Editing Extinction event (section)

====Human activities====
[[File:Ice_age_fauna_of_northern_Spain_-_Mauricio_Antón.jpg|thumb|The [[Late Pleistocene]] saw [[Quaternary extinction event|extinction]]s of numerous predominantly [[megafauna]]l species, coinciding in time with the [[early human migrations]] across continents.<ref>{{cite journal |last1= Smith|first1=Felisa A.|display-authors=etal.|date=April 20, 2018 |title=Body size downgrading of mammals over the late Quaternary|journal=Science |volume=360 |issue=6386|pages=310–313|doi=10.1126/science.aao5987 |pmid=29674591|bibcode=2018Sci...360..310S |doi-access=free}}</ref>]]
Scientists have been concerned that human activities could cause more plants and animals to become extinct than any point in the past. Along with human-made changes in climate (see above), some of these extinctions could be caused by overhunting, overfishing, invasive species, or habitat loss. A study published in May 2017 in ''[[Proceedings of the National Academy of Sciences of the United States of America|Proceedings of the National Academy of Sciences]]'' argued that a "biological annihilation" akin to a [[Holocene extinction|sixth mass extinction event]] is underway as a result of anthropogenic causes, such as [[Human overpopulation|over-population]] and [[Overconsumption|over-consumption]]. The study suggested that as much as 50% of the number of animal individuals that once lived on Earth were already extinct, threatening the basis for human existence too.<ref>{{cite journal | vauthors = Ceballos G, Ehrlich PR, Dirzo R | title = Biological annihilation via the ongoing sixth mass extinction signaled by vertebrate population losses and declines | journal =  Proceedings of the National Academy of Sciences| volume = 114 | issue = 30 | pages = E6089–E6096 | date = July 2017 | pmid = 28696295 | pmc = 5544311 | doi = 10.1073/pnas.1704949114 | bibcode = 2017PNAS..114E6089C | doi-access = free }}</ref><ref name="Sutter">{{cite news | vauthors = Sutter JD |date=July 11, 2017|title=Sixth mass extinction: The era of 'biological annihilation'|url=http://www.cnn.com/2017/07/11/world/sutter-mass-extinction-ceballos-study/index.html |website=[[CNN]] |access-date=July 17, 2017}}</ref>