I will return to the essential misconception of the Theory of Natural
Selection betrayed in this first _a priori_ when I consider Mr.
Belloc’s third feat of logic. But first let me glance at his second. In
this he says, very correctly, that every stage in the evolution of a
living creature must be a type capable of maintaining itself and every
change must be an advantageous change. I have noted this very obvious
point already in my second paper. But then Mr. Belloc instructs us that
the chances of its being so are, for no earthly reason, zero--that
fatal zero again!--and goes on to a passage so supremely characteristic
that it must be read to be believed:--
“A bird has wings with which it can escape its enemies. If it began
as a reptile without wings--when, presumably, it had armour or some
other aid to survival--what of the interval? Natural Selection
sets out to change a reptile’s leg into a bird’s wing and the
scales of its armour into feathers. It does so by making the leg
less and less of a leg for countless ages, and by infinite minute
gradations, gradually turning the scales into feathers.
“By the very nature of the theory _each stage_ in all these
millions is an advantage over the last towards survival! The thing
has only to be stated for its absurdity to appear. Compare the ‘get
away’ chances of a lizard at one end of the process or a sparrow at
the other with some poor beast that had to try and scurry off on
half-wings! or to fly with half-legs!
“Postulate a design, say, ‘Here was something in the making,’ and
the process is explicable, especially if fairly rapid so as to
bridge over the dangerously weak stage of imperfection. Postulate
Natural Selection and it is manifestly impossible.”
Let us note a few things of which Mr. Belloc shows himself to be
unaware in this amusing display of perplexity. In the first place he
does not know that the Mesozoic reptiles most closely resembling birds
were creatures walking on their hind-legs, with a bony structure of the
loins and a backbone already suggestive of the avian anatomy. Nor is
he aware that in the lowliest of living birds the fore-limbs are mere
flappers, that the feathers are simpler in structure than any other
bird’s feathers, and that the general development of a bird’s feather
points plainly to the elongation of a scale. He has never learnt that
feathers came before wings, and that at first they had to do, not with
flying, but with protection against cold. Yet all this was under his
nose in the _Outline of History_ in text and picture. The transition
from a quilled to a feathered dinosaur presents indeed no imaginative
difficulties, and the earliest birds ran and did not fly. One of the
earliest known extinct birds is _Hesperornis_, a wingless diving bird.
It is figured on page 30, and there is another bird on page 34 that Mr.
Belloc might ponder with advantage. A whole great section of living
birds, like the ostrich and the emu, have no trace in their structure
of any ancestral flying phase; their breast-bones are incapable of
carrying the necessary muscular attachments.
[Illustration: H. G. Wells.