HKB
60 passages · search this phrase →
Often appears with: strata, rocks, and the geological record · species, variation, and descent · the earth and its formation · weather, storms, and the seasons · geography and the description of places · experiment, observation, and evidence · scientific theories and their history · logic, method, and demonstration · fate, destiny, and necessity · reason and the intellect · volcanoes, earthquakes, and catastrophe · history and the writing of history
Usually: argument (242) · curiosity (130) · skepticism (119) · detachment (78) · reflection (34) · narrative (19) · wonder (16) · description (12) · confronting death (11) · record or table (10)
“How wonderfully are the different Orders, at the present time so well separated, blended together in different points of the structure of the Toxodon!” Charles Darwin, The Voyage of the Beagle · observation
“To admit that species generally become rare before they become extinct--to feel no surprise at the comparative rarity of one species with another, and yet to call in some extraordinary agent and to marvel greatly when a species ceases to exist, appears to me much the same as to admit that sickness in the individual is the prelude to death--to feel no surprise at sickness--but when the sick man dies to wonder, and to believe that he died through violence.” Charles Darwin, The Voyage of the Beagle · insight
“It is self-evident that a person following up the course of a stream, will always ascend at a greater or less inclination: Mr. Gill, therefore, was much astonished, when walking up the bed of this ancient river, to find himself suddenly going down hill.” Charles Darwin, The Voyage of the Beagle · insight
“It was amusing to hear the inhabitants discussing the nature of the fossil shells which I collected, almost in the same terms as were used a century ago in Europe,--namely, whether or not they had been thus "born by nature.” Charles Darwin, The Voyage of the Beagle · observation
“The green and budding twigs may represent existing species; and those produced during each former year may represent the long succession of extinct species.” Charles Darwin, On the Origin of Species By Means of Natural Selecti · vivid
“The explanation lies, as I believe, in the extreme imperfection of the geological record.” Charles Darwin, On the Origin of Species By Means of Natural Selecti · insight
“The several difficulties here discussed, namely our not finding in the successive formations infinitely numerous transitional links between the many species which now exist or have existed; the sudden manner in which whole groups of species appear in our European formations; the almost entire absence, as at present known, of fossiliferous formations beneath the Silurian strata, are all undoubtedly of the gravest nature.” Charles Darwin, On the Origin of Species By Means of Natural Selecti · observation
“It is most difficult always to remember that the increase of every living being is constantly being checked by unperceived injurious agencies; and that these same unperceived agencies are amply sufficient to cause rarity, and finally extinction.” Charles Darwin, On the Origin of Species By Means of Natural Selecti · insight
“We need not marvel at extinction; if we must marvel, let it be at our presumption in imagining for a moment that we understand the many complex contingencies, on which the existence of each species depends.” Charles Darwin, On the Origin of Species By Means of Natural Selecti · insight
“He who rejects these views on the nature of the geological record, will rightly reject my whole theory.” Charles Darwin, On the Origin of Species By Means of Natural Selecti · insight
“Hence it seems to me, as it has to many other naturalists, that the view of each species having been produced in one area alone, and having subsequently migrated from that area as far as its powers of migration and subsistence under past and present conditions permitted, is the most probable.” Charles Darwin, On the Origin of Species By Means of Natural Selecti · insight
“But the testimony of geological monuments, if frequently imperfect, possesses at least the advantage of being free from all intentional misrepresentation.” Charles Lyell, Principles of Geology · insight
Darwin transitions to variation in nature, discussing variability among species, the challenge of defining “species” versus “variety,” and whether even environmentally induced forms like Baltic shell dwarfs could be inherited.
