Comment on Forbidden Fruit
SoleInvictus@lemmy.blahaj.zone 5 days agoKeep in mind heterosis isn’t always the result of hybridization and even then the magnitude of isolation doesn’t always positively correlate. Outbreeding depression can also be the result, increasingly so when two groups are more genetically distant or when one group is already subject to heavy inbreeding depression, as the neanderthals were thought to be.
The_v@lemmy.world 4 days ago
Out-breeding depression primarily results in a decrease of fertility and infant mortality. So although it is occasionally observed in surviving offspring, in general it is much lower probability.
Also the neandertal crossing was deleterious it would be much lower percentage in modern humans. It also would not have come from multiple crossing events.
SoleInvictus@lemmy.blahaj.zone 4 days ago
Just to preface, I’m a scientist: micro- and molecular biology. I’m not saying to take what I say as gospel, just giving context that I might know things. Sometimes.
Outbreeding depression has more possible implications than fertility decrease and infant mortality increase, entirely dependent on the heritable traits responsible for the depression effects. While the probability of persistent outbreeding depression as a result of one or more crossings would be lower in traits subject to higher selective pressure, such as increases in early infant mortality, the overall probability of outbreeding depression itself isn’t influenced post facto by its results, just its persistence.
Given we don’t know the original extent of neanderthal/human interbreeding, what we’re seeing now COULD be the “much lower percentage” you mention and still could come from multiple events. In fact, if these crosses resulted in stronger depression effects, I’d argue a greater number of crossings would be one factor behind the persistence of some genes today.
The_v@lemmy.world 4 days ago
Just to preface, I am a plant breeder/geneticist with extensive experience in interspecific crosses in multiple species - all practical. This discussion should definitely be finished over some a few drinks.