Cultural evolution and human adaptation in Darwinian theory

Cultural and Climate Effects on Human Evolution

Cultural group selection's contribution to the progression of cooperation among humans is intensely contested. A majority of human behavior impacted by culturally diffused philosophies (including religious views) does not seem adaptively sensible. Whether or not strong socio-biological reasons are available for explaining such behavior marks the focal point of arguments between sociologists and critics of sociology. There are, in theory as well as (possibly) in fact, several instances, which combine aspects of both. Evolution in the cultural context, by adopting Darwin's model, is portrayed as a process of inheritance co-evolving with genes. Adaptive qualities as well as series processes are displayed, resulting in maladaptive deviation (Richerson and Robert 195). This paper's primary objective is employment of new analytical strategies that utilize the current scientific base, thus allowing rigorous testing of the manner in which mankind's evolution and species' adaptability is influenced by culture and climatic variations.

Cultural change

One has firm cause to believe that cultural change is significantly influenced by a transformation hereditarily passed-on tendencies, and that such tendencies usually lead to highly adaptive activities. Evolved tendencies, however, do not appreciably impact some categories of beliefs, which may strongly shape behavior. For instance, religious views are thoroughly formed to be tough to dispute based on empirical experience. The belief in punishment and rewards in the afterlife may, to a great degree, impact behavior of those having rather utilitarian evolved aims. When beliefs crop up which are hard to assess through evolved tendencies, activities like those that group selection based on cultural variance may prove strong. At times, behavioral patterns which could not be foreseen without considering evolutionary cultural properties can stem from these 'non-social biological' influences. 'Population genetics' applied to cultural change is deemed receptive to human sociobiology, and vital to a comprehensive Darwinian human behavior philosophy (Richerson and Robert 197).

When cultural background is assumed as given, one can still justify behavioral change in terms of the common Darwinian ideology. As behavior develops out of an interaction between culturally-learnt principles and an aim to meet evolved goals, cultural behavioral change may be justified with regard to these goals. Across the vast period of time in which hominids have evolved, there must have been an impact of cultural evolution on the predispositions that changed (Richerson and Robert 197). Homo-sapiens are highly skilled in the utilization of social learning or culture for obtaining adaptive information. A majority of psychological frameworks have evolved as a response to both limitations and possibilities presented by cultural inheritance idiosyncrasies. The offspring of hereditarily evolved tendencies may probably have appeared in the history of hominid evolution taking into consideration evolutionary cultural variables. Firstly, the paper will appraise the stance of socio-biologists regarding shaping of human culture via evolved, genetically transferred tendencies. Subsequently, impact of other processes on cultural change in a specific context -- the conviction that good deeds will be rewarded in the hereafter -- and the subsequent effect of this conviction on individuals 'effort to meet evolved goals, will be weighed up. Lastly, an argument will follow, that the notions displayed in the given instance can be generalized to a number of other examples of the interplay between evolved tendencies and cultural change. Key cultural alterations can take place in a rather short interval and significant cultural gaps are retained among adjoining groups of humans in spite of extensive gene transfer. To accept that homo-sapiens have had quite comparable hereditarily-evolved tendencies in the past several thousand years is not a difficult thing. Cultural change among modern man has been governed and guided by evolved tendencies, in this notion. As per this ideology, individuals are critical in their acquisition of outlooks, views, and principles describing those around them (Richerson and Robert 198).

On the whole, experts, who are of the opinion that cultural variances denote adaptation (playing a part in this issue), contend that behavior corresponds to eco-topical situations that were encountered by Pleistocene food hunters. As per this approach, some cultural change might be adaptive, since the related environmental aspects have remained fairly unaltered. A great deal of behavior will not be fitness-maximizing in present conditions, since the environment enforced by industry and farming, in accordance with cultural evolution, depicts a life that is poles apart from that of food foragers. Key cultural alterations took place in a rather short duration of time, and significant cultural disparities remained among adjoining groups of people in spite of significant gene transfer (Richerson and Robert 199).

The phenomenon of evolution has armed humans with psychological devices that make them inclined to develop mindsets, opinions, and principles that are either currently fitness-improving or, during the time of Pleistocene food hunters, were fitness enhancers. A majority of socio-biologists will likely be in agreement on these mechanisms' fundamental nature. Following evolution, individuals are afraid of death, escape discomfort and starvation, and value societal approval and gratification of their sexual needs. Using numerous mechanisms, individuals strove to appraise substitute mindsets, opinions, and principles and espouse the variants which best fulfill these hereditary goals, as assessed by hereditary cognitive abilities. Individuals may develop secondary cognitive abilities and cultural temperaments; however, the basic genetic ones predominantly shape cultural evolution's trajectory (Richerson and Robert 199; Nunn 37).