VARIATION UNDER NATURE. Variability. Individual differences. Doubtful species. Wide ranging, much diffused, and common species vary most. Species of the larger genera in any country vary more than the species of the smaller genera. Many of the species of the larger genera resemble varieties in being very closely, but unequally, related to each other, and in having restricted ranges. Before applying the principles a…
Darwin notes how a species that does little to diverge can still appear circuitously intermediate due to the extinction of connecting ancestors, and he links his model to extinct fossils as less-diverged early branches.
lines, beneath the capital letters, converging in sub-branches downwards towards a single point; this point representing a single species, the supposed single parent of our several new sub-genera and genera. It is worth while to reflect for a moment on the character of the new species F14, which is supposed not to have diverged much in character, but to have retained the form of (F), either unaltered or altered only…
Darwin expands the evolutionary tree metaphor: past species are like earlier twigs on a tree, with most branches dying out, leaving few lineages that still connect distant forms like Ornithorhynchus and Lepidosiren.
best of my judgment, it is explained through inheritance and the complex action of natural selection, entailing extinction and divergence of character, as we have seen illustrated in the diagram. The affinities of all the beings of the same class have sometimes been represented by a great tree. I believe this simile largely speaks the truth. The green and budding twigs may represent existing species; and those produ…
He begins the section on difficulties for his theory, especially the absence or rarity of transitional forms, explaining it via extinction during natural selection and the incompleteness of the geological record.
DIFFICULTIES ON THEORY. Difficulties on the theory of descent with modification. Transitions. Absence or rarity of transitional varieties. Transitions in habits of life. Diversified habits in the same species. Species with habits widely different from those of their allies. Organs of extreme perfection. Means of transition. Cases of difficulty. Natura non facit saltum. Organs of small importance. Organs not in all c…
He continues explaining how intermediate varieties vanish when populations become isolated or when separate varieties arise within a continuous area, leaving only representative species and fossil evidence.
portion of the land, but these links will have been supplanted and exterminated during the process of natural selection, so that they will no longer exist in a living state. Thirdly, when two or more varieties have been formed in different portions of a strictly continuous area, intermediate varieties will, it is probable, at first have been formed in the intermediate zones, but they will generally have had a short …
He argues that perfected specialized structures usually leave no living intermediates, but diversified transitions are possible, illustrating with birds’ altered wing uses and a hypothetical evolution from flying fish.
from disuse, indicate the natural steps by which birds have acquired their perfect power of flight; but they serve, at least, to show what diversified means of transition are possible. Seeing that a few members of such water-breathing classes as the Crustacea and Mollusca are adapted to live on the land, and seeing that we have flying birds and mammals, flying insects of the most diversified types, and formerly had …
Darwin’s chapter summary claims natural selection is slow, often works on few forms, and replaces intermediates through supplanting and extinction, while also supporting gradual transitions between habits like those of bats and upland geese.
trying to live wherever it can live, how it has arisen that there are upland geese with webbed feet, ground woodpeckers, diving thrushes, and petrels with the habits of auks. Although the belief that an organ so perfect as the eye could have been formed by natural selection, is more than enough to stagger any one; yet in the case of any organ, if we know of a long series of gradations in complexity, each good for it…
He replies that varieties seem fully fertile when crossed, but argues difficulties in classifying natural varieties as species, plus domestication and selective breeding of external traits, can obscure sterility differences.
crossed, and he consequently ranks them as undoubted species. If we thus argue in a circle, the fertility of all varieties produced under nature will assuredly have to be granted. If we turn to varieties, produced, or supposed to have been produced, under domestication, we are still involved in doubt. For when it is stated, for instance, that the German Spitz dog unites more easily than other dogs with foxes, or tha…
Switching to geology, Darwin argues that the absence of intermediate varieties in fossils is best explained by the extreme imperfection of the geological record, which hides countless transitional forms.
ON THE IMPERFECTION OF THE GEOLOGICAL RECORD. On the absence of intermediate varieties at the present day. On the nature of extinct intermediate varieties; on their number. On the vast lapse of time, as inferred from the rate of deposition and of denudation. On the poorness of our palæontological collections. On the intermittence of geological formations. On the absence of intermediate varieties in any one formation…
Darwin describes how tides, waves, and sand wear down sea cliffs very slowly, so retreating coasts show long pauses between active erosion periods and imply vast geological time.
at work grinding down old rocks and making fresh sediment, before he can hope to comprehend anything of the lapse of time, the monuments of which we see around us. It is good to wander along lines of sea-coast, when formed of moderately hard rocks, and mark the process of degradation. The tides in most cases reach the cliffs only for a short time twice a day, and the waves eat into them only when they are charged wi…
He argues that the thickness and extent of sedimentary strata reflect long crustal degradation, and that denudation evidence from volcanic islands and major faults like the Craven fault shows enormous lapse of time.
