Here is an essay on ‘Parenting’ for class 11 and 12. Find paragraphs, long and short essays on ‘Parenting’ especially written for school and college students.
Essay on Parenting
Essay Contents:
- Essay on the Introduction to Parenting
- Essay on Evolution and Social Ecology
- Essay on Evolution, Sociality, and Development
- Essay on Evolution and Parenting
- Essay on Evolution and Human Parental Behaviour
Essay # 1. Introduction to Parenting:
Parenting involves the protection and transfer of energy, information, and social relations to offspring. Natural selection has fine-tuned the mechanisms that serve these ends for the specific demands of each species’ ecology.
African hominoids, including chimpanzees (Pan troglodytes), gorillas (Gorilla gorilla), and humans, share a number of parenting mechanisms with other placental mammals, including internal gestation, lactation, and attachment mechanisms involving neuropeptides such as oxytocin.
These hominoids differ from most other mammals with respect to a life history strategy that involves intensive parenting over a long developmental period and, for some of these species, with respect to the importance of the social activities of males. As an example, for both gorillas and chimpanzees, the direct or incidental protection of offspring from infanticidal males is a critical component of these social activities.
Whether or not human males are infanticidal, human beings take the general hominoid pattern to an extreme, in terms of intensive parenting over an extremely long developmental period, in terms of the critical importance of the social activities of men, and in terms of other later described features.
The importance of social activities and especially social competition has, in fact, been emphasized in some models of hominoid evolution.
The model is built around the basic evolutionary logic that selection pressures will result in the evolution of characteristics that co-vary with survival and reproductive outcomes and the assumption that at a social and behavioural level these characteristics function to allow individuals to attempt to gain access to and control of the associated resources, such as food, mates, and territory.
At the core of the model is the proposal that the primary impediment to achieving control over these essential but limited resources is the conflicting interests of other human beings. Complex social ecologies, in turn, are characterized by kin-based coalitions that compete and cooperate to facilitate access to and control of essential resources.
As with these other species, human social competition is often coalitional, and the defining features of H. sapiens described in Table 1 are conceptualized as evolutionary adaptations that function to facilitate the formation of competition-related social networks, including families.
Concealed ovulation, and non-reproductive sexuality, for instance, function to maintain extended male-female relationships and are features of human social dynamics that have coevolved with male parenting and the motivational disposition to form nuclear families.
The family and wider kinship networks function to create a social ecology that facilitates the feeding and protection of children and that supports the long developmental period and activities (e.g., peer relationships) needed to acquire socio competitive competencies.
In this view, the relations between parenting and child outcomes are predicted to be nuanced, varying from one child to the next and from one ecology to the next. The ultimate function of parental behaviour is, however, the same- to provide a social context that enables the acquisition of socio competitive competencies.
These competencies often involve social skills that enable the cooperative formation of coalitions, but this form of cooperation is ultimately a social strategy to facilitate competition with other coalitions and to gain access to and control over essential resources.
Because the model that integrates all of these human characteristics is based on a complex evolutionary scenario, we begin with a brief tour of the basics of evolutionary mechanisms and the logic of natural selection. The tour ultimately leads to discussion of evolutionary mechanisms and natural selection in a dynamic, complex social context.
One of these was with respect to the importance of individual differences. “These individual differences are of the highest importance for us, for they are often inherited, as must be familiar to every one; and they thus afford materials for natural selection to act on and accumulate”– Individual differences largely arise as a result of sexual reproduction.
The process of natural selection occurs when variability in a characteristic, such as degree of parental protection of offspring, co-varies with variability in survival or reproductive outcomes. If the characteristic is inherited, then the survivors will produce offspring who, as adults, will also have a behavioural tendency to provide greater rather than lesser degrees of parental protection of offspring. If the characteristic continues to co-vary with survival and reproductive outcomes in the offspring’s generation, then the process will repeat itself.
Over many generations and sometimes in a single generation there is a change in the selected characteristic such that the average individual in the population now shows greater levels of parental protection than did the average individual several generations earlier. This process of natural selection shapes species to their ecology and will occur whether the trait is physical, physiological, or behavioural.
Thus, heritable individual differences provide the grist for evolutionary selection. Given that nearly all features of human anatomy, physiology, behaviour, and cognition show individual variability that is partly heritable, they are all potentially subject to selection pressures, including traits that can influence the dynamics of parenting and family formation.
