Can an evolutionist consistently believe in higher and lower life forms? That’s the subject of a recent essay by Emanuele Rigato and Alessandro Minelli, entitled, The great chain of being is still here, in Evolution: Education and Outreach, a SpringerOpen journal whose aim is to promote “accurate understanding and comprehensive teaching of evolutionary theory for a wide audience.” In their article (Evolution: Education and Outreach 2013, 6:18, 27 June 2013), Rigato and Minelli argue for a purge: they insist that “progressionist language” must be systematically eradicated from all scientific papers on evolutionary biology. The authors felt impelled to make this drastic recommendation, after making the shocking discovery that nearly 2% of all biological articles published between 2005 and 2010 in 16 top scientific journals contained what the authors call “scala naturae language” – that is, references to “lower” and “higher” life-forms. Rigato and Minelli contend that this kind of language is totally contrary to the Darwinian view of evolution as a tree-like process, in which all life-forms spring from a common stock:
The scala naturae, or great chain of being (Lovejoy 1936), as presented by Charles Bonnet in his Insectologie (Bonnet 1745), distributed nature’s products, living beings included, from the lowest steps of the ladder occupied by fire, air and water, up to the highest steps hosting monkeys, apes and humans, but there are not lower and higher branches in the evolutionary tree of life… [H]istory and genealogical continuity (Darwin’s common descent with modification) are the core of any evolutionary views of living beings. As a consequence, we should not expect in the current professional literature in biology, and evolutionary biology in particular, any survival of scala naturae thinking, or of the corresponding language…
“Talk of ‘higher’ and ‘lower’ organisms … does not so much reflect a specific misunderstanding of phylogenetic diagrams per se but a failure to grasp the very concept of common descent” ( Gregory 2008, p. 126)…
Famous last words! As we’ll see, some of evolution’s leading proponents used scala naturae language, while arguing for common descent.
Rigato and Minelli go on to argue that the use of “progressionist language” is educationally harmful when teaching students the Darwinian theory of evolution, as it conveys the misleading impression that some forms of life are “higher” or “more evolved’ than others. (As an aside, I’d like to suggest that “progressivist” might have been a more suitable term than “progressionist” in this essay; “progressionist language” gets a mere 7 Google hits, about half of which are foreign, while “progressivist language” gets 334.) Evolution, the authors contend, is a tree-like process, which leaves no room for terms such as “higher” and “lower”:
But this is not just an academic issue: the dangerous consequences of keeping a progressionist language alive extend, potentially at least, to critically important social issues: “an abandonment of progressivism in evolution rightfully undermines the unfortunate conflation of Darwinian evolutionary biology with social Darwinism. … Social Darwinism involves notions such as inherent progress in evolution and inherently favored classes or groups of humans as a basis for moral norms and social attitudes and action. … With regard to understanding the role of progress in evolution, the implications for getting evolution wrong are much graver than simply getting it wrong” (Johnson et al 2012, p. 137)…
Despite the explosion of tree-like diagrams in the recent biological literature, evolution is indeed often perceived as a linear, progressive process rather than as a story of unceasing branching and diversification ultimately resulting in a tree. This misleading progressionism is scientifically undefensible (sic) (e.g., Dawkins 1992; O’Hara 1992 1997; Gould 1994 1996; Nee 2005; Gregory 2008. ; Omland et al2008; Casane and Laurenti 2013)…
From an educational perspective, Werth (2012) has recently remarked that students referring to “higher” and “lower” life forms retain an Aristotelian view of the great chain of being, a wrong view of evolution to be corrected by training them in the theory and practice of cladistics.
A brief aside regarding metaphors
I’d like to make a simple suggestion here: maybe it is the tree metaphor itself that is the root of the problem. This picture of an ash tree (courtesy of Wikipedia) illustrates why:
The problem here is that whether we like it or not, trees grow upwards, towards the Sun (notice the teleological and “progressionist” language here?). What’s more, some branches of a tree are longer than others, and some are higher than others. So if you want to invoke a metaphor that makes all the branches equal, then a tree is a very poor choice. A vine metaphor is even less suitable, as the photo below (courtesy of Namazu-tron and Wikipedia) of a vine climbing a (shock! horror!) ladder illustrates:
To make matters worse, vines have a habit of growing up, towards the sunlight. What’s a better metaphor, then? Well, if you really, really want to eliminate all “progressionist” thinking from the teaching of evolution, then the metaphor of a reed mat would be pretty hard to beat. It has no preferred direction. Because it’s horizontal as well as vertical, it also incorporates the idea of lateral gene transfer, and finally, it can grow in all directions:
What about the tendency towards complexity over the course of time?
