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I think a lot of folks miss the point that gene theory and evolution theory can exist independently of each other and that an understanding of genes is not a pr
by LarsDu88 2y ago
I think a lot of folks miss the point that gene theory and evolution theory can exist independently of each other and that an understanding of genes is not a prerequisite for the understanding of evolution.
When Darwin's theory of evolution by natural selection came out, it was sensible from the perspective of animal breeding. It did not explain how new variation came about, but the fossil record alone in the mid 19th century was sufficient evidence for most educated people to undeniably understand that new variation did occur over time. For reference, the first complete Archaeopteryx fossil was discovered in 1861.
It is only today with hindsight, Mendel's gene theory, and molecular evidence from electron microscopy that the whole picture is pretty clear. Variation over (really long periods of time) comes from mutation, and natural selection is only one of four major mechanisms that alters gene frequencies in a population.
The four are mutation, natural selection, genetic drift, and migration.
- bubblyworld 2y agoRight, you can understand them independently, but of course in reality they are intimately linked. For instance, isn't genetic drift just a consequence of mutation and natural selection? Neutral mutations with weak selection pressure will tend to build up in a population over time.
- LarsDu88 2y agoGenetic drift is not actually a consequence of mutation and natural selection. Hypothetically, if there was some sort of alien planet where the living inhabitants reproduced and used a replication system that doesn't undergo mutation and has no positive or negative natural selection, there would still be genetic drift and you would still observe changes in the allele frequencies of the population over time, and in small populations, genetic variation could slowly disappear...
- bubblyworld 2y agoAh, if I understand you correctly, you're actually saying that genetic drift is not _only_ a consequence of mutation/selection, right? Because of course allele frequencies change in a population just from meiosis. (I'm not sure your hypothetical is valid though - where would the variation in alleles have come from in the first place without mutation/selection?)
- LarsDu88 2y agoSince this is hypothetical... a wizard did it... You're right though. The initial allelic variation would have to come from mutation, a wizard doing genetic engineering, or some sort of weird alien mechanism that actively creates allelic variation.