Emerald Isle, NC

Last weekend we had a short but nice going away get-away with some friends (psychology graduate students, a parole officer, and a lawyer/rockstar) in Emerald Isle, North Carolina.

My dorky goal was to find more fossilized shark teeth (see previous awesome finds here), in addition to the obvious general goal of having a salty time.

Unfortunately, a storm kept most of the cool ocean debris from washing ashore until Sunday morning. Nevertheless, I found quite a few interesting things.

First off: fossil shark teeth!

Fossil Shark Teeth

The Haul:

The Haul 1

The Haul 2

The Haul 3

Skate Egg Case:

Skate Egg Case

Unknown wicked fish jaw:

wicked fish jaw

Shell Fossils in matrix:

Shell Fossil Cast in matrix

Shell Fossil Cast in matrix

A cool fossil of what I think is a bryozoan.

Fossil Bryozoan

I found a nice piece of fossilized bone. Of what? Who knows? Probably whale or dolphin. Or perhaps mermaid.

Fossil Bone

I also found several chunks of what I believe is either anthracite coal, or the next metamorphic step - graphite (I'm no geologist - thoughts?). It's very light weight, very hard, and very faceted - which doesn't come across very well in still shots:

Anthracite Coal?

Anthracite Coal?

One of the coolest things I found is a relation to organisms I will soon be working with in my new lab: starfish!!
I found two of these, both beautifully colored and still alive. They were washed ashore by the storm, so I tossed em back. I have no idea the likelihood of their survival, but I can say they didn't wash back ashore over the next two days. (I'm awaiting the expertise of Christopher Mah of the Echinoblog for species identification).
Update: it's a Royal Sea Star, Astropecten articulatus. Quoth the EchinoMaster: "Basically..they are your stereotypical "sand star" predatory on infaunal bivalves and pretty common on sandy-muddy bottoms of the Northeast US.  Attractively colored animals to be sure!" Thanks Chris!

Starfish

Check out those details!

Tube Feet Alive!!

We also got to hit the NC Aquarium in Pine Knoll Shores. It's a pretty rad place, so I was way more interested in pointing my eyes at all the ocean wonders, rather than pointing a camera. But I did get this cool shot of a gator.

Gator

Ooh - and apparently someone else took a shot of us there - me and John playing with the rays (the ray touch tank was by far the coolest part!).

Petting the stingrays

Topsail Island, NC

A month ago, we also had the opportunity to hit Topsail Island, NC.

Fun was had. Things were seen.

Shark Teeth (Yes - I showed these before).

Great colors!

Ocean smoothed - but still pretty wicked

Mole Crabs (Emerita sp.)

Mole Crab (Emerita sp.)

Ghost Crab (Ocypode sp.)

Ghost Crab (Ocypode sp.)

And that's it - images are all I have for you at the moment. Enjoy.

I swear, I will have slightly more posts once I get moved to Pittsburgh and settled.

And just because I never show her (she's camera shy), I'm sneaking in this shot of my wife:

Three Psychologists

David, as his handle implies, is all about sharks and shark conservation - in fact it seems he's been making quite a name for himself in sharkworld. Well, David, as well as many others interested in shark conservation (or even ocean conservation/health) have some issues with the way the DC's Shark Week continues to peddle fear of sharks. I've been personally pretty sick with most nature documentaries these days - catering to the 10 most deadliest this, or the Worst Disease You Can Get From that, or the Freakiest X, or the fear, fear, fear, etc...

David, based on many submissions from his readers, assembled quite an impressive list of questions (pulling no punches, I might add). I highly recommend you check out Paul's answers as it makes quite an interesting read. That being said, the answers were pretty much exactly what you'd expect from the exec of such a huge business as the Discovery Channel - and not all that impressive.

As I stated in the comments over there - it's all a bit moot to me, as I think the Discovery Channel bankrupted the "Discovery" in its name ages ago. Really - just look at the schedule on any given day. How much "discovery" do you see?

Edit: If you think this is a harsh assessment - keep in mind the titles of the first few shows for Shark Week when you read Paul's answers: the 2 hour premier "Blood in the Water," followed by "Deadly Waters," followed by "Day of the Shark 2" (about "when a great white breaks through a 300-pound aluminum shark cage and traps the divers inside. Another shark tackles a former Navy Seal in shallow waters"), followed by "Sharkbite Summer" (about "The bite-by-bite account of America's notorious "Summer of the Shark" in 2001.")

Mind you, since moving here for graduate school, fossil hunting had fallen off of my priority list, largely owing to the fact that central Carolina rocks are basically all metamorphic (melted and recrystallized by heat and pressure). And I've never been the gung-ho research-fossil-sites-and-go-hunting type. Since I began collecting while living in the Ozark mountains, it was more of a walk-through-my-parents-woods-and-see-what-fossils-I-find-today sort of hobby, with a few far-flung excursions in the mix.

Well that all changed a few weeks ago. My wife, some friends, and I spent a couple of days at Topsail Beach, NC.

Actually - scratch that - it began a few month's ago, when Christie at Observations of a Nerd reported an awesome find of fossil shark teeth in Florida, and then - like the wonderful person she is - sent me a handful of them.

Shark Teeth from the wonderful Christie (Note to Christie - they are ray dental plates - not stingray barbs - just learned that - see below)

Back to Topsail Beach, circa a few weeks ago.

I said to myself, "Self - it's the ocean - there are bound to be fossil shark teeth. You (I) will not allow me (myself) to leave this beach without finding at least one shark tooth."

So I spent all my beach time on Saturday perusing the sands for teeth.

To no avail whatsoever. I never saw one.

The next day, I began again, searching much more intently. While combing the fresh tide-swept beach, I saw a tiny black triangle amidst the shells. It was a shark's tooth!!

The filters through which my perception is sifted were now calibrated. Within the next few hours I had a nice handful of tiny teeth. I was ecstatic.