In their essay, Rigato and Minelli acknowledge that the trend over time towards increasing degrees of complexity in the history of life on Earth might appear, at first sight, to warrant the use of “progressionist language”, but argue that the trend toward complexity merely reflects an outward movement of the right-hand tail end of the evolutionary curve. The mean level of complexity in organisms has not changed appreciably, over the course of time:
One may be tempted to defend the progressionist language by referring to a putative macroevolutionary trend towards increasing degrees of complexity…
Evolution seems to follow an intrinsic trend towards increasingly complex organisms as a result of people concentrating on the small number of large, complex organisms that inhabit the right-hand tail of the complexity distribution and ignoring the simpler and much more common organisms (the ‘full-house’ fallacy, Gould, 1996)…
…To conclude, with Werth (2012, p. 2135): “Complexity may be a trend, but it is not an inevitability. Naturalistic explanations can be offered for life’s diversity, but they need not imply a forward or upward march”…
How the authors used data mining to locate “scala naturae language” in science journals, and what they found
Next, Rigato and Minelli describe how they ferreted out “progressionist language” (which they define as “scala naturae language” in science journals, including some leading journals in the field of evolutionary biology. The authors were surprised to discover that specialist journals in evolutionary biology were among the worst offenders, in this regard:
We present here the results of a data mining exercise extending over the 67,413 biological articles published between 2005 and 2010 in the three top-ranking general-science magazines (Science, Nature and Proceedings of the National Academy of the United States of America) as well as in the pages of a dozen qualified biological journals, including the few top ones in evolutionary biology…
We aimed at discovering examples of scala naturae language. This is generally expressed by contrasting lower with higher representatives of a larger or smaller branch of the tree of life: for example, lower vs. higher vertebrates, lower vs. higher plants, and so on…
Results and discussion
Our search on journals’ databases (Figure 1) eventually spanned over a total of 67,413 articles. Of these, 1,287 (1.91%) returned positive hits from our search for scala naturae language… Interestingly, this happened especially for specialist journals in evolutionary biology. This goes against the expectation for a more accurate exclusion of linguistic expressions in fundamental contrast to the basic cultural perspective from which should arguably move an investigation in evolutionary biology; on the other hand, it is in this field that a chance of inattentively using this language is highest…
Articles with scala naturae language were particularly frequent in Molecular Biology and Evolution (6.14%), BioEssays (5.6%) and Annual Review of Ecology Evolution and Systematics (4.82%). The fact that two of these three journals are in an area of evolutionary biology shows that the use of pre-evolutionary language can survive even in the most renowned professional journals…
The authors found that “scala naturae language” was much more frequent in some countries than others: Russia was a conspicuous offender, while non-European countries such as India, Korea and Turkey did surprisingly well. The authors’ reference to Germany as “Darwin’s homeland” (!) made me laugh, as did their comical amazement at the fact that “progressionist language” was much more common in Germany than in “the America of Intelligent Design.” Could it be that America’s education system isn’t so bad after all?
Of the 16 countries that contributed most to the set of articles retrieved through the scala naturae search, 12 contributed with percentages of their total publication output in the journals and years covered by our search ranging from around 1.17% to 0.57%… On the upper end of the distribution we find Germany (1.51%) and Japan (1.55%), distinctly distanced, however, by Russia, whose 2.93% witnesses perhaps a less efficient involvement of the national scientific community into the conceptual debates on evolution that have been extensively developed in Western countries over the past decades…
The fact that Russia will present such high frequencies could be a long-term effect of Lysenkoism. This effect may have spread in East Germany. However, it is amazing to see how Germany, the country where Willi Hennig was born, is one of the most affected, as it is also Darwin’s homeland, still more than the America of Intelligent Design. The data show that scala naturae is a concept more entrenched in Europe compared to countries with less Westernized cultures, such as India, Korea and Turkey…
Thus, the great chain of being is still with us, 153 years after Darwin (1859) published The Origin of Species, eventually paving the way to modern tree-thinking (O’Hara 1992; Crisp and Cook 2005).
