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How do we know that evolution really occurred?

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April 23, 2010 9:58AM

Charles Darwin was by no means the first to say that evolution was the basis of the species we see today, but he did develop the Theory of Evolution by Natural Selection. And he addressed the very question, How do we know that evolution occurred, rather than a special act of creation?

Statistical distribution of species

Darwin realised that where many species of a genus have been formed through variation, circumstances have been favourable for variation. Hence we may expect that circumstances would generally be still favourable to variation. On the other hand, if we look at each species as a special act of creation, there is no apparent reason why more varieties should occur in a group having many species, than in one having few.

To test this hypothesis, Darwin arranged the plants of twelve countries, and the coleopterous insects of two districts, into two nearly equal masses, with the species of the larger genera on one side, and those of the smaller genera on the other side. Invariably a larger proportion of the species on the side of the larger genera presented varieties. Moreover, the species of the large genera which presented any varieties, invariably presented a larger average number of varieties than the species of the small genera.

What he was able to show was that, where many species of a genus have been formed, then on an average, many are still forming. This belies a special act of creation at a single point in the past.

Proliferation and eventual extinction of species

Since some creationists claim that the extinction of fossil species in the geological column can be blamed on Noah's Flood, it is also necessary to look at whether the scientific evidence favours the theory of evolution.

Scientists have found that, generally, if the number of species in a genus (group of closely related species), or the number of genera in a family, be represented by a vertical line of varying thickness, crossing the successive geological formations in which the species are found, the line will begin either as a sharp point or narrow line, then gradually thicken upwards, sometimes keeping for a space of equal thickness, then thin out in the upper beds, marking the decrease and final extinction of the group. This is consistent with evolution, but hard to explain by the creationists' argument of Noah's Flood.