The process of selection acting on variability can be complicated, however. Selection pressures can reduce or eliminate heritable variability and thus many traits that have undergone strong selection in the past no longer show heritable variability.
Selection pressures can also vary from one generation to the next or from one geographical region to the next. Strong selection results when competition is intense and individual variability in associated traits co-varies strongly with survival and reproductive outcomes.
For all species, there are many different forms of selection pressure, including parasites (e.g., those causing infectious disease), competition with other species (e.g., predators), and competition with conspecifics—that is, members of the same species.
When resources are limited, competition with conspecifics can be understood as resulting from attempts to gain access to and control of the social (e.g., competition over mates), biological (e.g., food), and physical (e.g., nesting sites) resources that co-vary with survival and reproductive outcomes.
Characteristics that result in the achievement of this control will enhance survival and reproductive prospects and thus evolve. In other words, Darwin’s conceptualization of natural selection as resulting from a struggle for life is more precisely defined as a struggle to gain access to and control of the resources that support life and that allow one to reproduce.
Essay # 2. Evolution and Social Ecology:
For species that live and evolved in complex social systems, survival and reproduction are highly contingent on the behaviour of conspecifics. Mating dynamics provide the clearest example and are termed sexual selection. Sexual selection involves two general processes-intrasexual competition over access to mates, usually male-male competition, and intersexual choice of mating partners, usually female choice. In most mammalian species, males compete one-on-one for access to mates, but in a few species males form coalitions, or social networks, to enhance their competitive abilities.
The second part sketches the fundamentals of coalition formation, or social networking, and provides a conceptual benchmark for human social dynamics, the human family, and the functions of parenting.
Social Coalitions:
Chimpanzee communities are composed of coalitions of males and subgroups of females and their offspring. Although social relationships among females can be quite intense, the focus here is the cooperative behaviour of male coalitions, as related to the sexual politics of intra- and intercommunity relationships.
Male coalitions are highlighted because they are unusual among primates and because they appear to be an important feature of human social evolution. Within communities, small coalitions of males cooperate to achieve social dominance over other males and coalitions and thereby gain control over the social and sexual behaviour of other community members. The function of this coalitional behaviour is largely to control the mating activities of other community members and, through this, control of reproductive outcomes.
These smaller within-community coalitions will often cooperate and merge to form larger coalitions that then patrol the border of their territory and make incursions into the territory of neighboring communities. When members of such patrols encounter one another, the typical response is pant-hooting (a vocal call) and physical displays on both sides, with the smaller group eventually withdrawing.
At other times, meetings between patrols from one group and members of neighboring communities are deadly. Good all described a series of such attacks by one community of chimpanzees on their southern neighbour. Over a 4-year period, the southern group was eliminated, one individual at a time, by the northern community, which then expanded their territory to include that of the now-extinct southern group.
The result for the successful group was the acquisition of prime feeding areas and the recruitment of females into the community. In other words, coalitional aggression in the chimpanzee often results in increased levels of access to and control of the physical (territory), biological (e.g., fruit trees), and social (e.g., mates) resources that co-vary with survival and reproductive outcomes.
As with chimpanzees, social cooperation and competition appear to co-vary with survival and reproductive outcomes in other species in which coalitions form. For all of these species, coalitional behaviour, or any form of social networking, can be readily understood as an aspect of the survival and reproductive strategies of each individual in the coalition and not as an adaptation for the species or even the wider group.
This is because individuals in successful coalitions achieve increased access to and control of essential resources—levels of access and control that would not be achievable if the individuals acted alone.
Inclusive Fitness, Reciprocal Altruism, and Social Dynamics:
The survival and reproductive, benefits associated with the formation of coalitions result in the evolution of a form of social “deep structure.” The deep structure is expressed as a motivational and behavioural disposition to create a social organization that reflects the associated selection pressures.
For coalitional species, the motivational disposition results in the attraction of individuals to one another and the resulting formation of social networks. The cooperative focus of these social networks will be on achieving the ends that resulted in the evolution of the deep structure, such as mate access in male chimpanzees.
Across species, the degree of social attraction, or the extent to which one individual is likely to cooperate with another in coalition formation, is influenced by genetic relatedness and reciprocal altruism.
