A Cultural Context for Human-Microbe Symbiosis 7
availability. Women often remain closer to camp, spending 2–3 hours each
day foraging in groups for tubers, baobab fruit, berries, and other plant foods.
Women commonly dig together for tubers, gathering multiple species. During
certain times of the year, Hadza women and men share more similar diets. For
instance, at the height of berry season, women and men leave camp together,
both collecting a variety of species.
SIDEBAR 1.2 Human Remains and Fossilized Evidence of the
Ancient Gut Microbiome
The search for fossilized human remains has provided some limited evidence
regarding the composition of our ancestors’ microbiome. Preserved human
specimens and byproducts from ancient human gut microbiota are difficult to
find. At the time of death, the ecology of the human microbiome shifts rapidly
to encourage soft tissue decomposition. Since the bacteria within the human
body change quickly after death, only two types of human materials are pre-
served sufficiently to be used as evidence for the composition of ancient oral
and intestinal microbiota.
The first of these materials, dental calculus, is a form of plaque created
by oral microbes that is semi-fossilized at death and does not decompose.
Comparisons of dental calculus bacteria in Neolithic and modern samples
show shifts in types of oral bacteria that correspond to significant dietary
changes associated with early agriculture practices as well as the industrial
revolution.
Human coprolites are the second of these valuable archeological materials.
Coprolites are a form of desiccated or mineralized fecal matter. Most coprolites
are not recovered from individual human remains but rather from communal
latrines. These fossilized human feces may therefore prove useful for char-
acterizations of microbiomes at a population level. Within coprolites are also
preserved evidence of bacterial, viral, and parasitic infections. In the future
these materials might provide insights as to the prevalence, transmission, and
evolution of infectious disease, as well as overall gastrointestinal health. Cop-
rolites could also potentially provide some evidence regarding ancient practices
of hygiene and sanitation.
Although human coprolites are quite rare, archeologists have discovered
some samples from a few different time periods. Specifically, samples from
Texas and Mexico provide some idea of pre-industrial human microbiomes.
The older coprolites, from Texas, date from approximately 8,000 years ago and
do not resemble modern-day human gut bacteria. However, the more recent
1,400-year-old Mexican coprolites showed bacteria somewhat more similar to
those found in modern feces. These samples point to changes in gut microbes
over time, with the development of modern agricultural practices.
availability. Women often remain closer to camp, spending 2–3 hours each
day foraging in groups for tubers, baobab fruit, berries, and other plant foods.
Women commonly dig together for tubers, gathering multiple species. During
certain times of the year, Hadza women and men share more similar diets. For
instance, at the height of berry season, women and men leave camp together,
both collecting a variety of species.
SIDEBAR 1.2 Human Remains and Fossilized Evidence of the
Ancient Gut Microbiome
The search for fossilized human remains has provided some limited evidence
regarding the composition of our ancestors’ microbiome. Preserved human
specimens and byproducts from ancient human gut microbiota are difficult to
find. At the time of death, the ecology of the human microbiome shifts rapidly
to encourage soft tissue decomposition. Since the bacteria within the human
body change quickly after death, only two types of human materials are pre-
served sufficiently to be used as evidence for the composition of ancient oral
and intestinal microbiota.
The first of these materials, dental calculus, is a form of plaque created
by oral microbes that is semi-fossilized at death and does not decompose.
Comparisons of dental calculus bacteria in Neolithic and modern samples
show shifts in types of oral bacteria that correspond to significant dietary
changes associated with early agriculture practices as well as the industrial
revolution.
Human coprolites are the second of these valuable archeological materials.
Coprolites are a form of desiccated or mineralized fecal matter. Most coprolites
are not recovered from individual human remains but rather from communal
latrines. These fossilized human feces may therefore prove useful for char-
acterizations of microbiomes at a population level. Within coprolites are also
preserved evidence of bacterial, viral, and parasitic infections. In the future
these materials might provide insights as to the prevalence, transmission, and
evolution of infectious disease, as well as overall gastrointestinal health. Cop-
rolites could also potentially provide some evidence regarding ancient practices
of hygiene and sanitation.
Although human coprolites are quite rare, archeologists have discovered
some samples from a few different time periods. Specifically, samples from
Texas and Mexico provide some idea of pre-industrial human microbiomes.
The older coprolites, from Texas, date from approximately 8,000 years ago and
do not resemble modern-day human gut bacteria. However, the more recent
1,400-year-old Mexican coprolites showed bacteria somewhat more similar to
those found in modern feces. These samples point to changes in gut microbes
over time, with the development of modern agricultural practices.
