Unraveling the Mystery: Why Giant Mammals Declined Over the Past 50,000 Years
For centuries, scientists have grappled with the mystery of why colossal mammals dwindled in numbers over the past millennia. Was it human influence or shifts in climate? A groundbreaking study from Aarhus University in Denmark now asserts that climate alone cannot explain this phenomenon.
Around 100,000 years ago, early modern humans embarked on extensive migrations out of Africa. Their remarkable adaptability allowed them to settle in diverse landscapes, ranging from arid deserts to lush jungles and the frigid taiga of the far north.
Their success hinged on their adeptness at hunting large game. Armed with cunning strategies and purpose-built weaponry, humans mastered the art of hunting even the most formidable beasts.
However, this success came at a cost for other oversized mammals. It’s well-documented that numerous large species vanished during the global spread of modern humans. Recent research from Aarhus University reveals that even the surviving large mammals experienced a dramatic decline.
By analyzing the DNA of 139 existing species of large mammals, researchers discovered a significant drop in abundance around 50,000 years ago. Jens-Christian Svenning, a professor at Aarhus University and the study’s lead, explains, “We examined the evolutionary paths of large mammal populations over the past 750,000 years. While populations remained relatively stable for the first 700,000 years, about 50,000 years ago, a sharp decline occurred, and populations never fully recovered.”
For centuries, scientists have been captivated by the enigma surrounding the decline of giant mammals over the last 50,000 years. Two prevailing viewpoints persist: some attribute the decline to rapid and drastic climate fluctuations, while others point to human expansion (specifically Homo sapiens) as the primary driver.
Historically, crucial evidence in this debate has emerged from fossils dating back 50,000 years. These ancient remnants reveal a consistent pattern of selective extinction among large mammals, closely aligned with the global spread of modern humans. However, climate change alone cannot fully account for the disappearance of these magnificent creatures. The debate continues to rage on.
Enter a groundbreaking study that introduces fresh insights into this discourse. Researchers at Aarhus University analyzed the DNA of 139 living large mammals—species that managed to survive without facing extinction over the past 50,000 years. Their findings unveiled a parallel decline in the populations of these creatures during that period. Surprisingly, this downturn appears to be linked more to human expansion than to climate change, as reported by Phys.org.
Advancements in DNA sequencing over the last two decades have revolutionized our understanding. Mapping entire genomes has become accessible and affordable, resulting in comprehensive genetic profiles for numerous species. These mapped genomes, available online, formed the extensive dataset utilized by the research team at Aarhus University.
Juraj Bergman, assistant professor and lead researcher of the study, explained, “We meticulously compiled data from 139 living large mammals, delving into a vast trove of information. Each species contributed around 3 billion data points, necessitating significant time and computational power.”
The dwindling numbers of giant mammals were assessed through contemporary species. The study encompassed a diverse range of animals, including elephants, bears, kangaroos, and antelopes, among others. Considering the approximately 6,399 mammal species worldwide, the 139 extant megafauna species provided critical insights into the complex interplay between human presence and ecological shifts.
Sources: sciencedaily.com; ourworldindata.org; journals.plos.org; phys.org; sciencemag.org; nature.com; cell.com;
Image Sources: shutterstock.com
