Darwin, known for providing a widely accepted mechanism for evolution, would be surprised to learn that this mechanism is far more complicated that just descent with modification or natural selection. The father of evolution proposes that all species share common ancestry, and they all–over the course of generations–have varied from the common ancestor through natural selection. To Darwin, humans diverged from apes due to environmental pressures. However, in the opinions of virologists and modern evolutionary biologists, humans evolved from apes due to Darwin’s theory and due to endogenous retroviruses.
Endogenous retroviruses are viruses that infect a host’s DNA and embed themselves within it. Millions of years later, the disabled, broken down viral fragments of the virus still resides in the species. The viral DNA was believed to just be junk in that they do not produce functional or harmful proteins. However, biologists now infer that there is a beneficial relationship between endogenous retroviruses and their hosts. They attribute mammalian placental development to endogenous retroviruses, and– most surprisingly –the resistance to other infectious viruses.
It seems almost ironic that an invasive pathogen can protect an organism from another, but in chimpanzees, the endogenous retrovirus Pan Troglodytes (PtERV) provides complete protection against HIV. Humans developed a mechanism to destroy PtERV when it was infectious; the protein TRIM5a. However in building up defense against PtERV, we weakened ourselves for HIV. Of course, in nature, a gain in one area always leads to a loss in another.
What this all suggests is that viruses play a crucial role in defining species. The reading tells that endogenous retroviruses are in the embryos of healthy chickens, are in the placenta of human beings, and are coding for defense against HIV in apes. Placental development due to endogenous retroviruses means that they are the reason for mammalian live births. Around the time that humans developed immunity to PtERV was when we diverged from apes. In other words, viruses are one of the reasons for why some animals are mammals: mothers are able to pass nutrients to babies due to placentas, and the elongated gestation periods caused by this ability lead to the advancement of complex motor and processing function for us. This ability, and the beneficial results, is what distinguishes us and makes us uniquely ourselves. Viruses such as PtERV suggest that the differentiation between two species is caused by them too; what may have led to the speciation of humans from apes, alongside environmental influences, could have been the development of TRIM5a in the DNA of one group (humans) and the fossilization of PtERV in the DNA of another (chimps). After reading this article, my ominous view of viruses has taken a slightly more optimistic lens. We may owe our humanity to viruses.
Viruses are very crucial to understand, seeing as how they are both killers and evolutionary helpers. Reviving ancestral endogenous retroviruses for the sake of understanding how modern viruses work is kin to the common adage: “to understand the present, you must understand the past.” The findings from viral revival, like Thierry Heidmann’s which shed light on how viruses embed themselves in DNA, gives details to the obscure painting of virtual operations and origin. However, heavy precaution and monitoring should be taken in these resurrections. In my opinion, the test subjects receiving these reconstructed viruses should align with ethics, and barriers should be put in place to make reviving these deadly viruses less accessible to just anyone. Some may view the ability of science to bring a dead thing back to life as freakish. I don’t exactly align with this point of view because viruses are not considered living organisms in the first place. Yet, that does not override the fact that viruses are powerful entities that are able to eradicate whole populations. I was alarmed to read that “Thanks to the steady advances in computing power and DNA technology, a talented undergraduate with a decent laptop and access to any university biology lab can assemble a virus with ease” (Specter, 66). The replication of diseases should not be easy. It gives allowance for people to use the revival corruptly rather than for scientific advancement. Knowledge, like any super power, comes with responsibility and depends on an ethically sound individual. And therefore, knowing how to build or rebuild a virus should be information reserved for dedicated experts and researchers, not for any ol’ student still working towards Bachelor’s degree!