A new review study published in the journal Trends in Ecology & Evolution by scientists in Australia and Germany found that the ‘Cambrian explosion,’ a period around 540 million years ago when the ancestors of most animal groups arose, may have been influenced and supported by an abundance of feces, left by those that came before.
"Next to rising oxygen levels and other
contributing factors, the importance of feces in ancient ecosystems is often
overlooked," says Russell Bicknell, an evolutionary biologist at Flinders
University in Australia.
"We have considered these ancient diets,
increasingly sophisticated digestive systems and trophic interactions as part
of a much bigger picture to help explain how more organic matter and nutrients
poured into the ancient oceans to accelerate ecosystem development at the end
of the Ediacaran and early Cambrian periods."
Thus, one could say that poop
basically fertilized Cambrian life, supporting its diverse development.
Life first appeared on Earth in
limited form billions of years ago, not long after it formed. However, it
remained quite limited. The Cambrian explosion is when oceanic life really grew
and diversified.
According to Science Alert:
“This spike in diversity occurred over a period of about
25 million years. That sounds like a long time, but it's just one frenzied
afternoon in the studio relative to the almost 4 billion years it took for
complex life to appear in the first place.”
“It's generally thought that the Cambrian explosion was
fueled by an increase in oxygen in the atmosphere and water, a new protective
layer of ozone, or an influx of nutrients washed into the oceans from erosion
as the Snowball Earth melted.”
“The new study suggests an overlooked factor: A fecal
revolution.”
Of course, fecal matter is organic
matter, and that matter still plays an important role in cycling nutrients,
including carbon, iron, nitrogen, and phosphorus, through the oceans’ different
regions, from surface to seafloor.
“During the Cambrian, the amount of particulate organic
matter reaching deeper water must have constantly increased as biomass grew
significantly and more animals with guts arose," the researchers write.
“To investigate whether the hypothesis was just a load
of crap, the researchers examined these ancient excretions, known as
coprolites, from across the Cambrian.”
The earliest fossilized feces date
to the early Cambrian, around 540 million years ago. The earliest forms were
small since the organisms that left them were small, but as organism size
increased, so did poop size.
"With this shift, we see increasingly complex
digestive systems, particularly in early arthropods which evolve specialized
foreguts and digestive glands capable of processing a wider variety of
food," says Bicknell.
"It becomes clear in the fossil record that the
evolution of feeding strategies aligns with the production and distribution of
organic carbon and nutrients to start creating conditions we see in modern
oceans and later on land, where fertilizer today is used to produce our food."
"Complex marine systems can only develop when a
combination of temperature, nutrition, and biological drivers are
present," the researchers conclude.
"The rapid acceleration of organism size during the
Cambrian Radiation increased coprolite size, which yielded a positive feedback
loop, further accelerating the establishment of these ecosystems."
Animals first appeared in the
Precambrian, about 600 million years ago, about 60 million years before the
advent of the Cambrian period. The Cambrian explosion, or radiation, was
basically a rapid diversification of oceanic life that occurred when guts first
appeared. More poop led to more species, and many of them utilized the
nutrients in the poop to create a cycle that led to both proliferation and
diversification of animal species.
References:
An
Ancient Poop Explosion Could Have Helped Complex Life Evolve. Michael Irving.
Science Alert. August 5, 2026. An Ancient Poop Explosion Could Have
Helped Complex Life Evolve : ScienceAlert
The Cambrian fecal revolution: Fueling the Cambrian Radiation.
Julien Kimmig and Russell D.C. Bicknell. Trends in Ecology & Evolution.
August 4, 2026. The Cambrian fecal revolution:
Fueling the Cambrian Radiation: Trends in Ecology & Evolution
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