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FOR READERS/WRITERS: Seeding Humanity

FOR READERS/WRITERS

Today’s topic comes from QSFer Ben Brock:

Some sci fi writers explain the similarities of humans to other alien races as “seeding”, as in an ancient race went through the universe and “seeded” the worlds with human-like DNA. Writers, have you ever used this idea in your work? Readers, what are your favorite stories that use this idea?

Writers: This is a reader/writer chat – you are welcome to share your own book/link, as long as it fits the chat, but please do so as part of a discussion about the topic.

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1 thought on “FOR READERS/WRITERS: Seeding Humanity”

  1. For me, as a science fiction author, I use Homoplasy. This includes parallel and convergent evolution. Similarity of appearance in unrelated or distantly-related organisms is often the result of similar evolutionary pathways under similar environmental conditions.

    Sometimes evolutionary change follows a common pathway in two or more unrelated or distantly-related organisms because of similar environmental pressures. It culminates in unrelated organisms with similar morphological characteristics even though they did not have a common ancestor. This phenomenon is called parallel evolution. There are many examples of parallel evolution in plants, including distantly-related plant families that have evolved from an autotrophic to a parasitic mode of existence. Some plants have evolved independently into a mycotrophic mode of existence where they obtain nutrients from mycorrhizal soil fungi, which in turn, are parasitic on the roots of nearby forest trees and shrubs. Photosynthetic pathways, such as CAM (crassulacean acid metabolism) and C-4 photosynthesis, have also evolved independently in distantly-related plant families.

    When parallel evolution under similar environmental conditions in distantly-related organisms results in plants and animals that are morphologically very similar in overall appearance, this is called convergent evolution. It should be noted here that some authors use these two terms interchangeably. North American cactuses (family Cactaceae) and South African euphorbias (family Euphorbiaceae) belong to different plant families and are distant relatives in the phylogeny of flowering plants; however, they both have succulent, thick stems that store water, they both have spines for protection, and the both are adapted for survival in arid desert regions with low rainfall. Without flowers, some African euphorbias are practically indistinguishable from their North American counterparts.

    I prefer to use the terms homology and homoplasy when discussing the evolution of similar characteristics in my ‘alien’ characters. Homology refers to similarity due to a common ancestor. Characteristics derived from a common ancestor are termed homologous. Homologous organs are similar in structure and embryonic origin but are not necessarily similar in function. Cactus spines are homologous to bud scales of an axillary bud. Seed-bearing carpels of flowering plants are homologous to leaves because of their similarity in form, anatomy and development. The bone structure in the wings of a bat is homologous to the forelimbs of humans and other mammals. For example, a bat’s wing and whale’s flipper both originated from the forelimbs of early mammalian ancestors, but they have undergone different evolutionary modification to perform radically different tasks of flying and swimming. The presence of homology is evidence that organisms are related.

    Homoplasy is a characteristic shared by members of a phylogenetic tree (cladogram), but not present in their nearest common ancestor. It arises independently by convergent evolution in more than one clade. For example, both mammals and birds are able to maintain a high constant body temperature (warm-blooded). However, the ancestors of each group did not share this character, so it must have evolved independently. Mammals and birds should not be grouped together on the basis of whether they are warm-blooded.

    Nature finds a trait that works, (she) tends to replicate it over and over again …

    Hope that makes sense.

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