The ongoing Holocene era, which began about 11,000 years ago after the Pleistocene Age, has seen the development of human civilisation. The Anthropocene is a proposed epoch that dawned when human activities began having an impact on Earth&’s geology and ecosystems.
However, there is yet to be a consensus on a starting date. The Industrial Revolution (late 18th century) was one point in history being considered as the beginning of the Anthropocene. But other links were also being studied, which included the rise of agriculture and migration of species to regions that were climatically unsuitable for them. Studies show that human activities are actually changing patterns related to location of other species.
Kimbra Cutlip, a science writer in the USA, who covers natural history, atmospheric sciences, biology and medicine, states that human activity and its influences, such as the impact of increased population, has in turn, increased agriculture and these factors have influenced the distribution of plants and animals. William Buddiman, a paleoclimatologist writes that the Anthropocene began not during the Industrial Revolution, but 8,000 years prior to that when ancient farmers cleared forests to cultivate crops. These activities began isolating plants, insects, birds and animals. David Attenborough, a famous zoologist, explained in his book, Life on Earth that insects like crickets, cicadas or dragon flies, are amongst the most ancient species on our planet. They shed their skins as they develop and had been living as subterranean creatures even before the first tree grew on this planet. Today their distribution has changed as the shrieking of cicadas are heard from trees and not the ground. We are witness to a new epoch in global evolution.
A team of researchers led by S Kathleen Lyons, a paleobiologist at the Smithsonian&’s National Museum of Natural History in Washington DC, USA, examined the distribution of plants and wild animals across landscapes from the present times to a study of fossil records. Despite the random nature of the study, they detected a sub-set of plants and animals that showed up in relationships much more than could be attributed to happenstance.
Species occurring together is illustrated by a brilliant example. In Kenya&’s vast expanses of grasslands where cheetahs and lions roam, there are often giraffes occupying the same habitat. A predator-prey relationship co-exists. In the late Pleistocene, Lyons’ study revealed that dire wolves preyed on baby ground sloths and these two species were observed, in research studies, together in the same habitat. A random example from India shows egrets often perched on cattle as they look for ticks and insects on its skins. As a result both species are seen together. Returning to Africa, Grevy&’s zebras and colobus monkeys are seldom seen together. That illustrates a segregation of species and they have, in a later period, evolved to exploit different habitats.
The pattern began to change 6,000 years ago. In North America, as human population increased, so did agriculture. That activity caused plant and animal communities, or groups to shift to a pattern evocative of segregation. Lyons and her colleagues studied 3, 60,000 pairs of organisms of different communities spanning continents. The best data was collected from North America. But Lyons is confident that the “pattern shift” will be evident all over the world if similar studies are conducted.
A vital question assails humans. What is our role in this change? Lyons asserts, “We are living in a lot of areas where species used to overlap their distribution. They cannot overlap anymore because they are unable to penetrate through areas where humans live.” Gregory Dietl, a paleoecologist,in the USA, says this disruption, in a 300 million year old pattern signals that we are living in a new world. We now need to pursue studies of the past to predict what may happen in the future. Lyons is convinced that more species are vulnerable to extinction. Human activities are destroying or fragmenting habitats as they are increasingly reducing in area and creatures cannot overlap. There is no escape route.
The Anthropocene Working Group, convened by Jan Zalasiewicz, professor of paleobiology, University of Leicester, UK, is due to mark the start of this period within 2016. They are in the process of earmarking events that spawned this new epoch. The Working Group may even consider the Anthropocene period as a subdivision of the ongoing Holocene epoch. They also wonder if the defining line is likely to be1952, when thermonuclear weapon tests deposited a “radioactive signature” around the world. This was one of the activities of mankind, in addition to what has already been studied, encompassing our contribution to carbon dioxide emissions, degradation and fragmentation of habitats due to deforestation. The sequence reads like the enunciation of a horrendous litany.