Nature and Origin of Life lecture 5 History part 1.

Nature and Origin of Lifelecture 5History part 1

ThemesA causal studyEvidence against spontaneous generation today.Carrying capacityDesign?Darwin precursorsDarwinGalapagos evidenceDarwins theory

God is not an issueThere is an order in the universe. We can call it the Laws of Physics, or the Laws of God. It will make no difference in how we go about predicting future behavior, nor how we infer how developments happened in the past.Is the order of the universe occasionally violated?Often such apparent occurrences are mixed in with issues about the validity of observers as good witnesses. And even if the events were real, what they would say about the nature of God is disputable.Either, life originated by a natural process, or it was a special occurrence. We can investigate the first, but not the second. That is what we will do here.

Is life continually created?Up until the 19th century, life was a mystery.There had been experiments in the late 1600sby Francisco Redi, to determine whether maggots spontaneously appeared in rotting meat. Hypothesis: Maggots come from flies.Redi put meat into three separate jars.Jar 1 was left open,Jar 2 was covered with nettingJar 3 was sealed from the outside.

Redis Experiment (1668)Jar 1,open. flies observed laying eggs on meat.maggots developed.Jar 2, netting. flies laid eggs on nettingmaggots developed on the netting.Jar 3, sealed. no flies, no maggots.

Conclusion: maggots are not the spontaneous formation of life. They are fly larvae.

Pasteurs experimenton sterilization 1862

Redi and Pasteur showedLife forms such as flies and microbes in theirreproduction, reproduce organisms. There is no current evidence that organisms have been produced from non living material.But, it could be that we have not adequately investigated circumstances that might give rise to life forms.

Malthus 1798 argumentHumans produces offspring in excess, otherwise humanity would easily die out.But therefore the inadequacies of the environment will limit population by starvation, or other ways in which the environment is inadequate.---------------------------------------------------------Is this a characteristic of humans, all life, or some larger group?

Malthus 1798 The power of population is so superior to the power of the earth to produce subsistence for man, that premature death must in some shape or other visit the human race. The vices of mankind are active and able ministers of depopulation. They are the precursors in the great army of destruction, and often finish the dreadful work themselves. But should they fail in this war of extermination, sickly seasons, epidemics, pestilence, and plague advance in terrific array, and sweep off their thousands and tens of thousands. Should success be still incomplete, gigantic inevitable famine stalks in the rear, and with one mighty blow levels the population with the food of the world. An essay on the principle of population. Chapter VII, p61

Tasmania sheep populationCarrying capacity

Paleys Watch (1802) 1Paley begins by postulating that if he is walking in country and stumbles against a stone that there is no objection to supposing that the stone had been there ever since the beginning of time. But suppose I had found awatchupon the ground, and one inquired how the watch happened to be in that place, I should not think that the watch might have always been there. Yet why should not this answer serve for the watch as well as for the stone?...For this reason, and for no other, that, when we come to inspect the watch we perceive (what we could not discover in the stone) that its several parts are put together for a purpose....[Description of watch omitted.] This mechanism being observed... the inference, we think, is inevitable, that the watch must have had a maker....who comprehended its construction, and designed its use.

Paleys watch 2If we find an intricate piece of machinery, is that evidence of :1) purpose?2) a designer?3) a design event?

What would be evidence of these items?

What is sufficiently intricate? Is a uranium atom sufficiently intricate? Is a virus sufficiently complex? And what about evolution? How does one distinguish design intricacy from evolution intricacy?

Development of OrgansThis is crucial to assessing the validity of the concept of intelligent design.Many versions of eyes are known, so that there is evidence of independent evolution.A specific pair are the mammal eye and the octapus eye.The octopus eye has its sensors on the outside. The vertibraete eye has its sensors on the inside, and so their nerve cells have to pass through the retina, leaving a blind spot.There must be a best design, so why are there also inferior ones?

Buffon 1749-88(from Wickipedia)In the course of his examination of the animal world, Buffon noted that despite similar environments, different regions have distinct plants and animals, a concept later known as Buffon's Law. This is considered to be the first principle ofbiogeography. He made the suggestion that species may have both "improved" and "degenerated" after dispersing from a center of creation. In volume 14 he argued that all the world'squadrupedshad developed from an original set of just thirty-eight quadrupeds.On this basis, he is sometimes considered a "transformist" and a precursor of Darwin. He also asserted that climate change may have facilitated the worldwide spread of species from their centers of origin. Still, interpreting his ideas on the subject is not simple, for he returned to topics many times in the course of his work. Buffon considered the similarities between humans and apes, but ultimately rejected the possibility of a common descent. He debated withJames Burnett, Lord Monboddoon the relationship of the primates to man, Monboddo insisting, against Buffon, on a close relationship.

