Origin of Species Variorum

exposed to great changes of climate and have migrated over great distances; whereas, in Egypt, during the last 3000 years, the conditions of life, as far as we know, have remained absolutely uniform. The fact of little or no modification having been effected since the glacial period would be of some avail against those who believe in ... an innate and necessary law of development, but is powerless against the doctrine of natural selection or the survival of the fittest, which implies only that variations or individual differences of a favourable nature occasionally arise in a few species, and are then preserved. ↑

It has been objected, if natural selection be so powerful an agent, why has not this or that organ been .. modified and improved? Why has not the proboscis of the hive-bee been lengthened so as to reach the nectar of the ... red-clover? Why has not the ostrich acquired the power of flight? But granting that these parts and organs have varied in the right direction— granting that there has been time sufficient for the slow work of natural selection, the effects being often checked as they will be by intercrossing and the tendency to reversion, who will pretend that he knows the life-history of any one organic being sufficiently well to say that any particular change would be on the whole to its advantage? Can we feel sure that a long proboscis would not be a disadvantage to the hive-bee in sucking the innumerable small flowers which it frequents? Can we feel sure that a long proboscis would not, by correlation, .. almost necessarily give increased size to other parts of the mouth, perhaps interfering with the delicate cell-constructing work? In the case of the ostrich, a moments reflection will show what an enormous supply of food would be necessary to supply force for this bird of the desert to ... move its huge body through the air.