How would you react if you read in the news that horses are on the endangered species list? Will you be untouched by news that all dogs will be extinct by 2025? How about cats?

Take a moment to think about this. Can you imagine a world with no horses, no dogs and no cats?

These best friends of humans are members of the vertebrae family, as are humans.

There are approximately 40,000 species of vertebrae in the world.

Now, I bet you didn’t have to take a moment to react to my question above. Your reaction was probably one of instant disbelief and horror.

Now, let’s take this a little further. How did you react when the last Catarina pupfish on Earth died and the Christmas Island pipistrelle vanished forever?

I bet your reaction is something like this: why should I care? I’ve never even heard of a pupfish or a pipistrelle.

Exactly. What we don’t see in front of us, what we don’t live with and grow familiar with, tend to not touch us.

I think this is one of the reasons why we now stand at what scientists call an era of mass extinction unparalleled since the dinosaurs died out 66 million years ago.

In a study published Monday in the Proceedings of the National Academy of Sciences, biologists from Stanford University and the Universidad Nacional Autónoma de México warn that Earth’s sixth mass extinction is on the horizon.

According to the International Union for Conservation of Nature (IUCN), about 41 % of all amphibian species and 26 % of all mammals face extinction.

Up to now, there has been a strong emphasis on species extinctions, which gives the impression of gradual biodiversity loss. This view overlooks the current trends of overall species declines, according to the researchers.

The study went beyond species extinction and looked at population loss in terms of dwindling ranges for species to move freely. The study finds more than 30 % of vertebrate species are declining in population size and geographic range. For the 177 mammals that the researchers had detailed data, all have lost 30 % or more of their geographic ranges and more than 40 % have lost more than 80 % of their ranges. (Picture your favorite animal friend represented in these numbers, to get a more immediate feel for what these figures are saying).

The study suggests that as many as 50 % of the animals that once shared Earth with humans have already disappeared.

“The massive loss of populations and species reflects our lack of empathy to all the wild species that have been our companions since our origins,” said the study’s lead author, Gerardo Ceballos of the National Autonomous University of Mexico.

Why is the disappearance of species such a big issue?

Apart from the fact that it is a tragic loss on a massive scale, extinction of the vertebrae species threaten the survival of all its members, including humans.

The extinction of animals across the globe is linked to the loss of complicated ecosystems involving plants and microorganisms. The loss of plants will be devastating. Plants are vital for oxygen, absorb atmospheric CO2, and provide food and medicine. Without plants, human extinction seems inevitable.

Whether we realize it or not, every time one of our vertebrae family members disappears forever, our own disappearance becomes more imminent.