Ah, the irony. After perusing the foregoing article by Rigato and Minelli, I was left shaking my head in disbelief. Not once did the authors address the question: if the evolutionary “tree of life” is fundamentally incompatible with belief in “lower” and “higher” life-forms, then why did Charles Darwin and Thomas Henry Huxley both openly espouse such terminology?
“Progressionist language” in the writings of Thomas Henry Huxley
I’ll begin with Huxley first. His 1861 essay, On the Relations of Man to the Lower Animals, is a masterly piece of prose, whose very title (with its reference to “lower animals”) completely upends Rigato and Minelli’s thesis that scala naturae language has no place in Darwinian biology. Who, after all, could be said to have a better grasp of Darwin’s theory of evolution than “Darwin’s bulldog”? Let us examine what he says in his essay.
It is a truth of very wide, if not of universal, application, that every living creature commences its existence under a form different from, and simpler than, that which it eventually attains.
The oak is a more complex thing than the little rudimentary plant contained in the acorn; the caterpillar is more complex than the egg; the butterfly than the caterpillar; and each of these beings, in passing from its rudimentary to its perfect condition, runs through a series of changes, the sum of which is called its Development. In the higher animals these changes are extremely complicated; but, within the last half century, the labours of such men as Von Baer, Rathke, Reichert, Bischoff, and Remak, have almost completely unravelled them, so that the successive stages of development which are exhibited by a Dog, for example, are now as well known to the embryologist as are the steps of the metamorphosis of the silk-worm moth to the school-boy. It will be useful to consider with attention the nature and the order of the stages of canine development, as an example of the process in the higher animals generally…
…[T]he difference in the volume of the cranial cavity of different races of mankind is far greater, absolutely, than that between the lowest Man and the highest Ape, while, relatively, it is about the same… [A]fter making all due allowance for difference of size, the cranial capacities of some of the lower Apes fall nearly as much, relatively, below those of the higher Apes as the latter fall below Man.
Thus, even in the important matter of cranial capacity, Men differ more widely from one another than they do from the Apes; while the lowest Apes differ as much, in proportion, from the highest, as the latter does from Man…
The brain of a fish is very small, compared with the spinal cord into which it is continued, and with the nerves which come off from it: of the segments of which it is composed – the olfactory lobes, the cerebral hemispheres, and the succeeding divisions – no one predominates so much over the rest as to obscure or cover them; and the so-called optic lobes are, frequently, the largest masses of all. In Reptiles, the mass of the brain, relatively to the spinal cord, increases and the cerebral hemispheres begin to predominate over the other parts; while in Birds this predominance is still more marked. The brain of the lowest Mammals, such as the duck-billed Platypus and the Opossums and Kangaroos, exhibits a still more definite advance in the same direction. The cerebral hemispheres have now so much increased in size as, more or less, to hide the representatives of the optic lobes, which remain comparatively small, so that the brain of a Marsupial is extremely different from that of a Bird, Reptile, or Fish. A step higher in the scale, among the placental Mammals, the structure of the brain acquires a vast modification–not that it appears much altered externally, in a Rat or in a Rabbit, from what it is in a Marsupial – nor that the proportions of its parts are much changed, but an apparently new structure is found between the cerebral hemispheres, connecting them together, as what is called the “great commissure” or “corpus  callosum.” The subject requires careful re-investigation, but if the currently received statements are correct, the appearance of the “corpus callosum” in the placental mammals is the greatest and most sudden modification exhibited by the brain in the whole series of vertebrated animals – it is the greatest leap anywhere made by Nature in her brain work…
In the lower and smaller forms of placental Mammals the surface of the cerebral hemispheres is either smooth or evenly rounded, or exhibits a very few grooves, which are technically termed “sulci,” separating ridges or “convolutions” of the substance of the brain; and the smaller species of all orders tend to a similar smoothness of brain. But, in the higher orders, and especially the larger members of these orders, the grooves, or sulci, become extremely numerous, and the intermediate convolutions proportionately more complicated in their meanderings, until, in the Elephant, the Porpoise, the higher Apes, and Man, the cerebral surface appears a perfect labyrinth of tortuous foldings…
As if to demonstrate, by a striking example, the impossibility of erecting any cerebral barrier between man and the apes, Nature has provided us, in the latter animals, with an almost complete series of gradations from brains little higher than that of a Rodent, to brains little lower than that of Man…
So far as cerebral structure goes, therefore, it is clear that Man differs less from the Chimpanzee or the Orang, than these do even from the Monkeys, and that the difference between the brains of the Chimpanzee and of Man is almost insignificant, when compared with that between the Chimpanzee brain and that of a Lemur.
