Stasis of Biological Forms After Appearance

“In four of the biggest climatic-vegetational events of the last 50 million years, the mammals and birds show no noticeable change in response to changing climates. No matter how many presentations I give where I show these data, no one (including myself) has a good explanation yet for such widespread stasis despite the obvious selective pressures of changing climate.” (Prothero, Donald E., “Darwin’s Legacy,” eSkeptic Magazine,

“Stasis is a common (I would say the dominant) pattern of anatomical (non)change in the evolutionary history of species; …And, of course, given a concatenation of many separate ‘punctuated equilibria’ events all happening more or less at the same time, Darwin, armed with his particular conception of evolution through natural selection, must have felt totally helpless in the face of such a monstrous pattern. He could blame stasis on a poor geological record, but faced with paleontologists talking up Cuvierian patterns, Darwin simply cut and ran.” (Eldredge, Niles, “Confessions of a Darwinist,” Spring 2006.)

“The empirical analysis of evolutionary tempo and mode has been one of the great contributions of paleontology. Phenotypic stasis has proven to be far more prevalent than expected, and the challenge is now to rigorously test alternative evolutionary models for long-term phenotypic evolution and seek explanatory mechanisms for the different trajectories exhibited in fossil time-series. …The authors again find that stasis and random walks best account for temporal patterns, rather than directional change, but also show that more complex models—particularly stasis plus punctuational change, and shifts from a random walk to stasis—tend to be increasingly supported in a maximum-likelihood framework with increasing numbers of samples within a study ” (Jablonski, David, Shubin Neil H., “The future of the fossil record: Paleontology in the 21st Century,” Proceedings of the National Academy of Sciences vol. 112 no. 16, April 21, 2015, p. 4855.)

“A localized population…suddenly appear(s) on the scene and then continue(s) essentially unchanged until [they] become(s) extinct.” (Mayr, Ernst, What Evolution Is, Basic Books, 2001 p. 63.)

“The complete standstill or stasis of an evolutionary lineage for scores, if not hundreds, of millions of years is very puzzling.” (Mayr, Ernst, What Evolution Is, Basic Books, 2001 p. 195.)

“Niles Eldredge and I …argued that two outstanding facts of the fossil record–geologically ‘sudden’ origin of new species and failure to change thereafter (stasis)–reflect the predictions of evolutionary theory, not the imperfections of the fossil record.” (Gould, Stephen J., “Evolution as Fact and Theory,” in Montagu, Science and Creationism, 1984, p. 123.)

“Stasis has become interesting as a central prediction of our theory.” (Gould, Stephen J., “Opus 200,” Natural History, 1991, p. 16.)

From (Gould, Stephen Jay, The Structure of Evolutionary Theory, 2002.):

  • “…the tale itself illustrates the central fact of the fossil record so well [the] geologically abrupt origin and subsequent extended stasis of most species…Anatomy may fluctuate through time, but the last remnants of a species look pretty much like the first representatives.” (p. 749.)
  • “…the greatest and most biologically astute paleontologist of the 20th century…acknowledged the literal appearance of stasis and geologically abrupt origin as the outstanding general fact of the fossil record and as a pattern which would ‘pose one of the most important theoretical problems in the whole history of life.’” (p. 755 quoting George Gaylord Simpson.)
  • “…the long term stasis following geologically abrupt origin of most fossil morphospecies, has always been recognized by professional paleontologists.” (p. 752.)
  • “The great majority of species do not show any appreciable evolutionary change at all. These species appear in the section (first occurrence) without obvious ancestors in the underlying beds, are stable once established and disappear higher up without leaving any descendants.” (p. 753.)
  • “…but stasis is data… Say it ten times before breakfast every day for a week, and the argument will surely seep in by osmosis: ‘stasis is data; stasis is data’…” (p. 759.)
  • Gould debunks the: “exceedingly few cases that became textbook ‘classics’ of coiling of Gryphaea and the increasing body size of the horses etc.” (p. 760.).
  • “Indeed proclamations for the supposed ‘truth’ of gradualism – asserted against every working paleontologist’s knowledge of its rarity – emerged largely from such a restriction of attention to exceedingly rare cases under the false belief that they alone provided a record of evolution at all! The falsification of most ‘textbook classics’ upon restudy only accentuates the fallacy of the ‘case study’ method and its root in prior expectation rather than objective reading of the fossil record.” (p. 773.)