erroneous; yet, considering over what wide spaces very fine sediment is transported by the currents of the sea, the process of accumulation in any one area must be extremely slow. But the amount of denudation which the strata have in many places suffered, independently of the rate of accumulation of the degraded matter, probably offers the best evidence of the lapse of time. I remember having been much struck with t…
Darwin contends that fossil records are highly imperfect because most areas are poorly explored, soft organisms rarely preserve, and sediment is often not deposited fast enough to embed and protect remains.
have escaped the action of the coast-waves. So that in all probability a far longer period than 300 million years has elapsed since the latter part of the Secondary period. I have made these few remarks because it is highly important for us to gain some notion, however imperfect, of the lapse of years. During each of these years, over the whole world, the land and the water has been peopled by hosts of living forms.…
He attributes much imperfection in geology to wide time gaps between formations, arguing that blank intervals and intervening continental history make it unlikely to reconstruct continuous evolutionary sequences.
been discovered either in caves or in lacustrine deposits; and that not a cave or true lacustrine bed is known belonging to the age of our secondary or palæozoic formations. But the imperfection in the geological record mainly results from another and more important cause than any of the foregoing; namely, from the several formations being separated from each other by wide intervals of time. When we see the formatio…
Darwin proposes that fossil-rich formations usually form during subsidence when seas stay shallow and life remains abundant, while elevation and subsequent coast-waves erase deposited beds.
balance each other, the sea will remain shallow and favourable for life, and thus a fossiliferous formation thick enough, when upraised, to resist any amount of degradation, may be formed. I am convinced that all our ancient formations, which are rich in fossils, have thus been formed during subsidence. Since publishing my views on this subject in 1845, I have watched the progress of Geology, and have been surprised…
He explains why gradual transitional series are rarely seen: species may immigrate and disappear locally, formations vary in duration, and marine migration during climate change prevents simple linking in single sections.
should not include a graduated series of links between the species which then lived; but I can by no means pretend to assign due proportional weight to the following considerations. Although each formation may mark a very long lapse of years, each perhaps is short compared with the period requisite to change one species into another. I am aware that two palæontologists, whose opinions are worthy of much deference, n…
Darwin argues that thick deposits require balanced subsidence and sediment supply, but this balance is rare and often produces barren layers; thus each formation is intermittent and species may reappear across levels.
embedded fossils had been less than that of the glacial period, instead of having been really far greater, that is extending from before the glacial epoch to the present day. In order to get a perfect gradation between two forms in the upper and lower parts of the same formation, the deposit must have gone on accumulating for a very long period, in order to have given sufficient time for the slow process of variatio…
He stresses that naturalists lack a “golden rule” for distinguishing species from varieties, and that limited fossil intermediates force many related forms to be ranked as separate species.
period, a section would not probably include all the fine intermediate gradations which must on my theory have existed between them, but abrupt, though perhaps very slight, changes of form. It is all-important to remember that naturalists have no golden rule by which to distinguish species and varieties; they grant some little variability to each species, but when they meet with a somewhat greater amount of differen…
Using an imagined future test, Darwin argues it would be hard to trace cattle and sea-shell lineages by fossil intermediates, and he concludes the Malay Archipelago would still look imperfect even with complete sampling.
local varieties and ultimately to new species; and this again would greatly lessen the chance of our being able to trace the stages of transition in any one geological formation. It should not be forgotten, that at the present day, with perfect specimens for examination, two forms can seldom be connected by intermediate varieties and thus proved to be the same species, until many specimens have been collected from m…
Darwin argues that long periods of geological subsidence and elevation would cause variation and extinction, making transitional fossils rare and often discontinuous, with far-ranging marine species spreading and later returning as new local species.
periods of subsidence there would probably be much extinction of life; during the periods of elevation, there would be much variation, but the geological record would then be least perfect. It may be doubted whether the duration of any one great period of subsidence over the whole or part of the archipelago, together with a contemporaneous accumulation of sediment, would *exceed* the average duration of the same spe…
Responding to palaeontologists, Darwin explains that abrupt appearances of whole groups in formations likely reflect imperfect geology and large time gaps, allowing slow evolution elsewhere before invading the European archipelagoes.
