Fred Hoyle and the “747” argument, that’s why the opposite theory to Darwin’s is not correct

Those who do not understand the Darwinian process often resort to so-called “common sense” arguments to try to convince the public both of its implausibility and of the existence of a teleological process, if not a designer, at the origin of the complex life that let’s see today. Furthermore, often some of these arguments incur a particular dialectical fortune, and continue to pollute the discussion on the subject without the demonstration of their invalidity definitively destroying their circulation: as long as there is a new audience that has not followed the previous discussions and as long as there is someone who has not understood the denials, they, thanks to their intrinsic ability to appeal to widespread cognitive biases, continue to be reused, without being able to expunge them from the debate.

A perfect example of this kind of arguments is the so-called argument “747” frequently revived by creationists and proponents of intelligent design, originally invented by Fred Hoyle, a prominent British astronomer who paradoxically discovered many of the mechanisms of atom formation in stars that gave rise to the matter we experience, but who, unfortunately as eminent scientists in their later years do, formed pseudoscientific convictions by the end of his professional career , and leveraged his fame to advertise them. This argument, once again, has come back from the past in a debate with yours truly, both explicitly and slightly modified.

The original argument is as follows: “The possibility that higher life forms could have emerged in this way is comparable to the possibility that a tornado passing through a scrap yard could assemble a Boeing 747 from the materials it contains. […] The trouble is that even a simple protozoan, or bacterium, requires the prior formation of about 2,000 enzymes, also complex proteins, which are critical to the successful formation of all the other 198,000 necessary proteins. The odds in favor of the accidental formation of all 2,000 by chance (not to mention the other 198,000), without which no living organism could have come into existence, approaches truly infinitesimal magnitude.”

In addition to the main topic, I was presented with the following analogue: a man’s DNA is made up of about 3 billion bases ordered in a specific sequence, the only one capable of making us work. Starting from a mixture of the four types of bases found in our DNA, it is impossible for a random process to have led to its formation, not even using all the time elapsed since the birth of the universe, because the probability of its composition due to stochastic events is infinitely small. For this reason, my interlocutors conclude, Darwin was trivially wrong and, for the most extremist among them, intelligent design is needed. In all its forms, however, the “747” argument is hopelessly wrong, e it only demonstrates a lack of understanding of how Darwin’s process of variation and selection works. To understand it in a pleasant and in-depth way, it would be enough to read “Chance and Necessity” by Jacques Monod; here I will try to make concise and very simplified considerations, referring the reader to that fundamental text for a much better treatment than mine.

First of all, let us consider Hoyle’s original argument: it is aimed at demonstrating how it is impossible to assemble components at random and obtain a functioning complex machine. The point is that things didn’t go like this at all: biological organisms are not born by random assembly of parts, and the theory of natural evolution does not support it at all. Instead, it was assembled from the bottom up, from very simple components, and at each step natural selection favored certain outcomes over others, cutting away a large number of “explorable probabilities” to obtain something like 3 billion functioning DNA of basics. I’ll try to make myself understood with a very simplified example, to illustrate in a nutshell how Darwin’s argument works.

Let us imagine observing a small genome made up of one hundred DNA bases, and arguing that the probability of obtaining it by randomly combining the four available base types is too low – in fact it is 1 out of 4 raised to 100, the number of possible combinations , which is less than 1 in 10 followed by 59 zeros. However, we can think of a process that works differently: let’s imagine obtaining the sequence of 100 bases by incrementally adding one base at a time. For each addition of a base, let’s imagine that there is a selection, which eliminates all three generated variants, except one, the only one able to pass the sieve. In the first step, we will have 4 single-base genomes; the selection will reduce them to one, and therefore we will have in the next step, by adding a new one at random to that single base, four genomes of two bases. These, in turn, will be reduced to one by natural selection, to obtain again four genomes of three bases, and so on, up to the sequence of 100 bases. In all, as it is easy to see, I will have explored 400 different genomes, rather than the astronomical number of all possible ones; selecting what works best at each step, I broke down the universe of possible sequences to be generated, following a precise evolutionary path up to the 100-base genome. It should then be further added that many, many molecular variants (be it DNA, proteins or other components) are equivalent from the point of view of the functioning of an organismthus reducing by redundancy (and by a lot) the space that natural selection explores to obtain a certain type of organisms.

Furthermore, once the evolutionary process generates fully functional components, these can be used in combination, without having to regenerate a string of DNA to obtain them, one base at a time. Functioning protein genes, for example, can be used to produce new genomes and new sets of proteins, without starting all over again by changing the DNA sequence one base at a time, in a sort of mosaic; thus new functions can emerge from the joint work of components that previously had their own specific functions. Even entire genomes can be joined together and entire organisms can be incorporated into others: we have not produced our mitochondria from scratch, but we have incorporated ancient bacteria and their genomes, without restarting by generating them one base at a time. The process of combining already functioning parts in an organism allows functions to be acquired, without having to find them from scratch by building genes one base at a time, shortening the time necessary to produce complex organisms; and the more the complexity proceeds, the more this bricolage has pieces available to produce further increasing complexity. At each step of innovation, what works worse gives way to what works better by competition, under the scrutiny of environmental conditions: this is the way in which natural selection, i.e. Monod’s necessity, opposes chance, i.e. the explosion of natural variants to be considered in order to obtain a functioning organism. There is no generative tornado, but, on the contrary, a development guided by precise external constraints, a development that proceeds at random only because the variants that are really generated at each step are a random subset of the possible ones and because the direction of the selection it is not constant, but in turn changes stochastically. So, in one sense, the “747” argument is right: if things had gone as creationists believe Darwinism claims, i.e. mixing simple components at random, life would never have arisen. But things didn’t turn out that way, and Darwinism wouldn’t be what it is, if it even remotely resembled the caricature of the “747” argument. We will talk another time about how we arrived at the first functioning components, ie how the first biological replicators emerged, the “functioning pieces” capable of triggering the Darwinian process just illustrated; suffice here to have shown that the process to get to us from them is perfectly explainable with the laws of physics and chemistry and with Darwin’s heuristics.