Re: Can single cell oranism be selfish.(I mean does it have survival instinct)

Dear questioner,

Thanks for your interesting questions. They are not easy to answer because we first have to discuss some of the words and phrases that you have used. These are "selfish", "survival instinct" and "artifical intelligence" - they are all words that are commonly used in everyday conversation but in biology, we have to be more careful how we define them.

First - can a single-celled organism be selfish? Webster's Dictionary defines selfish as "caring supremely or unduly for one's self; regarding one's own comfort, advantage, etc., in disregard, or at the expense, of those of others". These are the actions of a conscious mind, generated in the brain and so in one sense we might say that organisms without brains cannot be selfish.

However, the word "selfish" is used in other ways that do not imply conscious intent. I suspect that you are thinking of Richard Dawkins' famous phrase and book title "the Selfish Gene". This was a rather unfortunate use of the word selfish by Dawkins himself which has been misinterpreted and misquoted many times since the book was published. Selfish gene theory states that genes are merely replication machines and to maximise their chance of successful replication, they have housed themselves inside containers that we call organisms. The chance that a gene survives long enough to replicate is enhanced if the organism behaves in a way that prolongs its own survival. So we can certainly say that single-celled organisms, like all organisms will behave in this way - they may compete for food, discourage competitors by colonising an area or even attempt to kill competitors. Again though, none of this is "selfish" in any premeditated sense.

OK - how about "survival instinct"? There are lots of definitions of the word instinct. I think that we humans misuse this word a lot - we seem to imply that we somehow know what we want to achieve but without thinking about it. In fact the zoological definition of instinct is "the natural, unreasoning, impulse by which an animal is guided to the performance of any action, without thought of improvement in the method". In humans we speak of an instinctive reflex, such as quickly pulling away our hand if we touch a hot surface. This action is in a sense pre-programmed into our nervous system - it does aid in survival (which is why the trait has survived), but it is purely mechanical - no brain involved.
In this sense, single-celled organisms can certainly be said to have a survival instinct. Many of them will react to stimuli such as strong light, heat or toxic chemicals, usually by swimming in the opposite direction. Stress will also cause the expression of gene products to counteract it, such as heat-shock proteins. Perhaps we should better call these survival mechanisms, rather than survival instinct.

Finally, let's mention artificial intelligence. I'm not certain what you mean when you say it is far-fetched and will never be realised. I'm guessing that your point is, since even single-celled organisms are quite complex and the product of billions of years of evolution, we will never be able to create artificial life forms which react in the same way as real ones. Others would disagree, but I would agree with you. However, we again have a problem of popular versus scientific definition. Most people think of something like HAL in the movie 2001 when they think about artificial intelligence. The key word though is artificial. It is quite possible to design computational systems that respond to stimuli as though they were intelligent or alive and this is really what AI research is all about. Have a look at this Wikipedia page for some good AI links and discussion.