What is Life?:How chemistry becomes biology Read Online Free Page B

total faith in the principle by their everyday actions. Those scientists, like us all, actually stake their lives on its validity. Every time we get into a motor car, for example, we are betting our lives on teleonomy! Our purpose in getting into our car is to get to some destination, and to do so safely. On the roads we have to manoeuvre through an endless stream of vehicular metal—the other cars—careering about hither and yon, a real threat to life and limb. The consequences of a collision between any two metal hunks can be personally disastrous, yet we happily accept that risk day by day. Why? Because of teleonomy. We know that within every other metal hunk careering about, there is a driver whose purpose is identical to our own—to get to his destination in one piece! Though one occasionally comes across an erratic driver who seems to prove the exception to the teleonomic rule, for most of us, on most days, that teleonomic principle operates reliably and, as anticipated, we arrive at our destination safely. So those so-calleddisbelievers in teleonomy are actually silent and committed believers. The world we have to navigate our way through on a daily basis is composed of both biological and non-biological systems. When dealing with the non-biological world we intuitively apply the laws of physics and chemistry. But, consciously or unconsciously, no person would be able to get through a single day without continuous application of the teleonomic principle. No doubt whatever, in the living world, teleonomy, as a predictive and explanatory principle, is the way to go.
    The fact that multicellular animals, like us, behave in a purposeful manner may not appear that surprising. After all, as already noted, we animals are highly complex—we possess a brain and nervous system so it might be argued that in us animals the teleonomic character is just a reflection of significant neural complexity. But here’s the surprise. It is not just multicellular cognitive beings—humans, monkeys, camels, and the like, with a brain and central nervous system that manifest this teleonomic character. That character is also clearly manifest at the level of the single cell! Put a bacterium in a glucose solution in which the glucose concentration is variable and the bacterium ‘swims’ toward the high concentration region. That phenomenon is called chemotaxis. The bacterium, which utilizes the glucose’s chemical energy to power its metabolic processes, is effectively going out for dinner, much like the crouching lion about to pounce on a zebra.
    Of course a bacterial cell cannot swim in the conventional sense of the word. A simple bacterium such as
E. Coli
is powered by several flagella, which, depending on the direction of flagella rotation, enable the bacterium to direct its motion within the solution. If the solution contains nutrition, then the bacterium rotates theflagella in one direction such that its motion is toward the nutrition. However, if the solution contains toxins, then it rotates the flagella in the opposite direction causing the bacterium to tumble, thereby changing its direction away from those toxins. The directed swimming action of the bacterium is unambiguous: without a brain or in fact any neural activity whatever, that clump of chemical aggregates within a membrane (which is itself a chemical aggregate) that we call a living bacterium follows its agenda of seeking out its next meal, keeping out of trouble, and getting on with its life. The fundamental behavioural patterns of bacteria and humans are not as different as one might initially conceive.
    We have focused on the teleonomic behaviour of the living cell but in point of fact it’s not just the
actions
of the bacterium that reflect its teleonomic character. The highly complex cell
structure
that we have already discussed is the most explicit and profound expression of that teleonomic character. Pretty well every element within that bacterium can be associated