is not the Velociraptor that actually lived. It’s Deinonychus in disguise.

It’s a shame that Velociraptor has stolen the thunder from Deinonychus. It’s hard to underestimate how important Deinonychus was to our current conception of dinosaurs. When Ostrom (1969) published his description of Deinonychus, people were still showing sauropods in the swamps and lakes. Dinosaurs were sluggish lizards.

The description of Deinonychus blew those ideas of dinosaurs out of the water. The claw on the legs was the feature that led Ostrom to suggest that Deinonychus must have been an agile, active hunter. The claw only made sense as a slashing appendage.

The frontispiece of the description is this reconstruction by Bob Bakker (who would go on to be a major proponent of “hot blooded” dinosaurs):

Badass, right?

And not at all far from what you see in Jurassic World! The main difference is that Ostrom estimated Deinonychus stood about one meter high, and was maybe three meters from nose to tail. It’s a lot smaller than the Jurassic World beasts.

Here’s where the idea of theropods as pack hunters all started, on page 144 of Ostrom’s monograph:

(A)t least three and perhaps four or five individuals are represented among the Deinonychus remains collected from just a small area at the Yale site. These remains were associated with fragments of only one other species — a moderate-sized ornithopod that weighed perhaps five or six times as much as Deinonychus. The multiple remains of the latter suggest that Deinonychus may have been gregarious and hunted in packs.

(Ornithopods, incidentally, are big herbivores like Iguanadon.)

 So Jurassic Park did not just pull the idea of pack hunting dinosaurs out of nowhere. It was a serious suggestion made by a proper scientist in the scientific literature.

For some reason, when Michael Crichton wrote the book Jurassic Park, he took that idea of Deinonychus as pack hunters and applied it to velociraptors. I’m guessing that the reason he did this was so he could call them “raptors,” which people knew as birds of prey. Crichton was very big on emphasizing the relationships between birds and dinosaurs. It comes up over and over again in the book, and was carried through to the movie. (When I rewatched Jurassic Park in the last month in preparation for Jurassic World, the “just like birds” didactic dialogue felt the most dated.)

Crichton’s decision was weird, though, because velociraptors were, um, way less badass than Deinonychus:

Velociraptors were pretty small. (Dan Telfer does a hysterical riff about this in his stand-up routine, “The best dinosaur.”)

When Steven Spielberg made Jurassic Park, he thought even Deinonychus was too small and made his theropods bigger than any that had been found at the time. He was vindicated, however: the same year, a Jurassic Park-sized dinosaur called Utahraptor was described (Britt et al. 1993).

A year later, Ostrom gave a talk where he described Deinonychus as “the ultimate killing machine,” which suggests he was still on board with the portrayal of theropods in Jurassic Park.

How has the pack hunting hypothesis held up since 1969? Maybe not that great. Roach and Brinkman (2007) reevaluated the pack hunting idea:

(W)e conclude that this hypothesis is both unparsimonious and unlikely for these taxa(.)

Sigh. There you go again, science, wrecking childhood dreams! Years from now, we’ll get adults saying, “What do you mean, raptors weren’t pack hunters?!” with the same indignation that we’ve seen over the loss of Pluto or Brontosaurus as names. (Though we might have gotten bronto back!)

The portrayal of pack hunting meat eating dinosaurs is so entrenched now that we’ll probably get movies showing us feathered theropods before we get solitary ones.

Update: Anthony Martin pointed out that there has been some more evidence on theropod group behaviour. A 2008 paper by Li and colleagues found six sets of footprints of Deinonychus-like animals, running in parallel and closely spaced, apparently made simultaneously.

They interpreted this as evidence for group behaviour. For instance, that they are parallel suggests that these weren’t just six animals walking along in the same direction because of some physical feature in the landscape. Then, the tracks might go in the same direction, but overlap when one animal walked behind another.

Of course, this doesn’t prove pack hunting. The fossil you’d want to find would be one big animal buried with a few theropods with their claws embedding in the prey’s body. Maybe that fossil exists, still waiting for someone to dig it up...