It must not be overlooked, however, that there is a very striking difference in absolute mass and weight between the lowest human brain and that of the highest ape – a difference which is all the more remarkable when we recollect that a full-grown Gorilla is probably pretty nearly twice as heavy as a Bosjesman, or as many an European woman. It may be doubted whether a healthy human adult brain ever weighed less than thirty-one or two ounces, or that the heaviest Gorilla brain has exceeded twenty ounces.
This is a very noteworthy circumstance, and doubtless will one day help to furnish an explanation of the great gulf which intervenes between the lowest man and the highest ape in intellectual power; but it has little systematic value, for the simple reason that, as may be concluded from what has been already said respecting cranial capacity, the difference in weight of brain between the highest and the lowest men is far greater, both relatively and absolutely, than that between the lowest man and the highest ape…
But even leaving Mr. Darwin’s views aside, the whole analogy of natural operations furnishes so complete and crushing an argument against the intervention of any but what are termed secondary causes, in the production of all the phenomena of the universe; that, in view of the intimate relations between Man and the rest of the living world, and between the forces exerted by the latter and all other forces, I can see no excuse for doubting that all are co-ordinated terms of Nature’s great progression, from the formless to the formed – from the inorganic to the organic – from blind force to conscious intellect and will…
I have endeavoured to show that no absolute structural line of demarcation, wider than that between the animals which immediately succeed us in the scale, can be drawn between the animal world and ourselves; and I may add the expression of my belief that the attempt to draw a psychical distinction is equally futile, and that even the highest faculties of feeling and of intellect begin to germinate in lower forms of life. At the same time, no one is more strongly convinced than I am of the vastness of the gulf between civilized man and the brutes; or is more certain that whether from them or not, he is assuredly not of them. No one is less disposed to think lightly of the present dignity, or despairingly of the future hopes, of the only consciously intelligent denizen of this world.
To sum up: Huxley believed steadfastly in a “scale” of Nature, and he lauded “Nature’s great progression, from the formless to the formed – from the inorganic to the organic – from blind force to conscious intellect and will,” culminating in man, “the only consciously intelligent denizen of this world.” Nevertheless, he insisted that the progression was a smooth one, and that the gulf between man and the higher apes, vast as it is, is smaller than the gulf between the ape and the lemur. In short: scala naturae thinking was absolutely central to Huxley’s understanding of evolution.
But perhaps it will be suggested that Huxley’s understanding of Darwin’s thinking was imperfect. What, then, did Darwin himself think?
