Declining fertility rates may explain Neanderthal extinction, suggests new model

Neanderthals
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A new hypothesis for Neanderthal extinction supported by population modelling is put forward in a new study by Anna Degioanni from Aix Marseille Université, France and colleagues, published May 29, 2019 in the open-access journal PLOS ONE.

The lack of empirical data allowing testing of hypotheses is one of the biggest challenges for researchers studying Neanderthal extinction. Many hypotheses involve such as disease or climate change. In order to test alternative hypothetical extinction scenarios, Degioanni and colleagues created a Neanderthal population model allowing them to explore which might have resulted in declining populations and population extinction over a period of 4,000-10,000 years (a time frame compatible with known Neanderthal history). The researchers created baseline demographic parameters for their Neanderthal extinction model (e.g. survival, migration, and ) based on on modern hunter-gatherer groups and extant large apes, as well as available Neanderthal paleo-genetic and empirical data from earlier studies. The authors defined populations as extinct when they fell below 5,000 individuals.

The authors saw that in their model, extinction would have been possible within 10,000 years with a decrease in fertility rates of young (<20 year-old) Neanderthal women of just 2.7 percent; if the fertility rate decreased by 8 percent, extinction occurred within 4,000 years. If this decrease in fertility was amplified by a reduction in survival of infants (children less than one year old), a decrease in survival of just 0.4 percent could have led to extinction in 10,000 years.

The authors intended to explore possible Neanderthal extinction scenarios rather than to posit any definitive explanation. However, the researchers note that this study is the first to use to suggest that relatively minor demographic changes, such as a reduction in fertility or an increase in infant mortality, might have led to Neanderthal extinction. The authors note that modelling can be a useful tool in studying Neanderthals.

The authors add: "This study of the disappearance of the Neanderthals published today in PLOS ONE does not attempt to explain "why" the Neanderthals disappeared, but to identify "how" their demise may have taken place. This original approach is made on the basis of demographic modeling. The results suggest that a very small reduction in fertility may account for the disappearance of the Neanderthal population. According to this research, this decrease did not concern all female Neanderthals, but only the youngest (less than 20 years old)."


Explore further

Sudden extinction of Neanderthals followed population peak

More information: Degioanni A, Bonenfant C, Cabut S, Condemi S (2019) Living on the edge: Was demographic weakness the cause of Neanderthal demise? PLoS ONE 14(5): e0216742. doi.org/10.1371/journal.pone.0216742
Journal information: PLoS ONE

Citation: Declining fertility rates may explain Neanderthal extinction, suggests new model (2019, May 29) retrieved 20 July 2019 from https://phys.org/news/2019-05-declining-fertility-neanderthal-extinction.html
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May 29, 2019
History repeats itself..

May 29, 2019
Keeping dogs in camp eliminates the element of surprise in hunter gatherer warfare involving small raids on opposing camps.

Neanderthals didn't keep dogs.

That's why dogs are man's best friend.

May 29, 2019
The farther north a species resides, the more seasonal its reproduction becomes. This wouldnt have been a problem for neanderthal except for the arrival of tropical cromag interlopers who reproduced year round. They outgrew and overwhelmed the indigenes.

This is the most reasonable explanation.

Neanderthal seasonality may survive in the form of traditions such as june weddings and fertility rites of spring, or they may just be indications of cromag culture adapting to temperate climes. The tendency is probably latent in many species and could be activated epigenetically.

May 29, 2019
A case could be made that since we do already carry some Neanderthal DNA that they donated before loosing, possibly enevitably, fertility, that they may have plugged a genetic hole that allowed modern humans to thrive.

May 30, 2019
It's happening in the West now as well, for a number of social and physiological reasons. Want to see the return of the Neanderthal world? Watch this one once Westerners die out. So start chipping flint rocks...

May 30, 2019
It's happening in the West now as well, for a number of social and physiological reasons. Want to see the return of the Neanderthal world? Watch this one once Westerners die out. So start chipping flint rocks...
The tropical repro rate is incompatible with temperate civilization. Overpopulation has always been humanity's number 1 problem. Tech-driven overgrowth led to tribalism and constant intertribal conflict over resources. Tribes were locked in the struggle to outgrow and overwhelm everyone else.

Neanderthal lived in concert with their environment. We cromags have the opportunity for the first time in our existence to do the same. Our only chance for survival on this horribly overcrowded planet is to reduce growth.

But of course it wont work unless everybody complies, hence the current war on religion, the last war we should ever have to fight.

May 30, 2019
GIGO – Garbage In, Garbage Out
Old Wisdom from The Frugal Curmudgeon tm2019 MMD

When your ASSUMPTIONS are WRONG, then you guesses are not even close to reality.

First, they define "extinction" as less than 5,000 individuals. By that standard all these "lost tribes" we keep hearing about are "extinct".

They define "young" as less than 20-years old. Huh? Females reach puberty long before that and are fertile long after 20. Sounds like they are projecting modern conceptions onto ancient people.

They are not trying "to posit any definitive explanation."

They are "the first to use empirical data" despite "The lack of empirical data allowing testing of hypotheses".

They do NOT attempt to explain "why" but to identify "how" "their demise MAY have taken place. Sounds like they are just guessing.

May 30, 2019
So, here is MY guess which is as good as theirs.

Neanderthals ARE modern humans. You can see them walking around even today. Modern humans are 25% Neanderthal BECAUSE all the various ethnic groups INTERMARRIED. That is why you don't see large groups of Neanderthals today. That's why the 23 and me commercials consistently show surprising results. That's why the 50% Native American employee at Dunkin' Donuts doesn't look even a bit Native American. We are all ONE race and have a little bit of everything in every one of us.

May 30, 2019
Blue Cat is right. These researchers are just presenting a possible scenario utilizing the SMALL amount of empirical data available.
This is just one of their "guesses", given the available data.

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