The attractive force of genetic relatedness can be understood in terms of inclusive fitness. Here, the focus is on their productive success (i.e., number of off spring surviving to reproduce) of the individual and the individual’s effect on the reproductive success of kin.
This is because behaviours that benefit kin will necessarily contribute to the individual’s overall genetic contribution to the next generation, which is represented by the combination of the individual’s offspring and the offspring of kin.
An important feature of this behaviour is that it often does not result in a one-to-one exchange—that is, one member of a dyed (e.g., apparent) may invest more in the other member (e.g., offspring) than he or she receives in return.
The degree to which an unequal degree of exchange is tolerated should be—and appears to be in those species in which it has been empirically assessed —a direct function of degree of genetic relatedness.
Reciprocal altruism, in contrast, involves exchanges between individuals who are not necessarily kin. Most basically, reciprocal altruism involves an exchange of information, resources, or social support that is beneficial from the perspective of both parties.
The benefit of mutually cooperative behaviour is the attractive force that results in the formation and maintenance of the relationship, termed friendship by psychologists. At the same time, these benefits, like those directed toward kin, are ultimately aspects of the survival or reproductive strategies of both parties.
There are also forces that repel and thus act to disrupt individual relationships and social networks. These forces are conflicts of interest and the cost of maintaining reciprocal relationships. Even among kin, the genetic interests of two individuals, such as a parent and offspring, will differ to some degree. Conflict arises as one individual attempts to get more resources from the other than the other is willing or able to give based on their best or self-interest.
Essay # 3. Evolution, Sociality, and Development:
When survival and reproduction are intimately linked to the development and maintenance of social networks, the complexity of daily living increases considerably. Not only does the individual have to become a member of one such network, if not many such networks, the individual and the network must effectively compete or cooperate with other networks in the social ecology.
The complexity results from the increase in the number of conspecifics, the individual must come to know and maintain some form of relationship; the dynamics of the relationships among members of the network; and the politics, so to speak, of relations with other networks.
Given this, it is not surprising that across species there is a direct relation between the species’ social complexity and brain size. This finding suggests that brain and cognitive evolution have been, at least in part, a response to the complexities of social life.
A complex social life and a large brain are also associated, at least across species of primates, with a long juvenile period. Although there are several explanations for this relation, it appears that one function of the developmental period is to learn about the complexities of social life, seek a niche in the wider social ecology, and test and refine the social strategies used to gain access to and some level of control of essential resources.
The emergence of these social competencies must per force result from an interaction between genes and environment—that is, the result of an epigenetic process. Genetic constraints ensure that infants and juveniles attend to and process the appropriate forms of social information (e.g., the faces of conspecifics) and engage in species-typical social behaviours (e.g., rough-and-tumble play).
The potential for experience- driven modification of the supporting socio cognitive and emotional systems is likely, given the flux and dynamics of social relationships. Knowledge of the personality, social strategies, and so forth of other conspecifics in the local community as related to one’s own personality, social skills, and so forth cannot be genetically pre specified.
Rather, the knowledge and competencies needed to successfully compete in the local social ecology are predicted to be shaped through play, social discourse, and parental influence—activities constrained by species-typical patterns.
A long developmental period has an inherent cost, however- the risk of death before the age of reproduction. In fact, evolution will relentlessly select for a short developmental period and thus a short reproductive cycle unless the benefits of delayed maturation outweigh the risks of dying before reproducing.
One strategy for reducing the risk of premature death is to situate reproduction within a context that buffers infants and juveniles from potential threats. In many primate species this context is provided by female kin groups. These kin-based female coalitions compete to secure and retain access to the resources, such as fruit trees, that co-vary with survival prospects.
Offspring borne in coalitions that gain control of these resources are healthier and survive in greater numbers than do offspring borne in other networks. For these female-bonded primate species, the formation of stable social networks provides the context that reduces offspring mortality risks and allows for the long developmental period needed to learn the nuances of living in a complex social community, as well as other complex skills such as those involved in foraging.
The evolutionary factors underlying the relations among social complexity, the length of the developmental period, and brain size are not fully understood but are nonetheless consistent with co-evolutionary processes. In theory, slight improvements in social networking reduce mortality rates to such a degree that offspring with somewhat larger brains, more sophisticated socio cognitive competencies, and a somewhat longer developmental period survive to adulthood in sufficient numbers.
