Context: A team from Yale University has set out to investigate why certain big mammals in India continue to exist while they have been disappearing elsewhere.
Key Points

• During the course of the last 100 thousand years, the world has witnessed extinctions of several land-dwelling mammals, to cite few examples, North America lost its sabertoothed cat, North American lion, scimitartooth cat, American cheetah.
• The team is looking to establish factors that have contributed to extinctions.

Co-evolution

• The adaptation mechanism developed by the indigenous animal population to counteract the threat of a new predator is one such factor.
• The co-evolution involved practices shifting the dwelling place, a spatial change in hunting grounds etc to avoid being seen by the new set of predators.

Environmental factors behind extinctions in India

• Extinctions of elephant, rhino, horse species have been studied to establish common a thread that could link these extinctions.
• An observation made during this study was that all the species mentioned above were large, slow reproducers and were very susceptible to any fluctuations in climate.
• The climate variations can have a profound impact on species that produce slowly.
• Elephants have a two year pregnancy period and usually takes close to 6 years between calving events.
• The hippos when stressed is reflected in their breeding.

Human intervention

• The fossil remains have indicated that the above-mentioned animals were able to tide through numerous environmental changes, thus their extinction cannot be tied to environmental changes alone.
• The phase of the rise of humans has coincided with the decline in the population of few species.
• The case in point for humans contributing significantly to the extinction of certain species is the disappearance of Ostriches in India.
• There have been numerous pieces of evidence of Ostriches in India, ostrich eggshells were used in bead making.
• Ostrich eggs became a part of human dietary needs and this fastened up the pace of decline of Ostrich population in India.

Habitat shrinkage

• The species which survived had a large geographic range, but with rising population levels and the sophisticated technology available for tapping natural resources have meant that these populations have been confined to small pockets.
• Habitat shrinkage has led to several problems such as interbreeding, conflict over limited resources, increased human-animal conflict.

Road Ahead

• Several paleoanthropologists have cited that it is very difficult to pinpoint one reason behind extinctions of different species.
• Environmental factors such as availability of food, nature of the habitat, presence of predators along with climatic factors and human interventions have contributed to the extinction of species.
• However, it would not be entirely wrong to say that human activities have rendered a larger number of species vulnerable to extinction than ever before.