Nonlinear Hiccups

Darwin’s proposed mechanism for evolution was fairly linear, with convergent evolution and shared ancestry as the reasoning for similarities between species. But he might be surprised to learn that descending from a virus does not necessarily only refer to an evolution from virus to human, but the evolutionary change that humans have undergone due to endogenous retroviruses. This sequence of events, while not exactly as linear as Darwin might have imagined, might not actually have been that surprising to him. In basic terms, endogenous retroviruses are factors that caused genetic and then phenotypic change, which then can be acted on by the environment and perpetuated if advantageous. This is exactly what Darwin hypothesized, and, in fact, to him the most surprising thing about the article would probably be that it exists on the internet!

The only hiccup in aligning the article with Darwin’s theories comes with the mechanism for change. Rather than a mutation caused by the organism itself, the endogenous retroviruses were once completely separate viral entities that found themselves in germ cells, and happened to exist in some form in a viable embryo. With the knowledge of his time, Darwin would have had no reason to suspect that such an occurrence was possible, nor that “broken and disabled retroviruses” (Specter, 2007) would account for eight per cent of the human genome.

Eight per cent is a massive amount for such a seemingly unlikely occurrence (the article describes it as “rare” and “rarer still” (Specter, 2007)), and it provides convincing evidence for what I considered the most interesting point of the article. Endogenous retroviruses are not only tolerated in the human genome, but crucial as agents for genetic change and diversity. As counter-intuitive as it may sound, without viruses we would not be humans as we know them today.

The research associated with this discovery could lead to magnificent insights, but not without raising some eyebrows. Even though a virus is “assembled in such a way that it could reproduce only once” (Specter, 2007), there is still an element of risk associated with the unknown of extremely old viruses. If something did happen to go wrong in a lab and such a virus were to escape, it could unleash pandemonium on the modern world. But, following the current amount of precautions and success, the possible benefits of reconstructing the past should offer enough of an incentive to keep interest and funding alive.

This entry was posted in AP Biology, Evolution, Viruses. Bookmark the permalink.

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