The most striking features of large-scale evolution are the extremely rapid divergence of lineages near the time of their origin, followed by long periods in which basic body plans and ways of life are retained. What is missing are the many intermediate forms hypothesized by Darwin, and the continual divergence of major lineages into the morphospace between distinct adaptive types. The most conspicuous event in metazoan evolution was the dramatic origin of major new structures and body plans documented by the Cambrian explosion. Until 530 million years ago, multicellular animals consisted primarily of simple, soft-bodied forms, most of which have been identified from the fossil record as cnidarians and sponges. Then, within less then 10 million years, almost all of the advanced phyla appeared, including echinoderms, chordates, annelids, brachiopods, molluscs and a host of arthropods. The extreme speed of anatomical change and adaptive radiation during this brief time period requires explanations that go beyond those proposed for the evolution of species within the modern biota.” (Carroll, Robert L., “Towards a New Evolutionary Synthesis,” Trends in Ecology & Evolution 15, 2000, pp. 27-32.)

“Eldredge and Gould, by contrast, decided to take the record at face value. On this view, there is little evidence of modification within species, or of forms intermediate between species because neither generally occurred. A species forms and evolves almost instantaneously (on the geological timescale) and then remains virtually unchanged until it disappears, yielding its habitat to a new species.” (Smith, Peter J., “Evolution’s Most Worrisome Questions,” Review of Life Pulse by Niles Eldredge, New Scientist, volume 116, November 1987, p. 59.)

“The principal problem is morphological stasis. A theory is only as good as its predictions, and conventional neo-Darwinism, which claims to be a comprehensive explanation of evolutionary process, has failed to predict the widespread long-term morphological stasis now recognized as one of the most striking aspects of the fossil record.” (Williamson, Peter G., “Morphological Stasis and Developmental Constraint: Real Problems for Neo-Darwinism,” Nature, Vol. 294, 19 November 1981, p.214.)

“It is a simple ineluctable truth that virtually all members of a biota remain basically stable, with minor fluctuations, throughout their duration…” (Eldredge, Niles, The Pattern of Evolution, 1998, p. 157.)

“But fossil species remain unchanged throughout most of their history and the record fails to contain a single example of a significant transition.” (Woodroff, D.S., Science, vol. 208, 1980, p.716.)

“But fossil species remain unchanged throughout most of their history and the record fails to contain a single example of a significant transition.” (Woodroff, D.S., Science, vol. 208, 1980, p.716.)

“The record now reveals that species typically survive for a hundred thousand generations, or even a million or more, without evolving very much. We seem forced to conclude that most evolution takes place rapidly…a punctuational model of evolution…operated by a natural mechanism whose major effects are wrought exactly where we are least able to study them – in small, localized, transitory populations…The point here is that if the transition was typically rapid and the population small and localized, fossil evidence of the event would never be found.” (Stanley, S.M., New Evolutionary Timetable, 1981, pp.77, 110.)

“…why after such rapid diversification did these microorganisms remain essentially unchanged for the next 3.465 billion years? Such stasis, common in biology, is puzzling…” (Corliss, William R., “Early Life Surprisingly Diverse,” Science Frontiers, 88:2, 1993, p.2.)

“Just as we have long known about stasis and abrupt appearance, but have chose to fob it off upon an imperfect fossil record, so too have we long recognized the rapid, if not sudden, turnover of faunas in episodes of mass extinction. We have based our geological alphabet, the time scale, upon these faunal replacements. Yet we have chosen to blunt or mitigate the rapidity and extent of extinctions with two habits of argument rooted in uniformitarian commitments.” (Gould, Stephen J., “The Paradox of the First Tier: An Agenda for Paleobiology,” Paleobiology, 1985, p. 7.)

“Paleontologists ever since Darwin have been searching (largely in vain) for the sequences of insensibly graded series of fossils that would stand as examples of the sort of wholesale transformation of species that Darwin envisioned as the natural product of the evolutionary process. Few saw any reason to demur – though it is a startling fact that …most species remain recognizably themselves, virtually unchanged throughout their occurrence in geological sediments of various ages.” (Eldredge, Niles, “Progress in Evolution?” New Scientist, vol. 110, 1986, p. 55.)

“We expect life’s bushes…to tell some story of direction change. If they do not, we do not feature them in our studies – if we even manage to see them at all. …Paleontologists are now beginning to study this higher order stasis, or nondirectional history of entire bushes.” (Gould, Stephen J., “Cordelia’s Dilemma,” Natural History, 1993, p. 15.)

“The history of most fossil species includes two features particularly inconsistent with gradualism: Stasis: Most species exhibit no directional change during their tenure on Earth. They appear in the fossil record looking much the same as when they disappear; morphological change is usually limited and directionless. Sudden appearance:In any local area, a species does not arise gradually be the steady transformation of its ancestors; it appears all at once and ‘fully formed.'” (Gould, Stephen J., “Evolution’s Erratic Pace,” Natural History, May 1977, p. 14.)