had not the difficulty of our not discovering innumerable transitional links between the species which appeared at the commencement and close of each formation, pressed so hardly on my theory. *On the sudden appearance of whole groups of Allied Species*.—The abrupt manner in which whole groups of species suddenly appear in certain formations, has been urged by several palæontologists, for instance, by Agassiz, Picte…
Darwin supports his argument with examples—whales in the upper greensand before tertiary, cirripedes in secondary chalk despite earlier claims, and teleost fishes in the Chalk—showing missing fossils can mislead.
read in the Supplement to Lyell’s ‘Manual,’ published in 1858, clear evidence of the existence of whales in the upper greensand, some time before the close of the secondary period. I may give another instance, which from having passed under my own eyes has much struck me. In a memoir on Fossil Sessile Cirripedes, I have stated that, from the number of existing and extinct tertiary species; from the extraordinary abu…
Darwin adds that apparent “sudden” spread of teleost fishes may reflect previously enclosed tropical basins and later climate-driven dispersal, and he compares treating Earth’s history from one small locality to landing on a barren point in Australia.
until some of the species became adapted to a cooler climate, and were enabled to double the southern capes of Africa or Australia, and thus reach other and distant seas. From these and similar considerations, but chiefly from our ignorance of the geology of other countries beyond the confines of Europe and the United States; and from the revolution in our palæontological ideas on many points, which the discoveries …
Darwin addresses a graver difficulty: many species of allied groups appear in the lowest fossiliferous strata, implying vast undetected pre-Silurian life; he weighs evidence like phosphatic nodules and proposes explanations involving long periods and later erosion/metamorphism.
immense territories in Russia and in North America, do not support the view, that the older a formation is, the more it has suffered the extremity of denudation and metamorphism. The case at present must remain inexplicable; and may be truly urged as a valid argument against the views here entertained. To show that it may hereafter receive some explanation, I will give the following hypothesis. From the nature of th…
He proposes an overarching hypothesis: continents and ocean areas may have shifted over immense times due to oscillations of level and varying elevation/subsidence, so older strata may now be missing or metamorphosed; he concludes these difficulties remain serious arguments.
require some special explanation; and we may perhaps believe that we see in these large areas, the many formations long anterior to the silurian epoch in a completely metamorphosed condition. The several difficulties here discussed, namely our not finding in the successive formations infinitely numerous transitional links between the many species which now exist or have existed; the sudden manner in which whole grou…
Darwin reframes the geological record as an imperfect history and then argues that new species arise slowly and successively, rates differ among taxa, lost forms do not reappear, and extinction is gradual rather than catastrophe-driven.
ON THE GEOLOGICAL SUCCESSION OF ORGANIC BEINGS. On the slow and successive appearance of new species. On their different rates of change. Species once lost do not reappear. Groups of species follow the same general rules in their appearance and disappearance as do single species. On Extinction. On simultaneous changes in the forms of life throughout the world. On the affinities of extinct species to each other and t…
Darwin explains why a species once lost should never reappear identically, illustrates with fantail pigeons and breeding from different progenitors, and claims groups (genera and families) also do not reappear after extinction.
equal. Each formation, on this view, does not mark a new and complete act of creation, but only an occasional scene, taken almost at hazard, in a slowly changing drama. We can clearly understand why a species when once lost should never reappear, even if the very same conditions of life, organic and inorganic, should recur. For though the offspring of one species might be adapted (and no doubt this has occurred in i…
He summarizes: groups typically increase gradually to a maximum then decline, extinction of species and groups is usually slower than their first appearance, though some clades like ammonites may disappear rapidly near the end of the secondary period.
old and unmodified forms. Species of the genus Lingula, for instance, must have continuously existed by an unbroken succession of generations, from the lowest Silurian stratum to the present day. We have seen in the last chapter that the species of a group sometimes falsely appear to have come in abruptly; and I have attempted to give an explanation of this fact, which if true would have been fatal to my views. But …
Darwin argues that species extinction looks mysterious only because hidden, harmful factors steadily check population growth, as shown by fossil horses in La Plata that must have been rare and then replaced by competitors.
