I wonder what the uncertainties are on that number, or would that number be a lower bound.BWV said:1000 individuals
As I understand it from the description in Arstechnica, this number (about 1300) is the approximate number of individuals that contributed genetically to the population in a way that is reflected to our lineage today. Or, in other words, if you trace the ancestors of any human today back in time, it will eventually contain a subset of only those 1300 individuals. At least, that is how I understand it.Astronuc said:I wonder what the uncertainties are on that number, or would that number be a lower bound.
As I understand it, this bottleneck in the population on the African continent as detected up by the new analysis model is not (yet) correlated with any global change that has been picked up by other means or in other populations. Also, it is not clear to me if the new analysis "on purpose" has filtered out genetic "signals" from populations that already had left Africa around that time but later mixed back into the gene pool (e.g. Neanderthals) or not, but I did get away with a clear understanding this analysis only speaks about the African population at around 900k years ago, meaning if remaining global population had no such bottleneck the cause of an African bottleneck likely has to be fairly local.BWV said:1 MYA had a homo erectus population spread out across Eurasia, so hard to picture a widespread extinction.
if you define ‘speciation’ as a branch where the new organism can no longer create fertile offspring with the old organism (like donkey and horse) - then perhaps some genetic change made a population of early humans no longer able to breed and create fertile offspring with the rest of the population at that time?Filip Larsen said:As I understand it, this bottleneck in the population on the African continent as detected up by the new analysis model is not (yet) correlated with any global change that has been picked up by other means or in other populations. Also, it is not clear to me if the new analysis "on purpose" has filtered out genetic "signals" from populations that already had left Africa around that time but later mixed back into the gene pool (e.g. Neanderthals) or not, but I did get away with a clear understanding this analysis only speaks about the African population at around 900k years ago, meaning if remaining global population had no such bottleneck the cause of an African bottleneck likely has to be fairly local.
A population bottleneck is an event where a significant percentage of a population or species is suddenly reduced, leading to a decrease in genetic diversity. This can be caused by various factors such as environmental disasters, disease outbreaks, or human activities. The surviving population has a much smaller genetic pool, which can affect the species' ability to adapt and survive in the long term.
Evidence for a population bottleneck 900,000 years ago comes from genetic studies of modern human DNA. Researchers have identified patterns of genetic variation that suggest a significant reduction in population size during this period. Additionally, fossil records and archaeological findings provide supporting evidence of environmental changes that could have contributed to such a bottleneck.
The population bottleneck 900,000 years ago likely had a profound impact on human evolution. With a smaller population, genetic drift would have played a larger role, leading to the fixation of certain alleles and the loss of others. This could have accelerated the development of unique traits and adaptations in the surviving population. The bottleneck may have also heightened the importance of social structures and cooperation for survival, influencing the evolution of human behavior and culture.
The exact causes of the population bottleneck 900,000 years ago are not definitively known, but several hypotheses have been proposed. These include drastic climate changes, such as ice ages or volcanic eruptions, which could have created harsh living conditions and reduced available resources. Additionally, disease outbreaks or competition with other hominid species might have contributed to the population decline.
In the long term, a population bottleneck can have several implications for a species. Reduced genetic diversity can make the population more vulnerable to diseases and environmental changes, as there are fewer genetic variations that might confer resistance or adaptability. It can also lead to inbreeding, which increases the risk of genetic disorders. However, a bottleneck can also result in the rapid evolution of advantageous traits if the surviving population is subjected to strong selective pressures.