The ancestor of SARS-CoV-2’s Wuhan strain was circulating in late October 2019

Using a new approach
Conventional methods have not produced a reliable history of the emergence of this virus for several reasons. These include the numerous widespread sequencing errors in the available sequences, small degree of sequence divergence, and the fact that there are few sites that help to understand the descent of the virus.

Especially remarkable is the fact that all known early SARS-CoV-2 genomes from humans (up to January 2020) vary by less than 30 bases. Conversely, the most closely related non-human coronaviruses differ by over a thousand bases.

The importance of this is that “Without a reliable root of the SARS‐CoV‐2 phylogeny, the most recent ancestor sequence cannot be accurately reconstructed, and it is not possible to assess the genetic diversity of SARS‐CoV‐2 that existed at the time of its first outbreak.”
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