Saturday, February 26, 2011

The Bottle Gourd--Insane History of Possibly the First Domesticated Plant

A few days ago I was at a presentation by Dr. Glen Doran concerning his excavation of the Windover site near Titusville, FL--the largest deposit of ancient humans in the Western hemisphere.  It was engrossing to learn of the remains found at this site spectacularly preserved from over 7,000 years ago in a peat bog containing not just bones, but also delicate remains such as actual human brains, fabric and plant remains.

Something captured my attention and imagination.

One of those plants didn't belong there.

It was tens of thousands of miles away from where it should be.

The calabash, also known as bottle gourd is as ubiquitous as humans.  It's found on every continent and most well populated islands in Oceania.  Genetically it's most likely origins are in south Africa since this is the site of the greatest diversity (it's often true that diversity indicates provenience since it's been there longer and had more time to diversify).  While other origin explanations for the far-flung spread of bottle gourds certainly exist (like sea dispersal) one credible origin story is fascinating.

Historic Spread of the bottle gourd

Perhaps the bottle gourd is the first domesticated plant.  It's entirely possible that the first settlers of the Middle East and Asia brought it with them and that seeds were brought into the New World in the packs of the first few intrepid souls crossed the Bering Straits.  There's a bottle gourd found in a cave in Peru that may be as old as 13,000 years ago.   Can't you just see the first few wanderers that set out from Africa carrying calabash water jugs strapped over their sun scorched backs?  Can't you just see fur clad hunters trekking through snow over the Bering Straits after mammoth with gourds filled with folk medicinal herbs?  Can't you just see brave Polynesians sipping cool precious water from these vessels of life after many weeks at sea colonizing Hawaii and Oceania?  Can't you hear the earthen rhythms of this instrument played in every corner of the world?  It may have been one of the first instruments!  How many thirsty mouths have been quenched by this one fruit?!  How many sustaining foods stored in its safe recesses?  How many fire side ritual ceremonies performed to its hollow sounds?!

The significance is still felt today.  West Africans use these gourds for all kinds of containers and instruments.  Chinese use it for traditional medicine.  New Guineans use them for penis sheaths.  It's a traditional serving dish in Hawaii.  Incas passed symbolic bottle gourds from one generation to another.  Indians use the gourds to make the well known instrument called the sitar.  This is a fruit worthy of respect and learning more about.

Sunday, February 20, 2011

Evolution of Depression

Depression for many is more than a label, more than an inconvenience, more than just a certain percentage of the population--it’s a debilitating ailment that can seriously reduce the quality of their life. For reasons of compassion and not just dispassionate science, can evolutionary psychology help to shed any light on the nature of the problem and therefor the nature of a possible relief of depression?

First, let’s consider what an emotion is. Why do we feel anything let alone sadness or depression? Why be happy? Why be angry? Well, emotions are action incentivizers. They help us decide to do something. They are cognitive shorthand. Instead of having to think through a response to a stimulus; you feel and immediately act. To use an hackneyed example, say a cougar is crouching behind an acaia tree. Instead of programming a brain to do complicated risk analyses or cost/benefits assessment evolution has shorthanded that into a “o-shit” terror emotion. Emotions speed up thought.

Great. Now, more specifically, why do we feel sadness or depression? That’s a very complex question, but generally speaking the answer is going to lie within several categories:

Memory Tagging: Perhaps you’ve heard the truism that stupidity can be defined as doing the same thing repeatedly and expecting different results. Negative, ‘sad’ tags on memories can help us avoid the same mistakes twice.

Decision Making: This is much the same as the above, but is mentioned to emphasize that we don’t have to have gone through something to know that doing it would cause emotional pain. We want to avoid emotional duress both in the future and present and sadness helps us do that.

Social Cohesion: If a member of the group is lost then a new social structure, hierarchy, chain of command, reciprocal altruism network, etc. must be set up to maximize the potential of the group staying unified. A void has been created and sadness and mourning can cause the group to come together to reform and heal the wound inflicted on the group.

