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Darwin and the theory of punctuated equilibrium

Charles Darwin in his most famous work, surprisingly, almost no mention of the fossil that he picked up in South America , apart from brief references in 'Introduction.

"WHEN on board HMS 'Beagle,' as naturalist, I was much struck with Certain facts in the distribution of the Inhabitants of South America, and in the geological relations of the present to the past Inhabitants of That continent. These Seemed to me facts to throw Some light on the origin of species-that mystery of mysteries, as it Has Been Called by one of Our greatest philosophers. "

Fig.1. Il fossile che Darwin attribuisce a un piccolo mammifero roditore, dalla formazione di Monte Hermoso nell´Argentina (Pliocene inferiore), da DARWIN 1840, Fossil Mammalia Pl. XXXII.

Al contrario un intero capitolo di " Origin of Species " è dedicato alle lacune del record geologico è l'apparente mancanza di fossili di transizione. Questa discrepanza era nota già a Lamarck, che aveva postulato (e formulato una teoria) che le specie non sono fisse, è i limiti discreti tra di loro sono il risultato di una preservazione incompleta di forme di transizioni durante l'atto di fossilizzazione. Questa idea verra adoperata anche da Darwin (" Chapter IX, on the imperfection of the geological record ").
A meta del 19. secolo era chiaro che specie si potevano estinguere, ma rimase il problema di come queste estinzioni avvengono e come dopo una di queste fasi il pianeta veniva ripopolato. Anche Darwin durante il suo viaggio sul Beagle, ancora prima della formulazione della sua teoria di trasmutazione, si chiedeva se delle specie possono morire e in che modo vengono rinate (escludendo una creazione divina), un'idea che era stata anche ipotizzata dal geologo italiano Giovanni Battista Brocchi nel 1814 (dimostrando ancora una volta il profondo cambio di pensiero in quei decenni).
Osservando fossili simili all'odierna Mara ( Dolichotis patagonum ), A South American rodent that resembles a small deer, Darwin thought that species were replaced in time by similar forms together (Owen will determine the fossils belonging to a relative of today 's tuco-tuco tucutucu or small rodent of the genus Ctenomys ). However, these forms remains

concrete entities in space and time, for example at Warri, the fox endemic and extinct Darwin could still look on the Falkland Islands, wrote in 1834 "... indisputable proof of the ITS individuality as a species ..." . Darwin start working on his theory after his return home, and in a first attempt to try to reconcile his view of the species as concrete entities with a possible jump through transmutation of species specific, ie, a species could give "birth" to a new species within a short time.

Continued ...

Fig.2. The three possible relationships of fossil forms of a certain horizon and recently elaborated by Darwin between 1832 and 1835. In case A, the giant sloth / armadillo giant extinct and are replaced by the recent species. The species does not have a direct connection between them. In molluscs (case C), Darwin observed a continuum of species that persist through geological time. The case is B an intermediate version of the first two, the fossil remains of the peculiar South American rodents are relatively modern with rodent species, which occur over geological time (ELDREGE 2008).

Bibliography:

DARWIN, CR (1859): On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life. London: John Murray. [1st edition]
Darwin, CR ed. (1840): Fossil Mammalia Part 1 No. 4 of The zoology of the voyage of HMS Beagle. By Richard Owen. Edited and superintended by Charles Darwin. London: Smith Elder and Co.
Eldredge, N. (2009): A Question of Individuality : Charles Darwin, George Gaylord Simpson and Transitional Fossils. Evo. Edu. Outreach 2(1): 150-155
ELDREDGE, N. (2008): Experimenting with Transmutation: Darwin, the Beagle, and Evolution. Evo. Edu. Outreach 2(1): 35-54
QUATTROCCHIO, M.E.; DESCHAMPS, C.M.; ZAVALA, C.A.; GRILL, S.C. & BORROMEI, A.M. (2009): G eology of the area of Bahia Blanca, Darwin´s view and the present knowledge: a storay of 10 million years. Revista de la Asociacion Geologica Argentina 64(1): 137-146

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Sir Charles Lyell (1797 - 1875) The Monster of

"The greatest merit of the Principles was that it altered the whole tone of one's Mind, and That Therefore, When seeing a thing never seen by Lyell, one yet saw it through His eyes. "

C. Darwin

Fig.1. " Principles of Geology, 1st edition, 1st vol. Jan. 1830

The profound changes during the mid-19. century in paleontology and the advent of evolutionary theory can not be understood unless considering changes in geology promoted by a naturalist who is considered one of the fathers of geology: Charles Lyell.

