<P> If we consider the vegetable kingdom generally, it must be recollected, that even of the seeds which are well ripened, the greater part are either eaten by insects, birds, and other animals, or decay for want of room and opportunity to germinate . Unhealthy plants are the first which are cut off by causes prejudicial to the species, being usually stifled by more vigorous individuals of their own kind . If, therefore, the relative fecundity or hardiness of hybrids be in the least degree inferior, they cannot maintain their footing for many generations, even if they were ever produced beyond one generation in a wild state . In the universal struggle for existence, the right of the strongest eventually prevails; and the strength and durability of a race depends mainly on its prolificness, in which hybrids are acknowledged to be deficient . </P> <P> Charles Darwin initially shared the belief that nature was perfect and harmonious: after graduating as a student at the University of Cambridge in 1831, he was convinced by William Paley's Natural Theology or Evidences of the Existence and Attributes of the Deity which saw adaptation as purposeful design and presented population pressure optimistically; "it is a happy world after all". By mid January 1832, early in the Beagle voyage, Darwin saw geology from Charles Lyell's viewpoint . When the second volume of Lyell's Principles of Geology was delivered to the Beagle that November, Darwin accepted its argument that the "struggle for existence" disproved transmutation of species . He was reminded of Malthusianism when his sisters sent him out pamphlets by Harriet Martineau . Lyell had been unable to show the mechanism for introducing new species, and towards the end of the voyage Darwin noted that the distribution of mockingbirds found on the Galápagos Islands raised doubts that species were fixed . </P> <P> Early in 1837 John Gould in London revealed that the mockingbirds were separate species: Darwin was spurred into intensive research and the inception of his theory to find the mechanism introducing species . Unconventionally, he sought information from animal breeders . In September 1838, while investigating variation, averages and population statistics, he read Malthus' An Essay on the Principle of Population, and wrote: </P> <P> We ought to be far from wondering of changes in numbers of species, from small changes in nature of locality . Even the energetic language of Malthus Decandolle does not convey the warring of the species as inference from Malthus .--increase of brutes must be prevented solely by positive checks, excepting that famine may stop desire .--in nature production does not increase, whilst no check prevail, but the positive check of famine & consequently death . Population is increase at geometrical ratio in far shorter time than 25 years--yet until the one sentence of Malthus no one clearly perceived the great check amongst men </P>

All living organisms are constantly involved in a struggle for existence. this was proposed by