Were it only that easy. That’s sadness, but I’m defining depression as a subcategory of sadness as a debilitating, isolating, self-destructive emotion far beyond the normal, healthy emotion. How has evolution brought us to that point?

Conservation of Energy/Pathogen isolation: Depression can cause 
Psycho-motor retardation is essentially feeling is emotionally tired that you can't motivate yourself to even do simple tasks, which results in the conservation of energy as well as isolation from pathogens.  

Saving Face: Separating one’s self from the group during a period of depression might have served a function of preventing the loss of face and helped maintain social status upon reemersion and thereby increased reproductive success.

Virtual Stress Simulation/Survival of the Eeyors:  How does an animal learn what is dangerous and what isn't?  Well, it can be taught from relatives, trial and error, it can watch others be eaten or, more importantly for this discussion, it can cognitively simulate and predict.  It may have very well been a selective advantage to speculate every conceivable way things could go wrong and then to virtually and emotionally feel the threat of it so as to avoid the danger.  For instance, if you assume the winter will be frigid and bleak then you might survive better than ole Dr. Pangloss.  It's an emotionally awful way to live, but at least you survive.  Not only does it give you the incentive to avoid a stimulus to avoid the emotional pain that you've simulated before, but it also gives you a chance to run the simulation and problem solve valuable solutions.  You're priming the brain to deal with obstacles.

Brain Priming: It's been shown that as the number of traumatic events increase in a person's life, so does the risk of depression and cognitive unrest.  You've heard the phrase, "Use it or lose it."  Well, the opposite, of course, is also true.  If you use the stress centers of your brain often and for extended periods of times then they become primed and ready to release more stress hormone.  You can imagine that this once had a survival advantage for keeping animals constantly on edge to be ready for a threat.  Now it just ruins lives.

Rumination: Depression sufferers have heightened blood flow to an area known as the left ventrolateral prefrontal cortex as well as increased amounts of serotonin receptors like the 5-HT2A receptor. Both have been shown to serve a function in problem solving. There have even been
numerous studies that have shown that people put in situations that alter their moods toward melancholy score better on problem solving tests, habitually depressed people are more successful professionally and are better problems solvers and people asked in a study to problem solve are more depressed afterwards. Even the behavior of isolation aids in problem solving by reducing distractions.

Combination of Multiple Adaptations/Spandrel: It’s conceivable that depression isn’t one thing, but a multiplicity of mental agencies happening in conjunction. For instance, perhaps depression is the result of a heightened state of self-awareness (which could have selective advantage for obeying social mores and thereby gaining more mates) combined with a focused consciousness (which could have been an advantage for constantly being aware of a child’s safety/needs, problem solving, etc.). These two healthy mental functions aligned could produce a person fixated on self criticism and self condemnation.

Over-Amplified Adaptation/Too Much of a Good Thing: This is classic Darwinism. Within any population there will be variation in a typically bell curve fashion of the manifestation of healthy adaptations, some of which will have too much of a good thing.

Mutation: We shouldn’t ignore the fact that perhaps much of depression is just an unfortunate roll of the mutational dice producing a certain set of brain related genes (like a down regulation of serotonin, etc.). There are undoubtedly times where depression is clearly due to a malfunction such as after brain injuries/strokes.

Emotional Muting: Oddly enough, it’s possible that depression is actually a muting of emotions rather than an profusion of them. Those that are familiar with deep depression are familiar with the bland, dead, muting effect it can have on emotions (sometimes accompanied by manic swings to the opposite end of the emotional spectrum). Is it possible that this emotional flat lining or anhedonia is a form of emotional self protection to prevent something? Perhaps not, but its food for thought.

Defeat Signalling: Communication is paramount in communal animals like us. Just look at our faces. Our lips, eyebrows, facial muscles, larynx placement, Brocca/Wernicke’s area of the brain, are all adaptations that testify to the massive need we have to communicate as humans. Emotional also serve this function and it could be that sadness served as a communication display to end spats.

Submissive Placement: Groups that don’t have hierarchy have difficulty staying together. Groups that don’t stay together often don’t survive. Just as there are adaptations that promote leadership qualities and aspirations there are adaptations that are valuable in promoting omega positions in the group. Depression might aid in cognitively forming omega individuals which are valuable in social cohesion as the counterpoint to alphas.

Alien Environment: Let’s not forget what we’re really evolved for--small tight nit tribes on the African savanna. It doesn’t take a rocket surgeon :) to realize that much of the organization in our society might not be emotionally healthy for us. The double whammy of stress and isolation can be crippling for many of us setting us on a track of spiraling depression. It should be noted, however, that remote
hunter gatherer societies are equally rife with depression as well, though.

Works Sighted [sic]:

Sunday, February 13, 2011

Cambrian Explosion Explanations

Duck and cover! It’s the Cambrian Explosion!

Here’s a brief over view of evolution: Life started 3.5+ billion years ago. Then nearly nothing happens during the ‘boring billion’, as it’s affectionately known (with a lot of neat exceptions, like the Ediacaran fossils etc.). Then 580+- million years ago there was an ‘explosion’ of phylum constituting most of the 36 animal phyla now in existence. Some paleontologist estimate that as many as a 100 phylum were created over the period of only tens of millions of years. What gives? Why the billion years of nothing and then an explosion of diversity? Why haven’t we had a continuation or acceleration of this diversification? How come we’ve only added a hand full more phyla? Why hasn’t the pace continued? This blog will dabble in some of the exciting developments that have emerged in this exciting inquiry.

  • Hox Genes: Evolution only works by mutations.  ONLY.  That means it can take a stupefyingly long time for big changes since big mutations are rare and the amount of big changes that are positive is vanishingly small.  So, when a break through mutation happens, like in the hox genes (those genes that regulate embryonic development of body shape) that can give a whole new range of possibilities for evolution to play with.  That is most likely what happened during the Cambrian Explosion - major developmental genes were developed and the landscape was drastically changed.

  • Snowball Earth: If you don’t know about this, you are positively missing out.  Several times in the Earth’s history our planet has looked like the ice cube Europa.  Support for this includes evidence of glacier deposits at the then equator (based on paleomagnetism, marine sedimentation), and other chemical markers (like pH indicators, oxygen markers in iron deposits, iridium meteorite deposits, carbon isotope ratios, carbonite deposits, etc.)  The last major Snowball Earth period was right before the so called Cambrian Explosion.  This thaw out might have been the crack in the dam that had been building for some time.
Europa, one of the moons of Jupiter.
Artist's rendition of what Earth may have look like as a snowball.

  • Oxygen Levels: This chemical is a major limiting factor for life.  One might argue that we are oxygen powered animals since it serves such a vital function in making our energy.  There’s more to it than just energy, though.  What’s the most common protein in our body accounting for some 25-35%? Collagen.  What’s collagen need a whole lot of to be made?  Oxygen!  What’s it do?  It sticks cells together to make multicellular life and larger structures possible! So, during the Snowball Earth a massive amount of rock was pulverized and dropped into the ocean essentially as fertilizer to cyanobacteria that went nuts growing after the ice sheets melted away thereby producing a prodigious spike in oxygen levels.
That first bump up is the Cambrian Explosion.

  • Predation: Things had been eating each other for a long time, but not really at a multicellular level.  During the Cambrian Explosion an arms race took place to hunt and escape that resulted in some amazing adaptations.
    • Eyes: predation went from passive filter feeding to active hunting.
    • Hard and Bony Parts: Being able to chew and have armor changed everything.
    • Mouth: Just think sponge and jellyfish if you want kind of want to know what life was like before the C.E.  Jaws changed everything.
Gotta love the names of Cambrian stuff.  This is anomalocaris (from anomaly).   

So, why so little phylum generation since then?...Let me know if you have other thoughts, but I'd imagine that much of it would have to do with so many of the environmental niches being filled already...But, I'm open to other ideas!

Pix from here, here, here, here, here, here, here, here, here, here, here, here, here, here, and here.

Sunday, February 6, 2011


"For the life of the flesh is in the blood." Leviticus 17:11

There's an extraordinary variety of life giving blood in the world.  Enjoy!

Blue Blood: our blood, of course, is red because of iron.  Many insects, crustaceans, arthropods and mollusks use a different metal to cause oxygen to be reversibly bound - copper called hemocyanin (these proteins with metal in them are cleverly known as metalloproteins).  When unoxygenated, it's a boring grayish, but pepper it up with some oxygen and things get an exciting blue/green.

This hue is apparently from hemocyanin (copper/blue blood)
Anucleated: so, I knew that our human blood cells didn't have nucleuses, but what I did not know is that we're the exception and not the rule.  Almost all other vertebrates aside from mammals (more on exceptions later) have red blood cells that contain nuclei.  So, why have mammals evolved an awesome mechanism to expunge their nucleus at the right moment of red blood cell development (which I'd totally love to know more about that mechanism.  Please post if you know)?  Well, it kind of just takes up space.  The one and only job of red blood cells is to transport oxygen (to other cells) and carbon dioxide (away from cells) and anything else is just a waste.  Having small red blood cells also makes small capillaries possible which can mean much better diffusion of gases.  Since nothing's perfect the downside to this method of making red blood cells is that they have a limited ability to repair and create energy (since they have no DNA nor mitochondria).

Blood Without Blood Cells: It's kind of like bloodless blood or blood lite, but it's a way of saving metabolic energy.  There are certain circumstances that are oxygenated  enough that the organism doesn't need the help that blood cells provide (either hemoglobin or hemocyanin).  Many insects are small enough that diffusion through their spiracles (kind of like body vents) does the trick.  Another AMAZING exception is the crocodile icefish of the Antarctic waters.  It's so cold and the water is so oxygenated that it simply doesn't need red blood cells and simply has clear blood.  That's awesome!!!  The other exciting thing is that we can sequence the genome of these fish and see that the genes for red blood cells are there, but mutated.  Go evolution!

Crocodile Icefish
Vanadium Filled Blood: first you should know that Vanadium is a very rare element, hence probably why you don't know crap about it (much like me).  Tunicates and some sea cucumber have high concentrations of vanadium - as high as 1 million times that of the sea water around them.  Hypotheses vary on what it may be good for - toxin, oxygen transporter or other.

Some sea squirts/tunicates are pretty!

Deformed Red Blood Cells: yes, you've heard of sickle cell anemia and know that it's bad because the red blood cells aren't as flexible as they need to be (since capillaries are 25% smaller than red blood cells and they have to squeeze through) and they can get clogged.  You probably also know that it's a defense advantage for dealing with malaria.  One of the reasons is that cells with the sickle mutation look normal until they have low oxygen levels and then they change into the abnormal shape (that's why flying can be dangerous for people with sickle cell anemia).  If a cell is infected with plasmodium (the protist that causes malaria) its oxygen level drops, it then turns sickle shaped and is subsequently consumed by white blood cells - malaria's gone! Unusual shapes like fusiform, lanceolate, crescentic, and irregularly polygonal can also be seen in the elk of North America and their counterpart, the red deer of Europe. I couldn't find why, but I would bet good money this is another parasite defense since the draw backs to these shapes can be severe (ask any person with sickle-cell anemia).

Anucleated Amphibian Blood: as we've said earlier, amphibians almost always have red blood cells that have nuclei.  There's an exception and one that makes sense - some lungless salamanders.  Let's say you're a salamander and here's your problem: you've evolved away your lungs because you're small enough to not need them, but then you need to evolve to be bigger again or to be more active.  How do you do it?  Make your blood more efficient and ditch the nuclei of your red blood cells!
Amoebyctes/hemocytes: just think about that there are amoeba like white blood cells crawling around in your body right now.  Then think about that that's these amoebycte blood is the only kind of blood some invertebrates have!  Check it out!