infectious diseases that had haunted humanity for hundreds of years if not more
(Rivers 1937; King 1952). The origin and transmission of diseases such as smallpox,
influenza, yellow fever, Ebola, and other mostly zoonotic diseases were mysteries to
physicians, nurses, and the general public. Only the development of molecular
methods in the late 1980s allowed us to determine their presence in infected patients
and determine their natural reservoirs in the living and non-living environment
(Lipkin and Firth 2013).
Regarding structure and genetic makeup, viruses are the most primitive agents on
our planet that contain genetic information and can reproduce, not considering
viroids and other sub-viral agents that lack structure, such as a protective protein
coat or envelope. Nevertheless, the more we learn about them, their diversity and
their ability to evolve and adapt to different environments, viruses appear to be very
sophisticated and not primitive regarding survival in different environments by not
depending on metabolism that might limit their distribution. These agents and their
ancestors have been the most successful entities that ever evolved and thrived on our
planet for ~4 billions of years and should therefore be considered as part of the
foundation stone of the biosphere which have survived while many highly evolved
eukaryotic species are long extinct (Darroch et al. 2018; Dasgupta et al. 2019). Even
though it is debated if viruses are alive (Moreira and López-García 2009; Boyer et al.
2010; Hegde et al. 2009; Forterre 2010), their impact on prokaryotic and eukaryotic
diversity and survival has been recognized (Sullivan et al. 2017). Should environmental disaster wipe out life on our planet completely, it can rise again by using
information stored in prokaryotes and viruses, just giving them time . . . .. but “time
is an illusion” (quote: Albert Einstein).
Let’s have a closer look at what is currently believed about the origin, evolution,
structure, diversity, and impact of viruses on other organisms and how that helps us
to understand the impact viruses have on Life on Earth, meaning why they should be
considered as a foundation stone of the biosphere?
28.2 Origin of Viruses
The origin of viruses is a mystery, but several theories exist that try to explain how
viruses came into existence.
Panspermia
Hypothesis,
also
Referred
to
as
the
Hoyle–
Wickramasinghe Model We know that Earth has been bombarded with comets,
ateroids, and meteors bringing most of the water that filled our oceans for a long time
(Chyba 1987), and Earth still receives material from outer space supported by strong
solar winds that reach our planet (Hawkins 1964; Parkin and Tilles 1968; Brook
et al. 2000). The origins of this theory date back to the ancient Greeks; the Greek
philosopher Anaxagoras (500–428 BCE) asserted that seeds of life might be present
in the entire universe (Temple 2007). Most modern researches are reluctant to accept
this hypothesis, which was also proposed by William Thomson, known as Lord
28 Viruses, Underestimated Drivers of Ecology and Evolution of Life
615
(Rivers 1937; King 1952). The origin and transmission of diseases such as smallpox,
influenza, yellow fever, Ebola, and other mostly zoonotic diseases were mysteries to
physicians, nurses, and the general public. Only the development of molecular
methods in the late 1980s allowed us to determine their presence in infected patients
and determine their natural reservoirs in the living and non-living environment
(Lipkin and Firth 2013).
Regarding structure and genetic makeup, viruses are the most primitive agents on
our planet that contain genetic information and can reproduce, not considering
viroids and other sub-viral agents that lack structure, such as a protective protein
coat or envelope. Nevertheless, the more we learn about them, their diversity and
their ability to evolve and adapt to different environments, viruses appear to be very
sophisticated and not primitive regarding survival in different environments by not
depending on metabolism that might limit their distribution. These agents and their
ancestors have been the most successful entities that ever evolved and thrived on our
planet for ~4 billions of years and should therefore be considered as part of the
foundation stone of the biosphere which have survived while many highly evolved
eukaryotic species are long extinct (Darroch et al. 2018; Dasgupta et al. 2019). Even
though it is debated if viruses are alive (Moreira and López-García 2009; Boyer et al.
2010; Hegde et al. 2009; Forterre 2010), their impact on prokaryotic and eukaryotic
diversity and survival has been recognized (Sullivan et al. 2017). Should environmental disaster wipe out life on our planet completely, it can rise again by using
information stored in prokaryotes and viruses, just giving them time . . . .. but “time
is an illusion” (quote: Albert Einstein).
Let’s have a closer look at what is currently believed about the origin, evolution,
structure, diversity, and impact of viruses on other organisms and how that helps us
to understand the impact viruses have on Life on Earth, meaning why they should be
considered as a foundation stone of the biosphere?
28.2 Origin of Viruses
The origin of viruses is a mystery, but several theories exist that try to explain how
viruses came into existence.
Panspermia
Hypothesis,
also
Referred
to
as
the
Hoyle–
Wickramasinghe Model We know that Earth has been bombarded with comets,
ateroids, and meteors bringing most of the water that filled our oceans for a long time
(Chyba 1987), and Earth still receives material from outer space supported by strong
solar winds that reach our planet (Hawkins 1964; Parkin and Tilles 1968; Brook
et al. 2000). The origins of this theory date back to the ancient Greeks; the Greek
philosopher Anaxagoras (500–428 BCE) asserted that seeds of life might be present
in the entire universe (Temple 2007). Most modern researches are reluctant to accept
this hypothesis, which was also proposed by William Thomson, known as Lord
28 Viruses, Underestimated Drivers of Ecology and Evolution of Life
615