Ever since the world has realised the urgent need for preserving the planet’s biodiversity, serious efforts are being made not only to preserve what we still have but also to revive the extinct species. But, why is biodiversity so important? How does it matter if an animal or plant specie vanishes forever?
Well, biodiversity facilitates the processes that support all life on Earth. Without a wide range of animals, plants and micro-organisms, it is impossible to have healthy ecosystems which provide us with the air we breathe and the food we eat. About a third of the world’s total crop production depends on pollinators like birds, bees and other insects. Without pollinators we would not have apples, almonds, cherries and many more foods. Invertebrates help maintain the soil for agriculture. Life from the oceans provides the main source of animal protein. Trees, bushes, wetlands and grasslands slow down the flow of rainwater which enables the soil to absorb it. This helps prevent floods. With fast and unplanned urbanisation, floods have become quite common today because green cover has been destroyed over vast areas of land. We all know that trees and plants clean the air we breathe and, by absorbing carbon dioxide, help us in fighting the challenge of global climate change.
Spending time in nature is a time-tested way of improving mental and physical health.
Unfortunately, ever since the March of Civilisation picked up pace during the Industrial Revolution in the 19th century, countless species on land and sea have become extinct. Since 1900, at least 500 animal species and 571 plant species have become extinct. Among these are the Asiatic cheetah, Great Indian bustard, Sumatran rhinoceros, Passenger pigeon, Golden toad, Tasmanian tiger, Pink-headed duck, woolly mammoth, and the Himalayan quail etc. Among plants and trees, countless medicinal herbs and ferns have been wiped off, thanks to deforestation and mining in different parts of India, especially the Himalayas.
There are countless more on the verge of extinction because of our insatiable hunger for mineral and forest resources. However, governments and private organisations are waking up to the looming crises. Several attempts are being made to not only preserve the surviving species but also try and revive the extinct ones using different methods, such as cloning, genetic engineering, and selective breeding. However, none of these attempts have fully succeeded in producing viable and fertile offspring that can survive in the wild. Here are some examples of the attempts and their outcomes:
- The Pyrenean ibex became extinct in 2000. In 2003, scientists developed its clone from frozen tissue. But it could not survive.
- Australia’s gastric-brooding frog swallowed its eggs and gave birth through its mouth. It became extinct in the 1980s due to habitat loss, pollution, and disease. In 2013, scientists tried to create its embryos, but failed.
- The woolly mammoth was a giant hairy elephant that roamed the northern regions of Eurasia and North America during the Ice Age. It became extinct about 10,000 years ago because of climate change, hunting, and habitat fragmentation. In 2015, scientists used the gene editing technique by inserting mammoth genes into elephant cells, but only succeeded in creating a hybrid.
- The passenger pigeon was a migratory bird that once numbered in the billions in North America. It became extinct in 1914 due to overhunting and deforestation. In 2017, all attempts to revive the specie through gene editing failed.
- The aurochs was a wild ancestor of domestic cattle that lived throughout Europe, Asia, and Africa. It became extinct in 1627 due to hunting and habitat loss. The revival attempts through selective breeding succeeded only partially, because the hybrids were genetically different from the original.
In 2013 the National Geographic Society held an event on de-extinction to popularise the idea. Conservationists describe de-extinction as ‘deep ecological enrichment’ or restoring ecosystem functions lost through extinction. It is visualised that resurrected animals would be released into suitable habitats to increase biodiversity and revive ecosystem resilience. In other words, habitats like grasslands, forests or wetlands would be recreated for these animals, which would greatly improve carbon absorption and reverse the damage done to our environment.
How will this de-extinction come about? Now that’s a priceless question. So far, all attempts to resurrect the extinct species have failed. But the scientist community has not given up. They are working on new bioengineering techniques to manipulate genetic material in an organism. This traditional technique, coupled with the latest gene-editing technology, has ignited hope and excitement among conservationists. In other words, genetic engineering is being looked upon as the best bet for resurrecting the extinct species. This involves cloning, gene-editing with the help of synthetic genomics, and back-breeding. These approaches are explained here.
Cloning: This technique helps produce genetically identical species. On July 5, 1996, a lamb named Dolly was born from a female sheep—the first mammal cloned from adult animal cells. The scientists generated a nuclear gene sequence identical to the donor of the non-reproductive cell. However, cloning is effective only if intact living cells are available. It has not yet proved useful in the cases of long extinct species.
Gene Editing and Synthetic Genomics: Developed in the 1990s, gene-editing manipulates a living organism’s genetic material by deleting, replacing, or inserting a DNA sequence. This technique helps in changing physical traits, like eye colour and vulnerability to infections and disease. Synthetic genomics is similar to genome editing. Synthesised DNA pieces can be novel genes or genes found in other organisms, which could help improve a specie’s survival chance or even develop a new specie altogether. However, it is not confirmed whether this technology can resurrect an extinct specie in its original form.
Back-breeding: Back-breeding or selective breeding can increase the presence of specific traits within a population. Back-breeding has limitations as a de-extinction approach. This method works well when the extinct species are closely related to a still-living specie. There is no guarantee that the selected characteristics will occur since the current environment is likely far different from when the extinct species walked the earth.
De-extinction efforts are facing several challenges and controversies, including ecological and ethical. On the ethical front, it is being argued that such technologies, especially back-breeding, have the potential to change the course of natural history. Many species had become extinct because these were deprived of their habitats. Reintroducing the resurrected species into the wild may have unforeseen consequences. Many point out that de-extinction does not have positive ecological value in principle or otherwise.
Perhaps, it would be more rewarding to preserve what we are left with rather than resurrect what is lost. We also need to revisit the postulation that de-extinction is not a morally permissible activity.
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