in numbers of the species. In some cases, however, the extermination of whole groups of beings, as of ammonites towards the close of the secondary period, has been wonderfully sudden. The whole subject of the extinction of species has been involved in the most gratuitous mystery. Some authors have even supposed that as the individual has a definite length of life, so have species a definite duration. No one I think …
He argues that so-called sudden extinctions of groups like trilobites and ammonites can reflect both long intervals of gradual loss and rapid replacement when new groups immigrate and spread into new areas.
a correspondingly rapid manner many of the old inhabitants; and the forms which thus yield their places will commonly be allied, for they will partake of some inferiority in common. Thus, as it seems to me, the manner in which single species and whole groups of species become extinct, accords well with the theory of natural selection. We need not marvel at extinction; if we must marvel, let it be at our presumption …
Darwin presents the parallel succession of marine fossil forms across continents, notes it is not strictly simultaneous in years, and suggests widespread formations can be correlated even when climates differ greatly.
sea-shells; but as these anomalous monsters coexisted with the Mastodon and Horse, it might at least have been inferred that they had lived during one of the latter tertiary stages. When the marine forms of life are spoken of as having changed simultaneously throughout the world, it must not be supposed that this expression relates to the same thousandth or hundred-thousandth year, or even that it has a very strict …
Darwin claims the global parallel succession of life is explained by natural selection: dominant species generate new varieties, spread to new regions, and outcompete others, producing gradual worldwide turnover.
when we treat of the present distribution of organic beings, and find how slight is the relation between the physical conditions of various countries, and the nature of their inhabitants. This great fact of the parallel succession of the forms of life throughout the world, is explicable on the theory of natural selection. New species are formed by new varieties arising, which have some advantage over older forms; an…
He adds that much of the fossil record comes from periods of sea subsidence with long blank intervals, during which modification, extinction, and migration occur, making near-contemporaneous formations show similar but not identical faunas.
therefore as new and improved groups spread throughout the world, old groups will disappear from the world; and the succession of forms in both ways will everywhere tend to correspond. There is one other remark connected with this subject worth making. I have given my reasons for believing that all our greater fossiliferous formations were deposited during periods of subsidence; and that blank intervals of vast dura…
Darwin argues that extinct species fit into a single natural system with living forms via descent, so fossils often fill gaps between groups even if they are not directly intermediate in every character.
of life, and the order would falsely appear to be strictly parallel; nevertheless the species would not all be the same in the apparently corresponding stages in the two regions. _On the Affinities of extinct Species to each other, and to living forms_.—Let us now look to the mutual affinities of extinct and living species. They all fall into one grand natural system; and this fact is at once explained on the princi…
Using a simplified diagram, Darwin explains how divergence increases with time from common ancestors, why older fossils should differ more, and how missing records affect what look like intermediate relationships.
the older Fish, the older Cephalopods, and the eocene Mammals, with the more recent members of the same classes, we must admit that there is some truth in the remark. Let us see how far these several facts and inferences accord with the theory of descent with modification. As the subject is somewhat complex, I must request the reader to turn to the diagram in the fourth chapter. We may suppose that the numbered lett…
He shows that discovering fossils lower or higher in the stratigraphic sequence can make living families appear more or less distinct, yet the overall pattern still follows descent with modification and circuitous intermediary lineages.
of character, has become divided into several sub-families and families, some of which are supposed to have perished at different periods, and some to have endured to the present day. By looking at the diagram we can see that if many of the extinct forms, supposed to be embedded in the successive formations, were discovered at several points low down in the series, the three existing families on the uppermost line w…
Darwin argues that each geological period’s fauna should be intermediate between preceding and succeeding faunas, allowing for extinction, immigration, and long blank intervals, and he illustrates exceptions with mastodons, elephants, and domestic pigeon examples.
