By Jonny Lupsha, Wondrium Staff Writer
A decade of drought is making grass rare in Chile’s capital. The once lush, green landscape is become increasingly desert-like, leading to drier scenery—and shrubbery. Grass itself impacted evolution millions of years ago.
Chile is entering its 13th consecutive dry year, transforming the nation from a Mediterranean climate to a semi-desert climate. Such a drastic change heavily impacts the local flora and fauna, causing changes from landscaping—sales of desert plants are up—to water rations. Santiago, Chile’s capital, is a city of six million and is now facing its first water rationing in its history. In the city’s wealthiest areas, the grass is still green, but every Chilean is making sacrifices.
The drought may be having an impact on grass, but when grass first evolved, things were the other way around: Grass influenced climates and the evolution of animals as it spread across the globe. In his video series Introduction to Paleontology, Dr. Stuart Sutherland, Professor in the Department of Earth, Ocean, and Atmospheric Sciences at The University of British Columbia, explains how grass took over the planet.
The Grasslands Today
“On a planetary scale, probably more significant than the date of evolution of the first grasses is the development and evolution of the ecosystem that they would create—the ecosystem we call grasslands, or more commonly, the Grassland Biome,” Dr. Sutherland said. “There are many different types of grassland: There are savannas and velds of Africa, there are the pampas and Llanos in South America, and the steppes in Asia—and here in North America we have the prairies.”
According to Dr. Sutherland, grasslands cover 40% of the planet’s land surface. They’re usually associated with dry climates, but not desert climates. Their high rate of turnover makes it possible for them to support large animal populations.
“Another feature is their tendency to burn, creating grassland fires,” Dr. Sutherland said. “Rather than being detrimental to grasslands, fires may be an important part of some grassland ecosystems, removing trees and shrubs and allowing grasslands to spread.”
Although some of the 10,000 species of grasses existed during the Cretaceous period, grasslands weren’t prominent until the late Oligocene period. When they arrived, though, they did so with a bang.
Arrival of the Green Planet
It was long believed that certain dental evolutions are proof of the Grassland Biome—that larger teeth evolved to accommodate grasslands. However, this theory has widely been reconsidered.
“Even if the story of teeth evolution in our grazing mammals is not quite nailed down yet, there is certainly a case for co-association or perhaps co-evolution between grasses and mammals,” Dr. Sutherland said. “The snout of many creatures becomes broader and flatter to allow for effective grazing and jaws become longer and deeper, permitting more efficient grinding of plant material.”
It’s also theorized that since animals were unable to hide in grass as effectively as they could in forests, this danger caused adaptations for running. Dr. Sutherland mentioned the elongation of lower parts of limbs, more compact feet, and shoulders and hips with increased muscle mass, all of which would facilitate quicker getaways.
Grasslands may have facilitated human evolution, too.
“The spread of grasslands was proposed by some as a reason why our ancestors started to walk upright,” Dr. Sutherland said. “Ancestors like the famous Australopithecine Lucy, who lived around 3.2 million years ago, may have evolved an upright posture as an adaptation to look for predators in high grass. Walking upright would have also freed their hands to make tools, which may have set a series of events in motion that would ultimately lead to Homo sapiens and their big brains.”
The importance of this biome is a great reason why we should take the time to stop and smell the … grass.