Regardless of its gross nature, poop actually helped and continue to help fertilize Earth. Looking back, the giant mammals that once roamed the planet pooped across the land, fertilizing soil along the way.

Underwater, whales and other giant sea creatures also left huge amount of waste that kept the oceans fertile. Migrating mammals, fish and birds helped transport nutrients from one place to another through their waste. This harmony in nature has kept and continue to keep the Earth teeming with life from the depth of the oceans all the way up to the mountains.

A team of scientists analyzed how the massive extinctions and continuous declines of giant animals affect the planet's nutritional recycling process.

Lead author Christopher Doughty, University of Oxford's ecologist, explained that the animals were not known as key nutrient movers in the past. In the past, scientists focused on rocks erosion and bacteria's nitrogen collection to understand nutrient movement. However, the study revealed that these animals play key roles in transporting nutrients through fecal matter from one area to another, fertilizing the land in the process.

Prior to the extinction of nearly 150 mammal species during the last ice age, animals' ability to transport nutrients from concentrated 'hotspots' reduced by eight percent on land and five percent by sea. The study also revealed that the sea mammals' ability to transport phosphorous from the deep waters of the ocean is only at 23 percent of its former capacity due to hunting activities seen in the past centuries. In the past, marine animals, particularly whales, can transport as much as 340 million kg of phosphorus annually. As for seabirds and birds, which used to transfer as much as 150 million kg of phosphorous from the waters to land in a year, their transport capability has seen a decrease of four percent due to devastation of colonies and populations.

"This broken global cycle may weaken ecosystem health, fisheries, and agriculture," said co-author Joe Roman, University of Vermont's biologist. A fertilized ecosystem is also vital to humans. The study showed that restoring or increasing the whale population can lead to the waters' ability to absorb carbon dioxide caused by climate change.

The team published their findings in the Proceedings of the National Academy of Sciences on Oct. 26.