of the extinct forms of life to each other and to living forms, seem to me explained in a satisfactory manner. And they are wholly inexplicable on any other view. On this same theory, it is evident that the fauna of any great period in the earth’s history will be intermediate in general character between that which preceded and that which succeeded it. Thus, the species which lived at the sixth great stage of descen…
Darwin argues that closely consecutive fossil formations contain more closely related species than remote ones, which supports slow mutation over long intervals despite gaps and changing climates in marine life.
carriers which are extreme in the important character of length of beak originated earlier than short-beaked tumblers, which are at the opposite end of the series in this same respect. Closely connected with the statement, that the organic remains from an intermediate formation are in some degree intermediate in character, is the fact, insisted on by all palæontologists, that fossils from two consecutive formations …
Darwin argues that inheritance of later-life variations can leave embryos nearly unchanged, so embryos may preserve an ancient condition only partially; he also outlines continuity of types within continents across later Tertiary periods.
being inherited at a corresponding age. This process, whilst it leaves the embryo almost unaltered, continually adds, in the course of successive generations, more and more difference to the adult. Thus the embryo comes to be left as a sort of picture, preserved by nature, of the ancient and less modified condition of each animal. This view may be true, and yet it may never be capable of full proof. Seeing, for inst…
He applies “descent with modification” to explain the long-lasting but non-immutable succession of similar types in the same areas, rejects “degeneration” of extinct megatherium, and details extinction and limited progeny.
was formerly more closely related in its mammals to Africa than it is at the present time. Analogous facts could be given in relation to the distribution of marine animals. On the theory of descent with modification, the great law of the long enduring, but not immutable, succession of the same types within the same areas, is at once explained; for the inhabitants of each quarter of the world will obviously tend to l…
Darwin summarizes prior chapters by listing reasons the fossil record is extremely imperfect and transitional forms are rarely preserved, concluding that rejecting this view undermines his whole natural selection theory.
orders, with the genera and species decreasing in numbers, as apparently is the case of the Edentata of South America, still fewer genera and species will have left modified blood-descendants. *Summary of the preceding and present Chapters*.—I have attempted to show that the geological record is extremely imperfect; that only a small portion of the globe has been geologically explored with care; that only certain cl…
He argues that many patterns in paleontology follow naturally from descent with modification via natural selection, including slow replacement, extinction with broken generational links, divergence, and system-wide relatedness.
aspect; and that the older continents, formed of formations older than any known to us, may now all be in a metamorphosed condition, or may lie buried under the ocean. Passing from these difficulties, all the other great leading facts in palæontology seem to me simply to follow on the theory of descent with modification through natural selection. We can thus understand how it is that new species come in slowly and s…
Darwin argues that most species were produced in a single region and then migrated, with recent climate and geographic change interrupting continuous ranges and explaining distant occurrences through migration rather than separate creation centers.
in the series, to the individuals of the same species, a directly opposite rule prevailed; and species were not local, but had been produced in two or more distinct areas! Hence it seems to me, as it has to many other naturalists, that the view of each species having been produced in one area alone, and having subsequently migrated from that area as far as its powers of migration and subsistence under past and prese…
Darwin offers experimental evidence for land-shell dispersal by seawater—suggesting hybernating shells could survive immersion—and stresses island inhabitants’ closest affinities to nearby mainland forms.
complete; and if modification be admitted, all the forms of life would have been more equally modified, in accordance with the paramount importance of the relation of organism to organism. I do not deny that there are many and grave difficulties in understanding how several of the inhabitants of the more remote islands, whether still retaining the same specific form or modified since their arrival, could have reache…
Darwin claims extinction widens intervals between groups, explains why aberrant lineages persist with few species (e.g., Ornithorhynchus and Lepidosiren), and discusses general vs specific affinity using the bizcacha and marsupials.
single insect belonging to a new order; and that in the vegetable kingdom, as I learn from Dr. Hooker, it has added only two or three orders of small size. In the chapter on geological succession I attempted to show, on the principle of each group having generally diverged much in character during the long-continued process of modification, how it is that the more ancient forms of life often present characters in so…
He answers questions about absent pre-Silurian fossils by claiming the geological record is too imperfect to preserve all links, with long time, incomplete exploration, and selective fossilization shaping what we find.
