Since the Industrial Revolution, humankind has radically transformed the planet. Through industrial activities and urbanization, it has altered the natural environment at an accelerated pace, overexploiting resources and polluting ecosystems. The consequences of this overexploitation not only affect the environment but have also condemned a large number of animal and plant species to extinction. The list of extinct animals already includes many living beings that we will never see again. In this article, we will review some of the reasons behind this tragedy and explore examples of extinct species.
Environmental impacts of human beings
To ensure its development as a species, humankind has been extracting natural resources and modifying the environment. While it is true that we depend on these resources for survival, we have reached a point where overexploitation has caused irreparable damage to our planet. One of the main forms of environmental degradation comes from the intensive use of fossil fuels to generate energy, which has led to enormous amounts of greenhouse gases, contributing to climate change and global warming.
The richness of biodiversity is fundamental to ensuring food security, access to clean water, and climate regulation through biological processes. However, this essential balance for life on Earth is being threatened, putting not only species at risk, but also humankind. The mass extinction of species, primarily due to human activities, deprives us of access to essential nutrients and resources. Every day, we are witnessing the disappearance of more species; in fact, according to UN reports, 150 species become extinct every day.
Governments and international organisations are working on measures to halt this loss of biodiversity, but current efforts are not enough. Only one third of countries in the world are meeting the biodiversity preservation targets stipulated in international agreements. Environmental conservation, through the creation of reserves, the fight against animal trafficking or captive breeding, is essential to reverse the current trend. Extinct species are no longer salvageable, but we can protect what remains.
Extinct animals
Extinction is defined as the moment when the last individual of a species disappears without leaving any descendants. In many cases, determining whether a species is truly extinct is complicated. There is a phenomenon known as the Lazarus taxon , in which species that were thought to be extinct are rediscovered. Despite these rediscoveries, many other species have disappeared forever, such as the dodo, the woolly mammoth, and the Tasmanian tiger.
An important source of information on extinctions is the International Union for Conservation of Nature (IUCN) Red List , a global reference that classifies species according to their level of threat. This document has been developed for over 50 years with the help of biologists and conservationists to record the disappearance of species and assess their risk of extinction.
Types of extinction
When we talk about extinction, we can mainly distinguish two types:
- Phyletic extinction: It refers to the disappearance of a species that gives way to a more evolved one. In this case, although the original species has become extinct, its lineage continues. There is no loss in global genetic diversity; what disappears is a particular form of a species.
- Terminal extinction: Here we are talking about the complete disappearance of a species, without leaving any descendants. In turn, it is divided into:
- Background extinction: Occurs gradually over time. It can be caused by natural factors, such as climate change, or by human intervention, such as habitat destruction.
- Mass extinction: It is a global event that causes the disappearance of many species in a short period of time, as happened with the dinosaurs 65 million years ago.
Causes of species extinction
The extinction process is not always directly related to human intervention. There are evolutionary and environmental causes that can lead to extinction, such as gradual changes in the ecosystem and a species' inability to adapt to new conditions. Throughout Earth's history, five mass extinctions have been recorded, and we are currently experiencing what many scientists call the sixth mass extinction , which is being caused primarily by human activity. Among the main causes we have identified are:
- Demographic and genetic phenomena: Small populations have less ability to adapt to changes in their environment, making them more vulnerable to extinction.
- Habitat destruction: The main factor contributing to extinction is the loss of habitatAs natural habitats are destroyed for agriculture, industry or urbanization, many species lose their homes and cannot survive in other environments.
- Invasive species: The introduction of non-native species into new ecosystems can wreak havoc on local biodiversity. These invasive species compete with native species for resources, and in many cases displace them, leading to their extinction.
- Climate change: One of the factors that is accelerating extinction is climate change. Rising global temperatures alter natural cycles, affecting food availability, access to water and the living conditions of many species.
Some emblematic examples of animals that have become extinct due to these causes include the dodo, the quagga, the Javan tiger and the Caribbean monk seal. These species, featured in reports by organisations such as WWF and IUCN, are just a small sample of the devastating capacity of humans to alter natural environments.
Although the loss of biodiversity is undeniable, we still have time to save many of the species that are in danger. This will only be possible if, as a society, we manage to change our practices towards a more sustainable model committed to protecting the environment.