References

Britt B, Chure D, Stadtman K, Madsen J, Scheetz R, Burge D. 2001. New osteological data and the affinities of Utahraptor from the Cedar Mountain Fm. (Early Cretaceous) of Utah. Journal of Vertebrate Paleontology 21: 1-117. DOI: 10.1080/02724634.2001.10010852

Li R, Lockley M, Makovicky P, Matsukawa M, Norell M, Harris J, Liu M. 2008. Behavioral and faunal implications of Early Cretaceous deinonychosaur trackways from China. Naturwissenschaften 95(3): 185-191. DOI: http://dx.doi.org/10.1007/s00114-007-0310-7

Ostrom JH. 1969. Osteology of Deinonychus antirrhopus, an unusual theropod from the lower Cretaceous of Montana. Bulletin of the Peabody Museum of Natural History 30:1–165.
http://peabody.yale.edu/sites/default/files/documents/scientific-publications/ypmB30_1969.pdf

Ostrom JH. 1994. Deinonychus, the ultimate killing machine. In: Rosenberg GD, Wolberg DW, editors. eds. Dino Fest: proceedings of a conference for the general public, March 24, 1994. Knoxville, TN University of Tennessee, Department of Geological Sciences. pp. 127–137. (The Paleontological Society, Special Publication 7.).

Roach BT, Brinkman DL. 2007. A reevaluation of cooperative pack hunting and gregariousness in Deinonychus antirrhopus and other nonavian theropod dinosaurs. Bulletin of the Peabody Museum of Natural History 48(1):103-138. DOI: http://dx.doi.org/10.3374/0079-032X(2007)48[103:AROCPH]2.0.CO;2

Tuesday Crustie: Beautiful

Meet Cherax pulcher. Its last name, “pulcher,” literally translates to “beautiful.”

Unfortunately, the beauty of this species may be its downfall. They are already for sale, and collected in large numbers, in the pet trade. And since the species is new to science, we know almost nothing about its basic biology.

Astacologist Chris Lukhaup mentioned on his Facebook page that he’s spent over a decade working on the description of this gorgeous new species. They aren’t all this pretty; there are a couple of different morphs, and no doubt Chris’s considerable photographic talents are at play in this picture, too.

Update, 13 May 2015: This crayfish is featured in this New Scientist article. Warning: contains me.

Update, 15 May 2015: It’s so nice to see crayfish in the news, and attention being drawn to the potential dangers of exploiting an almost unknown species for the pet trade. This article in the Washington Post says the species looks like a Lisa Frank creation... wait, did they steal Jason Goldman’s joke?

Reference

Lukhaup C. 2015. Cherax (Astaconephrops) pulcher, a new species of freshwater crayfish (Crustacea, Decapoda, Parastacidae) from the Kepala Burung (Vogelkop) Peninsula, Irian Jaya (West Papua), Indonesia. ZooKeys 502: 1-10. http://dx.doi.org/10.3897/zookeys.502.9800

Studying species you like

As an undergraduate, one of my professors recommended that you should study organisms that you like. In a new paper, Ferry and Shiffman talk about not getting that advice... in fact, they received advice that was about 180° away from it:

Scientists should not, according to this instructor while singling out DS and a student studying marine mammals as examples, pick a species that they “like” and then come up with a research question related to it. Author LF had a similar experience in graduate school, as she was also studying elasmobranchs. Both are/were perceived as “shark-huggers,” and felt pressure to defend their study organisms.

Ferry and Shiffman mention one common reason to study a particular organism: some are just convenient. It’s convenient for neurobiologists that squid have especially large axons, for instance. This is encapsulated as the Krogh principle, after physiologist August Krogh (pictured), who codified it thus:

For many problems there is an animal in which it can be most conveniently studied.

However, convenience is not, and should not, be the sole arbiter of species that people study. In fact, Krogh himself mentioned this, in the very same article (my emphasis):

I want to say a word for the study of comparative physiology also for its own sake. You will find in the lower animals mechanisms and adaptations of exquisite beauty and the most surprising character(.)

