A new study states that the domestic cow may be the largest land mammal on Earth in 200 years if the loss of large-bodied and currently threatened animals continues in the future.
The research team led by the University of New Mexico demonstrated that mammal biodiversity loss, which is a major conservation concern today, is part of a long-term trend lasting at least 125,000 years.
The study was published in the journal Science.
• The study is the first to show that human effects on mammal body existed even before their migration as Neanderthals and other hominin species from Africa.
• It showed that size-selective extinction in mammals is a hallmark of human activities, both in the past and present and not the norm in mammal evolution.
• The researchers warned that if the trend continues then, the largest terrestrial mammal in 200 years will be the domestic cow.
• That would mean the extinction of elephants, giraffes and hippos.
• One of the lead researchers, Felisa Smith from the University of New Mexico said that one of the most surprising finds was that 125,000 years ago, the average body size of mammals on Africa was already 50% smaller than on other continents.
• This finding was surprising because Africa is a larger continent and typically, larger land masses house and support larger mammals.
• The researchers suspect that the archaic humans and other hominins had already influenced and reduced the mammal diversity and body size in the late-Pleistocene or Ice age.
• Over time, as humans migrated from Africa to around the globe, extinctions of the largest mammals followed, explained the researchers.
• The large mammals that went into extinction include mammoths, woolly rhinoceros, llamas, camels and giant ground sloths as well as predators such as the short-faced bear and the scimitar and saber-toothed cats.
The researchers also examined the potential influence of climate on extinction risk and selectivity over time. They found that for 65 million years, changes in climate did not result in more extinctions, nor was there a greater tendency for large-bodied mammals to go extinct.