Monday, 1 February 2010
Bringing back extinct species – a mammoth undertaking
Thylacines roaming free in the forests of Tasmania, herds of aurochs and tarpans running in the lowlands of northern Europe, and a Barbary lion pouncing on a herd of red deer in the Atlas Mountains. A typical wildlife scenery on Earth before the humans ruled it.
The extinction of a species represents the saddest moment in the conservation-minded human. Nowadays, all conservation projects implemented in every corner of the world have the same overarching vision: to reduce the rate of extinction and secure the survival of as many species as possible. Extinct species stay in the backyard of history to remind us of our past mistakes and to stop us doing similar ones in the future.
Yet, the chance is there for us to reverse the wheel of history and make up for those mistakes. The above scenario might not be that far from happening in the present day, after all.
The issue of “reviving species” has received growing attention in the past decades. Many scientists around the world have been involved in projects aiming to bring extinct animals back to life. This “Jurassic park”-approach has evolved in two main directions, namely reviving through selective breeding and reviving through cloning.
It was the 1920s when the two German brothers, Heinz and Lutz Heck initiated selective breeding programmes for bringing back two of the most charismatic herbivores that had once roamed Europe: the aurochs (Bos primigenius), last seen in Poland’s forests in 1627, and the tarpan (Equus ferus) the last individual of which died out in 1909 (www.petermaas.nl/extinct/speciesinfo/aurochs.htm). These are the wild ancestors of the present cattle and horse. The latter have lost their “wild traits” through millennia of domestication and selective breeding by humans for specific purposes and needs. The approach used by the Heck brothers is in theory, the reverse process of domestication, the so called “breeding back”, where domestic individuals that carry wild traits and features are bred together to enhance the species’ wild features. The resulting animals seen today in some natural reserves and zoos throughout Europe are strikingly similar to the extinct wild species.
Similar and more recent attempts of breeding back animals that are phenotypically similar to extinct relatives involve the Barbary lion (Panthera leo leo), the last of which was shot in Morocco in 1922 and the Quagga (Equus quagga quagga), a subspecies of the Plains zebra that lived in southern Africa up to the 1870s. Some Barbary lions survived in captivity as property of the Sultan of Morocco, however this was largely unknown to the world up to the 1970 and the subspecies was assumed as extinct. The remaining lions in Morocco had similar features with the descriptions of extinct Barbary lions. Nowadays there are less than 100 lions in captivity dispersed in zoological gardens in Europe, North America and Morocco and a project undertaken by Preservation Station Inc. (www.barbarylion.com) promotes the selective breeding of remaining individuals for preserving the genetic distinctiveness of the Barbary lion.
Attempts to breed back the quagga have initiated in the late 1980 by using individuals of Burchell’s zebra (Equus quagga burchelli). Quaggas, unlike other subspecies of the Plain’s zebra, lack the presence of stripes at the rump. In the reconstruction programme animals that display this trait are selectively bred to reconstruct the phenotype of the extinct subspecies (www.quaggaproject.org).
Many extinct animals do not survive in domesticated form nor have close relatives from which they can be reconstructed. However, for some of them we have left genetic material that could be used to revive animals through cloning. The issue of cloning brings together many controversies and has been in the centre of hot debates between scientists for many years now. In spite of this, there are current projects that aim to revive extinct species such as the Thylacine and the Pyrenean ibex through cloning.
The Tylacine, or Tasmanian tiger (Thylacinus cynocephalus) was last seen in 1936 and since 1999 a cloning project has been undertaken by the Australian Museum in Sydney (http://www.petermaas.nl/extinct/speciesinfo/tasmaniantiger.htm) however its success has been limited due to lack of technological advancements and the complexities arising from using another species as a host.
Similar cloning attempts have been implemented to resurrect the recently extinct Pyrenean ibex (Capra pyrenaica pyrenaica) in Spain by using domestic goats as surrogates. The first cloned ibex and the first extinct animal resurrected through cloning was born in January 2009 (http://www.petermaas.nl/extinct/speciesinfo/pyreneanibex.htm), however the newborn died after 7 minutes due to respiratory problems possibly directly related to the cloning process.
Besides the hope and enthusiasm that might arise from the above cases there are still many controversies around the revival of extinct animals. There are many questions in need of answers in this delicate process before we can proceed with a clear vision for the future. Which are the animals that we can bring back? Are they going to fit in nowadays landscapes? Is it worth trying to bring back species when we still can’t secure the survival of the existing ones?
These uncertainties have been the cause hot debates between scientists around this issue. However, the process of reviving species represents the potential of humans for positive change. If we can show that we can reverse extinction then we can change the human mindset towards positive change and evoke greater hope for the future of our planet.
Image credit: Wikimedia Commons