Every person picks what they study for their own reasons. It might be the organism, it might be the question, it might be something else. None of those many reasons reasons is inherently better than any other. To pick on someone for doing science than a different reason you do is pompous.

Additional: Katie Pieper made this useful remark:

But the system must be well suited for the question.

References


Ferry LA, Shiffman DS. 2014. The value of taxon-focused science: 30 years of elasmobranchs in biological research and outreach. Copeia 2014(4): 743-746. http://dx.doi.org/10.1643/OT-14-044


Krogh A. 1929. The progress of physiology. American Journal of Physiology 90: 243–251. http://ajplegacy.physiology.org/content/90/2/243

Elephants have more neurons than humans

We are always impressed by animals with large brains, because we have large brains. But, of course, even though we arguably show some of the greatest behavioural complexity, we don’t have the biggest brains, as this beautiful face reminds us.

Souzana Herculano-Houzel has proposed a simple hypothesis: the reason humans are as smart as we are is because we have more neurons than other animals.

What is it that we have that no other animal has? My answer is that we have the largest number of neurons in the cerebral cortex, and I think that’s the simplest explanation for our remarkable cognitive abilities.

“But we don’t have the biggest brains! Big animals have bigger brains! How can we have more neurons than they do?”

Herculano-Houzel has been investigating the scaling relationships between brain size and neuron number. The way brains get big differ in different groups of mammals (Herculano-Houzel 2009). In rodents, larger brains tend to have larger neurons. Primates follow different rules: larger brains tend to have neurons of about the same size.

This means that if you started with a rodent brain and a primate brain of the same size, and increased their volume by the same amount, the primate brain would get disproportionately more neurons.

This means that you can’t easily predict the brain size from one group of mammals using data from another group of mammals.

Herculano-Houzel and colleague recently published a pair of papers to test the “more neurons, more behavioural complexity” hypothesis using the elephant. First, Neves and colleagues (2014) examine the number of neurons in afrotherian mammals. The number of neurons in their brains scale with more like rodents than primates.

Although elephants are afrotherians, the analysis of their neuronal numbers comes in a separate paper (Herculano-Houzel et al., 2014). The total number of neurons in an African elephant’s brain is estimated to be three times greater than in humans (257 billion neurons compared to 86 billion)... but a huge proportion of those are in the cerebellum. And by huge, I’m talking about 97%.

The elephant’s cerebellum seems to be an outlier among mammals in several ways, but I’m not sure why. I’m not sure Herculano-Houzel or her colleagues know why, either. The “quick and dirty” function of the cerebellum in mammals is usually described as motor control, and maybe the distinctive trunk of elephants is playing an important role here.

How about the cortex, the centerpiece of Herculano-Houzel’s behavioural complexity hypothesis? An elephant’s cortex has about 5.6 billion neurons, compared to a human, which is estimated at around 16 billion.

This certainly seems consistent with her hypothesis, although I’m always a little wary of ascribing too much weight to the importance of the cortex. Karl Lashley spent a lot of time looking for the seat of memory in the cortex because people thought it must be important, and in so doing, overlooked the hippocampus in the formation of memory.

It would not surprise me in the slightest if Herculano-Houzel has whale brains in her lab awaiting analysis. Whales are the next obvious group to use these techniques with.

References

Herculano-Houzel S. 2009. The human brain in numbers: a linearly scaled-up primate brain. Frontiers in Human Neuroscience 3: 31. http://dx.doi.org/10.3389/neuro.09.031.2009

Neves K, Meireles Ferreira F, Tovar-Moll F, Gravett N, Bennett NC, Kaswera C, Gilissen E, Manger P, Herculano-Houzel S. 2014. Cellular scaling rules for the brain of afrotherians. Frontiers in Neuroanatomy 8: 5. http://dx.doi.org/10.3389/fnana.2014.00005

Herculano-Houzel S, Avelino K, Neves K, Porfirio J, Messeder D, Mattos Feijó L, Maldonado J, Manger P. 2014. The elephant brain in numbers. Frontiers in Neuroanatomy 8: 46. http://dx.doi.org/10.3389/fnana.2014.00046

Photo by Neil Hall on Flickr; used under a Creative Commons license.

