I was watching a show on discovery channel; people were discussing if life could have first started on Mars and then "landed" on earth...(watch Into the Unknown with Josh Bernstein)
The scientific community only started to really look into this issue after president Bill Clinton in 1996 said there was such a possibility. This was probably after they were able to retrieve a Martian rock sample. (It has a very strange name. It was a combination of words and numbers. I think its this one).
The documentary then went on to actually reveal various researches that would actually prove life was indeed possible on Mars, and it could have originated from there. All of these researches could not have been triggered without a discovery on Mars. There was a discovery by one of those Mars missions which showed the possibility of ice formations under Mar's rocky surface. If life was ever observed by someone to thrive underground, you could rule out such life forms relying on sunlight for their energy needs. But then again, that is against our 1st and most important criteria for the existence of life - sunlight. (Anyway this is what I studied in my school).
But people have gone to extreme depths, and discovered that life does exist, here on earth. I can't remember what they called that particular organism, but they had classified it to be an extremophile. It seems that this particular specie gets its energy by some chemical reaction, (which is not fully understood as of present). It was an entirely new specie that had never been catalogued before. It was found in a remote undisclosed cave located in New Mexico, USA. Those scientists did not disclose the location as they fear contamination with foreign life forms - the ones we are exposed to all the time. So now you get the picture of how extreme this specie is...
Another Martian discovery was the evidence of frozen river beds of high salt concentration. Of which salt(s)? I don't know. But generally the assumption is that these beds are salty. This does show the possibility that the Martian surface had rivers very long time ago. Life was actually present on the surface of Mars! But the focus here is on those salty beds. This leads us to assume that there were river/lake beds that were highly saline. So people, here on earth, tried to investigate if life could survive in these high saline conditions. Since these river beds were on the surface, they were exposed to sunlight and hence this led to the possibility of photosynthesis being one of the ways organisms actually produced food for their energy needs. But even photosynthesis needs water. A highly saline environment would actually strip a cellular body of its water content. So how do such bodies live?
Well, here on earth, scientists discovered organisms that lived in similar environments. These organisms have special cell membranes. They are hard and virtually immune of reverse osmosis. So salt does not enter their system and disrupt it. Studies have also showed that the concentration of such organisms were high when sunlight was peak.
So there; all these are seemingly proof that life could have existed on mars. We don't see diversity in life forms on mars like that on earth because at present the conditions on mars do not support a very rich and diverse earth-like ecosystem. But one should guess how does life on mars reach earth?
Asteroids could have brought them in
Yes, and it is not something new. People have looked into the possibility of asteroids and/or comets bringing life to earth before. Here is a possibility of a foreign body from another planet being introduced into earth. There is evidence of craters on the mars surface suggesting that it was bombarded by asteroids before. The collision would have been so enormous that some Martian rocks escaped Mar's gravitational field and got caught in earth's gravitational field. This could have possibly made life "flourish".
So where does this leave Panspermia?
Panspermia suggests that life on earth could have originated because of seeds planted by other alien civilizations/life forms. We may never really know if this was how life was indeed started. Even if it was we would even go the depth of understanding how that life form came to existence. What’s accepted currently is the Theory of Chemical Evolution: life could have started due to numerous chemical reactions between stable/unstable compounds over time, and under some highly improbable conditions. The results of such reactions could have fortunately become stable. And even these stable compounds could have could have participated in more such reactions over time. Experiments have been done in this area - a popular example we learn through out text books at school is Miller's Experiment.
Monday, March 30, 2009
Tuesday, August 19, 2008
Intoxication, Addiction and the birth of Addiction
Foreward (written after the post): This article is very vague in what it tries to explain - the evolutionary insight into addiction. It actually relies on evolutionary theory.
This post is a little about what happens in the brain when we get intoxicated or addicted to a substance. I suppose this post will highlight a little about the neurobiology of the brain. I don’t consider everyone to be an addict in any way; but I believe people are more susceptible to be a victim of addiction in general. The only way to understand ‘why this is so’ is to understand the biochemistry of the brain, and a little evolutionary history about it. Before I move on, I just want to clarify the two terms – intoxication and addiction:
Intoxication is the state of being affected by psychoactive drugs. It may also refer to the effects of consuming poison or excess amounts of harmless substances. Since I am not talking about intoxicating substances which are lethal or cause instant death I am ruling out the second definition. Intoxication may result in relative euphoria, feeling of pleasantness, etc. These are common symptoms. However not everyone experiences the same symptoms the same way. For some the relative euphoria is a sign of panic, and hence they develop a hate toward these substances. However the general trend is that people rather enjoy the feeling. Addiction is the next level of intoxication. It is much more serious. It is the physical dependence on a psychoactive substance which, when suddenly stopped, causes what is known as withdrawal symptoms. Some common withdrawal symptoms are anger, lethargy, depression, anxiety, etc.
