It is not the strongest of the species that survives… nor the most intelligent that survives. It is the one that is the most adaptable to change.
In the Camel, as well as in the Horse and Hippopotamus, the bodies of the lumbar vertebræ diminish in vertical extent, or become flatter, as they approach the sacrum; but this character is more strongly marked in the Macrauchenia than in either of the above species. But in the Camelidæ the transverse processes of the lumbar vertebræ, are elongated, flattened, and narrow, resembling ribs...1838-1843. The zoology of the voyage of H.M.S. Beagle. Edited and superintended by Charles Darwin. London: Henry Colburn.