Dr. Richard Béliveau, a molecular biologist at the University of Quebec comments humorously on the evolution of cellular functioning.
“Today’s cells are the result of the evolution of a primitive cell which appeared on earth 3.5 billion years ago and looked much more like a bacterium than cells do now. During this extended period, this ancestral cell was subjected to huge environmental variations which forced it to constantly search for modifications which could offer it better chances of survival. This considerable adaptive strength is due to its ability to modify its genes to enable the production of new, more efficient proteins in order to deal with new challenges: this is what scientists call “a mutation”. The ability cells have to mutate their genes is an essential characteristic of life without which we would never have seen the light of day.
About 600 million years ago, cells made a decision which would revolutionize life on Earth: they began to cohabitate and form the first organisms made of more than one cell. This was a radical change at the time, as this cohabitation implied that the survival of the organism would take precedence over that of the individual cells. Originally individualists, cells became altruistic and forewent the ability to transform their genes and initiate mutations whenever they wished as they had in the past. The advantage of this evolution was that tasks could be distributed and cells could specialize. In order to effect this specialization, cells modified their rules in order to form new kinds of proteins which would improve their performance. This power of adaptation is the basis for evolution.”
In human beings, specialization has reached record complexity: a skin cell has seemingly nothing to do with a kidney cell, and yet all of the cells in the human body have the same genetic baggage. They are identical, have the same genes, but don’t use the same genes to carry out their duties; in other words, every cell in the human body only uses those genes which are compatible with its function: this phenomenon is called “cellular differentiation“.