progenitors of the Silurian groups of fossils? For certainly on my theory such strata must somewhere have been deposited at these ancient and utterly unknown epochs in the world’s history. I can answer these questions and grave objections only on the supposition that the geological record is far more imperfect than most geologists believe. It cannot be objected that there has not been time sufficient for any amount …
Darwin argues that an imperfect fossil record still supports descent with modification, explaining extinction, intermediate fossils, and broad biogeographic patterns using natural selection and migration.
do the crossed offspring of acknowledged varieties. On the other hand, these would be strange facts if species have been independently created, and varieties have been produced by secondary laws. If we admit that the geological record is imperfect in an extreme degree, then such facts as the record gives, support the theory of descent with modification. New species have come on the stage slowly and at successive int…
Darwin says the “natural system” of classification reflects genealogical relationships, explaining why some traits are better for taxonomy and why embryos and rudimentary organs reveal common descent.
those of the Cape de Verde archipelago and other African islands to the African mainland. It must be admitted that these facts receive no explanation on the theory of creation. The fact, as we have seen, that all past and present organic beings constitute one grand natural system, with group subordinate to group, and with extinct groups often falling in between recent groups, is intelligible on the theory of natural…
Darwin explains geology’s imperfect fossil record, proposes using rates of organic change between formations as a rough measure of time, and argues that “secondary causes” rather than catastrophes produce species turnover.
sides of a continent, and the nature of the various inhabitants of that continent in relation to their apparent means of immigration, some light can be thrown on ancient geography. The noble science of Geology loses glory from the extreme imperfection of the record. The crust of the earth with its embedded remains must not be looked at as a well-filled museum, but as a poor collection made at hazard and at rare inte…
Darwin’s Bahia Blanca section links settlement geography and fossil discoveries to geological elevation, describes Pleistocene megafauna at Punta Alta with Owen’s identifications, and argues that large animals need not imply lush vegetation.
BAHIA BLANCA Bahia Blanca--Geology--Numerous gigantic Quadrupeds--Recent Extinction--Longevity of species--Large Animals do not require a luxuriant vegetation--Southern Africa--Siberian Fossils--Two Species of Ostrich--Habits of Oven-bird--Armadilloes--Venomous Snake, Toad, Lizard--Hybernation of Animal--Habits of Sea-Pen--Indian Wars and Massacres--Arrow-head, antiquarian Relic. The Beagle arrived here on the 24th…
Darwin quotes the idea that mammal species generally have shorter longevity than molluscs, then uses Owen’s reasoning to infer megatheroid diets and argues against the assumption that sterile regions cannot support big animals.
to which it is also allied. How wonderfully are the different Orders, at the present time so well separated, blended together in different points of the structure of the Toxodon! The remains of these nine great quadrupeds, and many detached bones, were found embedded on the beach, within the space of about 200 yards square. It is a remarkable circumstance that so many different species should be found together; and…
Darwin explains that megatherium-like animals’ fossil bed sits only slightly above high-water, estimates limited uplift since their time, and debates what vegetation existed then versus present-day sterility.
remarkable law so often insisted on by Mr. Lyell, namely, that the "longevity of the species in the mammalia is upon the whole inferior to that of the testacea." [3] The great size of the bones of the Megatheroid animals, including the Megatherium, Megalonyx, Scelidotherium, and Mylodon, is truly wonderful. The habits of life of these animals were a complete puzzle to naturalists, until Professor Owen [4] solved th…
In October Darwin examines fossil bones near the Rio Tercero/Saladillo, interprets decayed mastodon remains, notes Brackish streams, crosses toward Corunda and St. Fe, and observes climate and bird differences with only a few degrees of latitude.
does the horizon approach within these narrow limits; and this, in my opinion, entirely destroys that grandeur which one would have imagined that a vast level plain would have possessed. October 1st.--We started by moonlight and arrived at the Rio Tercero by sunrise. The river is also called the Saladillo, and it deserves the name, for the water is brackish. I stayed here the greater part of the day, searching for …
On November 26 Darwin travels toward Montevideo, buys Toxodon skull material at Sarandis/Rio Negro, finds associated fossil remains (armadillo-like animal, Mylodon), and reflects on how the Pampas preserves many extinct giants’ bones.
