How did the world recover after the extinction?

When human civilization causes more and more animals to become extinct, what will the world be and what shape and size of the remaining species will be?

How does the creature system change after the great extinction?

Looking backward

According to a recent study published in the latest issue of Science magazine, species that survive after a major extinction will have a new shape.

The author, Lauren Sallan of the University of Pennsylvania, told Discovery: "Surviving species tend to be much smaller or larger than most of their relatives. This life is whether it is through rapid reproduction with large herds, or large species sizes to be able to overcome the most austere stages. "

Sallan and co-author Andrew Galimberti, now a graduate student at the University of Maine, have focused on understanding the size trends of marine animals after the mass extinction in the late Devon period, occurring It was 359 million years ago.

However, when combined with previous studies, researchers believe that a major extinction can affect all animals, both at sea and on land.

After analyzing about 1,120 samples of fish fossils in the period from 419 to 323 million years ago, the scientists found a quite similar resemblance to Cope's rule. Accordingly, fish species tend to develop larger body sizes to avoid being eaten and can easily catch prey.

Cope's law is named after American archaeologist Edward Drinker Cope . This rule states that species tend to increase body size while evolving. However, the disadvantage of this rule is that there is no objective assessment of the causes that may lead to the increase in size.

On the other hand, Sallan and Galimberti also found more evidence to support Cope's law called Lilliput Effect . This is a term that refers to the decline in the size of biological systems after a mass extinction.

Sallan said it would take five to 20 million years for the animals that survived a major extinction to recover lost species and begin to diversify species.

5 great extinctions of the Earth: At the end of the Cretaceous period (extinct KT)> Trias-Jura Period> Permian period - Triassic Period> Late Devonian Period> Ordovician period - Silurian period (right to left).

Worried for the present

The mass extinction is currently happening at an unprecedented pace and scale. Their impact on Sallan is huge, the time it takes to recover will last, perhaps tens of millions of years. Gender is still fragile during that bad time.

In the deep sea, the animals that are currently at risk of extinction are sharks . The number of sharks is severely declining due to overfishing and exploitation by humans.

In fact, geophysicist David Jablonski, working at the University of Chicago, has coined the term "dead clade walking " to imply that the species that survived a major extinction would die soon after. Jablonski explains that large animals will eventually become their own victims due to their low population size and the time to nurture a generation that is too long.

A study published in Current Biology shows that when a species dies, it will create a domino effect leading to an increase in extinction rates in species . The study author from Exeter University calls this phenomenon "extinct waterfall".

The 6th great extinction is beginning?

Clearly, the life of the world after a great extinction is still an unexplored mystery. Only thing, researchers will need to be more active to find out the cause. In the short term, the problem may be difficult to clarify.

Humans are in a position that has never been better in the world. We are high-level primates capable of thinking and mastering the Earth. However, as Sallan reminds: "The last survivors will be very different from the victims around them." The "cards of the world" will "stir" in unpredictable ways about biodiversity. But the trends they create are predictable. " Therefore people need to know the harmony between the two concepts of existence and extinction so as not to be the factor leading to the extinction of other species, nor to become their own victims.