Intelligence in Nature - Jeremy Narby [57]
Machines that act on their computations and ensure their day-to-day maintenance and survival in a changing environment could be said to have chi-sei. But such machines, inasmuch as they exist, cannot do without being programmed. Nor can machines design and construct improved versions of themselves.
Machines may lack chi-sei, but the cells in our bodies do not. They constantly make decisions, responding to a variety of electrical, chemical, and tactile factors, so as to grow and differentiate in a coordinated way. Cells communicate with one another through âsignaling pathways,â which include dominolike cascades of proteins and a wide variety of signals with meanings such as âstay alive,â âkill yourself,â ârelease this molecule youâve been storing,â âdivide,â and âdonât divide.â Any given cell receives hundreds of signals at any one time and has to integrate them before acting.
The human body is an edifice made of about one hundred trillion cells that communicate with one another through an exchange of chemical signals. Human cells use about eleven thousand signaling proteins. They communicate using a chemical sign system that scientists have only started decoding.
According to biologist Julian Downward, âAll cells must continually sense their surrounding environment and make decisions on the basis of that information. Single-celled organisms must be able to tell which nutrients are nearby and regulate their metabolic processes accordingly. Cells in multi-cellular organisms such as ourselves must sense the presence of neighboring cells and hormones when making decisions such as whether to proliferate, move or die. These processes all require the transfer of information from detection systems referred to as receptors through intermediate molecules within the cell, to cause changes in the expression of genes and the activity of enzymesâ¦Cells receive inputs from many signaling pathways at the same time and must interpret them together, in the context of each other, before making decisions. There are several known ways in which cells do this, although this is an area where much work remains to be done.â
Even bacteria communicate. It turns out that all bacteria species relay information to one another in a âbacterial Esperanto,â which they use to work together. For example, some six hundred species of bacteria coat your teeth every morning, forming a bio-film by positioning themselves in exactly the same order every time. To do this, researchers surmise, they must be able to distinguish self from other. Bacteria use chemicals rather than words to communicate, but this does not stop them from acting efficaciously.
Some bacteria communicate with one another to determine how numerous they are and only launch an attack once they form a group large enough to fight their hostâs immune system. They like to gang up on their victims.
Some bacteria are particularly crafty. When a Salmonella bacterium first approaches a host cell, it produces at least ten proteins, some of which end up inside the host cell, where they trigger cascades of reactions. One of these proteins switches on critical protein regulators of host cell shape. This causes ruffles and convulsions in the host cellâs membrane, which engulfs any Salmonella present. Another Salmonella protein switches off the same regulatory proteins. A Salmonella bacterium breaks into cells like a bandit with a pair of keys. It acts with cheeky chi-sei, and it can also kill.
All cells are largely made of proteins. If individual cells including bacteria have a capacity to know, what about proteins? Some scientists seem to think so. Biochemist