Scala naturae thinking in the writings of Charles Darwin
The following passages are taken from Darwin’s Origin of Species (London: John Murray, 1st edition, 1859):
Again, plants low in the scale of organisation are generally much more widely diffused than plants higher in the scale… (Chapter II, pp. 54-55)
I am tempted to give one more instance showing how plants and animals, most remote in the scale of nature, are bound together by a web of complex relations. (Chapter III, p. 73)
How low in the scale of nature this law of battle [for a mate] descends, I know not; male alligators have been described as fighting, bellowing, and whirling round, like Indians in a war-dance, for the possession of the females; male salmons have been seen fighting all day long; male stag-beetles often bear wounds from the huge mandibles of other males. (Chapter IV, p. 88)
…[T]he foregoing remark seems connected with the very general opinion of naturalists, that beings low in the scale of nature are more variable than those which are higher. I presume that lowness in this case means that the several parts of the organisation have been but little specialised for particular functions… (Chapter V, p. 149)
…[O]rganic beings low in the scale of nature are more variable than those which have their whole organisation more specialised, and are higher in the scale. (Chapter V, p. 168)
A little dose, as Pierre Huber expresses it, of judgment or reason, often comes into play, even in animals very low in the scale of nature. (Chapter VII, p. 208)
If our systematic arrangements can be trusted, that is if the genera of animals are as distinct from each other, as are the genera of plants, then we may infer that animals more widely separated in the scale of nature can be more easily crossed than in the case of plants; but the hybrids themselves are, I think, more sterile. (Chapter VII, p. 252)
There is some reason to believe that organisms, considered high in the scale of nature, change more quickly than those that are low: though there are exceptions to this rule. (Chapter X, p. 313)
We can perhaps understand the apparently quicker rate of change in terrestrial and in more highly organised productions compared with marine and lower productions, by the more complex relations of the higher beings to their organic and inorganic conditions of life, as explained in a former chapter. (Chapter X, p. 314)
We should, also, remember that some, perhaps many, fresh-water productions are low in the scale of nature, and that we have reason to believe that such low beings change or become modified less quickly than the high.. (Chapter XII, p. 388)
There is, also, some reason to believe from geological evidence that organisms low in the scale within each great class, generally change at a slower rate than the higher forms… (Chapter XII, p. 406)
In both time and space the lower members of each class generally change less than the higher; but there are in both cases marked exceptions to the rule. (Chapter XII, p. 410)
Darwin explains his use of the tree metaphor
As buds give rise by growth to fresh buds, and these, if vigorous, branch out and overtop on all sides many a feebler branch, so by generation I believe it has been with the great Tree of Life, which fills with its dead and broken branches the crust of the earth, and covers the surface with its ever branching and beautiful ramifications. (Chapter IV, p. 130)
Darwin explains why recent life forms are higher than ancient ones, and more successful life forms are higher than those they out-compete
There has been much discussion whether recent forms are more highly developed than ancient. I will not here enter on this subject, for naturalists have not as yet defined to each other’s satisfaction what is meant by high and low forms. But in one particular sense the more recent forms must, on my theory, be higher than the more ancient; for each new species is formed by having had some advantage in the struggle for life over other and preceding forms. If under a nearly similar climate, the eocene inhabitants of one quarter of the world were put into competition with the existing inhabitants of the same or some other quarter, the eocene fauna or flora would certainly be beaten and exterminated; as would a secondary fauna by an eocene, and a palæozoic fauna by a secondary fauna… From the extraordinary manner in which European productions have recently spread over New Zealand, and have seized on places which must have been previously occupied, we may believe, if all the animals and plants of Great Britain were set free in New Zealand, that in the course of time a multitude of British forms would become thoroughly naturalized there, and would exterminate many of the natives. On the other hand, from what we see now occurring in New Zealand, and from hardly a single inhabitant of the southern hemisphere having become wild in any part of Europe, we may doubt, if all the productions of New Zealand were set free in Great Britain, whether any considerable number would be enabled to seize on places now occupied by our native plants and animals. Under this point of view, the productions of Great Britain may be said to be higher than those of New Zealand. (Chapter X, pp. 336-337)
The inhabitants of each successive period in the world’s history have beaten their predecessors in the race for life, and are, in so far, higher in the scale of nature; and this may account for that vague yet ill-defined sentiment, felt by many palaeontologists, that organisation on the whole has progressed. If it should hereafter be proved that ancient animals resemble to a certain extent the embryos of more recent animals of the same class, the fact will be intelligible. (Chapter X, p. 345)
Recent forms are generally looked at as being, in some vague sense, higher than ancient and extinct forms; and they are in so far higher as the later and more improved forms have conquered the older and less improved organic beings in the struggle for life. (Chapter XIV, p. 476)
Darwin also defined “high” and “low” in terms of complexity
The embryo in the course of development generally rises in organisation: I use this expression, though I am aware that it is hardly possible to define clearly what is meant by the organisation being higher or lower. But no one probably will dispute that the butterfly is higher than the caterpillar. (Chapter XIII, p. 441)
It is interesting to contemplate an entangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent on each other in so complex a manner, have all been produced by laws acting around us. These laws, taken in the largest sense, being Growth with Reproduction; Inheritance which is almost implied by reproduction; Variability from the indirect and direct action of the external conditions of life, and from use and disuse; a Ratio of Increase so high as to lead to a Struggle for Life, and as a consequence to Natural Selection, entailing Divergence of Character and the Extinction of less-improved forms. Thus, from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. (Chapter XIV, pp. 489-490)
For Darwin, the tree metaphor, far from being at odds with talk of “higher” and “lower” life forms, provided justification for it. For Darwin, the now-living branches of the tree were obviously “higher” than the extinct branches they’d replaced, and moreover, prolific branches that were currently out-competing other branches for sunlight were also “higher” as they were more successful. Finally, Darwin viewed the more complex branches of the tree of life as “higher” than the simpler ones, as they added more to the richness of life on Earth.