(Note for the fossil pros and beach inhabitants out there: feel free to laugh at my ignorance of what constitutes awesome shark teeth. But these were just about the coolest things I had ever found - at the time.)

Hold your applause - you ain't seen nothing yet

Tiger Sharks - grrrr...er...meow

Thus was I hooked on shark teeth.

The next necessary stops in my tale are the mountains of West Virginia and hills of Pennsylvania.

Some of you know that I will recently begin a new job at Carnegie Mellon University. As such, we have driven there twice recently. I am utterly awed by the massive amount of roadcuts through the mountains of the two states, all of which reveal millions upon millions of years of Earth's natural history in it's geological strata. I felt the fossil-hunting bug really kick up several notches while driving through those strata.

Thus, in anticipation of my move, I began hunting online for potential fossil sites in Pennsylvania. In this endeavor I discovered The Fossil Forum. Through this forum, I discovered not only a huge community of avid fossil hunters, experts, and enthusiasts, but also that North Carolina has some of the most amazing shark tooth sites in the country.

"Self," says I, "it's bad enough that you've been here so long without discovering North Carolina's fossil sites - but now you are leaving? I forbid you (myself) from leaving until you have visited these sites. Got it?"

It was decided - the July fourth weekend was my only free one from now until the move, thus I would make it a fossil-hunting weekend. I would spend Friday in Aurora, NC and Saturday at Green's Mill Run, a creek in Greenville, NC.

As fate would have it (though we will soon see that the result would have been the same with any weekend, fate or no) a dude by the name of MikeDOTB (Michael Taggert) on the Fossil Forum, was also making the exact same trip this weekend. We decided to meet at the shark-digging piles at the Aurora Fossil Museum on Friday (Note to parents in NC - TAKE YOUR KIDS HERE! Free digging teeth by the thousands to their little hearts' content). Mike said he would be there by 7AM and I would try to get there by 9AM (it's a 3.5 hour drive for me).

NOTE: See Mike's Trip Report here - he has some amazing shark teeth!

I was too excited. I couldn't sleep at all the night before. So I slid out of bed and out the door at 3AM arriving at the piles in Aurora by 6:30AM. (The piles are Pungo River Formation sediment - age ~18-22 million years -  donated by the nearby PCS phosphate mine).

It was just me. Not a soul in sight anywhere. Alone - in a beautiful dawn with giant piles of Miocene sediment to sift through at my leisure.

I saw my first tooth within about ten seconds of glancing at the piles. My collection grew fast and linearly from that point onward. Before too very long, a nice man showed up to sift as well. It turned out that he was a Fossil Forum member too (runner50) - a Kansas Science teacher on a trip around the country to spread his recently deceased wife's ashes at their favorite locations (including St. Claire, Pennsylvania which has some amazing fern fossils, which he showed me). Many of the ancient teeth he was collecting were for his students/class. Despite the sadness of his tale, it was incredibly heartening to meet such a man teaching in Kansas, a place we all probably know needs good science teachers!

In "the wild"

Mike showed up later than he had planned, but as soon as he got there we hit another nearby pile, meeting a guy named Brian in the process. We chatted for quite a few hours as the three of us sifted for teeth in a couple different locations. Brian, another Fossil Forum member, gave me a dolphin vertebra among other things.

Dolphin Vertebra - Thanks Brian!!

Fossil enthusiasts are awesome people, based on the few I've met!

Mike, Brian, and Me - sifting the piles in Aurora, NC

Mike, showing how it's done with his giant 1/2'' mesh screen

The piles

I almost look like a real paleontologist. Or not...

Before the day was up I had amassed a huge pile of little shark teeth, though no lunkers had given themselves up. I had already watched in envy as Mike pulled several beautiful teeth from the piles. However, I wasn't really jealous, as I was too excited from the insane numbers of teeth I  was finding with my smaller 1/4" mesh screen. After about 13 hours straight (no lunch break or anything), darkness began to loom. So Mike decided to collapse the pile we had been digging into. Wet internal sediment began falling and we both began picking through it as more fell. In about a third of a second a shiny glint caught my eye in the muddy dirt. I snapped at it like a greedy hungry chicken.

It was a big Extinct Giant Mako (Isurus hastalis)!

Extinct Giant Mako make-o me happy

Also, it had a small bit of feeding damage at the very tip (which makes it only cooler to me). Now go back and compare that to my first teeth from Topsail...

Without further ado, I give you the rest of my collection from Friday, filled with makos, tigers, sand tigers, snaggletooths, cow sharks, and even one small  nearly complete tooth and some pieces of megatoothed sharks (C. megalodon and/or chubitensis).

Note: I have zero tooth ID skills, so forgive any errors. There are almost certainly teeth "out of place"! I arranged these pretty quickly.

(Click for larger)

The Multi-Million Year Old Catch

Aren't they pretty?

A few of these were given to me by Mike - I don't remember which ones. Thanks Mike! He also gave me the coolest thing I now own...keep reading.

Snaggletooths and Tigers

Sand Tigers et al

Megalodon/Chubitensis?

Makos, giant megalodon chunk, and others...

Requiems, Coppers, Hammerheads? No idea...

Broken cow sharks

Ray dental plates (for grinding munchies)

The little guys (Mike estimated ~1200 total teeth)

Did you know a single shark can go through 30,000 teeth in a lifetime?

And of course, I found some other cool stuff as well...

Shark Vertebrae

How cool is that?

Coral

Love the detail in these things!

So I had a great haul - and searing back and arms as payment to Mother Nature for her bounty. But back pain or no, we had another whole day to go.

Mike and I high-tailed it to Greenville and crashed at the Motel 6, after spending at least an hour rinsing and gawking at our fossils. Mike gave me most of his teeth, except for the near perfect ones he deemed fitting for his collection. What an awesome dude!