in the same time. This would have been a prodigious task, for it is considered a good day's work to skin and stake the hides of fifteen or sixteen animals. November 26th.--I set out on my return in a direct line for Monte Video. Having heard of some giant's bones at a neighbouring farm-house on the Sarandis, a small stream entering the Rio Negro, I rode there accompanied by my host, and purchased for the value of e…
Darwin notes guanacos’ habits with water, dust-rolling, male fighting, exploratory tracks toward salt-water creeks, predictable dung-heap locations, and bone-filled death sites, which he links to hunting injuries and taphonomic burial processes.
become bewildered, and know not which way to run. This greatly facilitates the Indian method of hunting, for they are thus easily driven to a central point, and are encompassed. The guanacos readily take to the water: several times at Port Valdes they were seen swimming from island to island. Byron, in his voyage says he saw them drinking salt water. Some of our officers likewise saw a herd apparently drinking the b…
At Port St. Julian and nearby visits, Darwin records scarce fresh water, insect observations (including horseflies and beetles), and then lays out a major account of Patagonia’s geology: uplifted tertiary shell beds, infusoria-rich strata, and extensive shingle formations.
pinnacles of porphyry. I do not think I ever saw a spot which appeared more secluded from the rest of the world, than this rocky crevice in the wide plain. The second day after our return to the anchorage, a party of officers and myself went to ransack an old Indian grave, which I had found on the summit of a neighbouring hill. Two immense stones, each probably weighing at least a couple of tons, had been placed in …
Darwin continues his geological explanation of step-like raised plains and changing sea levels, then describes finding a half skeleton of Macrauchenia patachonica at Port St. Julian and argues its kinship with living South American mammals.
common prejudice of lying where one's ancestors have lain, would make the now roaming Indians bring the less perishable part of their dead to their ancient burial-ground on the coast. January 9th, 1834.--Before it was dark the Beagle anchored in the fine spacious harbour of Port St. Julian, situated about one hundred and ten miles to the south of Port Desire. We remained here eight days. The country is nearly simila…
He links fossil-extant relationships across South America—citing collections from Brazilian caves—to argue that studying dead and living species together will explain patterns of appearance and extinction, and concludes with reflections on mass extinctions.
of what animals do these insects commonly feed? The guanaco is nearly the only warm-blooded quadruped, and it is found in quite inconsiderable numbers compared with the multitude of flies. The geology of Patagonia is interesting. Differently from Europe, where the tertiary formations appear to have accumulated in bays, here along hundreds of miles of coast we have one great deposit, including many tertiary shells, …
Darwin argues that species rarely increase unchecked because food limits and other “checks” curb growth, so rarity often precedes extinction without needing extraordinary causes beyond gradual ecological pressure.
existing small Edentata of their numerous gigantic prototypes? Certainly, no fact in the long history of the world is so startling as the wide and repeated exterminations of its inhabitants. Nevertheless, if we consider the subject under another point of view, it will appear less perplexing. We do not steadily bear in mind, how profoundly ignorant we are of the conditions of existence of every animal; nor do we alw…
Around April 26 Darwin observes basaltic lava platforms blocking the Santa Cruz for 28 miles, argues rivers cannot transport such blocks, and proposes an ancient strait whose tides eroded the basalt.
in the Santa Cruz, and that no still reaches occur in any part, this example is a most striking one, of the inefficiency of rivers in transporting even moderately-sized fragments. The basalt is only lava, which has flowed beneath the sea; but the eruptions must have been on the grandest scale. At the point where we first met this formation it was 120 feet in thickness; following up the river course, the surface imp…
At Villa Vicencio and nearby mines around March 30–April 1, Darwin studies the geology of the Uspallata range and reports silicified fir-like petrified trees with bark impressions.
course was quite dry; by degrees it became a little damper; then puddles of water appeared; these soon became connected; and at Villa Vicencio there was a nice little rivulet. 30th.--The solitary hovel which bears the imposing name of Villa Vicencio, has been mentioned by every traveller who has crossed the Andes. I stayed here and at some neighbouring mines during the two succeeding days. The geology of the surro…