As adults, these individuals are more socially sophisticated and more likely to form effective competition-related coalitions than their faster maturing conspecifics, and they will likely have a survival and reproductive advantage, to the extent that social coalitions provide such an advantage.
Essay # 4. Evolution and Parenting:
Although Darwin identified and defined the principles of sexual selection (e.g. mate choice), he did not elaborate on the evolutionary origins of these principles. In fact, it is only recently that some level of consensus has been reached regarding the origins of intersexual choice and intra-sexual competition.
Early contemporary models of the origins of these forms of sexual selection were provided by Williams and Trivers and focused on sex differences in parental care, specifically sex differences in the relative costs and benefits of producing offspring.
Trivers formalized these relations in his model of PI and sexual selection. In this model, each individual’s overall reproductive effort is a combination of mating effort (e.g., time spent searching for mates) and parental effort, or PI. PI is any cost (e.g., time, energy) associated with raising offspring that reduces the parent’s ability to produce or invest in other offspring.
Given that some level of PI is necessary for the reproductive success of both parents, the nature of the PI provided by females and males creates the basic dynamics of sexual reproduction and sexual selection.
In Trivers’ words:
The sex whose typical parental investment is greater than that of the opposite sex will become a limiting resource for that sex. Individuals of the sex investing less will compete among themselves to breed with members of the sex investing more.
Stated somewhat differently, if one sex provides more than his or her share of PI, then members of that sex become an important reproductive resource for members of the opposite sex.
Basically, the reproductive success of members of the lower investing sex is more strongly influenced by the number of mates that can be found than by investing in the well-being of individual offspring, whereas the reproductive success of members of the higher investing sex is more strongly influenced, in most cases, by investment in offspring than in finding mates.
In this view, the dynamics of sexual selection are influenced by the ways in which each sex distributes their reproductive effort across mating and parenting, which, in turn, is influenced by a variety of factors. A full discussion of these factors is beyond the scope of this treatment, but one of these merits is briefly mentioned- the potential rate of reproduction.
Across species, it is generally the case that the sex with the higher potential rate of reproduction invests more in mating effort than in parental effort, whereas the sex with the lower rate of reproduction invests more in parental effort than in mating effort.
This is because, following mating, members of the sex with the higher potential rate of reproduction can rejoin the mating pool more quickly than can members of the opposite sex, and it is often in their reproductive best interest to do so, particularly when biparental care is not necessary for the viability of offspring.
For mammalian species, internal gestation and obligatory postpartum female care result in a slower potential rate of reproduction for females than for males. At the same time, internal gestation and the need for postnatal care have resulted in an evolved female bias toward PI and a sex difference in the benefits of seeking additional mates.
Males can benefit, reproductively, from seeking and obtaining additional mates, whereas females cannot. Thus, a sex difference in reproductive rates, combined with offspring that can be effectively reared by the female, create the potential for large female-male differences in the mix of mating and parenting efforts, and this difference is evident in 95% to 97% of mammalian species.
In these species, all of the PI is provided by females, either alone or as part of kin-based coalitions. Males, in turn, compete for access to mates or for control of the resources (e.g., territory) that females need to rear their offspring.
Constructing scientifically defensible models of human behavioural evolution is a difficult and often criticized endeavour. Nonetheless, defensible models can be constructed when evolutionary principles are judiciously combined with reverse engineering and comparative studies.
Reverse engineering involves starting with functional behavioural or cognitive patterns and from there developing models of the selection pressures that likely contributed to the evolution of these traits. The comparative method involves analyzing the relation between cross-species differences in behavioural strategies or cognitive and brain specializations and differences in ecological or social niche.
Although much is known about many of the species composing the genus Homo and the predecessor genus Australopithecus, there is controversy with respect to the classification of these species. Among these controversies are debates regarding whether variation in fossils presumed to represent a single species in fact represent two or more species, and regarding the evolutionary relatedness of various species.
Social Dynamics and Hominid Evolution:
Based on the co-variation between these variables and social and ecological differences across living primates, defensible inferences can be drawn about the nature of social dynamics in early hominids, although the associated models are not definitive. One framework for guiding these inferences is provided by contrasting likely characteristics of A. anamensis and A. afarensis with H. sapiens.
