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Thursday, July 31, 2014

Collective Mind in the Mound: How Do Termites Build Their Huge Structures?

Termite mound in Namibia
Termite mounds, like this one in Namibia, contain a series of bubble-like chambers connected by branching passages.

Termites move a fourth of a metric ton of dirt to build mounds that can reach 17 feet (5 meters) and higher.

Lisa Margonelli
PUBLISHED JULY 31, 2014
For the past 26 years, J. Scott Turner has filled termite mounds with propane, scanned them with lasers, and stuffed them with plaster. He has fed microscopic beads to termites, given the insects fluorescent green water, and even tried to turn termite behavior into a video game.
A single termite can be barely bigger than the moon of a fingernail, its semi-transparent exoskeleton as vulnerable to sunlight as to being crushed by a child in flip-flops. But in groups of a million or two, termites are formidable architects, building mounds that can reach 17 feet (5 meters) and higher. The 33 pounds (15 kilograms) or so of termites in a typical mound will, in an average year, move a fourth of a metric ton (about 550 pounds) of soil and several tons of water.A professor of animal physiology at the SUNY College of Environmental Science and Forestry in Syracuse, this rangy intellectual MacGyver does it all in search of clues to a biological mystery: How do tiny termites build such spectacular structures?
The termites also "farm" a symbiotic fungus that occupies eight times more of the nest than the insects do. And some termites eat as much grass each year as an 880-pound (400-kilogram) cow.
Like ants, bees, and other social insects, termites live in societies where the collective power of the colony far outstrips that of the individual. Being part of a super-organism gives the tiny termite superpowers. But a termite mound is like a construction site without a foreman—no one termite is in charge of the project. Is there a "collective plan" encoded in the collective mind of the colony? That question has obsessed Turner for years.
In addition to experimenting in the mounds, Turner designs computer simulations to explore deeper patterns in termite behavior. It wouldn't be wrong to say he's been searching for the psyche of the super-organism, but it wouldn't fully get at the richness of all of the other things he's noticed along the way—including clues to how humans might build more energy-efficient buildings, how we might design robots to build on places like Mars, and even peculiar termite behaviors that might help us understand how our own brains work.
'Nasute' soldiers shoot glue at each other from gun-like head nozzles.
Termites communicate with each other using touch and vibrations.
PHOTOGRAPH BY MARK W. MOFFETT, NATIONAL GEOGRAPHIC
Always Ready to Rebuild
Turner pursues his fieldwork amid the semiarid savannas of northern Namibia, on a government-owned research station named Omatjenne—the word for lightning in the local Herero language. Sure enough, on an afternoon tour of the farm, the horizon is loaded with fat, dark clouds that are soon gashed by electricity.
The life of the termite is a race against rain, Turner says. Termite mounds can take four to five years to build, but a really heavy downpour might cause a third of the mounds to collapse. So termites are always scurrying to rebuild their mounds as fast as the weather erodes them.
To demonstrate the rebuilding process, Turner uses an auger, a tool that looks like a big corkscrew, to cut into the rock-hard surface of a mound. As he pulls a six-inch (15-centimeter) plug of dirt from the side, termites pour out of the hole. Soldiers fan out with their pinching mandibles ready for battle, and workers with mouths full of dirt run to plug the hole. How do they know there's a hole in the mound?
Termites are "novelty detectors," attuned to excitement and always on alert, says Turner. (When there isn't external stimulation, termites sometimes stand in little clusters, massaging each other's antennae.) Experiments in Turner's lab suggest they respond to slight air movements and changes in humidity and concentrations of gases like carbon dioxide.
At the first sign of a disturbance, a termite runs to communicate the news with touch and vibrations. Roused, masses of termites fill their mouths with dirt and head toward the source of the problem. The commotion attracts more termites with more dirt, and within an hour or so the hole is patched.
'Scott Turner sticks his head inside paster cast of termite mound to ponder its architecture.
Scott Turner peers into a plaster cast of a termite mound to ponder its architecture.
PHOTOGRAPH BY MARK W. MOFFETT, NATIONAL GEOGRAPHIC
Peering Inside
The only way to get a glimpse of the termite super-organism in action is to rip the side off a mound. And so one morning Turner, along with entomologist Eugene Marais of the National Museum of Namibia, takes a backhoe to the test fields. With a single swoop, the backhoe removes the top of a mound and then precisely dismantles the rest, like pulling the walls off a dollhouse.
The termites are not happy that their walls have suddenly disappeared, and they swarm frantically around the exposed structure. Marais dislodges a chunk of dense soil about the size of a squashed soccer ball—the queen's chamber.
After repeated blows of a hand pick, the capsule breaks open suddenly, revealing a saucer about five inches (almost 13 centimeters) across containing the queen. Her sweating body is swollen to the size of a human finger. A coterie of workers carries the eggs she produces—at the staggering rate of one every three seconds—to nearby nurseries, while others feed and clean her.
The queen herself, once a relatively normal size, retains her original legs, but they are now nearly useless. Her pale body pulsates, the caramel-colored fats and liquids inside swirling under her skin.
The title "queen" leads people to imagine that she is in charge of the mound, but this is a misconception. "The queen is not in charge," says Marais. "She's really a slave." The queen is the epitome of the super-organism: one for all and all for one. She is a captive ovary, producing hundreds of millions of eggs over her life span of up to 15 years to populate the mound.