Then again, this is a guy who has 30,000 teeth! Also, he seemed to know every single shark species, their scientific names, whom is thought to have begat whom evolutionarily, and he could instantly tell the ID of each tooth. Oh yeah, and remember how I said "Fate" had led me to want this trip at the exact same time that Mike announced that he was planning a trip? Yeah, well, he has gone on this trip almost every weekend since January.

Yeah - he's an enthusiast alright... Thanks Mike - you rock!

We awoke the next morning and headed for the dirty, trash-filled, broken glass-laden creek running near East Carolina University campus known as "Green's Mill Run." This place is famous for yielding big megalodons and great whites (and ancient soft drink bottles and bongs). The creek cuts through layers from the cretaceous to the pliocene, so things found in it can range from about 2.5 to 145 million years old!

The story was much the same at "GMR". I found quite a few great teeth (though I didn't feel as inclined to pick up every tiny tooth after the previous day), including another awesome Mako.

This was while I was still clean...

Mike found an AMAZING great white, and lot's of other great teeth - many of which he gave to me.

Mike's Great Whites

I sat and watched an awesome freshwater eel hunting minnows in one beautifully sunny pool - a first for me. We didn't have freshwater eels in NW Arkansas (that I'm aware of).

Mike found and gave me what I easily consider the coolest fossil I now own (he already has several): the fossilized inner ear bone of a whale. What kind? not a clue.

Whale's inner earbone

We visited one particular spot in the creek that cuts through this crazy shell layer filled with huge scallops and various mollusks.

Fossil Sea Scallop (as opposed to land scallop)

Some sort of big bivalve - whole and heavy!

By 6PM my back and arms would not let me sift a single more shovel load. Thus we called it a day.

Here's the total haul from Saturday:

The GMR Catch

What would have been HUGE megalodons, a very nice Mako, and a rootless great white

The Makos and the White

The other shark teeth

Another cool fossil that exists by the millions in GMR is the belemnite. Belemnites were cephalopods related to modern cuttlefish. Only one part of it's body is normally fossilized: a calcite rod in it's body that assists in maintaining proper buoyancy. These things are just cool looking - orange and long and pointy, with a translucent character in the water.

Fossilized Belemnite guards (or rostrum)

And finally, the creek has quite a lot of pieces of whalebone:

Fossilized whale bone (and a cretaceous oyster - according to Mike)

All in all, this was by far the coolest natural history excursion I've been on (or perhaps second best behind a trip to Big Bend where I found an ammonite 4 feet in diameter - I left it there).  If you read this far - I hope you enjoyed my tale. If you didn't...well... you can't see this anyway.

The total weekend haul!

Cat included for scale

Next up: fossil hunting in Pennsylvania in the next month or two! When exactly or where I don't know. But it will be fun!

The Red Blood Cell-less Icefish © Dr Julian Gutt and Alfred Wegener Institute

Imagine that you are a fish - exothermic and thus unable to regulate your own body temperature - and the contingent foibles of natural history have all conspired to leave you and your kind in the frigid oceans of the Antarctic just as they are beginning to reach the freezing point (10-14 million years ago).

You like the cold and are well adapted for it, but these temperatures are beginning to give even you - a master of the cold - the icthy chills.

Now imagine that the hands of mother nature have given you the tools to change your own genetic code, and thus your nature, allowing you to make yourself even more suited for waters that are 2 degrees celsius below the freezing point of pure water.

What would you do? Would you inject your DNA with a molecular antifreeze? That seems like a reasonable addition - one we will get to momentarily.

But if you were a genius of bioengineering would you reach out a molecular scalpel and hack away the genes that allow the production of red blood cells, hemoglobin, and myoglobin, leaving only molecular fossils behind?

Icefish Larva © Uwe Kils

It doesn't seem like a particularly well thought out plan. But then again, neither you, the fish, nor mother nature are genius bioengineers. Fortunately for life, the forces of evolution still manage to get the job done, however sloppy the end results (yes, technically the job is never done - forgive my metaphor wearing thin).

In fact, natural selection performed just such a feat somewhere around 8.5 million years ago in the ancestors of a flock of related species in the Antarctic: the Channichthyidae icefishes (also known as crocodile icefishes or white-blooded fishes).

As we all know, liquids tend to become more viscous in the cold. Just compare maple syrup before and after refrigeration. Blood viscosity would have no doubt been an issue in the ancient ice fish ancestors, or at least one that could be improved upon. Normal vertebrate blood is filled with big, round, and red blood cells coursing through the blood vessels. Now imagine lowering the temperature of the blood below the normal freezing point of water - that's bound to create some significant resistance.

But aren't erythrocytes critical for carrying oxygen? How could an organism just dispense with them completely? As many scientists know, one of the great things about really cold water is that it can be packed with oxygen. Such is the case with the waters of the Southern Ocean, which are saturated with oxygen.

Thus, it seems that at some point, the icefish ancestors developed mutations in the pathways that result in red blood cell production. Furthermore, the species eventually acquired a deletion in the key genes of red blood cells: the alpha and beta hemoglobin genes. No longer could this fish produce hemoglobin.

As is often the case with evolution through loss of gene function, the deletion wasn't perfect. Almost all vertebrates have both hemoglobin genes lying next to each other within the genome. In most Channichthyidae icefishes, the beta hemoglobin gene has been completely deleted, along with all but the truncated end of the alpha hemoglobin gene (interestingly, these fish have lost their myoglobin gene as well)¹. To quote the original paper by Near et al.:

"Despite the costs associated with loss of hemoglobin and myoglobin in icefishes, the chronically cold and oxygen-saturated waters of the Southern Ocean provided an environment in which vertebrate species could flourish without oxygen-binding proteins."

The upshot of all this is that the icefish has completely clear blood lacking in any erythrocytes - and they are the only species of vertebrates to have such a trait.

