Cows may soon become the largest land animals
If species extinction continues at the rate it is now, cows could soon become the largest land mammals. Human expansion has already affected the diversity of large animal species thousands of years ago. According to a new study, mankind may have brought whole species to extinction as early as 120,000. years ago.
Thousands of years ago, the world was full of great creatures. But róThe diversity of speciesów larger than humans declined sharply. The researchers, in a study published in the „Science” suggest that human expansion is responsible for this. Zoo wkrótce may be the only place whereórym it will be possible to find any animal larger than a cow.
„Giant mammals once lived on all inhabited continents. Someóre of the species remaining todayów are largely confined to Africa. The decline in róof diversity is coinciding with the global expansion of hominidów w póLate Quaternary” – write the researchers in an article. They traced changes in animal size over the last 125,000. years and indicate that humans may be to blame.
The current rate of extinction of speciesów is the largest since the end of the Cretaceous. Regardless of whether the creatures were carnivores or herbivores, large animals were more likely to become extinct than small ones.
– Species thatóre extinct, they were from dwóch up to three times the size of mammalsóin, whichóre survived. This trend is evident globally. There is a clear pattern indicating the size of mammalsów and the state of their species, whichóry follows hominid migrationów from Africa – said Felisa Smith of the University of New Mexico. – Man is a really effective predator – added.
Neanderthals, Homo sapiens and other human species hunted large animals thatóre had no natural enemiesów. In turn, the removal of large herbivoresóin affected the chances of survival of large predatorsów feeding on their young. Researchers believe that someóre species of large mammalsóin the extinction of 90,000. years earlier than previously thought.
Earlier studies suggested that large mammals began disappearing faster than their smaller counterparts in Australia about 35,000 years ago. New research based on fossil data and the geological record indicates that this process began at least 125,000 years ago in Africa. Even then, the average African mammal was 50 percent smaller than on other continents.
Since humans migrated out of Africa, in regions and timelines thatóre are consistent with known migration patterns, species extinctions began to occurów – noted researchers. Over time, the average size of mammalsów on other continents approached and then fell well below the African level.
15,000 years ago, the average mass of native mammalsóin the American PóThe northern hemisphere was 98 kilogramsów. Today there are 7.7 kilograms. The study’s authors expect it to drop to 4.9 kilograms, and all animals larger than a cow could disappear within twoóch centuries.
Researchers porównali also the extinction rates of small and large animals in other eras. No period in the last 65 millionów years have not shown the extinction of large animals on such a scale. – Human influence has made body size a factor in extinction – said Kate Lyons of the University of Nebraska-Lincoln, coóauthor of the publication. – Archaeological records show that humans, as a species, appeared around 200,000. years ago. Wkrótce this was followed by the extinction of large mammalsów. It seems that we had something wspólnego – added.
Amongód scientistsóin the ongoing spór o whether the extinction of species in theów due to its size is a consequence of climate change throughout historyów. Published studies have not found support for this idea. – If caused by climate, we would expect the extinction traces to deviate from the pattern of human migration or correlate with climate events. However, we have not found any evidenceóin whichóre would support this concept – noted Lyons.
Syndromeół analyzed róAlso, in what wayób potential extinction of mammalianów could affect róworld biodiversity. To this end, the question was posed: what would happen if mammals, whichóre now threatened with extinction within the next 200 years?
Under such a scenario, the largest terrestrial mammal would become the cow, and the average body weight of mammalsów would have fallen to about three kilogramsów. This could have serious implications for the ecosystemów around the world. The research clearly shows that this trend does not apply to sea creatures.