'Termite workers building mud walls to repair mound.
Termites rebuild their mounds with mouthfuls of dirt when they're damaged or the weather erodes them.
PHOTOGRAPH BY MARK W. MOFFETT, NATIONAL GEOGRAPHIC
Farming Fungus
Below the queen's chamber lies the super-organism's largest organ: the fungus garden. In a symbiotic relationship dating back millions of years, the termites exit the mound through long foraging tunnels and return with their "intestines full of chewed grass and wood, which they defecate upon their return, and other workers assemble these 'pseudo-feces' into several mazelike fungus combs," Turner explains.
The termites then seed the comb with spores of fungus, which sprout and dissolve the tough cellulose into a high-energy mixture of partially digested wood and grass. For the termites, the fungus functions as a sort of external stomach, but the fungus gets the better deal. Ensconced in elaborate termite-built combs and constantly tended, the fungus receives multiple benefits, including food, water, shelter, and protection.
In fact, the deal is so lopsided that it calls into question just who's in charge of the relationship. Collectively, the colony's fungus accounts for nearly 85 percent of the total metabolism inside the mound, and Turner speculates that the fungus may send chemical signals to the termites that influence—control?—the way they build the mound. "I like to tell people that this may not be a termite-built structure," he says. "It may actually be a fungus-built structure."
'Small and large soldiers, Macrotermes termite nest.
The collective power of the termite colony far outstrips that of the individual.
PHOTOGRAPH BY MARK W. MOFFETT, NATIONAL GEOGRAPHIC
Living Quarters
Which brings us to the most extraordinary organ: the mound itself. Contrary to common notions, termite mounds are not high-rise residence halls. Rather, they are "accessory organs of gas exchange," in Turner's words, designed to serve the respiratory needs of the subterranean colony located several feet (a meter or two) below the mound.
For many years, researchers looked at termite mounds and supposed that the spires worked like chimneys, drawing hot air up and out. But Turner discovered that mounds function more like lungs, inhaling and exhaling through walls that appear impenetrable but are actually quite porous.
Inside the mound, a series of bubble-like chambers connected to branching passages absorb changes in outside pressure or wind and pass them through the mound. To regulate the mix of gases and maintain a stable nest environment, the termites are forever remodeling the mound in response to changing conditions.
"A termite mound is like a living thing," says Turner, "dynamic and constantly maintained."
'Queen (with smaller king next to her) in queen chamber of termite mound.
The queen (top right) produces hundreds of millions of eggs over her life span of up to 15 years to populate the mound.
PHOTOGRAPH BY MARK W. MOFFETT, NATIONAL GEOGRAPHIC
Wet Kisses
While studying termite building behavior, Turner noticed that his subjects seemed to be kissing each other, mouth to mouth, after a complicated ritual that included grooming and begging. Curious, he added fluorescent green dye to their water and discovered that all this "kissing" was actually a bucket brigade, transferring large amounts of water across the mound. A termite can drink half its own weight in water, scurry to a drier part of the mound, and distribute it to other termites. In addition to rebalancing the mound's moisture level, moving all of this water dramatically changes its shape.
Turner's work with termites has attracted some notable collaborators, among them British engineer Rupert Soar. Inspired in part by termite mounds, Soar has plans to build energy-efficient houses with porous walls that make use of passive wind energy. He's also looked into using termite-style building methods to help robots build structures in remote locations using only local materials.
'Experiment with termite workers regurgitating phosphorescent liquid to each other.
Turner added fluorescent green dye to termites' water to illuminate how they transfer large amounts of water across the mound.
PHOTOGRAPH BY MARK W. MOFFETT, NATIONAL GEOGRAPHIC
Group Brain
Termites may even change the way we think about thinking. A research project at Harvard's Wyss Institute for Biologically Inspired Engineeringbrought computer scientists and roboticists to Turner's site to observe termite behavior with a range of sophisticated scanners and software.
Harvard professor of robotics Radhika Nagpal makes an analogy between the behavior of termites and the brain. Individual termites react rather than think, but at a group level they exhibit a kind of cognition and awareness of their surroundings. Similarly, in the brain, individual neurons don't think, but thinking arises in the connections between them. (Single neurons, for example, may recognize a baseball bat and the smell of hot dogs, but working in concert they let you know you're at a baseball game.)
Nagpal's team set up dozens of experiments to try to observe just where this collective cognition arose. "What program are they running?" mused Harvard physicist Justin Werfel, comparing the termites to robots. "Can we get a stochastic model of a stateless automaton that has no memory but reacts to what it encounters?"
Nagpal, Werfel, and Kirstin Peterson, also from Harvard, recently used termite behavior as a model to build a small swarm of robots (named TERMES) that assembles a structure without any instructions.
"This is a system where complexity is of the essence," Turner says of the termites' behavior. "If you don't capture the complexity, there's no hope of understanding it." And so the quest continues for the elusive mind in the mound.
Lisa Margonelli is a senior research fellow at the New America Foundation and the author of Oil on the Brain: Petroleum's Long, Strange Trip to Your Tank. She is working on a new book about termites.

Daddy With Leatherback On Playa La Flor, Nicaragua, Holy Week, 1989

Displaying photo.JPG

Dear Maria and Danny,

This forgotten photo was just sent me by Ed Myer with whom I spent Holy Week, 1989, in the company of David Stolze and Tori Spellman. 

David and Ed were (and are) American physicians with whom I worked at the Managua Medical School. 

Four years ago, David moved his practice to British Columbia, leaving behind "America's Only Socialist Clinic" (in Las Vegas, New Mexico) which he operated for more than 25 years. 

"The F Word," Family Physician Of The Year Acceptance Speech By David Stoltze, M.D.


Las Vegas is where "Milagro Beanfield War" was filmed.

Many of "the extras" - including the old geezers who threaten to "blow off the nuts" of the National Forest Service agent - were David's patients. http://en.wikipedia.org/wiki/The_Milagro_Beanfield_War

We camped at La Flor, on the meter high bluff where the beach gave way to palm trees.  Just us and the turtles.

Part of our "adventure" was to read aloud John Nichols' novel, "The Milagro Beanfield War" - and the beginning of "The Magic Journey," the second book in Nichol's New Mexico Trilogy.



We laughed liked banshees.

Mommy was in Cuba that week.

Love

Daddy man

PS  The romantic subplot of "Magic Journey" was just too funny.



"Flung Down By Corpse Evangelists," Bob Dylan

My Back Pages

Bob Dylan

Crimson flames tied through my ears
Rollin’ high and mighty traps
Pounced with fire on flaming roads
Using ideas as my maps
“We’ll meet on edges, soon,” said I
Proud ’neath heated brow
Ah, but I was so much older then
I’m younger than that now
Half-wracked prejudice leaped forth
“Rip down all hate,” I screamed
Lies that life is black and white
Spoke from my skull. I dreamed
Romantic facts of musketeers
Foundationed deep, somehow
Ah, but I was so much older then
I’m younger than that now
Girls’ faces formed the forward path
From phony jealousy
To memorizing politics
Of ancient history
Flung down by corpse evangelists
Unthought of, though, somehow
Ah, but I was so much older then
I’m younger than that now
A self-ordained professor’s tongue
Too serious to fool
Spouted out that liberty
Is just equality in school
“Equality,” I spoke the word
As if a wedding vow
Ah, but I was so much older then
I’m younger than that now
In a soldier’s stance, I aimed my hand
At the mongrel dogs who teach
Fearing not that I’d become my enemy
In the instant that I preach
My pathway led by confusion boats
Mutiny from stern to bow
Ah, but I was so much older then
I’m younger than that now
Yes, my guard stood hard when abstract threats
Too noble to neglect
Deceived me into thinking
I had something to protect
Good and bad, I define these terms
Quite clear, no doubt, somehow
Ah, but I was so much older then
I’m younger than that now

Tea Party Coherence. (You Know... What Occupy Wall Street Lacked)

The Message Is ... (Tea Party vs. Occupy Wall Street)

The "long form" of Tea Party coherence reads like this: "Anti-Christ Barack HUSSEIN Obama is a Kenyan-born Muslim socialist, anti-American, job-killing  quisling, whose goal is to surrender the United States to a One World Government headed by Arab sheikhs." 

American conservatives were also bamboozled into thinking the invasion of Iraq was a good idea, that four American dead in Benghazi is "The Scandal of The Millennium" and that the most important civic projects are political obstructionism and voter suppression. 

"GOP Voter Suppression and Conservative Contempt for Democracy"
http://paxonbothhouses.blogspot.com/2014/03/gop-voter-suppression-and-conservative.html

"American Conservatives And Oppositional Defiant Disorder"
http://paxonbothhouses.blogspot.com/2013/09/arrested-development-american.html

***

If there is a functioning synapse on "the right side of the aisle," it has gone into deep hiding.



How Tea Party Could Get The Shaft In Border Fight


You can also write "Survival of The Republican Party" on this guy's nose.

***

Plus, women are pissed - including lots of white ones.
And women -- who are more numerous than men -- also vote more frequently than men.

***

"House GOP Spikes Border Bill Rather Than See It Defeated"
Only parties in total disarray "spike" bills they've bring to the floor.
http://www.washingtonpost.com/politics/house-gop-leaders-spike-border-bill-rather-than-see-it-defeated/2014/07/31/1b720ff2-18e0-11e4-9e3b-7f2f110c6265_story.html?wpisrc=nl_eve

***

"Speaker Cruz Tanks John Boehner's Border Security Bill"
http://www.motherjones.com/politics/2014/07/boehner-cruz-border-security-bill-fail?google_editors_picks=true

***


 July 31, 2014 



Today, the House is voting on two measures on the border, in a maneuver designed to get the GOP border bill past conservative opposition. The first vote is on the border bill itself, which includes scaled back funding to address the crisis and changes to the 2008 law to speed deportations — which GOP leaders want. The second vote is to block the expansion of Obama’s deferred deportation programs — which conservatives want.
The plan is to vote on the border bill first, and then, if it passes, to vote on the measure sought by conservatives to block Obama’s Deferred Action For Childhood Arrivals program — blocking future Obama lawlessness and functionally calling for maximum deportations from the interior.
But several Democrats point out to me that Tea Party conservatives really could get the shaft here — thanks to the GOP strategy of holding both votes separately.
That’s because if both bills pass the House, and are sent over to the Senate, Democrats will toss the second bill on DACA straight into the trash can. Because both would get sent over separately, that allows Democrats to trash the second one, while figuring out what to do with the first. In the event that Senate Dems do pass some version of the House border bill — which Tea Party conservatives oppose — this could happen without the Tea Party conservatives’ desired bill on deportations ever seeing the light of day in the Senate.
Reid spokesman Adam Jentleson tells me that this is exactly what will happen, emailing this:
“If the House passed the DACA provision, it would go straight into the trash and never get a vote.”
This represents Democrats playing legislative chess. It’s about exacerbating concerns among Tea Partyers that the two-bill structure Republicans are employing could end up leaving them with nothing, even as the GOP leadership gets its way. It’s about deepening the divide between Republicans who want to do nothing at all on the border — who were egged on this morning by Bill Kristol — and GOP leaders who think doing nothing could be politically catastrophic. It’s also about inducing Tea Party conservatives to demand that the two bills be fused.
Indeed, some of them are already raising concerns about the strategy of the two bills being voted on separately, and are insisting that the two bills should be merged into one. In fact, as one Democrat points out to me, Ted Cruz, who is currently insisting on an anti-DACA measure as part of the final package, previously railed during the government shutdown fight against such GOP leadership procedural gimmickry as an effort to hoodwink conservatives.
Here’s where the chess game gets really interesting. If conservatives do balk at the divided-bill structure, and insist on fusing them into one, and sending that over to the Senate, that could give Dems an easier way to kill the whole package — they can simply argue that they won’t vote on something that would maximize deportations, and blame the GOP insistence on the anti-DACA measure for the death of the whole package.

The Message Is ... (Tea Party vs. Occupy Wall Street)
The "long form" of Tea Party incoherence reads like this: "Anti-Christ Barack HUSSEIN Obama is a Kenyan-born Muslim socialist, anti-American, job-killing  quisling, whose goal is to surrender the United States to a One World Government headed by Arab sheikhs." 

American conservatives were also bamboozled into thinking the invasion of Iraq was a good idea, that four American dead in Benghazi is "The Scandal of The Millennium" and that the most important civic projects are political obstructionism and voter suppression. 

"GOP Voter Suppression and Conservative Contempt for Democracy"
http://paxonbothhouses.blogspot.com/2014/03/gop-voter-suppression-and-conservative.html

"American Conservatives And Oppositional Defiant Disorder"
http://paxonbothhouses.blogspot.com/2013/09/arrested-development-american.html

***
If House Republicans do send over two separate measures, of course, Senate Dems — after deep-sixing the anti-DACA measure — would then face the dilemma of what to do about the House GOP border bill. That won’t be easy for them, particularly if they can’t pass their own border measure.
But either way, it looks like the Tea Party anti-DACA bill, if it passes, will go right on to the trash heap.
UPDATE: And it won’t even get to this point. Because the House GOP leadership just announced that it is shelving its border bill. In a way this was the only way the Tea Party could win here — and it isn’t much of a win, because it may now create the space for Obama to do more on deportations on his own.


Greg Sargent writes The Plum Line blog, a reported opinion blog with a liberal slant -- what you might call “opinionated reporting” from the left.


Neuroscientists Explain Why Marijuana May Bring Serenity Or Psychosis



Alan: It appears that a significant percentage of marijuana users are genetically pre-disposed to psychological derangement when exposed to the substance. At minimum those states which have legalized marijuana should use profits to develop "predisposition profiles" and then make them freely available to those who want them.

