Speaking in Calcutta, during the infancy of the British raj in 1786, the philologist William Jones first noted impressive similarities between Sanskrit and the classical languages of Greece and Rome (an Indian king, or raja, matches rex, his Latin counterpart). Jones’s observation led to the recognition of a great Indo-European family of languages, now spread from the British Isles and Scandinavia to India, but clearly rooted in a single, ancient origin. Jones may have marked the basic similarity, but the brothers Grimm were among the first to codify regularities of change that underpin the diversification of the rootstock into its major subgroups (Romance languages, Germanic tongues, and so on). Grimm’s law … specifies the characteristic changes in consonants between Proto–Indo-European (as retained in Latin) and the Germanic languages. Thus, for example, Latin p’s become f ’s in Germanic cognates (voiceless stops become voiceless fricatives in the jargon). [32-3]
But, in fact, a breed, like a dialect of a language, can hardly be said to have had a definite origin. [ch. 1, 97]
If we possessed a perfect pedigree of mankind, a genealogical arrangement of the races of man would afford the best classification of the various languages now spoken throughout the world; and if all extinct languages, and all intermediate and slowly changing dialects, had to be included, such an arrangement would, I think, be the only possible one. Yet it might be that some very ancient language had altered little, and had given rise to few new languages, whilst others (owing to the spreading and subsequent isolation and states of civilisation of the several races, descended from a common race) had altered much, and had given rise to many new languages and dialects. The various degrees of difference in the languages from the same stock, would have to be expressed by groups subordinate to groups; but the proper or even only possible arrangement would still be genealogical; and this would be strictly natural, as it would connect together all languages, extinct and modern, by the closest affinities, and would give the filiation and origin of each tongue. [ch. 13, 406]
For my part, following out Lyell’s metaphor, I look at the natural geological record, as a history of the world imperfectly kept, and written in a changing dialect; of this history we possess the last volume alone, relating only to two or three countries. Of this volume, only here and there a short chapter has been preserved; and of each page, only here and there a few lines. Each word of the slowly-changing language, in which the history is supposed to be written, being more or less different in the interrupted succession of chapters, may represent the apparently abruptly changed forms of life, entombed in our consecutive, but widely separated formations. [ch. 9, 316]
Rudimentary organs may be compared with the letters in a word, still retained in the spelling, but become useless in the pronunciation, but which serve as a clue in seeking for its derivation. 
Darwinian evolution is the most robust of scientific theories, but many people find it easier and more reassuring to believe that something so intricately constructed as life on Earth must have had a designer. It is hard for us to accept that erverything around us, from the beautry of the butterfly to the complexity of the human eye, could have evolved simply through chance and the pressure to survive. But the scientific evidence that evolution by natural selection has occurred is unassailable.
The scientific method, which is today practised in all corners of the globe, builds on explanations based on evidence, and when new evidence emerges that does not fit with the model, the explanation must change. That is how science moves on. 
This consideration of the fact that theories or expectations are built into our very sense organs shows that the epistemology of induction breaks down even before taking its first step. It cannot start from sense data or perceptions and build our theories upon them, since there are no such things a sense data or perceptions which are not built upon theories (or expectations—that is, the biological predecessors of linguistically formulated theories). Thus the ‘data’ are no basis of, no guarantee for, the theories. They are not more secure than any of our theories or ‘prejudices’ but, if anything, less so (assuming for argument’s sake that sense data exist and are not philosophers’ inventions). Sense organs incorporate the equivalent of primitive and uncritically accepted theories, which are less widely tested than scientific theories. …
Thus life proceeds, like scientific discovery, from old problems to the discovery of new and undreamt-of problems. And this process—that of invention and selection—contains in itself a rational theory of emergence. The steps of emergence which lead to a new level are in the first instance the new problems (P2) which are created by the error-elimination (EE) of a tentative theoretical solution (TT) of an old problem (P1). 
What I regard as the most important point is not the sheer autonomy and anonymity of the third world, or the admittely very important point that was always owe almost everything to our predecessors and to the tradtion which they created: that we thus owe to the third world especially our rationality — that is, our subjective mind, the practice of critical and self-critical ways of thinking and the corresponding dispositions. More important than all this, I suggest, is the relation between ourselves and our work, and what can be gained for us from this relation.
[…] I suggest that everything depends upon the give-and-take between ourselves and our work; upon the product which we contribute to the third world, and upon that constant feed-back that can be amplified by conscious self-
This self-transcendence is the most striking and important fact of all life and all evolution, and especially of human evolution. 
Well, Popperians might speak of a theory being the best available for use in practice, given a certain problem-situation. And the most important features of a problem-situation are: what theories and explanations are in contention, what arguments have been advanced, and what theories have been refuted. ‘Corroboration’ is not just the confirmation of the winning theory. It requires the experimental refutation of rival theories. Confirming instances in themselves have no significance. …
Under inductivism, observation was supposed to be primary. One imagined a mass of past observations from which the theory was supposed to be induced, and observations also constituted the evidence which somehow justified the theory. In the Popperian picture of scientific progress, it is not observations but problems, controversies, theories and criticism that are primary. Experiments are designed and performed only to resolve controversies. Therefore only experimental results that actually do refute a theory – and not just any theory, it must have been a genuine contender in a rational controversy – constitute ‘corroboration’. And so it is only those experiments that provide evidence for the reliability of the winning theory. …
And even then, the ‘reliability’ that corroboration confers is not absolute but only relative to the other contending theories. That is, we expect the strategy of relying on corroborated theories to select the best theories from those that are proposed. That is a sufficient basis for action. We do not need (and could not validly get) any assurance about how good even the best proposed course of action will be. Furthermore, we may always be mistaken, but so what? We cannot use theories that have yet to be proposed; nor can we correct errors that we cannot yet see. [148-9]
In science the object of the exercise is not to find a theory that will, or is likely to, be deemed true for ever; it is to find the best theory available now, and if possible to improve on all available theories. A scientific argument is intended to persuade us that a given explanation is the best one available. It does not and could not say anything about how that explanation will fare when, in the future, it is subjected to new types of criticism and compared with explanations that have yet to be invented. A good explanation may make good predictions about the future, but the one thing that no explanation can even begin to predict is the content or quality of its own future rivals. [64-5]