Ecological Factors in the Attainment of Puberty: Introduction

Abstract

A mammal can be considered as having reached puberty or sexual maturity when it is capable of producing gametes, the fusion of which will result in the production of viable young. This process is complicated in many species by the presence of recurring intervals (the non-breeding or anoestrous seasons) when gamete production is interrupted. The initial onset of puberty is a period in the life of the individual which is difficult to define except in terms of the discipline under consideration. From the point of view of genetics, an individual has not reached puberty until fusion of the gametes produced has actually occurred, whereas from the standpoint of reproductive physiology, the initial production of viable gametes would suffice to mark the onset of reproduction. From the standpoint of population dynamics, the female may be considered as having reached puberty when she first gives birth or the male when he first causes a conception which will subsequently result in birth, whereas the ethologist may consider an animal as being pubertal when it first exhibits patterns of behaviour associated with sexual maturity. These approaches conflict in certain mammals which, though physiologically able to produce young, are prevented from doing so by social or ecological factors (see page 34). Thus the state of sexual maturity is an easily acceptable concept to biologists but the definition of the initial onset of this state is complex and largely depends on the discipline concerned.