Build your brain by losing that gut

The old joke goes that places with terrible weather are made that way so only the best people live there. Dullards can’t hack it.

This little guy shows there may be some truth to that.

This is a black-capped chickadee (Poecile atricapillus). It’s a small bird that ranges over much of North America. Because it has such a wide distribution, the birds that live in different areas are slightly different from those that live in other areas. A recent paper by Kozlovsky and colleagues takes advantage of that to test an idea about brain size.

The expensive tissue hypothesis is an idea that says if you have more of one kind of expensive tissue (like brains), you will either have to:

• Increase your overall metabolic rate to pay for the extra tissue.
• Give up something. The original paper suggested that the gut was a prime candidate for reduction when brain size went up. It was also expensive, and you could compensate for a small digestive system with higher quality food.

A few papers have tested this, but this one is nice because it is all a single species. Kozlovsky and colleagues show nicely that the bigger the brain in the chickadee, the smaller the stomach and gut. This cleanly fits the expensive tissue hypothesis.

Heart size, on the other hand, does not correlate with brain size in any way. Again, this fits the original formulation of the expensive tissue hypothesis,  which predicted that heart muscle would be unaffected by brain size. The need to pump blood kind of limits how much you can reduce heart tissue.

What was a little less expected was the influence the climate had on the birds.

The birds living in cold climates, like Fairbanks, Alaska (pictured) had bigger brains, and smaller bodies, than those living in more moderate, easy-going climes. Either one might be easy to explain on its own, but the combination is unexpected. Usually, both body size and brain size go up hand in hand (or, in this case, wing in wing). It’s not entirely clear how this is happening, although it certainly suggests there are some strong weather-related selection pressures shaping both features.

One factor that might be coming into play is that chickadees are food caching birds, and cold weather may actually allow the northern chickadees to store higher quality food for longer. The Alaskan chickadees live in a deep freeze, as it were, that lets them store insects and such for longer, because the cold weather means they don’t rot.

Just when I was finishing this blog post, I saw this tweet:

Completing a PhD requires brains, guts, perseverance(.)

But... but... if you have more brains, you can’t have as much guts! It reminded me of another old joke: “Good. Fast. Cheap. Pick two.”

Reference

Kozlovsky DY, Branch CL, Roth II, TC, Pravosudov VV. 2014. Chickadees with bigger brains have smaller digestive tracts: a multipopulation comparison. Brain, Behavior and Evolution 84: 172-180. DOI: http://dx.doi.org/10.1159/000363686

Bird photo by Rick Leche on Flickr; winter picture by Curt on Flickr; both used under a Creative Commons license.

Glam sticks: the next crystal ball for academic success

A new paper by van Dijk and colleagues claims to have figure out how to predict “success on the academic job market,” according to the title. Given how tight the academic job market is, you might expect this paper to get a lot of downloads.

But the paper’s title promises waffles and the paper delivers pancakes.

If you have a paper that claims to be able to predict success in the job market, you might expect that the authors have measure things like how many people in their pool get tenure-track job offers, how many are awarded tenure, and so on. They don’t measure employment at all.

This paper says it measures the probability of someone becoming a principle investigator. That term is mostly user in reference to grants, so you might think that they are looking through award databases to see what people have gotten grants. They don’t measure granting success, either.

What this paper measures is how people become last author on papers. There is an assumption here that the last author is the “boss” of the paper. This isn’t a bad assumption, but authorship is a compleicated game, and people don’t always follow expected conventions for authorship (Shapiro et al. 1994).

van Dijk and company dug into PubMed, and tracked the publication records of many thousands of individual authors. They were careful to try to remove people who have similar names, so that each record is a single author. Using PubMed as a data source has its limitations, since PubMed’s purpose is to archive biomedical literature. It is an open question whether the patterns van Dijk and colleagues find would hold for other fields, like physics, social sciences, or even non-medical biology.