Normal two hemoglobin genes vs. lost icefish hemoglobins - cropped figure from Near et al 2006

Of course, a few other supporting traits evolved as well. Their hearts are significantly larger than other fish hearts, and they pump 4 to 5 times larger volume of blood per stroke². Their capillary beds have become much more dense as well to make sure all their tissues get adequate oxygenation. Of course, like amphibians that breathe through their skin, with the loss of red blood cells, those that were better able to absorb oxygen tended to outperform their cohorts. Thus they became scaleless as well.

As if these adaptive feats weren't cool enough (pun intended), the antarctic icefishes have evolved their own antifreeze as well^3,4. What's amazing about this antifreeze (an Antifreeze Glycoprotein - or "AFGP") is that it represents one clear cut case in which a gene with a specific function has evolved into a separate gene used for a completely different function in a novel way. In the case of the icefish, the ancestral gene was a trypsinogen (a pancreatic digestive enzyme), which has been mutated and co-opted to be secreted and distributed throughout the body to act as an antifreeze. Specifically (for you biologists out there), the 5' secretory signal and 3' UTR sequences of trypsinogen were tacked onto an amplified nine nucleotide sequence from within the trypsinogen precursor to create the novel antifreeze peptide.

So here we have in the icefish's adaptation to the cold, at least one case of de novo creation of a novel gene with a new function from an old gene, as well as the loss of two other genes that have left genomic fossils behind to whither in the weathers of time.

It may not be the cleanest or best engineered solution to the problem of living in an Antarctic Hell (or perhaps Heaven from the perspective of the fish), but this messiness of evolution is precisely what makes it so incredibly beautiful.

References

1. Near T.J., Parker S.K.,  Detrich H.W. A genomic fossil reveals key steps in hemoglobin loss by the Antarctic icefishes. Molecular Biology and Evolution, v.23, 2006, p. 2008 - 2016.
2. William C. Aird. Endothelial biomedicine. Edition: illustrated. Published by Cambridge University Press, 2007
3. Chen L., DeVries A.L., Cheng C-H. C. Evolution of antifreeze glycoprotein gene from a trypsinogen gene in Antarctic notothenioid?fish. PNAS, April 15, 1997 vol. 94 no. 8 3811-3816
4. Chen L., DeVries A.L., Cheng C-H. C. Convergent evolution of antifreeze glycoproteins in Antarctic notothenioid fish and Arctic?cod. PNAS, April 15, 1997 vol. 94 no. 8 3817-3822
5. Top image © Dr Julian Gutt and Alfred Wegener Institute
6. Icefish larval image by Uwe Kils

Previous Adaptations of the Week:

1. Timber Rattlesnake Camoflage
2. The Aye-Aye’s Freaky Finger (I’ve Been Cursed by an Aye-Aye!)
3. Flatfish Eyes & Recapitulation Theory
4. Bird/Crocodile Symbiosis?
5. Insect Dorsal Ocelli

Why do sharks matter?

One of my science blogger buddies, WhySharksMatter over at Southern Fried Science, has received the opportunity to interview an influential shark researcher, Dr. Dan Abel. He is asking for anyone and everyone to pose a question you would like asked of Dr. Abel. Perhaps you want to know something about sharks or maybe something about what it's like to study sharks or why he chose to study them. There are any number of fascinating things to be asked. I asked an interesting one myself (at least I think it's interesting).

So if you have any shark-related questions you'd like answered by an actual shark expert, head over to this post right now and leave your question in the comments section.

Our self-aware cousins

This weekend I heard an incredibly interesting story on NPR's This American Life titled "Almost Human Resources" (Act 3). The story was all about the issues surrounding chimpanzees in the human world surpassing their usefulness and how we should care for them. Apparently this now includes retirement homes with TVs.

This story, along with a recent tangential debate over at Southern Fried Science and PETA's "sea kittens" campaign, sent my mind down a familiar path - one that anyone working in biology inevitably travels from time to time: the ethics of animal research for science.

There have been myriad writings, books, movies, discussions, and laws surrounding the practice of using animals for research. I'm sure most of us in the science world have come to very similar conclusions on the subject, though we may vary widely in the details.

Nonetheless, I'm very interested to hear where YOU, my readers and my fellow scientist peers, currently stand on the subject. I would like this post to be interactive.

First, I'd like to give my own thoughts.

In general, I view all living things as uber-complex organic robots (humans included). All life is amazing, precious, and beautiful - from bacteria to humans - but I still see us all as robots, running our nearly unfathomable genetic programs, developmental processes, and higher-level emergent programs of conscious and sub-conscious thought.

Mirror Test

At the same time, I feel - for no rational reason really - that consciousness and self-awareness inherently grant those that harbor them the right to live relatively free from human induced suffering. This is a feeling. We all feel it, at least for humans. We feel the immorality of conducting experiments on other human beings (though this was not always the case). Why? Because it's...just...wrong.

It's for this reason that I'm completely opposed to any medical research on chimpanzees or any great apes. There is no doubt that our great ape cousins share many if not most of our own emotional and sensory perceptions, as well as similar intellectual abilities (similar in type - not necessarily degree). For all intents and purposes, I see them as people. Not human people. Not anthropomorphized animals. But sentient to semi-sentient beings.

It's hard to measure degrees of self-awareness and know whether another creature has it. But the classic mirror test is one simple way to find when the answer is a clear yes. As of right now, great apes, dolphins, elephants, and at least one bird species, the magpie, have passed the test and shown that they have some understanding of "self."

If a creature can have any understanding of what is being done to "them," I am completely against it. Recently Orac at Respectful Insolence posted on the discontinuation of using dogs for teaching surgery techniques. He caught some flak from a few commenters for showing an emotional relief that dog use was being halted - at least partially because he loves dogs. As if any decisions on the use of other beings for our own benefit could be arrived at using only reason!

No - we as humans place some inherent value on consciousness, on self-awareness. Dogs may or may not be "self-aware" as defined by behavioral scientists. They can't pass the mirror test, but anyone who has had a dog knows that they clearly experience something akin to guilt, and a whole host of emotions similar to those of our own (I'm being careful here not to anthropomorphize). They know when they have done something wrong.

