The main aim of obstetric practice is to ensure that mothers and babies remain healthy during pregnancy and birth. A variety of techniques may be employed to monitor and assess fetal health. This chapter concentrates upon techniques available to assess the health of the fetus. However it should be noted that the mother's health and wellbeing is inextricably linked to that of the fetus and a key element of antenatal care is the careful monitoring and management of the mother's health (see ‘Antenatal care’).

Key issues in assessing fetal wellbeing

The high-risk fetus in the low-risk population

Some mothers are classed as high-risk, i.e. at increased risk of having a baby with a problem due to some known factor, e.g. maternal age and Down's syndrome. Such mothers are relatively easy to identify and offered tests to assess the condition of their fetus (see ‘Screening: antenatal’). However the majority of fetal problems arise in the low-risk population of mothers, who present no obvious signs of having a fetus with an abnormality. A reduction in the incidence of fetal problems rests with advances in identifying the high-risk fetus in the low-risk population (McKenna et al., 2003).

Screening and diagnosis

Diagnostic techniques, whilst providing a definitive answer regarding the presence of a particular problem, can be expensive in time and money and carry a serious risk to the fetus, e.g. amniocentesis, which may result in a miscarriage. These tests are thus unsuitable for widespread use with the low-risk population.

Introduction

Much evidence has now accumulated to demonstrate that individuals respond differentially to conspecifics according to their genetic relatedness (e.g. Hepper, 1986a; Fletcher & Michener, 1987; see also this book). Furthermore, this differential responding is not confined to one particular behaviour but is found in a diverse variety of situations and behaviours (see this book). This strongly suggests that individuals have some means which enable them to identify genetic relatedness. It is the aim of this chapter to explore how individuals recognize their kin. Previously (e.g. Hepper, 1986a; Porter, 1987; Waldman, 1988) this ability has been considered under the general rubric of the ‘mechanisms’ of kin recognition. This chapter will discuss factors which contribute to the individual recognizing its kin and will, by addressing these factors, enable the underlying basis of kin recognition to be elucidated. Although the chapter will concentrate on mammalian kin recognition it is hoped that the considerations presented will be applicable to other animal groups. I shall first discuss present approaches to mechanisms of kin recognition.

In Hamilton's seminal papers of 1964 (a,b), as well as demonstrating the fitness benefits to an individual of responding differentially to kin and nonkin, a number of ways were proposed by which individuals would be able to discriminate between kin and non-kin in social situations. From this discussion (Hamilton, 1964b) and that of others (e.g. Alexander, 1979; Bekoff, 1981; Hölldobler & Michener, 1980) four basic ‘mechanisms’ have been proposed to explain how individuals recognize their kin (Holmes & Sherman, 1983). These have become firmly rooted in the literature and I shall outline each briefly.

Studies of kin recognition have progressed rapidly during the past decade. One of the most exciting aspects of this research is that the ability to recognize kin has been found, in some form or other, throughout the animal kingdom, from single-celled organisms to man. The increase in studies reporting kin recognition has led to a widespread acceptance of the role of kinship in behaviour. There is, of course, good theoretical reasons, provided by kin selection theory and mate choice theory, why this should be so, however, the importance of kinship for behaviour has often been unquestioned. One of the reasons for compiling this volume was to critically assess the role of kinship in behavioural interactions: is kin recognition responsible for the many observed differential interactions between kin and non-kin? Whilst many species have been demonstrated to recognize their kin, little attention has been given to determining how this is achieved and consequently the mechanisms underlying this ability are poorly understood. A second goal of this book was to present research which has investigated how individuals recognize their kin.

Rather than provide a taxonomic discussion of kin recognition, I have aimed to provide a book which deals with particular themes. Leading researchers in these areas were asked to discuss these issues with respect to their own expertise and species or group studied. The book may be broadly divided into two sections – that dealing with function and that dealing with mechanisms.

The importance of kinship for human societies has long been recognized, indeed the interest in kinship is reflected in the large number of works, plays, books, operas, etc., which have kinship, often mistaken, as their central theme. Whilst there has been little doubt that humans recognize their kin and respond differentially to them, the ability of animals to recognize and respond differentially to kin has received little attention. In recent years, however, study of the influence of kinship on the social behaviour of animals has increased dramatically. Much of the impetus for this research can be attributed to the seminal works of Hamilton (1964a,b) and later Wilson (1975). Evidence that kinship, or genetic relatedness, influences an individual's behaviour has now been documented in all the major groups of animals – from single-celled organisms (e.g. Grosberg & Quinn, 1986) to man (e.g. see Porter, this volume). Reptiles remain an exception to this and only recently have studies appeared providing evidence of kin recognition in this group (e.g. Werner et al, 1987), which probably reflects a lack of empirical investigation rather than a lack of ability to recognize kin. As diverse as the groups of animals which exhibit evidence of kin recognition are the behaviours in which individuals respond differentially on the basis of kinship; colonization patterns, mating, play, aggression, feeding, schooling, swarming, defence, etc. all are influenced by kinship. Investigations of the ability to recognize kin have revealed that individuals have well developed capabilities to recognize kin; siblings, half-siblings, cousins, parents, offspring, grandparents, aunts and uncles are all capable of being discriminated. Kinship thus appears to influence behaviour throughout the animal kingdom.