“In other words, when the assumed evolutionary processes did not match the pattern of fossils that they were supposed to have generated, the pattern was judged to be ‘wrong.’ A circular argument arises: interpret the fossil record in terms of a particular theory of evolution, inspect the interpretation, and note that it confirms the theory. Well, it would, wouldn’t it? …As is now well known, most fossil species appear instantaneously in the record, persist for some millions of years virtually unchanged, only to disappear abruptly – the ‘punctuated equilibrium’ pattern of Eldredge and Gould.” (Kemp, Tom S., “A Fresh Look at the Fossil Record,” New Scientist, vol. 108, 1985, pp. 66-67.)

“When fossils are most common, evolution is most rarely observed. …Again, we note the paradox: nothing much happens for most of the time when evidence abounds; everything happens in largely unrecorded geological moments. We could attribute this pattern to either a devious or humorous God, out to confuse us or merely to chuckle at our frustration. But I choose to look upon this phenomenon in a positive light, for it is trying to tell us something important. There is a lesson, not merely frustration, in the message that change is concentrated in infrequent bursts and that stability is the usual nature of species and systems at any moment.” (Gould, Stephen J., “Ten Thousand Acts of Kindness,” Natural History, 1988, p. 14.)

“The old Darwinian view of evolution as a ladder of more and more efficient forms leading up to the present is not borne out by the evidence. Most changes are random rather than systematic modifications, until species drop out. There is no sign of directed order here. Trends do occur in many lines, but they are not the rule.” (Newell, N. D., “Systematics and Evolution,” 1984, p. 10.)

“For more than a century biologists have portrayed the evolution of life as a gradual unfolding…Today the fossil record…is forcing us to revise this conventional view.” (Stanley, S. M., The New Evolutionary Timetable: Fossils, Genes, and the Origin of Species, 1981, p.3.)

“Well-represented species are usually stable throughout their temporal range, or alter so little and in such superficial ways (usually in size alone), that an extrapolation of observed change into longer periods of geological time could not possibly yield the extensive modifications that mark general pathways of evolution in larger groups. Most of the time, when the evidence is best, nothing much happens to most species.” (Gould Stephen J., “Ten Thousand Acts of Kindness,” Natural History, 1988, p. 14.)

“And so it goes for most groups in most long segments of geological time – lots of evolutionary change, but no story of clear and persistent direction. (Gould, Stephen J., “Cordelia’s Dilemma,”Natural History, 1993, p. 18.)

“Darwin’s prediction of rampant, albeit gradual, change affecting all lineages through time is refuted. The record is there, and the record speaks for tremendous anatomical conservation.. Change in the manner Darwin expected is just not found in the fossil record.” (Eldredge, N. and Tattersall, I., The Myths of Human Evolution, 1982, p. 48.)

“Paleontologists just were not seeing the expected changes in their fossils as they pursued them up through the rock record. …That individual kinds of fossils remain recognizably the same throughout the length of their occurrence in the fossil record had been known to paleontologists long before Darwin published his Origin. Darwin himself, …prophesied that future generations of paleontologists would fill in these gaps by diligent search …One hundred and twenty years of paleontological research later, it has become abundantly clear that the fossil record will not confirm this part of Darwin’s predictions. Nor is the problem a miserably poor record. The fossil record simply shows that this prediction is wrong. …The observation that species are amazingly conservative and static entities throughout long periods of time has all the qualities of the emperor’s new clothes: everyone knew it but preferred to ignore it. Paleontologists, faced with a recalcitrant record obstinately refusing to yield Darwin’s predicted pattern, simply looked the other way.” (Eldredge, N. and Tattersall, I., The Myths of Human Evolution, 1982, p. 45-46.)

“There is no recognizable trend toward increased complexity that is clear enough to use for dating purposes. …Increasing complexity through time is elusive at best. (This is one of the interesting aspects of evolution: the process is not clearly directional.)” (Raup, D.M., “Testing the Fossil Record for Evolutionary Progress,” 1983, p. 154.)

“Stasis, or nonchange, of most fossil species during their lengthy geological lifespans was tacitly acknowledged by all paleontologists, but almost never studied explicitly because prevailing theory treated stasis as uninteresting nonevidence for nonevolution. …The overwhelming prevalence of stasis became an embarrassing feature of the fossil record, best left ignored as a manifestation of nothing (that is, nonevolution). (Gould, Stephen J., “Cordelia’s Dilemma,” Natural History, 1993, p. 15.)

“It is counterintuitive but revealing that the morphological motifs animals began with were carried over to the present, with few additions.” (Newman, Stuart A., “Physico-Genetic Determinants in the Evolution of Development,” Science, Oct. 2012, Vol. 338 no. 6104 pp. 217-219.)

A “200 million year old” fossil Lobopodian reveals that “The morphology has not changed in any significant aspect.” (Haug, et. al., “A Carboniferous Non-Onychophoran Lobopodian Reveals Long-term Survival of a Cambrian Morphotype,” Current Biology 22, 2012, p. 1673-1675.)