As any behavioral biologist, psychologist, or cognitive neuroscientist knows, there is no clear dividing line between conscious being and automaton. What about rhesus monkeys and the other more "primitive" primates? I personally feel that much monkey research - particularly those studies on the cutting edge of such diseases as A.I.D.S. - are critical right now. However, I also know that I could never be one to perform such studies. There is a mental hypocrisy here in my own mind. I would feel wrong performing primate research. But I support it to a limited extent.

But for some animals, it seems clear when they are well beyond that gray fuzzy line. Xenopus frogs, as far as any observation or measurement can tell, are much too dumb to have any sort of self-awareness. The same can be said of mice or rats. They simply do not have the cognitive capacity - the hardware - to generate emergent properties like self-awareness as we know it. It seems more than clear to science, I believe, that these creatures are fuzzy automatons. I have performed studies (using incredibly regulated and humane methods) using these creatures, and I have no qualms about it, so long as the use of animal models are absolutely critical to the study at hand. Hundreds of thousands of lives have been saved or vastly improved by such studies. Few people alive today (in America at least) can imagine what the state of human health would be without mice and rat studies.

And just to go one level further "down" the evolutionary ladder, consider fish.

Fish are NOT "sea kittens." We understand at least at a basic level what overall types of brain structures and neural pathways are required for higher cognition. Fish do not have these structures. They are insanely complex, from a genetic standpoint. They are beautiful. They are unimaginably important to the ecosystems of the earth. But they are still slimy scaly robotic automatons incapable of "suffering" in any human sense.

And invertebrates? Well, they're clearly organic machines. Would any of you really argue otherwise?

However, with all of the above being said, I often think about how barbaric people were only a generation ago (or sometimes less), and I wonder which of my beliefs will be considered equally barbaric by the next generation. As Richard Dawkins mused in "The God Delusion," perhaps animal rights is the issue upon which our generation will be judged to have sinned. Perhaps our ancestors will cringe at our actions (while praising the 500 year lifespans our research has given them - kidding).

What do you think? Take these polls and leave your comments below.

[polldaddy poll="1444538"] [polldaddy poll="1444551"] [polldaddy poll="1444559"]

Under the Sea 3D

This weekend my wonderful wife arranged a date night for us. And how awesome does it make her that it consisted of the single most breathtaking documentary I've ever seen - "Under the Sea 3D," a stroll through the evolution of life at the NC Museum of Natural Sciences, followed by a heaping plate of crab legs at the 42nd St. Oyster Bar in Raleigh? (no the irony of that last part is not lost on me - but hey - I loves me some crab legs!)

This post is both a review and a shout out to everyone who has not seen "Under the Sea 3D" at your nearest IMAX to immediately drop what you are doing and go watch it (check out its nifty flash site as well).

I'm not being overly hyperbolic here - this film (directed by Howard Hall) is utterly stunning.

There is basically no narrative in this film. But for what it wants to accomplish, I don't think any documentary I've watched has achieved its goal so succinctly.

The film begins with nothing more than sequence after sequence of mesmerizing coral reef habitats and creatures. It's narrated by Jim Carrey (who is great - I found myself forgetting that it was even him most of the time - there were no characteristic Carrey antics here).

But the key to this film is in the fact that the footage itself leaves you begging for more. Everyone in the theater watched in wonder - their mouths forced open by the alien creatures - usually only realizing later that they've been slack-jawed like goons for five minutes. The three dimensionality is pulled off to such a great extent that the creatures seem like they are moving and living mere inches from your face. I have never been scuba diving (and can't due to my marine unworthy inner ear), but I have been snorkeling - and I consider it one of the most amazing experiences of my life. That being said, the detail in this film far exceeded any real-life ocean experience I've had.

Each of the reef scenes is so filled with action - shrimp scuttling in the background, various fish doing their things, corals waxing and waning in the current - that you literally will want to watch it again just to focus on different aspects of each scene (not to mention the fact that the IMAX screen fills your entire field of view - it's impossible to see it all in one sitting).

Aside from the imagery which is hands down among the best I've seen, the conservation message is presented in the absolutely perfect way for its target audience (basically - everyone in the world and especially kids or the uneducated). Conservation or the ills facing the marine world are not even mentioned until your mind has been boggled by the crazy critters of the sea.

Only after bringing you into a state of constant awe does Jim Carrey begin hinting that things aren't alright. The message ramps up to the inevitable images of dead reefs, bleached by ocean acidification. However, I don't think it ever became overly preachy.

Under the Sea 3D

In fact the conservation message ended on an overly optimistic high note (overly from a scientific perspective) but one necessary if we ever want the general populace to care. Basically it paints the current state of the conservation movement as a hopeful paradigm shift in human society. It plainly states that humankind is beginning to realize its mistakes and that most people are coming around. Whether or not this is true is irrelevant because it leaves you thinking "hey, caring about CO2 and the oceans and biodiversity is the normal smart thing now. I want to be part of the informed and enlightened crowd. I want to care too."

In other words it doesn't just say "The oceans are screwed. It's all our fault. We should all be ashamed of what we've done." It says "the better angels of human nature are trying to turn it all around. And they are giving the world hope." And because of the tone, one cannot help but naturally want to be one of those better angels.

For you marine biologists, the very simple message will seem quaint. But I'm sure you will understand the necessity of this sort of film serving as an initiator for conservationist thinking.

I honestly believe that every person on the planet should watch this film. Especially the children.

Oh, and did I mention that there are TONS of cuttlefish in it?

Don't even think for half a second that the following trailer comes close to doing the 3D beauty justice!

WANDERING EYES from Science News on Vimeo.

FROM FRY TO FISH from Science News on Vimeo.

The theory's thesis: "Ontogeny recapitulates phylogeny." Don't worry - it's not as complicated as the biological jargon might imply.

Ernst Haeckel's Drawings (1892 Romane copy). Note: Haeckel oversimplified these drawings. I use them here as a simple illustration of the concept of developmental similarity.

