Title: Study reveals ancient decline of African megafauna driven by environmental factors
Date: July 24, 2023
Researchers from the Museum für Naturkunde in Berlin and the University of Alcalá in Madrid have conducted a groundbreaking study on the size and population of large African mammals over the past 10 million years. Utilizing thousands of fossil teeth measurements, the scholars have unveiled intriguing patterns that shed light on the ancient decline of African megafauna.
The study, led by Faysal Bibi and Juan L. Cantalapiedra, challenges the prevailing notion that the decline of African megafauna was primarily caused by human activities. The researchers found evidence suggesting that megafaunal losses in Africa began approximately 4 million years ago, long before humans developed efficient hunting techniques. Instead, they propose that environmental factors such as the sustained decrease in global temperatures and the expansion of tropical grasslands played a significant role in the extinction of large species.
One of the study’s major findings is the striking correlation between an animal’s size and its population density. The researchers discovered that larger species have lower population densities compared to smaller ones, aligning with the ecological ‘rule of metabolic scaling’. Additionally, they found that mammals weighing between approximately 15 (33 lbs) and 45 kg (99 lbs) were significantly fewer in numbers than expected in both living and fossil communities. This scarcity was interpreted as a signature of savanna habitats, where small forest-living antelopes and monkeys are also rare.
Moreover, the researchers observed a gradual loss of large-sized individuals in more recent fossil records, indicating the decline of late Pliocene and Pleistocene large mammal diversity. This decline has ultimately led to the impoverished and ‘miniaturized’ communities we see today. The abundance of large individuals in ancient African communities, some reaching sizes over 10 tons, is unparalleled in modern ecosystems.
The study also suggests a link between the restructuring of biomass distributions in African large mammal communities and decreases in primary productivity. Utilizing the relationship between mammalian tooth shapes and plant productivity, the researchers calculated productivity for past African communities. They found a significant decrease in productivity since the Late Miocene, which could have severely impacted the carrying capacity of large mammal communities, ultimately resulting in reduced diversity and accelerated extinctions of large species.
The publication of this scientific paper marks a significant milestone in understanding African megafaunal extinctions over geological time scales. Bibi and Cantalapiedra’s findings not only contribute to the knowledge of ancient ecosystems but also hold potential implications for conservation efforts. By understanding the ecological dynamics underlying extinction, scientists can better predict and manage the consequences of biodiversity loss in the face of environmental change.
The research article titled “Plio-Pleistocene African megaherbivore losses associated with community biomass restructuring” was published in the journal Science on June 8, 2023, and paves the way for further exploration of the dynamics of ecosystems and their complex interactions.
Reference:
“Plio-Pleistocene African megaherbivore losses associated with community biomass restructuring” by Faysal Bibi and Juan L. Cantalapiedra, Science, June 8, 2023.
DOI: 10.1126/science.add8366