Understanding Sieverts and Radiation

XKCD has pretty much the best graphic for understanding radiation exposure. You can see it here.

Note that according to the NYT the hospitalized workers were exposed (at least to their legs) to 2-6 sieverts. Check the chart to see what that means.

Article here.

Rethinking Incentives

Daniel Pink has a video over at TED talks about the reverse nature of incentives.

It turns out that incentives such as money only work to increase productivity for mechanical actions. For tasks requiring even rudimentary cognition, incentives act to decrease productivity.

And it's proportional. Higher incentives cause more reduced productivity.

Here's the video.

Think about it. In the United States we have the greatest income gap between the highest earners and the lowest earners we have ever had. CEOs, stock brokers, are all incentivized by huge bonuses.

That may not even work.

Behavioral Evolution

(Picture from here.)

Let me tell you a story told to me.

Back before the end of the Cretaceous when I was still in graduate school I was studying neurophysiology. I had the opportunity to work in a lab that was experimenting California Sea Lions. During that time, Sam Ridgway came to the University and spoke on his research with dolphins and other marine mammals. Doctor Ridgway told the following story as I recall. (Any mistakes are purely mine and cannot be attributed to him.)

They were working with Gray Seals.

They had built a water proof box with a hole on one of the top ends. Over the hole they had constructed an air tight "bell" so that gases could be examined. The box was then filled with water.

The seals wore a harness that recorded EKG and temperature and had been trained to take a breath at the opening and go down to the other end of the tank and hold down a button. Then, on a signal, the animal came back to the opening and breathed. The gases were then analyzed. They were looking at CO2, EKG, etc.

Now, Gray seals are excellent divers with recorded depths of greater than 1500 feet. Some of their habitat includes pack ice so they have to be able to manage a sealed environment. Going down a couple of feet in a box and holding down a buzzer for a few minutes wasn't even taxing them. So one of the researchers got a bright idea.

When the seal took a breath and went down to the other end they closed of the opening.

Two things happened quickly. The seals heart beat dropped to about 3 beats/minute. The seal then went to the top of the tank and breathed out. The bubbles collected at the top of the box. After a moment, the seal then neatly sucked that air back up.

When the seal was allowed to breath again the heart speeded up and a significant amount of CO2 were blown in through the opening and analyzed.

The behaviors are brilliant: dropping the heartbeat reflected a lowering of metabolism. Other research has shown that circulation in the flippers is reduced when undergoing a dive. The seals body has shut down the periphery and preserved the core systems: brain, heart, lungs. The lungs are a storage are of oxygen but metabolism reduction reduces the demand. Seals have been shown to be quite tolerant of high levels of CO2 in the blood stream.

But the CO2 is still a problem.

CO2 is highly water soluble-- much more soluble in water than in air and much more soluble than O2 under the same conditions. Hence, the behavior of breathing out against the pack ice surface (i.e., the top of the box) to get rid of the CO2 and breathe in the "purified" O2.

A neat trick.

But the reason for the story isn't just extolling the wonders of animal adaptation. Bradycardia in marine mammals is voluntary. They can be taught to do it. The behavior the gray seal used to get rid of CO2 was similarly voluntary. The adaptation here was behavioral not physiological.

This is an important point. Creating a physiological adaptation is expensive. There are developmental considerations, biochemical consequences, and it takes a long time. Behavioral adaptations are much more quick to achieve and once the organism has created one behavioral adaptation the mechanism for further behavioral adaptations is already in place.

Nowhere is this more apparent than in human beings. We've so completely committed to behavioral adaptations that physiological adaptations other than those that serve behavior have become hard to discern. We no longer have an obvious ovulation cycle. Our reproductive practices are as varied as there are tribes on the planet. Our child rearing strategies are equally varied except in one respect: we are committed to rearing children. In this we are consummate K-strategists (see here) in that we invest in the quality of offspring at the expense of the parents.

We have so committed to behavioral adaptations that we develop a model of the world to which we adapt rather than the real thing.

By this I mean that humans abstract the world into a model, analyze the model and react to the world as if it were the model. Hence, cultural institutions, religion, superstition and science. One could argue that the main difference between science and other forms of modeling is that science submits its models to the rigor of testing and discards them when they don't measure up.