The idea boils down to a simple one - one that seemed to make sense in light of the fact that the science of developmental biology had only just begun from a systematic standpoint. The idea: if you watch an organism develop from an embryo to an adult, you can watch it slowly move through the evolutionary steps that had created it. That is: development repeats evolution.

So a human embryo would first look like a fish, then a reptile, then a mammal, and finally a human. Of course, we now know that in a literal sense, the theory is completely and utterly wrong. No stage of human development, or of any other organism, correlates with a discrete step in evolution.

We are never fish. (Though we do have embryonic tails).

However, that doesn't mean that there aren't kernels of truth to the idea, if applied loosely. Take the most famous and classic example: embryonic human gills. You may have heard yourself that humans have gills as embryos. Unfortunately this claim arises from misconception and incomplete understanding of developmental biology. Humans do not - ever - have gills. But as embryos we do have "pharyngeal arches." These are little bumps around what you might consider the neck area of a developing embryo (see Haeckel's drawings above). And these little mounds of tissue do in fact remarkably resemble similar mounds found in fish - mounds that in fish develop into gills (Note: Haeckel vastly oversimplified these drawings. I use them here as a simple illustration of the concept of developmental similarity. See: http://zygote.swarthmore.edu/evo5.html. Thanks Bjørn!).

One of the amazing aspects of developmental biology that much of the public does not generally understand is that evolution does not occur by adding new organs, appendages, or tissues to adult animals (whether through gradual steps or not). Evolution works by slowly sculpting the early embryonic clay of an organism.

Fish evolved these gill pouches as embryos - pouches that could then be sculpted into gills. As evolution waltzed and hopped along at its geological pace, genetic mutations began to change how these little mounds were sculpted, such that now in humans, these arches are sculpted into various parts of the face and head. A genetic program was already in place to control the shaping of the pouch. All that natural selection did was slightly tweak that program. For example, instead of a group of cells moving one direction, they moved another. Instead of becoming blood vessel cells, they became cartilage or bone cells.

Thus, while we now understand that we are not witnessing evolution in miniature during development, we are seeing pieces of our evolutionary history - little remnants that remind us of our relationships to our ancestors and also help inform us on what morphogenetic processes underlie evolution.

Which brings us to our adaptation of the week: the freaky asymmetric eyes of the flatfish.

Flatfish (www.seawater.no)

Most people have probably seen a flounder - one member of the flatfishes. They have adapted to lie amongst the silty ocean bottom, hidden from predators and prey, flat on their sides. For a normal fish this might be maladaptive - they would constantly have one eye buried in the sand. Of course the negative of being one-eyed might be offset by being much more camouflaged and undetectable.

Luckily for the flounder, the eye that should be buried in the sand has moved around its forehead so that both eyes are on one side.

The flatfish eye served as one line of attack against natural selection back in the day - and Darwin himself didn't quite know how to answer the charges. Evolutionary gradualism would predict that through successive steps, the eye slowly moved upward toward the forehead and eventually to the other side of the face. But what advantage could a slightly moved eye give, if it still was on the wrong side? Alternatively, as Richard Goldschmidt postulated in the 1930s and 40s, perhaps a single monstrous freakfish was born with both eyes on one side, and this allowed it to lie flat without losing half its vision. It could have then survived and had lots of little freak fish babies of its own.

So how did the flatfish become the strange creature it is now? Let's first look at the developmental biology of the flatfish eye.

WANDERING EYES from Science News on Vimeo.

FROM FRY TO FISH from Science News on Vimeo.

Flatfish Metamorphosis (Schreiber 2006)

It's been know for quite some time that flatfish larvae look like perfectly normal, symmetrical, and upright fish. The picture to the right is from a study by Alexander Schreiber in the Journal of Experimental Biology from 2006. As you can see, at early stages the larvae are normal, but progressively tilt and become horizontal as one eye moves across the face. He also showed in this study that eye movement and flattening behavior occur independently during development - but that's a much longer story.

Alright, so one eye gradually moves across the skull during development. What about during evolution? Do we have any clues as to the steps involved? Well, as many biologists know, the fossil record has now answered the question for us.

In a well-known study that was published last summer in Nature and received much media attention, Matt Friedman showed findings from a series of fossils delineating a clear gradual evolution from symmetrical to asymmetrical flaltfishes. (For excellent in-depth coverage looking at this study and the debate over flatfish evolution, see one of my favorite science bloggers, Ed Yong at Not Exactly Rocket Science, and also see the popular science writer Carl Zimmer at The Loom, and GrrlScientist at Living the Scientific Life).

Flatfish Evolution (Friedman 2008)

The evolution of the flatfish eye seems to mirror what we see during development. Thus, here we have a case of ontogeny appearing to recapitulate phylogeny quite wonderfully. There are many excellent examples of this throughout the biological world, though few that show such incredible similarity between the two processes of development and evolution. Nonetheless, this isn't really evolution we're watching during flatfish development - we're merely seeing how slight changes of the developmental programs are themselves responsible for the changes we see over time through evolution. Generally speaking, earlier developmental processes appear much more similar across varied species than later processes.

Development is in fact one of the primary constraints against evolution.

So while you were never a fish, you still showed remnants of fishy development during your own development. For it was these fishy developmental process that allowed the evolution of your own.

Scientific References:

• Schreiber AM. Asymmetric craniofacial remodeling and lateralized behavior in larval flatfish. J Exp Biol. 2006 Feb;209(Pt 4):610-21.
• Friedman M. The evolutionary origin of flatfish asymmetry. Nature. 2008 Jul 10;454(7201):209-12.

Previous Adaptations of the Week:

1. Timber Rattlesnake Camoflage
2. The Aye-Aye’s Freaky Finger (I’ve Been Cursed by an Aye-Aye!)

Happy 200th birthday, Charles Darwin!
Happy 200th birthday, Abraham Lincoln!
Happy 150th anniversary, On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life!
And here's to a happy Darwin Day and upcoming Valentine's Day to everyone else.

