Comment on Forbidden Fruit
neidu3@sh.itjust.works 2 months ago
How do we know it wasn’t the other way around?
fossilesque@mander.xyz 2 months ago
TropicalDingdong@lemmy.world 2 months ago
FosterMolasses@leminal.space 2 months ago
This is a fantastic thread, I love this meme sub
FreshLight@sh.itjust.works 2 months ago
SoleInvictus@lemmy.blahaj.zone 2 months ago
Two ways.
First, sex chromosomes. In mammals, sex is determined by the sex chromosomes - males have XY, females XX. If interbreeding was equal between the sexes of both species, this would be reflected in the frequency of neanderthal genes on each chromosome in the current human population, but it’s more heavily skewed toward the Y chromosome than we’d expect if equal pairing was true. This suggests a higher proportion of successful male neanderthal/female human offspring.
Second, mitochondrial DNA. While genomic DNA in a sexually-reproducing species is a mix between the parents, in most species the inherited mitochondrial DNA (mtDNA) is purely maternal. This is because only the egg’s mitochondria typically survive, though on rare occasion paternal mitochondria are also passed on. There is no known existent neanderthal mtDNA in the human population. This suggests either female neanderthal/male human crosses didn’t happen much and/or didn’t often produce offspring capable of further reproduction.
Of course, there are many other explanations for all of these. These are just amongst the simplest possible options, and in population genetics, it’s not uncommon that the simplest answers are frequently correct.
IAmNorRealTakeYourMeds@lemmy.world 2 months ago
a paper came out recently. it’s also possible that male humans and female neanderthals made non viable babies.
The_v@lemmy.world 2 months ago
There is a few different potential reasons as well as sexual preference.
Genetic incompatibility - the interspecific cross could only occur one way.
Genetic bottlenecks in the neandertal lineage. A high inbred coefficient could have decreased the neandertal females overall fertility (high deleterious alleles load). This could also cause a rapid reduction in the percentage of neandertal DNA in a mixed population.
Maternal behavior - Neandertals females might not have cared for hybrid offspring appropriately. This could be for anything from milk production requirements to differences in physiological developmental rates.
azi@mander.xyz 2 months ago
I think the idea of there being health issues in certain types of mixed families is super interesting because that almost certainly would have been noticed and lead to certain cultural practices or taboos within both species’ societies.
The_v@lemmy.world 2 months ago
If I had to guess the successful crosses were potentially much healthier than either parent line. Heterosis (hybrid vigor) would likely be pretty extreme in genetic lines that has been isolated by 300,000+ years of time. Of course the degree of fertility was likely lowered due to genetic distance. Once the initial cross was made however, back-crossing to either species by the hybrid would likely be much easier.
Many of those ancient stories about individuals with super strength and size etc could have likely been based upon these crosses.
The evidence is showing neadertals never truly died out. Their smaller population bred back into the modern humans who came later.
m0darn@lemmy.ca 2 months ago
This could be human male-neanderthal female (HMNF) coupling didn’t result in fertile offspring right? Could it also be that HMNF (coupling) didn’t result in fertile female offspring, but did have fertile male offspring?
The_v@lemmy.world 2 months ago
Usually these issues are caused by mitochondrial DNA not nuclear DNA. Mitochondrial DNA is only passed on from the female. So if there is an incompatibility, it’s usually completely lethal to any offspring.
So a HMNF coupling could not have been possible because of the neanderthal’s female mitochondrial DNA.