As an enthusiastic undergraduate biochemist having studied A level biology, I had been made very aware that the most important intellectual milestone in the life sciences was the publication of Darwin's Origin of Species by Means of Natural Selection. In fact this book is widely regarded as one of the most influential books in history. With this in mind I set out to read it. From the very start I found I was struggling to reconcile what I was reading with my rather limited knowledge of evolution theory. Of course I blamed myself and found it a painful experience. I concluded that Darwin's theory must by much more complicated than I had realized and that I was a very long way from understanding it.
Fortunately, I attended a course in evolution given by John Maynard Smith which was highly entertaining and interesting. At one point he made a throw away comment about Chapter 1 of the Origin of Species being nonsense. This came as a shock and prompted me to try reading the book again. Armed with the knowledge that the book had deficiencies it was easier to relate what I was reading to my knowledge of evolution theory.
We certainly would not expect the first publication of a theory to be perfect and it should be no surprise that The Origin of Species is not perfect. However it turns out that Darwin's book is not the first publication of the theory and that the first publication, by Patrick Matthew 28 years before The Origin, despite many deficiencies, is in some respects a more satisfactory treatment of Natural Selection than Darwin's.
The first sentence of The Origin describes a phenomenon which is very important for the development of Darwin's argument. The second sentence provides an explanation for the phenomenon. This explanation is wrong and illustrates a deficit in Darwin's understanding of Natural Selection. Far from being an isolated error, it permeates and diminishes the remainder of the book and, in my opinion, partly explains Darwin's adherence to Lamarkian mechanisms for evolution in addition, of course, to Natural Selection.
So what is this phenomenon? Here it is in the first sentence of the Origin of Species:
WHEN we look to the individuals of the same variety or sub-variety of our older cultivated plants and animals, one of the first points which strikes us, is, that they generally differ much more from each other, than do the individuals of any one species or variety in a state of nature.
Patrick Matthew, 28 years earlier, had published the exact same observation and this phenomenon probably was well known and as far as I know it is not disputed now. For Darwin the phenomenon was a big problem because his theory rested on making the analogy of humans practising artificial selection in developing new breeds and varieties with the natural world exhibiting natural selection and thereby developing new varieties and species. If, as he tells us, there is more variation under domestication than under nature then the two situations are not strictly analogous. Could there be too little variation in natural populations for natural selection to operate on and create new species?
In order to solve this potential problem, Darwin provides an explanation for domestic populations having more variation which he argues could on occasion operate in natural populations generating the much needed variation on which natural selection can act to drive evolution. Darwin goes on to postulate that when, as he implies is the case for domestic organisms, the conditions of life are "not so uniform as, and somewhat different from those to which the parent-species have been exposed under nature" organisms respond by generating more variation amongst their progeny. This imprecise notion of "not so uniform as, and somewhat different from" is for Darwin the cause of increased variation in the progeny. No evidence is presented for this. In later parts of the Origin he postulates that changes in the conditions of life may act on the reproductive organs in a manner which makes them produce more variety amongst their offspring.
This unsatisfactory explanation for the observed difference in variability between domestic and natural populations can be seen as an understandable consequence of the fact that almost nothing was known about the basis for individual differences between individuals in a population. The laws of genetics and embryogenesis were not known so how could anyone understand the generation of variants? However, the real issue here has nothing to do with the generation of variants and everything to do with the differential survival of variants due to the action of natural selection. The unfortunate fact is that Darwin, in his great work on natural selection, has failed to see that natural selection acts to reduce variation and that because natural selection acts more rigorously in nature than under domestication, it removes more variation in nature. That is why less variation is observed in nature than under domestication.
Patrick Matthew's book, On Naval Timber and Arboriculture, was published in 1831, 28 years before The Origin. Darwin claims to have never heard of it let alone read it. When he did hear about it in 1860 after publishing the Origin he read it and subsequent editions of The Origin acknowledge that Matthew's theory is essentially equivalent to that given by Darwin and of course Wallace. What subsequent editions of The Origin do not do is correct the errors described above to incorporate Matthew's insight that the differences in variation between domestic and natural populations is due to the differential action of natural selection.
Patrick Matthew's account of natural selection strongly emphasizes the role that natural selection plays in maintaining species as they are which is of course the opposite of evolution. In an advertisement for the book taken out in The Encyclopedia Britannica, Matthew singles out the subject of species and variety and what he calls "conformity of species" from the book:
"In embracing the Philosophy of Plants, the interesting subject of Species and Variety is considered [...] the principle also which in the untouched wild 'keeps unsteady nature to her law' inducing conformity of species and preventing deterioration of breed is explained [...]".
The phrase "keeps unsteady nature to her law" is from Milton's Arcadia. It is interesting that Matthew feels that Milton has identified a law of nature, that of species conformity, that he, Matthew, can explain through what he calls "the natural process of selection" in his book, Naval Timber and Arboriculture. Again in the book he states that "This law sustains the lion in his strength, the hare in her swiftness, and the fox in his wiles.".
Matthew's insight into the role of natural selection in suppressing variation can be seen in this extract from his book:
"The use of the infinite seedling varieties in the families of plants, even in those in a state of nature, differing in luxuriance of growth and local adaptation, seems to be to give one individual (the strongest best circumstance-suited) superiority over others of its kind around, that it may, by overtopping and smothering them, procure room for full extension, and thus affording, at the same time, a continual selection of the strongest, best circumstance-suited, for reproduction. Man’s interference, by preventing this natural process of selection among plants, independent of the wider range of circumstances to which he introduces them, has increased the difference in varieties, particularly in the more domesticated kinds;"
In the passage quoted above the phrase "The use of the infinite seedling varieties" initially seemed obscure to me. I now think it means something akin to the "purpose of having such a lot of variation amongst seedlings". He then goes on to explain that the purpose "seems to be to give one individual [...] superiority". He points out that there are "infinite seedling varieties [...] even in those in a state of nature". Clearly he agrees with Darwin that natural populations have less variation but goes on to say that even natural populations have considerable variation.
