Social speciation and genetic speciation in human evolution

27 Dec

A preliminary discussion of Species and Speciation in how modern humans emerged from ancestral species was discussed here: https://dispersalofhumanityfromhomoegaster.wordpress.com/2012/07/28/species-and-speciation-in-human-evolution/
It was stated that:

The intractable problem of speciation in evolutionary biology may be addressed as follows: should populations be defined as distinct species specifically in relation to the degree of speciation that will prevent the reproductional fusion of gametes for embryogenesis to a viable foetus, or should speciation be defined in terms of phenotypic parameters that takes into account morphological, physiological, biochemical and behavioural separations to the point that incompatiblity between representative samples of male and female from being able to engage in sexual intercourse can be established whether or not mating between fertile and healthy individuals can demonstrably result in a successful offspring that, in turn, was able to pass on its own genes to another generation.

Speciation is entirely defined by the genetics of incompatibility that develops between populations through different types of DNA mutations affecting the phenotype. The mechanism of speciation in Homo lineage may be as follows: Minor DNA mutations on sexually-functional genes can produce attractional features that are stimulated by complimentary traits in the opposite sex. Sexually compatible features are selected for reproductive behaviour and over time spreads in the population. The process complimentary features is reinforcing and intensifies leading to the formation of a separate social group within the population. This population will continue to diverge away with mutations in other traits and gene development as the population adapts to the environment as well. If the process of group formation through such sexual selection is incomplete the social subgroup may still have individuals that readily mate with the parent population. But the process of group formation continues. This is social speciation and can be said to be complete when 100 percent of the subppulation shows a preference in its reproductive behaviour for its own phenotype. Even when social speciation is complete artificial insemination between the subgroup and the main population will show reproductive compatibility as far as fertilisation, embryogenesis and the generation of a viable and fertile offspring is concerned.

As the subgroup develops social cohesion in mating behaviour one or more Robertsonian translocation or choromosome fusion mutation may occur spontaneously and spread through the subgroup to produce genetic incompatibility with the parent population in fertilisation, embryogenesis and the generation of a viable and fertile offspring. This is the point at which the combination of social speciation and genetic speciation has caused total incompatibility, and a new species has resulted. The process involves degrees of genetic reinforcement of social speciation that first coalesces into minor changes in subgroup behaviour, which is then gradually transformed into a cultural separation, followed by the genetic development of ethicities, and then races; these representing degrees of social speciation within populations that is distinguished from the extent of within-group mating behaviour. Upon this sequence of social speciation a single or more Robertsonian translocation or major chromosomal fusion may occasionally act to make the process of genetic speciation irreversible by disrupting genetic compatibility in fertilisation whence a new species can be said to have arisen.

The dynamics is that as a sub-group forms as a clan to begin with and proves itself to be successful in its ghetto it will displace the other groups out of the ghetto to the surrounding areas. The process of culturisation intensifies as the group spreads as its size increases and intensifies genetically into ethnicity and finally race. The social structures that work against interethnic breeding are subconscious restriction of mating behaviour. This means that from a position of small group with only behavioural differences, within-group mating starts to take place; when this reaches the proportions that results in culture to give this group its identity, say 30 per cent of this sub-group will not mate outside the group; when the group reaches the proportions of identity for which the a the term ‘ethnicity’ is applicable it will mean say 60 per cent will not mate outside the group; and when it reaches the proportions for which the term ‘race’ can be applied 90 percent of the subgroup will have the tendency to only mate within itself. That is how social speciation intensifies given all other things are equal (which it is not in the real world so that other developments in the ecological niches cloud this fundamental model of social speciation in Homo sapiens.

The process of social speciation would lead to subgroups forming in which geography, climate and food resources would be the major influences that would limit group size in an ecological niche. If resources are limitless the population will grow and expand into other territories. At the margins of ecological niches there would be evolutionary pressures to generate their own different subgroups. Whether these materialise or not would depend on whether the subgroups are viable entities. The two would develop into separate ethnicities and races with intermingling of subgroups at the boundaries of the niches. This has been the process for the past 15,000 years after the colonisation of the world was complete and populations could not transgress into other ecological zones which were already occupied by other groups. The ethnicities and races in Europe, in Africa, in South Asia, South East Asia, China and the Americas show this pattern of the development of humanity.

The current racial groups were in their geographical places of endemism 15,000 years ago and they are supposed to have arisen from an out of Africa population 80,000 years ago. So that is how long social speciation takes place. Total genetic speciation is a chance process and has not occurred since Homo ergaster was around 2 million years ago as far as I understand the data. Let us take an example of an sizeable island within which populations developed: the British Mainland. It is a geographical area with only minor mountains so people could travel about quite freely. It had and very similar climate everywhere except for the north Scotland which was slightly colder and a little wetter. It became populated only 10,000 years ago since the last Ice Age. One would expect that all of the island was occupied by humans fairly rapidly as a single migration arrived from Europe. Yet in this short space of time, we have Scottish, Welsh, Geordie, Brummies, Scouse, Cockneys, Cornish, and English (Anglians) that developed as more than cultures: ethnicities. That is how fast social speciation can take place in a small area.

Living is societies in various ways as communities, ethnicities, nations, or religious groupings enabled humans to propagate themselves (some groups more effectively than others as one would expect evolution to take place) such that humans eventually colonised the entire world in distinct groups.

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2 Responses to “Social speciation and genetic speciation in human evolution”

  1. Koza September 3, 2013 at 8:01 am #

    “One would expect that all of the island was occupied by humans fairly rapidly as a single migration arrived from Europe”

    What “one would expect” is rather secondary when its contradicted by actual, well-known history. There were several major and many minor waves of migration to Britain in the last 2-3 millennia alone: The La Tène culture (commonly identified with the Celts) around 400BC, The Angles, Saxons and Jutes in the 5th century AD, and the Norse (look up “Danelaw” and “Scandinavian Scotland” on Wikipedia for a head start) among the major ones.

    • shantanup September 3, 2013 at 8:29 am #

      Koza,
      The question that needs to be addressed is when did the British Isles receive its first major wave of immigrants following the melting of the ice during the last Ice Age some 8000 years ago. The evidence of Stonehenge indicates that this must have taken place at least 5000 years ago. All subsequent migrations that you mention were absorbed into the existing populations until each area of the British isles became saturated to the point of not being able to absorb any more immigrants given the food resources (holding capacity of the land). This is when social speciation starts to take place and has happened continuing on to the modern times to generate the ethnicities that I have mentioned.

      I would dispute that there apart from the first slow occupation of the British Isles there were ever any further major immigrations of a people belonging to a single culture. You would need to define the term major in this respect also. There were just not the populations in Europe mainland to come in to UK by sea in a major ingress of peoples. All immigrations were slow and were absorbed by the existing cultures and over time created the ethnicities that we call Celts, Angles, Saxons, Romans etc.

      Shantanu

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