The unchanging evolved tendency theorized by socio-biologists resulted in cultural variation, as they twist cultural change in various directions and environments. The attitudes, beliefs, and principles that triggered reproductive triumph can vary vastly in varying environments. Highly divergent types of survival skills and related organizations were portrayed by traditional African communities dwelling in wet tropical highlands and savannah regions. Socially aware conformism and sedentary cultivation appeared to be successful in densely-populated, fertile highlands, whereas the savannah region depicted fierce individuality and nomadic pastoralism. In both of the above examples, the contention is that individuals are capable of evaluating the attitudes and beliefs which may generate success in any given environment, and subsequently tend to implement those attitudes and beliefs. The notion of evolved aspects of culture impacting cultural change enables socio-biologists to make certain generalizations while predicting human behavior. Such a task may appear simple to those who regard cultural change to be currently adaptive; principles and ideas prevailing in a certain culture must maximize reproductive achievement in the imminent environment (Richerson and Robert 203).

With weakening of evolved aims' impact on cultural evolution, culture progressively turns similar to a mechanism of inheritance. The major portion of a person's behavior is an outcome of social attitudes, opinions, skills, and ethical values learned from a group of other individuals via social learning. One needs to be familiar with an individual's cultural background for predicting their behavior; but this does not indicate insignificance of evolved tendencies underlining individual learning. In fact, without these, cultural change would become detached from hereditary evolution, thereby providing no fitness-enhancing benefits that were possibly responsible for furthering evolution of cultural capacities. Cultural elements are assimilated by imitation; evolved goals have a weak effect on them. From the above deliberation, it is understood that one can only grasp a particular culture by considering the characteristics of its population (Richerson and Robert 205).

Cultural features witnessed in any society, such as genetic makeup noticed in a given population, represent the long-run outcome of the repetitive work of evolutionary influences and diffusion patterns. Individual preferences will likely increase the incidence of attitudes and beliefs serving evolved aims. But when evolved aims' impact becomes feeble, there is a greater possibility of other mechanisms, at the population level, becoming more instrumental. An example of such a mechanism is group selection affecting cultural change. These mechanisms may or may not aid evolved aims. Cultural change as viewed from a methodologically Darwinian perspective relays that there exists a co-evolutionary link between genetic and cultural evolution (Richerson and Robert 206; Facchini 53).

The most intriguing examples of co-evolutionary frameworks are characterized by the trajectory of change of either of a duo of species being incomprehensible unless the other's evolutionary trajectory is taken into account. For instance, poisonous-plant compounds' evolution cannot be understood unless one looks at insects' progressing ability of detoxification of these compounds; likewise, the evolution of insects' detoxification system is incomprehensible until one considers toxin evolution of poisonous plant species. There is an evolutionary link between cultural and genetic change, in two discrete senses. The types of genetic constitutions natural selection prefers will be dependent on the types of cultural variations that typify populations. It is not possible for one to comprehend cultural evolution without knowledge of the essence of hereditary predispositions that impact cultural attributes that are assimilated. Cultural adaptations whose progression is principally governed by evolved tendencies evolve along with those whose progression is principally governed by non-socio-biological mechanisms (Richerson and Robert 210).

For instance, in the cultural evolution contexts, unreasonable fashion extremes in clothing can be reversed or constrained by reverting to clothing trends that are economical, serviceable, and comfortable. Evolved goals powerfully affect evolution of a number of cultural attributes, which will evolve in almost the same manner as though influenced by natural selection; there will be increased incidence of variants that best fulfill evolved aims. Nevertheless, the types of adaptations viewed as fulfilling evolved aims will hinge on several other cultural characteristics; this includes those evolving under non-socio-biological mechanisms' impact (which might not enhance frequency of characteristics meeting evolved aims). From a cultural standpoint, genes are disciplined with the assistance of a cultural entity that is group-favored. But the genetic approach perceives the selfish genes to have only exploited their tether on cultural change to devise an effective system for policing abroad, all-encompassing reciprocal altruism framework. The evolution of man portrayed in the work in question as an open Darwinian revision to conventional socio-biological premises reveals all regarding cultural change. To the authors' dismay, bewilderment, and chagrin, some readers have taken it as suggesting that cultural change mechanisms are dissociated from genetic evolution. According to Alexander (1939 79), the work argues that their distinct inheritance modes result in a disengagement of culture and genetics (Richerson and Robert 212).