Before turning to this discussion, note that the most common alternative approach is to assume that the behavioural characteristics of the ancestor common to these australopithecine species and human beings were very similar to those observed in modern chimpanzees or bonobos.
This is a reasonable assumption in some respects. As noted, the encephalization quotient of chimpanzees, bonobos, australo-pithecines, and presumably the common ancestor are very similar. However, the sexual dimorphism in chimpanzees and bonobos represents about a 20% to 25% weight advantage for males.
Although bonobo males do not show consistent coalitional aggression, male-on-male physical aggression is common and presumably a feature of the ancestor common to chimpanzees and bonobos.
In any case, the degree of sexual dimorphism in chimpanzees and bonobos is considerably lower than that estimated for A. anamensis and A. afarensis. The contrast suggests that the reproductive strategy of male australopithecines may have differed in some respects from that of male chimpanzees or bonobos, and thus the social patterns found with chimpanzees and bonobos might not fully capture the social dynamics in australopithecines.
For reasons described next, we suggest that certain features of the social behaviour of australopithecines may have been more similar to that seen in modern gorillas than in chimpanzees or bonobos. We are not arguing that australopithecines were gorilla-like in every sense, as they clearly were not (e.g., they were bipedal).
Rather we believe that a gorilla-like model for australopithecine social dynamics provides an evolutionary launching point that more readily accommodates certain patterns of human parental behaviour, such as male parenting, and family formation than does either a chimpanzee-like or bonobo-like social structure.
At the same time, there are also similarities between human and chimpanzee behaviour, especially male coalitions, and thus arguments can be made that australopithecines also evidenced this form of social competition.
This is, of course, a possibility that cannot be ruled out. We are suggesting that an alternative be considered- Male coalitional behaviour may have evolved independently in humans and chimpanzees and may not have been an important feature of the reproductive strategy of male australopithecines.
Male-Male Competition, Social Structure and Brain Size:
The degree of sexual dimorphism in A. anamensis and A. afarensis suggests intense one-on-one male-male competition and perhaps a gorilla-like social structure. Although other social structures are, of course, possible, a gorilla-like social structure is consistent with many features of human social organization.
The modal social organization of both lowland gorillas (Gorilla gorilla gorilla) and mountain gorillas (Gorilla gorilla beringei) is single-male harems, which typically include one reproductive male, many females, and their offspring. In lowland gorillas, several of these families may occupy the same geographical region and are often in proximity, whereas in mountain gorillas they are geographically isolated.
In both cases, adult male and female gorillas often form long-term social relationships, and male gorillas, presumably due to high levels of paternity certainty associated with single-male harems, show high levels of affiliation with their offspring. “Associated males hold, cuddle, nuzzle, examine and groom infants, and infants turn to these males in times of distress”.
The reduction in the magnitude of the sexual dimorphism, combined with coalitional aggression in extant human populations, is consistent with the emergence of coalition-based male-male competition during hominid evolution, perhaps with the emergence of H. erectus.
Still, coalitional behaviour is more typical among female primates than among male primates. In these species, females are the philopatric sex—that is, the sex that stays in the birth group. Female-biased philopatry results in a degree of genetic relatedness among females that supports coalition formation when such behaviour co-varies with survival or reproductive outcomes.
For human beings, chimpanzees, bonobos, and gorillas (sometimes sons inherit the harem), philopatry is male biased, not female biased, suggesting that the male- biased philopatry has a long evolutionary history in African hominoids. Male-biased philopatry is important because it creates social conditions that can lead to the evolution of male kin-based coalitions.
Unlike female coalitions, male coalitions are focused on competition for mates rather than competition for food. As described for chimpanzees, a coalition of male hominids would have had a competitive advantage over a lone male, even a larger male.
The social demands of coalition formation and competition should have resulted in an increase in social competency and a larger brain, in theory. Not only do males have to coordinate their activities regarding in-group and out-group competition, they need to compete with members of their own in-group for social dominance.
Paternal Investment, Concealed Ovulation and Female-Female Competition:
If the social structure of A. anamensis and A. afarensis was similar to that found in gorillas, then it would be possible that there are continuities in male parenting, male-female relationships, and family structure between these australopithecines and human beings. In fact, if the social structure of these australopithecines were similar to that found in gorillas, and then the evolutionary emergence of human families would be straightforward.