It is interesting to note the last sentence of the passage quoted above where he alludes to "Man's interference by preventing this natural process of selection". He explains that this "increases the difference in varieties, independent of the wider range of circumstances to which he introduces them". He is making it clear here that domestication increases variation due to its affect on natural selection and not due to the wider circumstances experienced on domestication. Darwin, 28 years later, erroneously attributes the greater variation in domestic populations to the wider circumstances they experience. As we saw earlier, Darwin described this as the conditions of life being"not so uniform as, and somewhat different from those to which the parent-species have been exposed under nature".
The role of natural selection in maintaining the conformity of species is today called stabilizing selection which is contrasted with directional selection which leads to a change in a population. It is impressive that Matthew saw this role and to some extent he explains it more clearly than directional selection. Some people have questioned whether Matthew actually thought natural selection was responsible for the evolution of species. However, Darwin, Wallace and almost all eminent biologists believe he did. Matthew certainly claims he did once he became aware of The Origin of Species in 1860.
Matthew did not seem to attribute great significance to his theory although it is notable that he singles it out for mention in his Encyclopedia Britannica advertisement for his book. He was an agriculturalist not a naturalist or other type of biologist and therefore to him the theory may have seemed less profound. As well as his insight into stabilizing selection he also seems to have embraced the concept of what today we might call social Darwinism or even eugenics. He discusses the deleterious consequences of reducing the intensity of natural selection as societies become more divorced from the natural world. He feels this deterioration is most advanced amongst the aristocracy.
It is often pointed out that Matthew's theory of natural selection is somewhat chaotically organized in a book with a title bearing no relation to the theory. It appears that for him the theory is one consideration, an important and interesting one, in fully addressing the issue of growing trees successfully for producing timber suitable for building ships. As the theory relates to various aspects of the book's main theme it is distributed amongst various parts of the book, largely in the appendix.
While it is understandable that naturalists such as Darwin and Wallace may not be interested in a book on Naval Timber and Arboriculture, it seems unlikely to me that ideas from the book did not indirectly come to the attention of Darwin and Wallace in the 28 years between its publication and their publications. In the mid nineteenth century the number of books and people involved in science was a tiny fraction of today's world. The Encyclopedia Britannica advertisement would not have been obscure and specifically states that the book discusses the "subject of species and variety". Darwin's large scientific circle knew very well he was obsessed with this issue. It has been pointed out that there is no known review of Matthew's book which discusses his ideas on natural selection. However I personally think that the number of informal discussions about books must outweigh the number of reviews by several orders of magnitude. I discuss every book I read but, apart from this article, have never written a book review. It is highly likely that somebody influenced by Matthew's book would have discussed it with Darwin and that neither of them would have been aware of it.
A more common criticism of The Origin is that Darwin does not preclude Lamarkian mechanisms of evolution from acting in addition to natural selection. Lamarkism, also known as use and disuse, postulates that individuals which change during their lifetime pass those changes to their progeny providing a mechanism for populations to adapt to their environment. Darwin particularly opts for Lamarkism over natural selection in cases of disuse. Examples he gives include flightless insects and birds and sightless mammals such as bats and moles. Explaining the loss or reduction of an organ when it is not needed through the action of natural selection is not possible if you are aware of directional selection but unaware of stabilizing selection as we have seen was the case for Darwin. The action of stabilizing selection maintains the constancy of wings and eyes in animals that need to fly and see in order to survive. When some change of habit results in there being no need for flight or sight it is difficult to envisage directional selective pressure acting to reduce the organs of flight and sight as there is no obvious advantage to having reduced organs. However, having no need for the organs removes the stabilizing selection which previously was maintaining them and therefore results in their reduction. As Darwin had not appreciated that stabilizing selection exists he concluded that natural selection was probably not involved and that lack of use during an organism's lifetime was leading to reduction of the organs of flight and sight in individuals which were then passing their acquired characteristics on to their progeny resulting in Lamarkian evolution. Darwin was increasingly attracted by Lamarkian evolution as evidenced by later editions of The Origin. He went on to publish in 1868 a complex mechanism for the transfer of information about the state of an organ in an individual to the reproductive organs which then transmitted the information to the individual's progeny. Darwin's theory borrowed heavily from that of Herbert Spencer published in his book, Principles of Biology in 1864.
The suspicion that Darwin may have obtained his theory of natural selection from Matthew can never be eliminated because absence of evidence is unsatisfactory as evidence. Conversely, we know with certainty that Matthew did not derive his theory from Darwin because he published it before Darwin published anything about evolution. This is one reason why priority is generally considered to belong to the prior publisher. Another consideration is the quality of the work. I think given the information I have reviewed here there are good reasons to consider Matthew's work to, at least in some respects, be of superior quality to that of Darwin.
Ultimately Matthew may prevail because he was the first person in the United Kingdom to plant a number of time bombs in the form of coastal redwood and giant redwood trees from California. These trees and others planted after him are now growing more vigorously and healthily and in far greater numbers than those in California. I feel sure that when these giants reach 250 years of age and stand over 100 meters in height the awe they inspire will generate a surge of interest in the unusual and creative individual who first planted them and the seeds of the theory of natural selection.
Michael E. Weale (2015)
Patrick Matthew's law of natural selection
Biological Journal of the Linnean Society, Volume 115, Issue 4, August 2015, Pages 785–791