Brain Evolution
Sometimes our brain can be considered to be a huge response system. It responds to various stimuli. And to get these signals or messages across to various regions for processing, the brain relies on its intricate mesh of neurons and neural network. There are some signals that can trigger panic, or readiness to attack, etc. These particular signals are ‘wired’ for the primary reason of survival. We perceive panic or the readiness to attack through a phenomenon called emotion. Neurologically, this is how we would behave when there are certain levels of chemicals (neuro-transmitters) present, taking a particular emotional phenomenon in context; for e.g. when feeling sad or suffering from anxiety, we can observe high amounts of a neurotransmitter called serotonin. (Serotonin has other function like regulating sleep, the cardio-vascular system, etc).
There are two kinds of emotion – positive emotion and negative emotion. Positive emotion works in a scenario where the brain (or the organ called the brain) has realized that there is something positive. For e.g. edible fruits on a tree. If we come to know that we are able to eat fruits from a tree, and that they are abundant, we would naturally be happy. This is a positive emotion which would make us want to consume more fruits from that tree. You can derive a corresponding case for a negative emotion too. Hence as a conclusion you can say that the brain seeks positive or rewarding scenarios most of the time for the simple reason called survival.
The reward system
Now that you know that the brain seeks for positive signals, you should also know that there exists neural pathways or channels and/or reactions which would generally come under the an umbrella the reward circuitry system. In the days of prehistory, the reward system in humans was relatively undeveloped. Perhaps early humans who primarily relied on hunting/gathering for survival did not require one. They were not exposed to intoxicating substances like modern humans. Reward for them was being a successful hunter and acquiring lots of food. Or being reproductively successful, etc. But as food became scarce they became physically unfit for hunting; they discovered that these intoxicating substances could boost their hunting stamina, or even sometimes their reproductive success. However, these substances were not administered in amounts that would cause chronic addiction.
As we became more civilized and started to settle our urge to hunt and feel superior etc, still remained. These programs were still running inside their brains. And consuming intoxicating substances was the only way out. Thus we see the evolutionary birth of addiction.
This post is a little about what happens in the brain when we get intoxicated or addicted to a substance. I suppose this post will highlight a little about the neurobiology of the brain. I don’t consider everyone to be an addict in any way; but I believe people are more susceptible to be a victim of addiction in general. The only way to understand ‘why this is so’ is to understand the biochemistry of the brain, and a little evolutionary history about it. Before I move on, I just want to clarify the two terms – intoxication and addiction:
Intoxication is the state of being affected by psychoactive drugs. It may also refer to the effects of consuming poison or excess amounts of harmless substances. Since I am not talking about intoxicating substances which are lethal or cause instant death I am ruling out the second definition. Intoxication may result in relative euphoria, feeling of pleasantness, etc. These are common symptoms. However not everyone experiences the same symptoms the same way. For some the relative euphoria is a sign of panic, and hence they develop a hate toward these substances. However the general trend is that people rather enjoy the feeling. Addiction is the next level of intoxication. It is much more serious. It is the physical dependence on a psychoactive substance which, when suddenly stopped, causes what is known as withdrawal symptoms. Some common withdrawal symptoms are anger, lethargy, depression, anxiety, etc.
Brain Evolution
Sometimes our brain can be considered to be a huge response system. It responds to various stimuli. And to get these signals or messages across to various regions for processing, the brain relies on its intricate mesh of neurons and neural network. There are some signals that can trigger panic, or readiness to attack, etc. These particular signals are ‘wired’ for the primary reason of survival. We perceive panic or the readiness to attack through a phenomenon called emotion. Neurologically, this is how we would behave when there are certain levels of chemicals (neuro-transmitters) present, taking a particular emotional phenomenon in context; for e.g. when feeling sad or suffering from anxiety, we can observe high amounts of a neurotransmitter called serotonin. (Serotonin has other function like regulating sleep, the cardio-vascular system, etc).
There are two kinds of emotion – positive emotion and negative emotion. Positive emotion works in a scenario where the brain (or the organ called the brain) has realized that there is something positive. For e.g. edible fruits on a tree. If we come to know that we are able to eat fruits from a tree, and that they are abundant, we would naturally be happy. This is a positive emotion which would make us want to consume more fruits from that tree. You can derive a corresponding case for a negative emotion too. Hence as a conclusion you can say that the brain seeks positive or rewarding scenarios most of the time for the simple reason called survival.
The reward system
Now that you know that the brain seeks for positive signals, you should also know that there exists neural pathways or channels and/or reactions which would generally come under the an umbrella the reward circuitry system. In the days of prehistory, the reward system in humans was relatively undeveloped. Perhaps early humans who primarily relied on hunting/gathering for survival did not require one. They were not exposed to intoxicating substances like modern humans. Reward for them was being a successful hunter and acquiring lots of food. Or being reproductively successful, etc. But as food became scarce they became physically unfit for hunting; they discovered that these intoxicating substances could boost their hunting stamina, or even sometimes their reproductive success. However, these substances were not administered in amounts that would cause chronic addiction.
As we became more civilized and started to settle our urge to hunt and feel superior etc, still remained. These programs were still running inside their brains. And consuming intoxicating substances was the only way out. Thus we see the evolutionary birth of addiction.
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