We are what we do and we do what we do because of what we are.


PS: I'm sorry I've been a bit hap hazard of late. Work has been, well, tough. I'll do better.

The Human Revolution

(Picture from here.)

For a long time anthropologists and archeologists have viewed human evolution as gotten some sort of kick start about 50k years ago. "Something happened" that gave rise to modern humans.

But some recent genetic work (see here) and anthropological work (see here) has called that into question.

A little history.

While human beings have a long history, hominins that are recognizably human don't really appear until between 200k and 400k years ago. The idea is that humans and Neanderthals had a common ancestor about 700k years ago. That common ancestor moved north into Europe and became Neanderthal. Our ancestors stayed home and evolved into human beings (likely, I think, down in South Africa) and rolled out of Africa about 200k-400k years ago. The first Homo sapiens fossils are dated to 100-200k years ago, implying the stock was already established earlier.

There's some debate about this-- notably involving some teeth discovered in Israel (see here)-- but mostly over whether the location of where the actual evolution of humans occurred. The migration of humans out of Africa is pretty well established.

Once they did migrate they acted pretty much the same until about 45k years ago marking the Upper Paleolithic. Then, all of a sudden, we came up with complex stone tool technology, bone tools, projectile weapons, etc. We had become, in effect, behaviorally modern humans. Earlier humans, the ones dated 100k-200k years ago, had none of these inventions and are lumped together as not behaviorally modern.

Hence, the "Human Revolution" idea.

John Shea of Stony Brook suggests things ain't quite so simple.

A Human Revolution implies a change in variability of behavior, an dramatic increase in the repertoire of what humans did. So he examined stone tools dating from 250k to 6k years in Eastern Africa. He found over that time no single behavioral revolution in that time. Changes in stone tools here and there could be explained in variability in the available materials or in the needs of a specific time and place. A Human Revolution was unnecessary to explain these changes.

Coincidentally, a different study has come from a team by Ryan Hernandez of UCSF. They examined the human genome looking for selective sweeps. A "selective sweep" is a genome change that is so beneficial that it spreads throughout the population very quickly. Along with the "Human Revolution", class sweeps were thought to have driven human evolution. Hernandez found only a few sweeps present in the genome and none that could drive human adaptability. Instead, he came to the conclusion that human adaptation has a complex genetic architecture and derived by subtle shifts in the genome and not any major changes.

So: we have no Human Revolution, behaviorally or genetic.

Shea goes so far to say that the is no such thing as a "modern human". We are the same animal now as we were 200k years ago.

But whether we are different genetically or cognitively is somewhat beside the point. We aredifferent from our ancestors in how we live and what we are capable of. While I think these scientists are correct in that the differences between our ancestors and ourselves may not be in the shape of our brain or our genes, there is no doubt we are culturally different. And that culture drives our ability to cooperate to astounding levels-- not even ants are capable of the our scale and level of cooperation. That had to come from somewhere.

Personally, I think it started when we started sequestering information. I suspect, like elephants, we've been capturing information since Lucy. But if you observe nomadic tribes that are without writing and presume they reflect our history before writing, there is a tremendous drive to retain knowledge across the group, across generations. Often in the form of story and song. Retention of information is a driving force in our species in the last several thousand years. It's no accident, I think, that control and destruction of information (think the Reformation, Nazis, Soviets and the Taliban) are among the levers of power.

Once we started retaining information-- broad, deep rivers of it-- we had the motivation to create writing. And once we had writing we had a mechanism in place to truly exploit the our phenomenal ability to cooperate.

If there was a "Human Revolution" it started with the valuing of information. Civilization started there.

Fox News Lies

I've been observing distortion on Faux News for a while now but I didn't think they actually lied-- I thought they just mixed up opinion and news so much they could not be disentangled. Hence, Faux News.

However, here's a case for outright lying.

I can't say I'm surprised.

Jackass for Techno Nerds

Harcos Laboratories

Seeing Through

(Picture from here.)

Some things are just weird.

The little gem to the left here is the Barreleye Fish, Macropinna microstoma. The green spheres are the eyes. The things that look like Sad Sack eyes are in fact nostrils.