They find some very interesting patterns. The best predictor of quickly becoming last author on a series of papers is the Impact Factor of the journals you publish in early in your career. Frankly, this is extremely depressing news for those of us interesting in breaking the back of Impact Factor into a thousand pieces, because it shows, “Glam sticks.”

There is hope, though: if you can’t publish in the glamor magazines, you can publish a lot. People could also make the transition to last author by publishing a lot of papers, although the effect wasn’t as big as Impact Factor.

The authors also show that – to almost nobody’s surprise – it helps to be a guy. And it helps to have a degree from a fancy university. I’m still trying to work out if there are any confounds in their discussion of university rankings, however. The universities are partly ranked using the same publication metrics that they use elsewhere in the paper, so it’s not surprising that the university rankings are correlated with other features they include in their prediction algorithm.

If you are willing to accept the authors’ peculiar definition of “PI” as a proxy for “academic success,” there is a lot of interesting stuff in this paper.

Additional, 3 June 2014: If you want to play around with the authors’ prediction algorithm, they have a website called PI Predictor. It is a bit reassuring to know that the odds were in my favour.

Also, I’m quoted in this Nature News piece about the article.

Reference

Shapiro DW, Wenger NS, Shapiro MF 1994. The contributions of authors to multiauthored biomedical research papers. JAMA 271: 438-442. http://dx.doi.org/10.1001/jama.1994.03510300044036

van Dijk D, Manor O, Carey LB 2014. Publication metrics and success on the academic job market. Current Biology 24(11): R516-R517. DOI: 10.1016/j.cub.2014.04.039

External links

Van Noorden R. 2014. Computer model predicts academic success. Nature. http://dx.doi.org/10.1038/nature.2014.15337
Bohannon J. 2014. Science Moneyball: The Secret to a Successful Academic Career
Bohannon J. 2014. Want to Be a PI? What Are the Odds? Science Careers http://dx.doi.org/10.1126/science.caredit.a1400136
Bohannon J. 2014. Career moneyball. Science Careers. http://dx.doi.org/10.1126/science.caredit.a1400135

Deep freeze leech, or: the ultimate brain freeze

Recently, I spotted this graph on one of my social media platforms:

For those not familiar with the kelvin scale, 100 kelvin is -173°C. But soon after I saw this, I read a paper that is going to require a slight modification to this graph:

Meet the animal that forced the rewrite: Ozobranchus jantseanus.

This is a leech that lives on Japanese turtles. Some turtles can spend most of the winter under ice, so they get very cold, which in turn means anything on them will also get very cold. Cold is a problem for animals, for reasons you can see in this video:


The can is actually a good model for why freezing is bad for organisms. Water is weird: it expands when it freezes. If you think of the can as being like a cell, freezing causes all sorts of damage. Some species are able to tolerate freezing temperatures with biological antifreezes and other tricks.

But very fee are able to take it to the extreme of the leech above.

Suzuki and colleagues (2014) tested seven different species leeches, and froze then at -90°C.

Six of those species died. Ozobranchus jantseanus lived. Not only that, they could survive being frozen at -90°C for almost a year. And they could be frozen and thow out again up to five times before suffering any mortality.

Not content, Suzuki and colleagues decided to up the ante. They dropped these animals into liquid nitrogen, and left them there for 24 hours. All of them (tried with five individuals) revived when they were thawed back up, and lived over a month. Now, the animals that were frozen were not entirely normal. They couldn’t stretch the way they could before hand, but they were most definitely alive, moving under their own power.

This stunned me, and I thought for sure that this must be a record holder. But it turns out that there are a few other species that can take extreme temperatures, with the coldest being the larva of a fly (Polypedilum vanderplanki) that can survive a stunning -270°C. It does this by drying itself out completely, virtually becoming a living rock (“vitrifcation”).

How the leeches are doing this is not worked out at all in this paper. It must be some standing feature of the animal, because they are essentially flash frozen. There is not time for any sort of physiological or cellular response to kick in from a reaction to the cooling.