However, it might be argued that Darwin was still relatively youthful when he wrote The Origin of Species. What did he think in his later years? To answer this question, let us examine Darwin’s work, The Descent of Man, and Selection in Relation to Sex (London: John Murray, 1st edition, 1871). Surprisingly, we find that scala naturae thinking permeates this book, even more than it permeated The Origin of Species. Here, for the first time, we find Darwin attempting to formulate a rigorous definition of “higher” and “lower”, based on von Baer’s writings. Here, Darwin explains why he regards specialized life-forms as “higher” in the scale of Nature than simpler life-forms:
Darwin’s definition of “higher” and “lower”
The best definition of advancement or progress in the organic scale ever given, is that by Von Baer; and this rests on the amount of differentiation and specialisation of the several parts of the same being, when arrived, as I should be inclined to add, at maturity. Now as organisms have become slowly adapted by means of natural selection for diversified lines of life, their parts will have become, from the advantage gained by the division of physiological labour, more and more differentiated and specialised for various functions. The same part appears often to have been modified first for one purpose, and then long afterwards for some other and quite distinct purpose; and thus all the parts are rendered more and more complex. But each organism will still retain the general type of structure of the progenitor from which it was aboriginally derived. In accordance with this view it seems, if we turn to geological evidence, that organisation on the whole has advanced throughout the world by slow and interrupted steps. In the great kingdom of the Vertebrata it has culminated in man. It must not, however, be supposed that groups of organic beings are always supplanted and disappear as soon as they have given birth to other and more perfect groups. The latter, though victorious over their predecessors, may not have become better adapted for all places in the economy of nature. Some old forms appear to have survived from inhabiting protected sites, where they have not been exposed to very severe competition; and these often aid us in constructing our genealogies, by giving us a fair idea of former and lost populations. But we must not fall into the error of looking at the existing members of any lowly-organised group as perfect representatives of their ancient predecessors. (Chapter VI, pp. 211-212)
Darwin on man’s relation to the higher apes
Nor shall I have occasion to do more than to allude to the amount of difference between man and the anthropomorphous apes; for Prof. Huxley, in the opinion of most competent judges, has conclusively shewn that in every single visible character man differs less from the higher apes than these do from the lower members of the same order of Primates. (Introduction, p. 3)
But it would be superfluous here to give further details on the correspondence between man and the higher mammals in the structure of the brain and all other parts of the body. (Chapter I, p. 11)
It is, in short, scarcely possible to exaggerate the close correspondence in general structure, in the minute structure of the tissues, in chemical composition and in constitution, between man and the higher animals, especially the anthropomorphous apes. (Chapter I, p. 14)
The nictating membrane … is fairly well developed in the two lower divisions of the mammalian series, namely, in the monotremata and marsupials, and in some few of the higher mammals, as in the walrus. But in man, the quadrumana, and most other mammals, it exists, as is admitted by all anatomists, as a mere rudiment, called the semilunar fold. (Chapter I, p. 23)
Darwin on man’s mental continuity with the higher animals
If no organic being excepting man had possessed any mental power, or if his powers had been of a wholly different nature from those of the lower animals, then we should never have been able to convince ourselves that our high faculties had been gradually developed. But it can be clearly shewn that there is no fundamental difference of this kind. We must also admit that there is a much wider interval in mental power between one of the lowest fishes, as a lamprey or lancelet, and one of the higher apes, than between an ape and man; yet this immense interval is filled up by numberless gradations. (Chapter II, p. 35)
My object in this chapter is solely to shew that there is no fundamental difference between man and the higher mammals in their mental faculties. (Chapter II, p. 35)
The fewness and the comparative simplicity of the instincts in the higher animals are remarkable in contrast with those of the lower animals. (Chapter II, p. 37. Darwin goes on to mention exceptions to this general rule.)
