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For millions of years, the extinction of species was a natural process, the causes of which were in many cases unknown.
Scientists, according to the analysis of fossils, have managed to determine certain epochs, of several tens of thousands of years, in which species disappeared, usually in massive form. These records show the disappearance of groups of organisms, leaving room for new or already existent forms of life to survive, as occurred with the extinction of dinosaurs, which eased the development, evolution and proliferation of mammals.

However, the appearance of Man marks a before and after when it comes to the extinction of species. Primitive Man had to feed himself and find shelter, so he used the resources within his reach to survive: flora and fauna. Then, he settled in communities, altering the natural environment of diverse organisms and intervened for his own benefit, without considering the gradual impact his actions would have on the survival of many species.

If all of the above took place during the first years of populating the Earth, imagine the grave consequences brought on by the further development of civilization, the Industrial Revolution and a series of other phenomena that, over time, have affected nature and the species that inhabit in an ever stronger way.

It is not unusual then, to point out that in the last 500 years human intervention on our planet has meant loss.

Natural causes

Some meteorological events have a direct influence on the survival of species, both animal and plant. Droughts, floods, tornados, and hurricanes are just a few of the phenomena that alter the environmental equilibrium and cause a significant movement of animals and considerable drops in population.

Another of nature’s natural processes is competition among species. In any ecosystem, animals carry out a specific function and their actions are focused on satisfying their vital needs. In order to do so, they compete to get the necessary resources in a constant sequence of energy transference and nutrition. However, when entire populations are forcefully moved (due to other processes, mainly the destruction or reduction of their habitat), competition is notably altered. When new species arrive to an already established ecosystem that has its hierarchies clearly stated, a race begins to see who gets the most of and in the best way the necessary resources for survival, a process that is only achieved by the strongest and those that can accommodate themselves the fastest to the new conditions.

The loss of genetic variability due to the gradual reduction of animal populations also affects a species’ ability to survive. Drop-offs in the population of a species causes it to have less tools to quickly adapt to changes, making the individuals that make it up more and more vulnerable to natural and human threats.

Human threats

In the last few centuries, human action upon nature has been the main cause of the vulnerability or total extinction of some species. The human being is pointed to as the great culprit of the disappearance of many organisms, because he damages them directly or indirectly, destroys their habitat and introduces foreign species, drastically altering ecosystems.

The destruction of alteration of different species’ habitats is the main anthropogenic (related to Man) cause that results in the extinction of animals.

This way, chopping down a forest, drying up a wetland, the transformation of vast surfaces into crop areas and the expansion of urban centers are only a few of the actions taken on by Man that drastically reduce the natural environment of many organisms.
The latter do not manage to adapt to these new quickly shifting life conditions, reason for which the amount of individuals that make up a population begins to do down, reaching limits that near extinction or possibly lead to it.

Man has also used some animal species as a commodity. This commerce is considered the third most profitable illegal business after drug trafficking and arms sales, because annually, it generates numbers that surpass 10 thousand million dollars. However, the most alarming thing has to do with the species that are being traded and they have the following breakdown: some 50 thousand primates, 140 thousand ivory tusks (from animals like hippopotamuses, elephants and narwhals, among others), 350 million tropical fish, 10 million units of reptile skin, 5 million live birds and 15 million units of mammal skins. All of these commodities are traded as high valued goods worldwide, ignoring all of the laws that exist about the protection and trafficking of animal species.

Many of these species end up as pets, turned into shoes, purses, wallets or fur coats. A considerable number of them even die before being processed and encaged because the transport from their natural environment to an unknown one affects their behavior and organic functioning.

The pollution of natural environments is another of the many problems that hurt species. Many animals die poisoned by the accumulation of chemical substances that result from some industrial processes, because the water they drink and the air they breathe contain high doses of pesticides, oil or polluting gasses, among other harmful agents.

A few disappearances

Unfortunately, the gradual threats that affect the animal kingdom made several species disappear for centuries now. Some of them became extinct in a faraway past and we only have a notion of their passing through our planet through their fossil remains, some tales or illustrations from the time they existed.

One of the most popular cases of early extinctions is the Dodo bird (Raphus cucullatus), which disappeared during the XVII century. This bird, a typical inhabitant of the Islands of Mauritius, acquired some pretty particular characteristics: since they had to predators, they had no need to fly, and therefore, their wings atrophied.

In addition, it developed muscular and robust legs and moved clumsily. The latter eased its capture by the sailors that arrived to the area, which coupled with the destruction of the forests it lived in and the introduction of domestic foreign species (which soon became direct predators), caused its definite disappearance in only 80 years.

Another emblematic case of extinction happened with the tiger. Until a few decades ago, eight subspecies of tiger were known, of which three disappeared for good: the Caspian Tiger (Panthera tigris virgata), the Bali Tiger (Panthera tigris balica) and the Javan Tiger (Panthera tigris sondaica). The direct cause of the extinction of these species was the destruction of their habitats as well as the beginning of an indiscriminate hunt for sport or in order to get their eye-catching fur.
The Tarpan (Equus ferus) was an animal that was quite similar to the horse. It lived in the more temperate zones of Europe and Asia. It was rather short (it did not surpass a meter and a half) and had a robust body. It went from being a common inhabitant of the Eurasian steppes to becoming totally extinct. This was due to the fact that it was hunted to prevent damages of the farmers’ crops and the breeding with domestic horses. The last specimens were seen at the end of the XIX century.

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