Once lone males were replaced by kin-based multi-male coalitions, the males and females of these species would likely maintain the pre-existing social deep structure—a basic social organization that included one adult male, one or a few adult females, and their offspring, as well as long-term male-female relationships and male parenting.
The primary difference is that these families would be nested within the larger community rather than being geographically (mountain gorillas) or socially (lowland gorillas) separated. Lowland gorilla families are often in proximity, but they are not socially bonded together through a kin- based coalition or social network.
The emergence of male kin-based coalitions and thus multi-male, multi-female communities with many reproductive males would have resulted in an exponential increase in the complexity of social relationships relative to that evident in gorillas.
In particular, this change in social structure increases the mating opportunities of both males and females, increases the risks of cuckoldry, and thus creates a social ecology that could potentially result in the evolution of reproductive dynamics similar to that found in other mammals—a male focus on mating and a female focus on parenting. The issue is the mechanisms responsible for the maintenance of a family-focused social organization rather than the eventual evolution of the standard mammalian pattern.
We suggest that these mechanisms include concealed ovulation (where ovulation is not signalled to either the male or the female) and continuous, non-reproductive sexuality as well as pair bonding. The combination of concealed ovulation and non-reproductive sexuality is rare or perhaps unique in primates.
To be sure, a lack of estrous swelling at and around the time of ovulation also occurs in some other primates (e.g., gibbons, Hylobatidae, and marmosets, Callitrichidae), but this is not the same as concealing ovulation, which can be signaled in other ways (e.g., through pheromones).
Development:
An evolutionary increase in the complexity of male-male, male-female, and female-female relationships suggests a degree of social complexity in hominid evolution that is unique among extant primates.
The co-variation of social complexity, brain size, and the length of the developmental period in living primates is consistent with the position that the evolutionary increase in hominid brain size and the likely increases in social complexity are features of a coevolving suite of adaptations that included an increase in the length of the developmental period.
The flux and complexity of social relationships necessarily mean that only the skeletal structure of the supporting social competencies can be inherently pre specified. The fleshing out of these competencies results from an epigenetic process and a resulting adaptation of social and resource-acquisition (e.g., through hunting) strategies to the ecology of the local community.
In other words, an increasing complexity of hominid social dynamics would require a coevolving increase in brain size and cognitive competency (e.g., theory of mind) as well as a longer developmental period that would enable the acquisition of socio competitive or other (e.g., hunting) competencies appropriate to local conditions.
An increase in the length of the developmental period and corresponding changes in the complexity of social dynamics place a premium on parental behaviour that fosters and enables the developmental acquisition of socio competitive or other competencies.
From this perspective, the inclusive fitness of both males and females during hominid evolution was related to their offspring’s ability to successfully reproduce in adulthood, and this, in turn, would have favoured not only the maintenance of male parenting but also increased levels of cooperative parenting.
Menopause:
Across extant primates, a long developmental period and intensive parenting are associated with a long lifespan. One unique feature of the life history and long lifespan of women is menopause. Although there is no current consensus regarding the evolutionary function (if any) of menopause, we suggest that it is a feature of the just mentioned suite of coevolving characteristics.
Basically, menopause results in an extended period during which women can invest in the well-being of their later-born children, as part of an adaptation that enables the long-term investment in a smaller number of children and other relatives, such as grandchildren.
It allows them to focus on children they have already produced, avoiding the costs of additional pregnancies at a time when their health and the likelihood of their survival to the end of later-born children’s dependency are diminishing.
A parallel is found in many preindustrial societies today, whereby parents will often commit infanticide to reduce the risks to their older children. In other words, infanticide, as well as reduced fertility associated with suckling, enables parents to reduce the number of dependent offspring and direct more PI to older children than would otherwise be the case.
When this pattern is combined with a substantial increase in the length of the developmental period, menopause follows as a logical evolutionary adaptation that serves the same function—to reduce the number of dependent children and thus free parental resources that can be invested in a smaller number of children.
To the extent that menopause allowed more intense investment in a smaller number of children and thereby increasing the survival rate and later competitiveness of these children, it would have co-varied with reproductive outcomes and thus evolved.
One Species of Homo:
There is only a single remaining species of Homo, which is significant because many of our predecessors, such as A. afarensis and H. erectus, were ecologically well-adapted species that survived for hundreds of thousands of years.