To return to our immediate subject: the lower animals, like man, manifestly feel pleasure and pain, happiness and misery. Happiness is never better exhibited than by young animals, such as puppies, kittens, lambs, &c., when playing together, like our own children. Even insects play together, as has been described by that excellent observer, P. Huber, who saw ants chasing and pretending to bite each other, like so many puppies. (Chapter II, p. 39)
Most of the more complex emotions are common to the higher animals and ourselves. Every one has seen how jealous a dog is of his master’s affection, if lavished on any other creature; and I have observed the same fact with monkeys. (Chapter II, pp. 41-42)
As dogs, cats, horses, and probably all the higher animals, even birds, as is stated on good authority, have vivid dreams, and this is shewn by their movements and voice, we must admit that they possess some power of imagination. (Chapter II, p. 46)
The fact of the higher apes not using their vocal organs for speech, no doubt depends on their intelligence not having been sufficiently advanced. (Chapter II, p. 59)
We will confine our attention to the higher social animals, excluding insects, although these aid each other in many important ways. The most common service which the higher animals perform for each other, is the warning each other of danger by means of the united senses of all. (Chapter III, p. 74)
The social animals which stand at the bottom of the scale are guided almost exclusively, and those which stand higher in the scale are largely guided, in the aid which they give to the members of the same community, by special instincts; but they are likewise in part impelled by mutual love and sympathy, assisted apparently by some amount of reason. (Chapter III, pp. 85-86)
Nevertheless the difference in mind between man and the higher animals, great as it is, is certainly one of degree and not of kind. (Chapter III, p. 105)
We have seen that the senses and intuitions, the various emotions and faculties, such as love, memory, attention, curiosity, imitation, reason, &c., of which man boasts, may be found in an incipient, or even sometimes in a well-developed condition, in the lower animals. They are also capable of some inherited improvement, as we see in the domestic dog compared with the wolf or jackal. If it be maintained that certain powers, such as self-consciousness, abstraction, &c., are peculiar to man, it may well be that these are the incidental results of other highly-advanced intellectual faculties; and these again are mainly the result of the continued use of a highly developed language. At what age does the new-born infant possess the power of abstraction, or become self-conscious and reflect on its own existence? We cannot answer; nor can we answer in regard to the ascending organic scale. (Chapter III, pp. 105-106)
The early progenitors of man were, no doubt, inferior in intellect, and probably in social disposition, to the lowest existing savages; but it is quite conceivable that they might have existed, or even flourished, if, whilst they gradually lost their brute-like powers, such as climbing trees, &c., they at the same time advanced in intellect. But granting that the progenitors of man were far more helpless and defenceless than any existing savages, if they had inhabited some warm continent or large island, such as Australia or New Guinea, or Borneo (the latter island being now tenanted by the orang), they would not have been exposed to any special danger. In an area as large as one of these islands, the competition between tribe and tribe would have been sufficient, under favourable conditions, to have raised man, through the survival of the fittest, combined with the inherited effects of habit, to his present high position in the organic scale. (Chapter IV, p. 157)
When we see in many parts of the world enormous areas of the most fertile land peopled by a few wandering savages, but which are capable of supporting numerous happy homes, it might be argued that the struggle for existence had not been sufficiently severe to force man upwards to his highest standard. (Chapter VI, p. 180)
…[T]he mental faculties of man and the lower animals do not differ in kind, although immensely in degree. A difference in degree, however great, does not justify us in placing man in a distinct kingdom, as will perhaps be best illustrated by comparing the mental powers of two insects, namely, a coccus or scale-insect and an ant, which undoubtedly belong to the same class. The difference is here greater than, though of a somewhat different kind from, that between man and the highest mammal. (Chapter VI, p. 186)
