38 
VERTEBRATA. 
the twelve posterior molars, ■which are permanent, there arc four which make their appearance at 
four years and a half, four at nine years ; the kxst four being frequently not cut until the twentieth 
year. 
The foetus grows more rapidly in proportion as it approaches the time of birth. The infant, on 
the contrary, increases always more and more slowly. It has upward of a fourth of its height 
when born, attains the half of it at two years and a half, and the three-fourths at nine or ten years. 
By the eighteenth year the growth almost entirely ceases. Man rarely exceeds six feet, and sel- 
dom remains under five. Woman is ordinarily some inches shorter. 
Scarcely has the body attained its full growth in height before it commences to increase in' 
bulk ; fat accumulates in the cellular tissue. The different vessels become gradually obstructed ; 
the solids become rigid ; and after a life more or less prolonged — more or less agitated^ — more or 
less painful — old age arrives, with decrepitude, decay, and death. Man rarely lives beyond a hun- 
dred years ; and most of the species, either from disease, accidents, or merely old age, perish long- 
before that term. 
The child needs the assistance of its mother much longer than her milk, whence results an ed- 
ucation intellectual as well as physical, and a durable mutual attachment. The nearly equal num- 
ber of individuals of the two sexes, the difficulty of supporting more than one wife, when wealth 
does not supply the want of power, intimate that monogamy is the natural condition of our 
species ; and as, wherever this kind of union exists, the sire participates in the education of his 
offspring, the length of time required for that education alloAvs the birth of others, whence the 
natural perpetuity of the conjugal state. From the long period of infantile weakness results do- 
mestic subordination, and, consequently, the order of society at large, as the young persons which 
compose the new families continue to preserve with their parents those tender relations to which 
they have so long been accustomed. This disposition to mutual assistance multiplies to an almost 
Unlimited extent those advantages previously derived by isolated man from his intelligence ; it has 
assisted him to tame or repulse other animals, to defend himself from the effects of climate, and 
thus enabled him to cover the earth with his species. 
In other respects, man appears to possess nothing resembling instinct — no regular habit of in- 
dustry produced by innate ideas ; all his knowledge is the result of his sensations, his observations, 
or of those of his predecessors. Transmitted by speech, increased by meditation, applied to his 
necessities and his enjoyments, they have given rise to all the arts. Language and letters, by 
preserving acquired knowledge, are a source of indefinite perfection to his species. It is thus that 
he has acquired ideas, and made all nature contribute to his wants.* 
STRIKING CHAEACTERISTICS OF THE HUMAN RACE. 
It is a remarkable fact, and worthy of particular notice, that in the economy of his body 
man is endowed with the ability to live on almost any part of the globe, and of thriving alike in 
either extreme of natural temperature. Thus the Greenlanders and Esquimaux have reached 
between 10° and 80° N. latitude, while the negro of Africa and the red man of America live 
under the equator. But even Europeans, accustomed to a temperate climate, can bear either of 
these extremes of cold and heat, as has been sufficiently proved by the numerous instances in 
which those who have gone on the Arctic expeditions have been obliged to winter in high north- 
ern latitudes ; and, on the other hand, by the slight degree in which European settlers in the 
hottest parts of Africa are influenced by the temperature. 
Man subsists with equal facility under various degrees of atmospheric pressure — as well in the 
deepest valleys as upon the most elevated table-lands. In correspondence with his ability to in- 
habit every zone, he is able to subsist on the most varied food. In these respects he stands alone. 
But however widely he may be distinguished from other animals in the peculiarities of his struc- 
ture and economy, yet the sentiments, feelings, sympathies, internal consciousness, and mind, and 
the habitudes of life and action thence resulting, are the real and essential characteristics of hu- 
manity. The difference in these respects between man and all other animals is indeed so great 
* Cuvier's Animal Kingdom." 