As a part of my own contribution to the Blog for Darwin campaign, I present to you "Darwin and the Heart of Evolution."

What do all four of the above events have in common, other than being events of celebration? The answer will become obvious, but as a clue, I will begin with an appropriate Valentine's question:

A Frog's Heart

Why do humans have hearts?

I can see it already – you’re rolling your eyes thinking, “Well duh…because we need a way to circulate oxygen, hormones, immune cells and other signals, and transport waste compounds and gases.”

Ahh, but you would be wrong. For the above describes only what a heart does – not why we have one. As I wrote a few days ago, evolution pays no attention to "needs." Species don't evolve because they "need" to adapt or change some trait. Natural selection is blind to all intention and desire.

Before Charles Darwin (and his buddy Alfred Russell Wallace) gave us the theory of natural selection, the above "necessity" explanation would have sufficed – with an added “because God designed it that way” just for good measure.

The genius, beauty, and simplicity of Darwin’s big idea was in how it utterly reshaped the manner in which all “why” questions about reality are posed and how their answers are understood. The Origin of Species laid the foundation for the complete upheaval of the very word “why.” In fact, when it comes to describing biology, astronomy, physics, geology, and every other empirical look into reality, the word “why” now means nothing more than the word “how.” The how is the why.

So again, I ask - why (how) do humans have hearts?

To answer this question we need to jump back about 500 million years ago into the ancient ocean. Based on the fossil record, this is a good date to pick, considering that worms don’t make great fossils; however, the exact date is not at all important for this discussion. Nor does it matter the exact species of worm-like creature we consider, or the exact details of the hypothetical time-traveling adventure upon which we will now embark.

Imagine it - we’re swimming now in the ancient ocean sometime after the massive explosion in the evolution of all sorts of strange ocean-dwelling invertebrate body forms (the Cambrian explosion). One of the many advantages that certain individuals of various species find is that their larger body sizes makes them better able to compete – up to a point. Once a small early worm-like species reaches a certain size, it finds that it cannot grow any bigger with its current body plan. This is because at this point, our hypothetical creatures do not have circulatory systems. They must absorb all their oxygen from the surrounding water. Any individuals born larger than a certain size can no longer get enough oxygen due to the oxygen not reaching deep enough into their tissues, and so they die (or are our-competed).

The Vertebrate Family

Now imagine an individual of this species is born with what others of its species would consider a defect (if they had brains with which to consider such a concept). This individual has certain cells that have formed a small simple tube-like structure. Perhaps it is only a vague cavity – or some extra space between its cells. Now when this individual swims around, contracting its primitive muscles, the fluid within its body spreads a little bit more and a little bit faster through this cavity or space.

Our little worm leads a happy life, finding mates (or perhaps reproducing asexually) and leaving an ocean full of cavity-containing offspring. It seems self-evident to us now, but Darwin found himself surprised at the amount of variability in traits throughout the animal kingdom. All populations vary; thus, some of our worm’s children are a little bit bigger than their siblings. And some of these worm children will have inherited papa worm’s fluid cavity, which meant that they could survive with a slightly larger body than those without the primitive vessel, due to the oxygen distributing power of the fluid filled vessel.

Thus began the evolution of the heart. By a series of easy to imagine steps through thousands or millions of generations, the cavity became slightly more developed, eventually forming an actual tube. I would like to note here that the above scenario is strongly supported by much embryological, anatomical, and genetic data. However, I would like keep this simple and vague for the layperson.

Now, we move forward in time, though how far is unclear. Our little worms are now bigger worms, insect ancestors, and a myriad other small invertebrate species. Some of these species have evolved their tubes to have contractile regions - that is, a region of the tube than can actually squeeze and pump. Some, like our modern earthworm, have seven of these pumping “hearts”. Others, like the Drosophila fly, have only one heart - called a "dorsal vessel" (see the Drosophila larvae movie below).

The Fish Heart

We swim forward to 525 million years ago, just as the first fish appear in the fossil record. A lineage of the invertebrates has slowly morphed through primitive chordates (organisms with a nerve cord) to become the most primitive fishes. Along with the changes in many other body structures, the basic contractile heart and vessel system has itself become more complex. Instead of one contractile chamber, the fish heart has divided into two chambers: an atrium and a ventricle (and a stretchy region called the conus that isn’t contractile). The fish themselves then radiate over time, each lineage slowly accumulating many small changes, resulting in the gradual evolution of an ocean teeming with fish species – all with two-chambered hearts (see image at right).

Eventually, some fish species start shacking up near shorelines or in shallow ponds and lagoons. Some are born with thicker fins, which allow them to push along the bottom of the pools a little more quickly or lithely than others. They mate, and the process continues. Finally, one of them decides to just get it over with and leaps out of the water to land as a frog on four fully-formed legs.

The Amphibian Heart

Not really, but you get the picture.

We now see amphibious creatures roaming the shorelines like beastly salamanders. Their hearts have changed even further as other aspects of their bodies evolved to take in oxygen through lungs. Why did this happen? Because the changes that make it possible did happen. These shallow water-dwelling creatures began to develop vessel-filled outpockets on their esophagus, giving them the advantage of pulling oxygen from the air. In addition, the individuals with slightly better circulatory systems found their bodies better at all sorts of other things, such as regulating their bodies with hormones and getting rid of cellular wastes.

At this point, a series of further changes occurred in the amphibian heart. The atrium became two separate atria, either through a physical division of the one atrium, or through a duplication of the vessels coming into the heart. Thus, the frog ancestors developed three-chambered hearts, which were subsequently passed down to every frog currently inhabiting the earth (see image).