Erasmus Darwin 1794-6 (Charles grandfather)Would it be too bold to imagine, that in the great length of time, since the earth began to exist, perhaps millions of ages before the commencement of the history of mankind, would it be too bold to imagine, that all warm-blooded animals have arisen from one living filament, whichTHE GREAT FIRST CAUSEendued with animality, with the power of acquiring new parts, attended with new propensities, directed by irritations, sensations, volitions, and associations; and thus possessing the faculty of continuing to improve by its own inherent activity, and of delivering down those improvements by generation to its posterity, world without end!

Lamarckian Evolution 1800Lamarck stressed two main themes in his biological work. The first was that the environment gives rise to changes in animals. He cited examples of blindness in moles, the presence of teeth in mammals and the absence of teeth in birds as evidence of this principle. The second principle was that life was structured in an orderly manner and that many different parts of all bodies make it possible for the organic movements of animals.Although he was not the first thinker to advocate organic evolution, he was the first to develop a truly coherent evolutionary theory.He outlined his theories regarding evolution first in his Floreallecture of 1800,

Lamarcks adaptive forceA component of Lamarck's theory of evolution was the adaptation of organisms to their environment. Lamarck argued that this adaptive force was powered by the interaction of organisms with their environment, by the use and disuse of certain characteristics.First Law: In every animal , a more frequent and continuous use of any organ gradually strengthens, develops and enlarges that organ ; while the permanent disuse of any organ imperceptibly weakens and deteriorates it, and progressively diminishes its functional capacity, until it finally disappearsSecond Law: All the acquisitions or losses wrought by nature on individuals, through the influence of the environment hence through the influence of the use or permanent disuse of any organ; are preserved by reproduction to the new individuals which arise, provided that the acquired modifications are common to both sexes, or at least to the individuals which produce the young.

What did Darwin did included:Galapagos observations of species diversification.Collected S. American fossils showing localization and development.Found geological evidence for uniformitarianism.Applied the Malthusian concept to all life forms.Considered the effect of diversity on the survival lines.Considered the development of new organs.Considered the effects of sexual preference.

Differentiation is agreedWhat is the cause?Can it be purely by use? If a man loses his legs before having children, will they be born legless? Can it be purely by inheritance? Would that not restrict the range of variation?So there must be an intrinsic or extrinsic continual process of differentiation. Darwin did not argue the cause. He argued that observations demonstrated the effect. Therefore Darwinian Evolution is an effect without agreed cause. However it is agreed that the result travels down the genetic line.

GalapagosThese are volcanic islands ~1000 km, from S. America. They were presumably populated by rare accident, usually the transfer of a single pregnant female. More easily, they transferred to many of the islands, but sufficiently rarely that island species developed independently.The lizards, birds and tortoises showed a development of divergence, of speciation.

Following his return from the voyage, Darwin presented the finches to theGeological Society of London at their meeting on 4 January 1837, along with other mammal and bird specimens he had collected. The bird specimens, including the finches, were given toJohn Gould, the famous Englishornithologist, for identification. Gould set aside his paying work and at the next meeting on 10 January reported that birds from theGalpagos Islandswhich Darwin had thought wereblackbirds, "gross-beaks" andfincheswere in fact "a series of ground Finches which are so peculiar [as to form] an entirely new group, containing 12 species."

The marine iguana is the only ocean-dwelling lizard in the world. Endemic to the Galpagos, the seven subspecies are dark-coloured and emblazoned with various reds, grays and greens, depending on what island they are from.

The Galapagos Land Iguana varies inmorphologyand coloration among different island populations.There are two taxonomically distinct forms inhabiting the western part of the islands and one in the central part

Galapagos TortoiseShell size and shape vary between populations. On islands with humid highlands, the tortoises are larger, with domed shells and short necks- on islands with dry lowlands, the tortoises are smaller, with "saddleback" shells and long necks.of evolution.

Darwins Theory (from Wikipedia)Darwin was the first to formulatea scientific argument for thetheoryof evolution by means ofnatural selection. Evolution by natural selection is a process that is inferred from threefactsabout populations: 1) more offspring are produced than can possibly survive, 2) traits vary among individuals, leading to differential rates of survival and reproduction, and 3) trait differences areheritable.Thus, when members of a population die they are replaced by theprogenyof parents that were betteradaptedto survive and reproduce in theenvironmentin which natural selection took place. This process creates and preserves traits that areseemingly fittedfor thefunctionalroles they perform.Natural selection is the only known cause ofadaptation.It is NOT the only known cause of evolution. Other, nonadaptive causes ofevolutionincludemutation andgenetic drift and lateral gene transport.