"Cannabis Use And The Risk Of Developing A Psychotic Disorder"

"Cannabis-Induced Bipolar Disorder With Psychotic Features"

"Marijuana-Cannabis And Development Of Schizophrenia"

"The Neuroscience Of Pot: Researchers Explain Why Marijuana May Bring Serenity Or Psychosis"

***

Marijuana users a significant number of health risks, including serious psychological derangement in people who are predisposed to instability for genetic or environmental reasons.
http://www.drugabuse.gov/publications/drugfacts/marijuana

***

What are the risks of marijuana? More than many realize. 
Liz Szabo in USA Today

***

The Neuroscience of Pot: Researchers Explain Why Marijuana May Bring Serenity or Psychosis

Alice G. Walton

Forbes

http://www.forbes.com/sites/alicegwalton/2012/01/11/the-neuroscience-of-pot-researchers-explain-why-marijuana-may-bring-serenity-or-psychosis/


According to the experts, and to people who use it, pot can have widely disparate effects on people’s behavior, depending on…well, that part is still a bit unclear. Marijuana has been shown to have both anxiolytic (anti-anxiety) effects and to induce anxiety and psychosis in certain people. In schizophrenics, it canincrease symptoms, and in healthy people it can increase the risk of schizophrenia. Now, new study shows that the two active ingredients in pot, Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) may have quite opposite effects on the brain – and behavior – and could explain why pot’s effects can be unpredictable.
In the new study, the researchers had 15 men who were relatively unseasoned pot users take capsules containing THC, CBD, and flour (placebo) on each of three occasions. The participants then took simple computer tests in which arrows, pointing either left or right, flashed on the screen; the men had to respond based on their direction. Occasionally, an “oddball” arrow was thrown in to the sequence, which was at a 23-degree angle.
This setup allowed the researchers to compare the men’s reactions to usual vs. oddball stimuli, and to see how the various chemicals affected it. How people react to mundane environmental cues vs. the unexpected ones is thought to be linked to mental health, and therefore, to disorders. So, the men’s reaction times were measured, and their brains were scanned with fMRI to see what was going on neurologically. Their psychotic symptoms were also compared across conditions.
The men who had taken THC had more psychotic symptoms like altered thinking (paranoid and delusional thoughts) than men who’d taken either CBD or placebo.
The THC also had a greater effect on reaction time to the standard, rather than the oddball, conditions. This suggests that THC could change what people see as important environmental stimuli (more on this later). Men who had taken the THC also had less activation in the caudate nucleus: and the less activity in the area, the more marked the men’s psychotic symptoms and affected their reaction times. Alterations in the activity in the striatum and prefrontal cortex also suggested a possible mechanism for the increase of psychotic symptoms.
Taking CBD, however, had the opposite effect of THC. It tended to speed up response time to the oddball stimuli, compared to the standard ones, which suggests that it works with our natural tendency to react to unexpected stimuli, rather than against it. And the brain regions that were activated after CBD ingestion were largely counter to those activated with THC. Previous research has suggested that CBD has antipsychotic effects, and this seems to be supported by the current study.
So what’s the relationship between response to arrows on a screen and psychotic symptoms? Normally, people tend to react to out-of-the-ordinary stimuli over the usual ones. In this study, however, people on THC had boosted responses to the mundane stimuli, and were less responsive to the unexpected ones. In the real world, if one has problems ignoring ordinary stimuli in the environment – and even has a ramped-up or atypical response to them – this could creep into the territory of hallucination. Earlier studies have found links between chronic marijuana use and an increased risk for developing psychotic symptoms. Of course, it’s hard to tell whether marijuana use leads to mental health problems or already having mental health problems leads to increased marijuana use, but this and other studies suggest that it’s more likely the former case.
On the other hand, CBD seems to counter the effect of THC, and could (possibly) be used as an antipsychotic. The team’s earlier work actually showed that pretreatment with CBD can block the psychotic effects of THC administration.
The problem is that most people don’t ingest CBD or THC capsules in real life. They smoke pot, which includes both chemicals. Therefore, the study doesn’t quite explain why taking in both chemicals in at the same time would have different effects in different people (or different effects in the same person on different occasions). For example, why some people are more susceptible to the negative effects of the drug than others is still unclear, but it may be due to the patterns of the different cannabidiol receptors in the brain or other differences that have yet to be determined.