The Reptile heart

As time passed, the frogs began drying off their slime, sprouting scales and forked tongues, and inspiring instinctive reptilian nightmares in their prey. They became lizards. As the lizards moved fully to land and grew even larger, certain inherited variations in their hearts naturally worked a little better – thus natural selection continued the continuous sculpture of life. The ventricle began to separate into two chambers, much like the atrium had done in the amphibians. However, the ventricles didn’t fully divide. As one can see in almost every reptile on earth today, the ventricular division is incomplete – almost like a four-chambered heart, but with a hole between the ventricles (see image). However, I said that almost all reptiles have the pseudo four-chambered cardiac morphology; in fact, one branch of the reptiles went on to develop a fully-featured, true four-chambered heart: the crocodile - but that's a side story.

From some of the lizards the dinosaurs then sprung forth, populating the land from the small dark corners to the open plains. A short while later (a paltry 170 million years) most of the dinosaurs died off. Along with their distant crocodilian, lizard, and snake cousins, at least one dinosaur lineage and one reptilian lineage survived. We now call them birds and mammals, respectively.

Both the bird and mammalian lineages mirrored the path of the crocodile, completing the division between the ventricles (probably prior to their divergence). Natural selection has continued to sculpt our own mammalian hearts, resulting in marvelous structures such as the multiple different valve types, chordae tendenae ("heart strings"), and trabeculae (fibrous strings in the ventricle's interior).

The Bird and Mammal Heart

And with that, we have answered our initial question, in a massively oversimplified fashion. We have hearts because each change leading to our hearts conferred some small advantage to the individuals that inherited them (or at the very least, were not disadvantageous).

Of course, all of these cumulative small changes in the shape of the vessels and hearts, ultimately involved millions of small changes in the genes that controlled the behavior, shape, and functions of the circulatory cells. Scientists have now discovered an incredibly large and complex network of such genes controlling development of the heart.

One of the most astonishing yet completely expected facts we have garnered through studying organisms from Drosophila to the African clawed frog (Xenopus) to humans is the discovery that every organism on this planet with some version of a heart contains the same or a similar set of genes to control heart development.

That’s right. Read it again.

Many of the genes involved in the formation of the relatively primitive “dorsal vessel” in a fly are versions of the same genes that initially form our own hearts. Think about that! Think about how massively more complex we are compared to flies (which are themselves insanely complex in their own rights). Think about the hundreds of millions of years that separate us from our most recent common ancestor with a fly. Yet your heart still uses many of the same genes and in the same ways during early heart development. Of course flies and humans have continued to evolve in parallel ever since our lineages split those hundreds of millions of year ago – we have both made countless changes and tweaks to our own cardiac programs and networks. Nonetheless, our hearts remain related.

In fact, if you watch heart development in an embryo, such as in the Xenopus movie below, you can almost see the course of heart evolution itself. Of course this isn't really ontogeny recapitulating phylogeny - but some of the evolutionary history behind cardiac development is at least evident.

Tbx20 expression in a frog larva heart

One example of a cardiac gene that I’m particularly familiar with, having received my doctorate studying it, is a gene called “Tbx20”. For this discussion, its exact function does not matter. Suffice it to say that when I began my studies, we had a clue that this gene was important in heart development. Why? Because flies have a copy of this gene, as do humans, mice, and every other heart-bearing organism we’ve looked at; furthermore, in each of these organisms this gene is “turned on” in the developing heart tissue.

I went on to show that when you prevent frog larvae from making the Tbx20 protein, they develop incredibly malformed hearts (see the videos below). This means that the Tbx20 gene is indeed important in making a heart. Other researchers later went on to show similar results in mice and flies. Finally, about two months before I finished graduate school, another group of researchers found that some humans born with congenital heart defects have mutations in the Tbx20 gene.

Normal African Clawed Frog (Xenopus) heart

African Clawed Frog (Xenopus) heart lacking Tbx20 protein

So here we have found in only a few years of research a single gene that supports the entire model of evolutionary theory. To rephrase the famous quote from Theodosius Dobzhansky, the existence of Tbx20 in controlling the development of the heart in organisms from flies to humans does not make any sense – except in the light of evolution.

Due to the rich evolutionary history behind the development of this complex organ, the genetic network has become incredibly complex, involving hundreds of genes in thousands of cells all working, moving, and functioning in precise coordination. The higher the complexity, the more things that can possibly go wrong. Unsurprisingly, congenital heart defects are among the most prevalent of all inherited diseases, resulting in about 9 babies out of every one thousand being born with some sort of cardiac abnormality.

I’m sure many of you were wondering how I would manage to tie Abraham Lincoln tie into all this. Although still hotly debated and unproven, at least some researchers believe that Abraham Lincoln may have been afflicted with a disease called Marfan Syndrome, a connective tissue disorder affecting the heart and many other organs. Other researchers believe that he had an unrelated disease. Regardless, it remains at least possible that President Abraham Lincoln was the inheritor of one of the billions of less advantageous variances in heart development that have presented themselves throughout the heart’s evolutionary history.

In summary, the heart of Darwin's theory of natural selection is the idea that evolution comes not through the "why." It comes through the how - through the accumulation of minute individual variations that spread like wildfire when they contribute an advantage.  There remains no better demonstration of this principle than the myriad heart morphologies and functions we can trace today.

Each of you has most certainly inherited a cardiac variation, whether it be a major mutation in a gene, or a tiny change in one letter of your genetic code (a "single nucleotide polymorphism").

Who knows...perhaps yours is the one upon which an entirely new evolutionary history will be built.

So here’s to your own personal variation, and to the man who made our understanding of it all possible. We would have gotten there without him – but I doubt anyone could have rivaled the combination of his incredible intellect and beautiful prose.
Happy birthday Darwin!

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Image credits

Frog heart photograph: Me
Phylogenetic tree: McGraw-Hill and Biology Corner (links to original source broken)
Drosophila heart tube movie: unknown
Heart diagrams: Oracle ThinkQuest Education Foundation
Cardiogenesis animation: Me
Frog heart movies: Me
Lincoln photograph: Visiting DC

Lincoln photo: