Wednesday, November 21, 2012

Engineered bacteria sacrifice themselves for others

Altruism is a form of behaviour thought only to exist in animals that are highly intelligent, such as us human beings. It is defined as having concern for the welfare of others, without having a certain moral obligation. Sacrificing your own life for the well-being of someone else could be considered the ultimate form of altruism, although scientists are still debating whether true altruism exists at all, evolutionary speaking. Scientists have now found such behaviour in bacteria, although this required a bit of modification.

Scientists from the Duke University performed experiments on a bacterium known as E. coli, which populates your intestines and is frequently used for all kinds of research. The study focused on the so-called suicide program that every cell possesses: when things go wrong, there is a cellular 'button' that activates the suicide pathway, which means that the cell will eventually die. Our bodily cells contain such a switch, but bacteria have them as well.

The suicide pathway is exactly what the scientists focused on in their study. By means of genetic modification, they altered this pathway in order to make the bacteria 'care' more for the 'public good'. That means they were able to make the bacteria sacrifice themselves when necessary: the scientists introduced a stress factor that the population can only overcome if there are 'volunteers' that switch on the suicide program.

By doing these experiments, the scientists showed that in some conditions, it is beneficial for a certain species to have individual members sacrifice themselves. We already know it happens in our body with individual cells, but with individual members of a population, this is disputed. While there are people that sacrifice their lives for others, this is commonly attributed to culture, but not to evolution. The study by the Duke University clearly shows that our genes are able to influence such forms of behaviour. Naturally, these experiments would be quite unethical to replicate in humans.

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