Climate and the Evolutionary Histories of Homo sapiens and Neanderthals

Doubts persist concerning the potential impact of regional climatic differences on Homo neanderthalensis' and Homo sapiens' evolution. The latter were first seen in Africa, during the onset of Marine Isotope Stage 6 (MIS 6). Europe was the place of origin of Neanderthals; they surfaced in the exceedingly cold climates of the mid- Pleistocene epoch, and continued existing there throughout the course of the rapidly transforming glacial as well as interglacial periods. All species possess typical, unique anatomies, which can be surmised as variations based on environmental conditions -- Neanderthals had lesser height, shorter forearms and stronger limb bones, akin to modern-day Inuit and other populations of harsh, cold climates; modern man's skeleton, on the other hand, has slenderer, longer limbs suggesting an adaptation for warmer climates. Homo-sapiens ultimately spread out all over the planet, while the Neanderthal population declined and finally became extinct approximately 28 thousand years ago. While the argument that the environment was a contributory factor in generating and controlling adaptive dissimilarities between the above two species is endorsed, causative relationships between species anatomy and climatic events are yet to be established (National Academy of Sciences 11-12).

Bipedality and Vegetation Changes

It has been assumed for long that hominins transformed into bipeds because of climatically regulated African grassland expansion. This theory, however, has been contested as more hominin fossils, discovered in the last 15 years, have been located along with fauna atypical of grasslands. African grassland expansion in the last three million years has been employed for suggesting causation for several human evolution phenomena, including bipedalism's onset (and therefore, the first hominins), as well as megadont molars' development, Homo erectus' origins, and the initiation of two distinct lineages of hominins. The latter researchers indicated that, at the time of arrival of Paranthropus and Homo, there was vegetation that is more open and trees were fewer; this was prompted by drier and cooler climate regimes in Africa. Also, grassland habitats proved to be instrumental in further speciation phenomena for both groups. In the last five million years, African grassland habitats extended and contracted; the extent of these events' effect on human evolution is yet unknown (National Academy of Sciences 12).

Despite experts in the field frequently aiming to establish causative and temporal relationships between evolutionary and climatic events, the mechanisms underlying the linkages among them are not fully established. The processes have developed over protracted time periods, and not instantaneously, as is usually cited in other areas of science for establishing correlation. Nonetheless, geological and fossil records of previous climates may be combined and utilized for persuasively proving that interactions of organisms with earth system played a role in species evolution on the planet in the last many billions of years (Ga) (National Academy of Sciences 12-13).

Ecological influences like predation, disease, and competition among organisms function in all ecosystems; these interactions prove highly influential on species' evolutionary history. These interactions may be (but are not essentially) strongly governed by climate conditions with resulting habitat features. Therefore, comprehensive climatic research may provide an important context for comprehending evolution. For instance, animals that prey upon others in the grassland ecosystem have capturing tactics different from predators in rain forests. These ecological behaviors that may be recognized fossil accounts prove to be crucial ties, which facilitate testing of potential climatic impacts on organisms' evolution (National Academy of Sciences 13-14; Flinn 27).

Climate variation in the Neogene epoch is displayed on different timescales; each of these may have held some significance in the process of hominin evolution. In the longest periods, climatic trends over several million years (global cooling and polar ice-sheet development) set the scene for overall hominin evolution. In shorter spans, Earth orbital systems were imperative to regulating African aridification cycles, which may have affected hominin adaptation, diffusion, and local availability of water resources. At shorter and millennial spans, sudden climatic events may have affected distinct hominin groups' demography, population distribution near water resources and local extinctions (National Academy of Sciences 24-25; Bruxelles & Jarry 538).

Conclusion

The conception that wide-ranging climatic shifts or variability changed land ecosystems, which, subsequently, posed distinct speciation or adaptive pressures causing genetic innovation and selection is a common idea to all theories that associate climate evolution with faunal evolution. This approach maintains that the evolutionary stages of greatest significance, i.e., the behavioral and evolutionary changes, central in the shaping of present-day man -- were all related to some element of paleo-environmental evolution. As has been noted, the possibility of environmental evolution having a minor influence on evolution must also be taken into account, as aspects like gene mutation, social interaction, and resource competition were operating under all climatic conditions; hence, they may have had a bearing on evolution, separate from specific ecological transitions. Even in the event that this happened, extinction or evolutionary success are dependent on the reduction or increase of a group and its specific way of living, which are inexorably impacted by sudden or extensive changes in ecological conditions. Thus, based on well-tested evolutionary biological ideas, ecological variables prove instrumental in affecting all organisms' geographic spread and adaptations, and are assumed to have played a part in directing human evolution's course, success and subsequent extinction of previous hominin species, as well as, eventually, our own influence and existence.