Sir Charles Lyell (1797 - 1875) he enrolled at the University of Oxford at the age of 19 years. First study mathematics, classical arts and law (he graduated in law), but after he attended a lecture William Buckland was born his interest in geology. After beginning as a lawyer, in 1827 his interest in the natural sciences and geology led him to travel far and wide across the continent.

In the period 1830 to 1833 published the results of his studies in the incumbent " Principles of Geology," in which he applied and developed his version of the theory of "news", conceived in principle by James Hutton, and opposed to catastrophism in that period, especially developed by the naturalist Georges Cuvier . not catastrophic and rapid changes sculpted the land, but the slow processes of erosion and deposition, also seen in modern times (hence the name "Current"), even if they need thousands if not millions of years. Nell'Uniformitarismo Lyell the forces of nature are the same as in the past, present, and future . Lyell thus rebelled against the established geological theories of his time. In the third edition of his "Principles " deals with palaeontology and stratigraphy, it is also the natural history of man. Lyell say that the age the earth and with it the human race was much older than previously thought.

It was a copy of Lyell's book, given to Darwin by Captain Fitzroy, Charles to give an idea of \u200b\u200bthe depths of time (and new interest in geology, that after the first course conducted at the University considered a boring science) that the earth is the life had gone through a period of time for the slow evolution of organisms as many years later postulerò Darwin.

become friends Lyell and Darwin, and after the presentation of Darwin's theory of transmutation, Lyell, after the initial skepticism (Which, however, lasted for more than 25 years) will be one of the most important supporters.

Castles From 1100-1200

Kitchenuhmaykoosib

The year 2008 was the "Monster of Montauk " in 2010 after the "Yeti Eastern " Kitchenuhmaykoosib here is the monster that comes to us via the Internet from Canada (Ontario )

Fig.1. The "monster" in all its splendor .

According to witnesses, two girls, the corpse was discovered on the shore of a lake by their dog. They had time to make some photographs, after which they return to the city to alert the authorities. Returning to the place of discovery, the carcass was gone.

Fig.2. The monster, of course, the carcass is gone, and biologists are not able to determine it (apart from that definitely were not informed of the matter), to identify the bets are open ...

PS is not so difficult to determine the animal ... and Darren Naish explains why .

Meanwhile, this crap is spreading the network without the slightest hint of skepticism or desire to understand what it really is.

The way the news is handled is a shame, but perhaps even more surprising is the apparent lack of the most minimal knowledge of the shape and anatomy (. .. an almost human face ... !) of mammals common in the press and the public.

Milena Velba Cd Store

Methane blamed for the extinction of late Pleistocene

There are many hypotheses that attempt to explain the extinction of the megafauna in the late Pleistocene ( here, here and here ). Now a team of researchers at the University New Mexico in Albuquerque adds a different approach to the problem of climate change observed in early Holocene and that is recognized as the most likely factor to cause extinction.
SMITH et al. published the results of a search, in which they compared and modeled the production of methane by farm animals with modern extinct herbivores. Methane is a greenhouse gas known as very effective.

The research team compared the values \u200b\u200bobtained from observations in the geologic record of strong variations in the concentration of methane between the last glacial maximum, 18,000 years ago, and the Younger Dryas (13,000 years ago). Especially at the beginning of this period con notevole abbassamento delle temperature si osserva anche una diminuzione della concentrazione del metano.
Il gruppo di ricerca ipotizza che con l´inizio dell'estinzione dei grandi erbivori una fonte importante di metano è stata rimossa dal sistema climatico, destabilizzando come conseguenza ulteriormente il clima e l´ambiente, e aumentando il tasso di estinzione.

Il cambiamento osservato secondo la ricerca é avvenuto molto più veloce rispetto a variazioni precedenti. Forse questa differenza é legata a delle attività umane, smentendo ricerche precedenti che escludevano un significante contributo dell´uomo per l'estinzione di fine Pleistocene.

REFERENCES

SMITH, FA, ELLIOTT, MS. & YONS, K. (2010): Methane Emissions from extinct megafauna. Nature Geoscience. Published online: 23. May 2010: doi: 10.1038/ngeo877