This is a very cool result (pun intended). One of the research groups that must be excited about this are the people interested in exobiology and the prospects of life on other planets. If something can survive these sorts of extremes, it significantly stretches the possible environments in which we might find life.

And this post gives me an excuse to feature one of my favourite movie musical numbers in years, this show stopper from Frozen:


Reference

Suzuki D, Miyamoto T, Kikawada T, Watanabe M, Suzuki T, Uemura M. 2014. A leech capable of surviving exposure to extremely low temperatures. PLoS ONE 9(1): e86807. DOI: 10.1371/journal.pone.0086807.t001

The frog came back, the very next day

Given how often we can’t find our car in a parking lot, it’s no wonder that the wayfinding abilities of animals impress and amaze us. We’ve all heard the stories of pets that find their way back to their homes, how salmon find their way back to the particular they were hatched in years after roaming around in the open oceans, and how pigeons can find their roost, even when taken to places that they have never been before.

A new paper adds another animal to the list of pathfinders, and it’s this little guy here:

This is a poison dart frog (Allobates femoralis). We normally don’t think of amphibians as animals that travel great distance, but this species has complicated territorial behaviour. The frogs defend a territory that is is about 14 meters across, which is pretty large compared to their body size. This led Pašukonisand and colleagues to test whether this frog could find its way around in its natural habitat.

The experimenters “translocated” a bunch of male frogs from their territories to new locations. To these frogs, this is probably what the scientists seemed like:

Translocation is basically the scientific equivalent of stuffing you in a car trunk, driving around for a few hours, then letting you out in the middle of the nowhere and telling you that you’re walking home.

The frogs were moved anywhere from 50 to 800 meters. The frogs performed very well for distances up to 200 meters: 87% of them made the long walk back to their original territory. At 400 meters, only about a third of the frogs got home, and none made it back from 800 meters.

The authors looked at a few other variables, like the directions the frogs were moved, the presence of streams or rivers between the catch and release sites, but distance was the only factor that predicted whether the frogs found their way home. The authors also think that the failure of the frogs to get back from the long distances is not likely to be due to things like exhaustion or predation. The frigs can go quite long distances, and because they are poison dart frogs, predation seems low.

How do these frogs do this? There are many ways that animals can navigate, from simply learning the local area very well (fails if you move to a new place) to true navigation (where you can find your way back from anywhere). Trying to sort out the mechanism the frogs are using to get back to their favourite spot is surely one of the next logical experiments to do, although the authors seem to favour the “know the locale really well” hypothesis.

Maybe the frogs have ruby flippers. “There’s no place like (croak) home.”

Reference

Pašukonis A, Ringler M., Brandl HB, Mangione R, Ringler E, Hödl W, Tregenza T. 2013. The homing frog: high homing performance in a territorial dendrobatid frog (Dendrobatidae). Ethology: in press. DOI: 10.1111/eth.12116

Photo by Sean McCann (ibycter.com) on Flickr; used under a Creative Commons license.

Everything is connected: How a snail in a lake helps a crab in the sea

Many people who have epiphanies often boil their realization down to, “Everything is connected.” Some may have achieved this through meditation, dreamquests, spirit walks, or illicit substances.

They could just study some biology instead.

Perhaps, like van Oosterhout and colleagues, you could study this on the western Atlantic island of Tobago off the coast of Venezuela:

Where van Oosterhout and company found this snail:

This snail, Melanoides tuberculata, is one of a couple of freshwater snail species introduced into the island of Tobago; this one was introduced in the 1970s. Another, which van Oosterhout and colleagues documented for the first time in Tobago, is Tarebia granifera.

The cool part of this story is that although these are freshwater snails, their presence may turn out to be beneficial for saltwater hermit crabs.

Hermit crabs live in snail shells. Tobago has a few species that live offshore, particularly Clibanarius tricolor (pictured) and Clibanarius vitattus. Looking around Tobago, and you will find these sea-dwelling hermits in freshwater snail shells. 

These two new snail species are abundant enough that their shells are common in Tobago rivers. During heavy rains, the increased water flow carries these shells down to the sea, where hermit crabs can pick them up. The further away the crabs are from the mouth of the river, the less likely you are to find one with a freshwater shell.

