The Sixth Extinction Chapter Summary

Reflective Journal 6- The Sixth Extinction: Chapter 11 Throughout history, mass populations of mammals have become extinct. Despite their large size being an advantage when considering the likelihood of species becoming prey, populations have gone through significant periods of reduction (Kolbert 224). In recent years, species of bears, elephants, rhinos, large cats, and other mammals have become labeled as vulnerable or endangered (Kolbert 223). While these declining populations relate to natural processes that mammals go through, human activity remains one of the greatest threats to the extinction of these significant species. In some circumstances, human efforts are the only hope for reviving mammalian populations, by correcting behavior

In comparison to other species, mammals often have longer pregnancies, which slows their reproductive rates. For example, elephants have a gestation period of twenty-two months and they are unable to reproduce until they reach their teenage years (Kolbert 233). As a result, mammals experience a big restraint on how fast they can reproduce (Kolbert 233). If a female mammal can only birth one offspring every twenty-two months, her species is at a much higher risk of becoming extinct than species that birth numerous offspring in a shorter time period. Female rhinos are considered induced ovulators, meaning they are unable to release eggs unless there is a suitable mate nearby (Kolbert 219). This is not a favorable element of reproduction in regards to endangered species because if a female is in a secluded environment, she will not ovulate. This lack of eggs will make it difficult or impossible for the rhino to conceive, since she has no access to a mate. Because female reproductive systems in rhinos are so complex, less offspring is produced, contributing to the likelihood that their species will become endangered or