Final answer:
Extinction is the irreversible loss of a species when the last individual dies, and it's more than just forgetting; it's a significant and often permanent change in biodiversity. Earth is currently undergoing what is believed to be a sixth mass extinction due to human impact on the environment.
Step-by-step explanation:
Understanding Extinction
Extinction is not simply forgetting, but rather the disappearance of a species from Earth when the last individual of that species dies. It is an irreversible event that has occurred repeatedly throughout Earth's history. One famous example is the Cretaceous extinction event that resulted in the demise of the dinosaurs and many other species. Scientists believe we are currently experiencing a sixth mass extinction, known as the Holocene extinction event, largely due to human activities such as habitat destruction and global climate change.
While most people are aware of the extinction of large and well-known animals, many extinctions go unnoticed, particularly those involving less conspicuous or undescribed organisms. This underlines the challenge in estimating extinction rates, as many species disappear without being observed. Contributing factors to current extinctions include pollution, climate change, and reduction in genetic diversity among species.
Biologists are concerned about biodiversity loss because it can have severe implications for human welfare, through the collapse of ecosystems and the costs associated with maintaining food production and human health. The loss of biodiversity, therefore, has practical as well as emotional significance, and conserving it is crucial for the sustainability of life on Earth, including our own species.