therefore the composition of the microbiota. I am not aware of any studies that
address this issue, which remains a speculation.
18.5 Is the Microbiota of the Natural World Still
“Natural”?
Can we benefit from our evolved dependence on the microbiota of the natural
environment if that microbiota is not natural anymore? The influence of mankind
on the biosphere has been massive. The issue of the effects of industrial and
agricultural pollution, including antibiotics, herbicides, insecticides, other agrochemicals, plastics, and monoculture has been reviewed elsewhere (Flandroy et al.
2018; Jin et al. 2017; Hallmann et al. 2017), though it is worth pointing out that
glyphosate was identified as a microbicide before it was found to be a useful
herbicide (Abraham and Monsanto Technology LLC 2010), and glyphosate was
recently detected in the urine of more than 90% of a cohort of pregnant American
women, so it is now ubiquitous (Parvez et al. 2018). We do not know whether this
matters or not.
Rather than expanding on the issue of chemical damage, I will mention two other
interrelated microbially relevant issues. First, we are rapidly replacing the naturally
evolved biomass of our planet. At least 90% of mammal biomass is now human or
domesticated livestock. Similarly the chicken, first domesticated around 8000 years
ago, is now the most numerous terrestrial vertebrate, and at least 70% of all bird
biomass is now domesticated poultry (Bar-On et al. 2018). This replacement of
vertebrates with chickens, humans, and livestock also changes the faecal matter
deposited on the planet. The production of faeces from all cattle, sheep, goats, pigs,
and chickens has been estimated at about 14 Â 10
12 kg/year (Waltner-Toews 2013).
Individual humans produce about 145 kg of faeces each year, so the human
population of about 7 billion produces about 1 Â 10
12 kg/year. Does this have a
significant effect on the types of gut-adapted strains in our environment? It can
perhaps be argued that the biomass of bacteria (about 15% of total biomass on the
planet) is about 1000Â the biomass of humans, and about 700Â the biomass of
livestock, so the contribution that our faeces make to the microbiota of the planet
must be modest (Bar-On et al. 2018). However, in the places where humans live the
effect may be large. We have little understanding of the impact of our faecal output,
factories, chemicals (industrial and in the home), and industrialised agriculture on
the microbiota to which we are exposed.
352
G. A. W. Rook
address this issue, which remains a speculation.
18.5 Is the Microbiota of the Natural World Still
“Natural”?
Can we benefit from our evolved dependence on the microbiota of the natural
environment if that microbiota is not natural anymore? The influence of mankind
on the biosphere has been massive. The issue of the effects of industrial and
agricultural pollution, including antibiotics, herbicides, insecticides, other agrochemicals, plastics, and monoculture has been reviewed elsewhere (Flandroy et al.
2018; Jin et al. 2017; Hallmann et al. 2017), though it is worth pointing out that
glyphosate was identified as a microbicide before it was found to be a useful
herbicide (Abraham and Monsanto Technology LLC 2010), and glyphosate was
recently detected in the urine of more than 90% of a cohort of pregnant American
women, so it is now ubiquitous (Parvez et al. 2018). We do not know whether this
matters or not.
Rather than expanding on the issue of chemical damage, I will mention two other
interrelated microbially relevant issues. First, we are rapidly replacing the naturally
evolved biomass of our planet. At least 90% of mammal biomass is now human or
domesticated livestock. Similarly the chicken, first domesticated around 8000 years
ago, is now the most numerous terrestrial vertebrate, and at least 70% of all bird
biomass is now domesticated poultry (Bar-On et al. 2018). This replacement of
vertebrates with chickens, humans, and livestock also changes the faecal matter
deposited on the planet. The production of faeces from all cattle, sheep, goats, pigs,
and chickens has been estimated at about 14 Â 10
12 kg/year (Waltner-Toews 2013).
Individual humans produce about 145 kg of faeces each year, so the human
population of about 7 billion produces about 1 Â 10
12 kg/year. Does this have a
significant effect on the types of gut-adapted strains in our environment? It can
perhaps be argued that the biomass of bacteria (about 15% of total biomass on the
planet) is about 1000Â the biomass of humans, and about 700Â the biomass of
livestock, so the contribution that our faeces make to the microbiota of the planet
must be modest (Bar-On et al. 2018). However, in the places where humans live the
effect may be large. We have little understanding of the impact of our faecal output,
factories, chemicals (industrial and in the home), and industrialised agriculture on
the microbiota to which we are exposed.
352
G. A. W. Rook