The study does help explain why synthetic marijuana has been linked to more adverse effects than natural cannabis. Synthetic forms of the drug, like K2, which have been associated with more hallucinations, agitation, and ER visits, are made largely of chemicals that are thought to mimic THC.
Future studies will have to look into some of these remaining questions, but this study makes a good stab at explaining why marijuana can lead to such different experiences in people who use it.

Judged By E.R. Visits, Marijuana Is Safer Than Alcohol. Pot Also Causes Psychoses

Alan: It appears that a significant percentage of marijuana users are genetically pre-disposed to psychological derangement when exposed to the substance. At minimum those states which have legalized marijuana should use profits to develop "predisposition profiles" and then make them freely available to those who want them.

"Cannabis Use And The Risk Of Developing A Psychotic Disorder"

"Cannabis-Induced Bipolar Disorder With Psychotic Features"

"Marijuana-Cannabis And Development Of Schizophrenia"

"The Neuroscience Of Pot: Researchers Explain Why Marijuana May Bring Serenity Or Psychosis"

***

Marijuana users a significant number of health risks, including serious psychological derangement in people who are predisposed to instability for genetic or environmental reasons.
http://www.drugabuse.gov/publications/drugfacts/marijuana


***
 July 31, 2014

Opponents of marijuana legalization return to one particular number over and over in their arguments: the number of emergency room visits involving marijuana. This ONDCP fact sheet breathlessly reports that "mentions of marijuana use in emergency room visits have risen 176 percent since 1994, surpassing those of heroin." The Drug Enforcement Administration's "Dangers and Consequences of Marijuana Abuse," a 41-page tour-de-force of decontextualized factoids, reports that marijuana was involved in nearly half a million E.R. visits in 2011, second only to cocaine.
The problem, of course, is that these numbers are meaningless without knowing how many people are using those drugs to start with. When you consider that there are approximately 70 times more marijuana users than heroin users in the United States, it makes sense that more of the former are going to the hospital than the latter.
Since the government doesn't provide these comparisons in a meaningful way, I've done it myself below. The raw numbers behind the chart are in a table at the end of this post.
mj-er
The methodology is important here, so I hope you'll forgive a few paragraphs on where these numbers came from.
For 2010, the latest year for which complete alcohol data are available, I grabbed the number of regular users from the National Survey on Drug Use and Health. "Regular," in this case, means people who report using a given substance in the past month.
I then grabbed 2010 E.R. visits involving these substances from the Drug Abuse Warning Network. This is a hospital reporting system that collects detailed data on all E.R. admissions involving a given drug. These E.R. visits can involve the use of multiple substances, so the numbers for each drug involve all visits for which that drug was listed as a contributing factor.

Since the Drug Abuse Warning Network doesn't provide information on alcohol-related visits, I obtained the numbers for all E.R. visits involving alcohol from a 2010 National Institutes of Health report.
The figures clearly show that on a per-user basis, marijuana is considerably less likely to send you to the E.R. than heroin, cocaine or meth. Marijuana users are also 75 percent less likely to face an E.R. visit than prescription drug abusers.
But most surprisingly, marijuana is significantly safer to use than alcohol. For every thousand regular alcohol drinkers there are eight more trips to the E.R. than for every thousand marijuana users. Or in other words, alcohol is about 30 percent more likely to send you to the E.R. than marijuana.
These are all the federal government's own numbers, and they show that marijuana is considerably less harmful to users than alcohol. At the risk of sounding like a broken record, this comports with just about every other credible study of the drug.

Drug and alcohol usage numbers and E.R. visits

SubstanceNumber of monthly usersNumber of substance-related E.R. visits, 2010E.R. visits per 1,000 users
Heroin239,000224,706940.19
Cocaine1,500,000488,101325.40
Meth353,000102,961291.67
Pharmaceuticals (recreational use)7,000,000778,923111.27
Alcohol131,300,0004,622,41135.20
Marijuana17,400,000461,02826.50


Christopher Ingraham is a data journalist focusing primarily on issues of politics, policy and economics. He previously worked at the Brookings Institution and the Pew Research Center.