Not only are the shells just available for the hermit crabs, the hermits actually preferred the freshwater shells over a couple of the shells normally found in the oceans with the hermits. Shells can be a limited resource: there may just not be enough shells to go around for all the hermit crabs. All of these new shells from the introduced snails could actually help these hermit crabs.

Newly introduced species like these freshwater snails are often called “invasive,” which has a negative connotation. But if the invaders are winners, at least some of the bystanders might also be winners.

Reference

van Oosterhout C, Mohammed R, Xavier R, Stephenson J, Archard G, Hockley F, Perkins S, Cable J. 2013. Invasive freshwater snails provide resource for native marine hermit crabs. Aquatic Invasions 8(2): 185-191. DOI: 10.3391/ai.2013.8.2.06

Tobago photo by cheesy42 on Flickr; snail photo by Mean and Pinchy on Flickr; hermit photo by Cephalopodcast.com on Flickr; both under under Creative Commons licenses.

The cheetah and the hare: the great muscle match-up

There is one fact that everyone knows about cheetahs.

They’re adorable.

Actually, the one fact that everyone knows about cheetahs is that they are the fastest land animal. A recent paper came up with new estimates for just how fast (26 meters per second!), but didn’t answer the question of exactly how it is these animals outperform every other beast on land. So let’s do a quick stretch before taking a run at the answer...

Ultimately, the ability to move depends on muscle. There are different types of muscles: some generate lots of power fast^* but tire easily, while others are not as explosive^* but won’t tire easily. A forthcoming paper by West and colleagues compares cheetah muscles to another species to see if there is something exceptional about the cheetah’s muscles that can help explain this lanky cat’s stunning sprints.

In this corner, we have the undisputed speed champion, Acinonyx jubatus.

And in this corner, we have the challenger:

A bunny.

Rabbits are quick, but they are not in the cheetah’s league for speed. West and colleagues tried to compare the power output of the muscles from these two mammals, predicting that the cheetah’s muscle power would easily outstrip the rabbit’s power.

The rabbit won.

It wasn’t just that the the cheetah’s muscles and the rabbit’s muscles had comparable power, which would have been unexpected enough. The rabbit had significantly more power on a straight-up muscle fibre to fibre comparison.

This may not be the last word on this subject. The cheetah sample posed some problems. The team got the sample when a captive cheetah died unexpectedly, so the authors had to preserve the cheetah’s muscle tissue instead of working with fresh tissue. Estimating muscle power from preserved tissue is not a straightforward “put it in the machine and read out the number” measurement. There are assumptions in estimating power, the types of fibre, and so on.

All of these mean that it is possible that the muscles of cheetah’s produce more power than a rabbit when the muscles are in an intact, living cheetah. The authors suggest cheetah muscle power might be half again what they measured here, due to factors like the temperature of the living animal.

Even so, it may be that the secret to the cheetah’s speed is not so much in the physiology of the muscles, but how those muscles are attached to the skeleton, how the skeleton is shaped, or other factors.

And maybe, just maybe, like pro sports announcers keep telling us in races, it all comes down to just how bad the cheetah wants it.

^* Dear physicists: Yes, I know I may be using this imprecisely. I will accept any rebukes in the comments.

Reference


West TG, Toepfer CN, Woledge RC, Curtin NA, Rowlerson A, Kalakoutis M, Hudson P, Wilson AM. 2013. Power output of skinned skeletal muscle fibres from the cheetah (Acinonyx jubatus). Journal of Experimental Biology: in press. DOI: 10.1242/jeb.083667

Related posts

The elephant and the shrew, an axonal story
The costs of being tall: lessons from giraffes

External links


Collars reveal just how extreme cheetahs can be

Cub by Tambako the Jaguar on Flickr; cheetah stretch by RayMorris1 on Flickr; cheetah against sky photo by RayMorris1 on Flickr; rabbit by Robobobobo on Flickr; all used under a Creative Commons license.