Alfred Russel Wallace: Direction

Alfred Russel Wallace was British naturalist, explorer, geographer, anthropologist and biologist. Explore interesting quotes on direction.
Alfred Russel Wallace: 24   quotes 0   likes

“This progression, by minute steps, in various directions, but always checked and balanced by the necessary conditions, subject to which alone existence can be preserved, may, it is believed, be followed out so as to agree with all the phenomena presented by organized beings, their extinction and succession in past ages, and all the extraordinary modifications of form, instinct, and habits which they exhibit.”

"On the Tendency of Varieties to Depart Indefinitely From the Original Type" (1858).
Context: The powerful retractile talons of the falcon- and the cat-tribes have not been produced or increased by the volition of those animals; but among the different varieties which occurred in the earlier and less highly organized forms of these groups, those always survived longest which had the greatest facilities for seizing their prey. Neither did the giraffe acquire its long neck by desiring to reach the foliage of the more lofty shrubs, and constantly stretching its neck for the purpose, but because any varieties which occurred among its antitypes with a longer neck than usual at once secured a fresh range of pasture over the same ground as their shorter-necked companions, and on the first scarcity of food were thereby enabled to outlive them. [... ] We believe we have now shown that there is a tendency in nature to the continued progression of certain classes of varieties further and further from the original type - a progression to which there appears no reason to assign any definite limits - and that the same principle which produces this result in a state of nature will also explain why domestic varieties have a tendency to revert to the original type. This progression, by minute steps, in various directions, but always checked and balanced by the necessary conditions, subject to which alone existence can be preserved, may, it is believed, be followed out so as to agree with all the phenomena presented by organized beings, their extinction and succession in past ages, and all the extraordinary modifications of form, instinct, and habits which they exhibit.

“On the question of the "origin of species" Mr. Haughton enlarges considerably; but his chief arguments are reduced to the setting-up of "three unwarrantable assumptions," which he imputes to the Lamarckians and Darwinians, and then, to use his own words, "brings to the ground like a child's house of cards." The first of these is "the indefinite variation of species continuously in the one direction." Now this is certainly never assumed by Mr. Darwin, whose argument is mainly grounded on the fact that variations occur in every direction. This is so obvious that it hardly needs insisting on. In every large family there is almost always one child taller, one darker, one thinner than the rest; one will have a larger nose, another a larger eye: they vary morally as well; some are more poetical, others more morose; one has a genius for numbers, another for painting. It is the same in animals: the puppies, or kittens, or rabbits of one litter differ in many ways from each other - in colour, in size, in disposition; so that, though they do not "vary continuously in one direction," they do vary continuously in many directions; and thus there is always material for natural selection to act upon in some direction that may be advantageous. […] I will only, in conclusion, quote from it a short paragraph which contains an important truth, but which may very fairly be applied in other quarters than those for which the author intended it: - "No progress in natural science is possible as long as men will take their rude guesses at truth for facts, and substitute the fancies of their imagination for the sober rules of reasoning."”

"Remarks on the Rev. S. Haughton's Paper on the Bee's Cell, And on the Origin of Species" (1863).