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1891.] Psychology. 845 
PSYCHOLOGY. 
Note on the Evolution of the Upright Tail in the Do- 
mestic Dog.—My attention has recently been called to the work on 
‘“ Organic Evolution ’’ by Professor Eimer, page 114, to a paragraph 
in which he seems unable to account for the dogs in Constantinople 
carrying the tail upright. In speaking of the subject he says: ‘‘ But 
the reason why these dogs begin to erect the tail and carry it upright, 
while the ancestral jackal, like the wolf, carries it hanging down, is 
not so easy to discover, although the fact could scarcely be explained 
as a case of adaptation.’ I beg to offer a provisional explanation of 
this phenomenon, and also to take exception to the latter statement, 
—that it cannot be explained as a case-of adaptation, While my ob- 
servations were not made at Constantinople, the dogs accompanying 
the several tribes of Indians I observed in the Western United 
States, some of which arc tamed wolves, or are directly descended 
from the wild American wolf known as the coyote, offer opportunities 
of study which brought me to a realization of this subject, which may 
be summed up in a few epitomized remarks. 
As the dog becomes domesticated it is prone to use the tail as an 
organ of expressing mental states, especially those of emotion’ for 
example, the wag of the tail expressive of delight, or sudden dropping 
of the tail between the legs at some disappointment or fright. The 
ancestral or wild wolf carries the tail hanging down, because that 
position (the tail being especially bushy and large in the wild animal) 
would be less conspicuous and more compatible with life in a free 
state of nature, or, as it were, to better elude detection. A family 
of wolves playing together undisturbed occasionally carry their tails 
curled upwards. By degrees the tail acquires naturally the upright 
position as a result of coincident evolution of the mind of the wolf 
incidental to domestication, and moreover thus instancing the slow. 
adaptation of the appendage as an organ of expression. The cessation 
of ‘natural selection in the domestic dog would give to the tail greater 
freedom of motion without detriment to life; and artificial selection. 
perfects the caudal appendage into many diverse shapes. Still greater 
influence is exerted by certain expressions of. the mind by that appen- 
dage, tending to keep it up, and by the influence of heredity, trans- 
mitting those tendencies. The muscles correlatively become strength- 
ened and developed, and the erect position ultimately passes into an 
apparently fixed character in some varieties of the dog.—Dr. ue 
L. Hancock, July roth, 1891. 
1 The words ods and wolf are used er in this note. 

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