446 
DARWINISM 
CHAP. 
them. He possesses the same number of limbs terminating 
in the same number of digits as belong fundamentally to the 
mammalian class. His senses are identical with theirs, and 
his organs of sense are the same in number and occupy the 
same relative position. Every detail of structure which is 
common to the mammalia as a class is found also in man, 
while he only differs from them in such ways and degrees as 
the various species or groups of mammals differ from each 
other. If, then, we have good reason to believe that every 
existing group of mammalia has descended from some common 
ancestral form — as we saw to be so completely demonstrated 
in the case of the horse tribe,— and that each family, each 
order, and even the whole class must similarly have de¬ 
scended from some much more ancient and more generalised 
type, it would be in the highest degree improbable — so 
improbable as to be almost inconceivable — that man, agreeing 
with them so closely in every detail of his structure, should 
have had some quite distinct mode of origin. Let us, then, 
see what other evidence bears upon the question, and whether 
it is sufficient to convert the probability of his animal origin 
into a practical certainty. 
Rudiments and Variations as Indicating the Relation of Man to 
other Mammals. 
All the higher animals present rudiments of organs which, 
though useless to them, are useful in some allied group, and 
are believed to have descended from a common ancestor in 
which they were useful. Thus there are in ruminants rudi¬ 
ments of incisor teeth which, in some species, never cut through 
the gums; many lizards have external rudimentary legs; 
while many birds, as the Apteryx, have quite rudimentary 
wings. Now man possesses similar rudiments, sometimes 
constantly, sometimes only occasionally present, which serve 
intimately to connect his bodily structure with that of the 
lower animals. Many animals, for example, have a special 
muscle for moving or twitching the skin. In man there are 
remnants of this in certain parts of the body, especially in 
the forehead, enabling us to raise our eyebrows ; but some 
persons have it in other parts. A few persons are able to move 
the Avhole scalp so as to throw off any object placed on the head, 