An unresolved issue is, Why did all of these successful and well-adapted species disappear? We agree with Alexander that their disappearance is a direct consequence of the co-evolutionary processes that resulted in an unprecedented level of cognitive and social complexity in modern human beings, which, in turn, resulted in a competitive advantage over related species, such as H. erectus and H. neanderthalensis.
As noted, recent evidence suggests that H. erectus may have survived in some parts of the world until about 26,000 years ago, and Neanderthals survived in Europe until about 30,000 years ago. Fossils for both these species have been found in the same geographical areas as fossils of early modern humans, although it cannot be stated with certainty whether these species had contact with early humans.
Contact, however, is plausible, and given that the evolution of many human competencies almost certainly occurred as a result of competition with other human beings, there is no reason to believe that these competitive forces would not have been levelled against related species. Even without direct contact, the expansion and ecological dominance of early modern humans may have displaced related species and other populations of conspecifics.
Esay # 5. Evolution and Human Parental Behaviour:
The goal here is to understand the most critical evolutionary changes in social deep structure since A. anamensis and A. afarensis and to do so in a way that is plausible and parsimonious.
If we assume that the launching point was a gorilla-like social structure in A. anamensis and A. afarensis, then the evolution of current forms of human parental behaviour requires fewer evolutionary changes than if the launching point was a chimpanzee-like or bonobo-like social structure.
With a gorilla-like pattern, current patterns of human parenting and family structure, as well as long-term male- female relationships, have been a feature of the hominid social deep structure for at least 4 million years.
With a chimpanzee-like social structure, multiple evolutionary changes in a specific sequence, such as concealed ovulation evolving before male parenting, would have been necessary to create current patterns of human parental behaviour, especially male parenting and male-female pair-bonding.
A gorilla-like pattern, in turn, is similar in many respects to the polygynous and often times single-male harem social structure found in many mammalian species. The primary difference is that gorilla families are socially isolated, and thus cuckoldry risks are low, and the benefits of male parenting are increased accordingly.
In other words, a gorilla-like social structure with male parental behaviour is readily understandable within the broader range of mammalian reproductive strategies, especially if gorilla families were socially isolated.
Moving from a single-male harem to a multi-male, multi-female community required the formation of male kin- based coalitions; stable multi-male communities are not likely to evolve unless the males are genetically related. The first evolutionary step to multi-male communities would simply involve greater stability and cooperation among adult males.
Such coalitions could easily arise from a gorilla-like system, with the formation of father-son coalitions or coalitions among brothers, and the gradual increased tolerance of each other’s mating relationships. Once formed, stable groups of cooperating males could easily displace a lone male.
The transition would require only one change in hominid sociality, or social deep structure—an inherent tendency of males to form competition-related coalitions. As with chimpanzee coalitions, these early hominid communities were likely to have been characterized by coalitions of related males that defended a demarcated territory against groups of conspecific males. Unlike chimpanzee communities, the basic gorilla-like social structure—that is, families—would have been retained.
Rather than occurring before and being a necessary condition for the evolution of long-term male-female relationships and male parenting, concealed ovulation would function to maintain a gorilla-like family social structure. In fact, unlike female chimpanzees or female bonobos, female gorillas do not typically have conspicuous sexual swellings, although they often have minor swellings, and primarily solicit copulations behaviourally.
Thus, moving from a gorilla-like pattern of female sexual solicitation to the current human pattern requires fewer changes than if humans evolved from a more promiscuous chimpanzee-like or bonobo-like pattern. Still, there may have been a strengthening of male-female pair bonds during hominid evolution, for reasons we already know, to reduce cuckoldry risks and maintain male parenting in a multi-male, multi-female community.
Again, any such change would have evolved much more readily from a gorilla-like pattern of male-female relationships than from a chimpanzee-like or bonobo-like pattern, where long term male-female relationships are uncommon- Male-female relationships are common in bonobos, but these tend to be mother-son pairs, not reproductive couples.
Evolution from a gorilla-like pattern would simply require a quantitative change in the strength of the pair-bond, whereas evolution from a chimpanzee-like or bonobo-like pattern would require a more substantive and qualitative change in the nature of male-female relationships.
Moreover, it is likely that concealed ovulation, non-reproductive sexuality, and pair-bonding enabled female hominids to exert great social influence over male hominids than is currently found in gorillas and chimpanzees, where adult males dominate adult females.