On the whole, the difference in mental power between an ant and a coccus is immense; yet no one has ever dreamed of placing them in distinct classes, much less in distinct kingdoms. No doubt this interval is bridged over by the intermediate mental powers of many other insects; and this is not the case with man and the higher apes. (Chapter VI, p. 187)
Man’s relation to the higher and lower animals
It would be beyond my limits, and quite beyond my knowledge, even to name the innumerable points of structure in which man agrees with the other Primates. Our great anatomist and philosopher, Prof. Huxley, has fully discussed this subject, and has come to the conclusion that man in all parts of his organisation differs less from the higher apes, than these do from the lower members of the same group. Consequently there “is no justification for placing man in a distinct order.” (Chapter VI, p. 191)
We have seen that birds and reptiles were once intimately connected together; and the Monotremata now, in a slight degree, connect mammals with reptiles. But no one can at present say by what line of descent the three higher and related classes, namely, mammals, birds, and reptiles, were derived from either of the two lower vertebrate classes, namely amphibians and fishes. In the class of mammals the steps are not difficult to conceive which led from the ancient Monotremata to the ancient Marsupials; and from these to the early progenitors of the placental mammals. We may thus ascend to the Lemuridae and the interval is not wide from these to the Simiadae. The Simiadae then branched off into two great stems, the New World and Old World monkeys; and from the latter, at a remote period, Man, the wonder and glory of the Universe, proceeded. (Chapter VI, p. 213)
The most humble organism is something much higher than the inorganic dust under our feet; and no one with an unbiassed mind can study any living creature, however humble, without being struck with enthusiasm at its marvellous structure and properties. (Chapter VI, p. 213)
Hence in these classes, such as the Protozoa, Coelenterata, Echinodermata, Scolecida, true secondary sexual characters do not occur; and this fact agrees with the belief that such characters in the higher classes have been acquired through sexual selection, which depends on the will, desires, and choice of either sex. (Chapter IX, p. 321)
Man is at the summit of the scale of Nature
He who believes in the advancement of man from some lowly-organised form, will naturally ask how does this bear on the belief in the immortality of the soul. The barbarous races of man, as Sir J. Lubbock has shewn, possess no clear belief of this kind; but arguments derived from the primeval beliefs of savages are, as we have just seen, of little or no avail. Few persons feel any anxiety from the impossibility of determining at what precise period in the development of the individual, from the first trace of the minute germinal vesicle to the child either before or after birth, man becomes an immortal being; and there is no greater cause for anxiety because the period in the gradually ascending organic scale cannot possibly be determined. (Chapter XXI, p. 395)
Man may be excused for feeling some pride at having risen, though not through his own exertions, to the very summit of the organic scale; and the fact of his having thus risen, instead of having been aboriginally placed there, may give him hopes for a still higher destiny in the distant future. (Chapter XXI, p. 405)
In short: there can be no doubt that Darwin regarded man as occupying the summit of the scale of Nature, and he also believed that man was destined to progress on to greater things in the future. Darwin believed this, even while he insisted that the gap between man and the animals was bridgeable, and that the gap between man and the apes was not as large as that between the apes and the lower animals.
I would like to conclude by asking Rigato and Minelli if they’d like to remove Darwin’s Origin of Species from school libraries, too, lest it give students the wrong idea. That would be the ultimate irony: Darwin getting censored by a pair of evolutionists!
Finally, they say that a picture is worth a thousand words. The following picture from Haeckel’s Anthropogenie oder Entwicklungsgeschichte des Menschen (The Evolution of Man),1874, shows the human pedigree as a Great Chain of Being, illustrated by modern and fossil species. Let no-one say that 19th century thinking about evolution was not progressivist. This picture says it all, warts and all. I shall let it speak for itself.