The fish has to watch up to find food and look for predators but, as can be seen, the mouth is below where the eyes can look-- or, below where the could look if the head wasn't transparent.

Transparency has evolved over an array of organisms, mostly pelagic. Worms, medusae and fish and other groups all have transparent representatives.

Transparency derives from a low refractive index between animal and environment coupled with a lack of opacity. Transparency, then, must be a joining of several complimentary factors:

1. A similarity in the refractive index between the internal chemical environment of the animal and the external environment.
2. A physical adaptation of the placement and function of organs in the transparent component such that external material doesn't get in the way. (The "I can see what you have for breakfast." problem.)
3. A selective pressure towards transparency once the opportunity to select for it is presented.

In other words there has to be the potential for transparency, a means to get stuff out of the way and a reason to do so. Many microscopic organisms are already nearly transparent.

Given the above it's no surprise that transparency is almost exclusively found in aquatic animals. The refractive index of cellular fluids is close to that of water since it's mostly water anyway. Consider ice outside of water. It's visible even when transparent by its reflectivity.

Besides, it's hard to achieve transparency when you need bones.

The selective advantages of transparency aren't as obvious as one might think. Most transparent animals are found deep in the sea where there is light available-- not surprising. After all, if there is no light what is the advantage? In the deep ocean there is a marked shift away from transparency to red or black pigmentation. This also makes sense since any light at this depth is generated by biological entities themselves and tends to lack red wavelengths. Consequently, red or black both will absorb the light rendering the pigmented fish essentially invisible.

So transparent species live where there is enough light for it to be an advantage. However, there are a number of animals that live right at the surface. One would think transparency would be an advantage since much of the predation would come from below the animal where any pigment would show as a shadow against the light. However, transparency right at the surface is quite rare.

For evolution to work to favor a trait the rudiments of that trait have to available prior to selection. Consequently, Barrel Bob, above, had to have some transparent qualities on his forehead for selection to favor opening a window to the world.

For selection on Barrel Bob to occur not only does he have to have the rudiments of transparency at hand, his eyes have to be receptive to the frequency of the photons permitted by that transparency.

Transparency as well as opacity depend on what is meant by "visible" light.

Thinking about transparency opens up all sorts of other perceptual ideas.

In the articles I read on transparency it was presumed that reduction of visibility was the selective advantage. The best camouflage is to be invisible, right? But there's another approach to camouflage: disruptive camouflage. This approach has been explored by the military. The idea is not to blend in but to disrupt the perception by the observer. It is also one of the hypotheses behind a zebra's stripes: the striping causes the predator to confuse the individual zebra to blend into with other zebras making it difficult to single out a particular prey animal. I wonder if the distortions inherent in transparency act as a disruptive camouflage.

To a creature that sees in x-rays we would be transparent. In point of fact, such a creature would not be able to perceive opacity as a selective quality-- even though we would. In our creature's home biological environment, transparency would be the norm rather than the exception. There might be an advantage to depositing lead in the skin-- an X-ray based predator might not be able to detect weakness and therefore be less inclined to attack. Internal organ camouflage might be developed-- putting bones (or opacities that appear to be bones) where bones shouldn't be to fool the attacker into thinking the prey was stronger than it was or which end to attack. There are insects and lizards that have "eye spots" on their hind end, presumably to fool predators into attacking the wrong thing.

In my first novel, Caliban Landing, the aliens saw by radio waves. I had presumed they would see surfaces differently and not see inside of things. However, photon penetration is dependent of frequency. Microwaves, as we know, penetrate biological material. That's how microwaves cook a steak or trigger an MRI.

All biological organisms evolve between what the environment presents and what mechanisms in their repertoire are available to them. Had animals on earth pigments that absorbed X-rays and were X-rays readily available, some animal would have evolved a means to use them.

Barrel Bob uses transparency to get around a tricky anatomical problem. He wants to see up. His eyes are badly place for it. So if he sees through his head he can see what he wants to eat. Presumably, in his history, he was eating fine looking down but at some point food above became the better food source.

Barrel Bob selected for a different point of view.

The article that was largely the source for this blog entry is here.