SARS-CoV-2 is a new form of a virus that belongs to a family of viruses that share structural and genetic similarities, including the eponymous crown like spikes on the viral surface membrane. These protein spikes emerge from the lipid bilayer of the virus and perform an important role in infecting human cells.
Research indicates that viruses have existed since prehistoric times, perhaps in parallel with the evolution of animal life or even earlier. Both animals and humans can be infected by different viruses. Through a process termed Zoonotic Shift, a virus can be transmitted from an animal to a human.
For Zoonotic Shift to occur, a human must come in contact with an infected animal. Then, the virus must be able to survive in the human host and successfully enter a human cell and replicate. This often requires mutation of the virus, either randomly through many variations or more specifically to avoid the human immune system.
Research is not yet uniformly conclusive that SARS-Covid-19 virus originated in a species of the horseshoe bat in China but there is growing evidence to make the case.
The combination of humans with wildlife can be detrimental to both groups, then. Using the example of bats, we can see how these mammals, when left to their own habitat, play an important role in insect control and plant pollination. When deforestation occurs, bats and other wildlife compete for natural resources with humans and raise the potential for spreading viruses and other pathogens with human populations.
§ Ortega JT, Serrano ML, Pujol FH, Rangel HR. Role of changes in SARS-CoV-2 spike protein in the interaction with the human ACE2 receptor: An in silico analysis. EXCLI J. 2020;19:410-417. Published 2020 Mar 18. doi:10.17179/excli2020-1167
§ University of Sydney. (2018, April 4). Ancient origins of viruses discovered: New study transforms understanding of virus origins and evolution. ScienceDaily. Retrieved December 5, 2020 from www.sciencedaily.com/releases/2018/04/180404133510.htm
§ Zhu, Z., Lian, X., Su, X. et al. From SARS and MERS to COVID-19: a brief summary and comparison of severe acute respiratory infections caused by three highly pathogenic human coronaviruses. Respir Res 21, 224 (2020). https://doi.org/10.1186/s12931-020-01479-w