(2) _The Influence of Parental Care._ Sex alone could never have produced the family in the sense of a relatively permanent group of parents and offspring. We do not begin to find the family until we get to those higher types where we find some parental care. In the lowest types the relation between the sexes is momentary and the survival of offspring is secured simply through the production of enormous numbers. Thus the sturgeon, a low type of fish, produces between one and two million of eggs at a single spawning, from which it is estimated that not more than a dozen individuals survive till maturity is reached. Thus sexual reproduction of itself necessitates no parental care and in itself could give rise in no way to the family; but quite low in the scale of life we begin to find some parental care as a device to protect immature offspring and secure their survival without the expenditure of such an enormous amount of energy in mere physiological reproduction. Even among the fishes we find some that watch over the eggs after they are spawned and care for their young by leading them to suitable feeding grounds. In such cases a much smaller number of young need to be produced in order that a few may survive until maturity is reached. In the mammals the mother, obviously, must care for the young for some time, since mammals are animals that suckle their young. But this care of the young by a single parent only foreshadows the family as we understand it. Among the mammals it is not until we reach the higher types that we find care of offspring by both parents,--a practice, however, which is common among the birds. It is evident that as soon as both parents are concerned in the care of the offspring they have a much better chance of survival. Hence, natural selection favors the growth of this type of group life and develops powerful instincts to keep male and female together till after the birth and rearing of offspring. Such we find to be the condition among many of the higher mammals, such as some of the carnivora, and especially among the monkeys and apes and man.