Relationships among female gorillas vary from supportive grooming, which typically occurs among kin (e.g., mother- daughter), to competition over food. Relationships among hominid females were likely to have been more complex than those seen among female gorillas, given the female-female competition over male parenting and other forms of investment (e.g., protection), as well as an increasing need for social support during the long developmental period of offspring.
In fact, it has been argued that supportive relationships among females, even unrelated females, has been an important feature of hominid evolution and one that functions to provide social support during periods of stress and to assist with parenting. The result would be an important change in the social deep structure of hominids—a strengthening of the inherent tendency of females to form social networks.
In this evolutionary scenario, male parenting, long-term female-male relationships, and a basic family structure following the gorilla-like pattern may have been in place since A. anamensis. The move from a gorilla-like pattern to the current human pattern required only a few evolutionary changes, including the formation of male kin-based coalitions, a strengthening of the pair-bonds between males and females, the emergence of female bonding, and female- female competition.
Finally, as noted, Australopithecus was a well-adapted genus that exited for millions of years, and many individual australopithecine species survived for hundreds of thousands of years. This long period of relative stasis began to change with the emergence of the genus Homo, and especially with the emergence of H. erectus and later of modern humans.
In comparison to australopithecines, H. erectus is estimated to have had a substantially larger encephalization quotient, a longer developmental period, and a smaller sex difference in physical size, suggesting important shifts in the pattern and complexity of social dynamics.
Social Competition and Rapid Evolution:
The factor that ties all of the previously described evolutionary changes together, especially the very rapid changes associated with the emergence of H. sapiens, is social competition. However, the mechanisms by which social competition could have operated to produce these rapid evolutionary changes are in need of articulation.
Although it cannot be known with certainty, the general mechanism appears to be competition for social status and power and the accompanying increase in the ability to gain access to and control of the resources that co-vary with survival and reproductive outcomes, although status striving in and of itself is an insufficient explanation for many uniquely human characteristics, such as a very large brain.
This is because status striving and resource competition are not unique to human beings and, in fact, are a common feature of social life in many species. Human beings are, however, unique in that social competition occurs in the context of ecological dominance- In most ecologies, human groups have achieved a level of control over essential resources (e.g., food, use of land) that is not evident in other species.
As noted by Alexander, the ecological dominance of evolving humans diminished the effects of “extrinsic” forces of natural selection such that within-species competition became the principle “hostile force of nature” guiding the long-term evolution of behavioural capacities, traits, and tendencies, perhaps more than any other species.
In this view, once ecological dominance was achieved, the traits that began to strongly co-vary with individual differences in survival and reproductive outcomes were those that allowed hominids to socially “out manoeuvre” other hominids. These traits would include sophisticated social competencies, such as language and theory of mind; an accompanying increase in brain size; and other adaptations that facilitated the formation and maintenance of kin-based social coalitions.
The evolutionary changes associated with social competition might have been further accelerated if there were an inverse relation between the resulting individual differences in social status and mortality risks and regular but unpredictable population crashes. From this perspective, a portion of the reproductive effort is diverted from simply producing children to investment that focused on achieving social status and through this greater social power (ability to influence others) and access to essential resources (e.g., food).
Social status, in turn, enables parents to create an environment that reduces infant and child mortality risks, especially during population crashes, such as during an epidemic. In other words, social competencies and an increasing ability to exploit the ecology (e.g., through tool use) during hominid evolution reduced offspring mortality rates and resulted in temporary population increases.
Competition within and between these communities was analogous to climbing a ladder, with each step up resulting in greater access to and control of essential resources. During population crashes, those on the bottom rungs of the ladder suffered disproportionate mortality. The result would be that individuals who were toward the middle rungs of the ladder before the population crash were now toward the bottom rungs of the ladder.
In keeping with this hypothesis, in extant preindustrial populations there is an inverse relation between social status and infant and child mortality rates. The relation between infant and child mortality risks during population crashes and social status has also been extensively studied for populations in preindustrial and industrializing Europe, and again the pattern supports the prediction.
As an example, in an extensive analysis of birth, death, and demographic records from 18th-century Berlin, Schultz found a strong correlation, r = .74, between socioeconomic status (i.e., social status in industrial nations) and infant and child mortality rates.