Editing Population bottleneck (section)

===Humans===
{{See also|Founder effect#Among human populations}}
According to a 1999 model, a severe population bottleneck, or more specifically a full-fledged [[speciation]], occurred among a group of [[Australopithecine|Australopithecina]] as they transitioned into the species known as ''[[Homo erectus]]'' two million years ago. It is believed that additional bottlenecks must have occurred since ''Homo erectus'' started walking the Earth, but current archaeological, paleontological, and genetic data are inadequate to give much reliable information about such conjectured bottlenecks.<ref name="hawks">{{cite journal |vauthors=Hawks J, Hunley K, Lee SH, Wolpoff M |title=Population bottlenecks and Pleistocene human evolution |journal=Molecular Biology and Evolution |volume=17 |issue=1 |pages=2–22 |date=January 2000  |pmid=10666702 |doi=10.1093/oxfordjournals.molbev.a026233|doi-access=free }}</ref> Nonetheless, a 2023 genetic analysis discerned such a [[human ancestor]] population bottleneck of a possible 100,000 to 1000 individuals "around 930,000 and 813,000 years ago [which] lasted for about 117,000 years and brought human ancestors close to extinction."<ref name="NYT-20230831">{{cite news |last=Zimmer |first=Carl |authorlink=Carl Zimmer |title=Humanity's Ancestors Nearly Died Out, Genetic Study Suggests - The population crashed following climate change about 930,000 years ago, scientists concluded. Other experts aren't convinced by the analysis. |url=https://www.nytimes.com/2023/08/31/science/human-survival-bottleneck.html |date=31 August 2023 |work=[[the New York Times]] |url-status=live |archiveurl= https://archive.today/20230831182259/https://www.nytimes.com/2023/08/31/science/human-survival-bottleneck.html |archivedate=31 August 2023 |accessdate=2 September 2023 }}</ref><ref name="SCI-20230831">{{cite journal |author=Hu, Wangjie |display-authors=et al. |title=Genomic inference of a severe human bottleneck during the Early to Middle Pleistocene transition |url=http://www.science.org/doi/10.1126/science.abq7487 |date=31 August 2023 |journal=[[Science (journal)|Science]] |volume=381 |issue=6661 |pages=979–984 |doi=10.1126/science.abq7487 |pmid=37651513 |bibcode=2023Sci...381..979H |s2cid=261396309 |url-status=live |archiveurl=https://archive.today/20230901024052/https://www.science.org/doi/10.1126/science.abq7487 |archivedate=1 September 2023 |accessdate=2 September 2023 }}</ref> 

The controversial [[Toba catastrophe theory]], presented in the late 1990s to early 2000s, suggested that a [[supervolcano]] eruption in Indonesia approximately 75,000 years ago caused a [[human]] population bottleneck to 10,000–30,000 individuals.<ref name="Ancestors_Tale">{{cite book
|first=Richard |last=Dawkins |author-link=Richard Dawkins |title=The Ancestor's Tale, A Pilgrimage to the Dawn of Life |chapter=The Grasshopper's Tale |page=416 |publisher=Houghton Mifflin Company |location=Boston |year=2004 |isbn=0-297-82503-8|title-link=The Ancestor's Tale }}</ref> The hypothesis was based on the apparent coincidence of geological evidence of [[sudden climate change]], [[Coalescent theory|coalescence]] evidence of some genes.<ref>{{cite journal |author=Ambrose SH |title=Late Pleistocene human population bottlenecks, volcanic winter, and differentiation of modern humans |journal=Journal of Human Evolution |volume=34 |issue=6 |pages=623–51 |date=June 1998  |pmid=9650103 |doi=10.1006/jhev.1998.0219|bibcode=1998JHumE..34..623A |s2cid=33122717 }}</ref> and the relatively low level of genetic variation in humans.<ref name="Ancestors_Tale"/> However, subsequent research, especially in the 2010s, appeared to refute both the genetic argument and the extent of climate change at the time.<ref>{{cite news|url=http://phys.org/news/2013-05-volcanic-winter-toba-super-eruption.html |title=Doubt over 'volcanic winter' after Toba super-eruption. 2013 |work=Phys.org |date=2013-05-02 |access-date=2015-10-31}}</ref> 

In 2000, a ''Molecular Biology and Evolution'' paper suggested a transplanting model or a 'long bottleneck' to account for the limited genetic variation, rather than a catastrophic environmental change.<ref name="hawks" /> This would be consistent with suggestions that in [[sub-Saharan Africa]] numbers could have dropped at times as low as 2,000, for perhaps as long as 100,000 years, before numbers began to expand again in the [[Upper Paleolithic|Late Stone Age]].<ref>{{cite journal  |vauthors=Behar DM, Villems R, Soodyall H, etal |title=The dawn of human matrilineal diversity |journal=American Journal of Human Genetics |volume=82 |issue=5 |pages=1130–40 |date=May 2008  |pmid=18439549 |pmc=2427203 |doi=10.1016/j.ajhg.2008.04.002}}
*{{cite news |author=Paul Rincon |date=April 24, 2008 |title=Human line 'nearly split in two' |work=BBC News |url=http://news.bbc.co.uk/2/hi/science/nature/7358868.stm}}</ref>

The ''Neolithic Y-chromosome bottleneck'' refers to a period around 5000 BC where the diversity in the male y-chromosome dropped precipitously, to a level equivalent to reproduction occurring with a ratio between men and women of 1:17.<ref>{{cite news | access-date=12 September 2023 | first1=Michelle | last1=Starr | url=https://www.sciencealert.com/neolithic-y-chromosome-bottleneck-warring-patrilineal-clans | title=Something Weird Happened to Men 7,000 Years Ago, And We Finally Know Why | publisher=sciencealert.com | date=31 May 2018}}</ref> Discovered in 2015, the research suggests that the reason for the bottleneck may not be a reduction in the number of males, but a drastic decrease in the percentage of males with reproductive success.<ref>{{cite journal |author=Karmin |display-authors=et al. |year=2015 |title=A recent bottleneck of Y chromosome diversity coincides with a global change in culture |journal=Genome Research |volume=25 |issue=4 |pages=459–466 |doi=10.1101/gr.186684.114 |pmc=4381518 |pmid=25770088 |doi-access=free}}</ref>