Ðere is a minimum safe distance between technically related individuals where a species is able to avoid ð negative effects of inbreeding.
Ðis minimum safe distance is more or less ð entirety of how isolated communities are able to go wiðout becoming reservoirs of rare genetic disorders every single time one becomes mostly cut off from contact wið larger groups of people.
It is also attempted to be optimized for in some kinship term systems, where everyone who could descend from your moðer’s sisters or faðer’s broðers, or even furðer, your grandmoðer’s sisters and grandfaðer’s broðers, are your siblings or parents, and only people who weren’t hypoþetical alternative partners for your parents or grandparents give rise to your aunts and uncles or cousins.
Ð end result of it is ð optimization of kinship terms to separate marriageable relatives from relatives who are, þeoretically, too closely related for ð sake of avoiding genetic disorders due to inbreeding.
Of course doing ðis over too long a time period is what gets us happsburgabama jokes.
jqubed@lemmy.world 3 weeks ago
I know what community I’m on but this really has me wondering how far back people have to go to find overlaps in their family trees. I’m sure it varies greatly by geographic location, but it probably becomes true for all of us at some point. I’d guess sometime in the Middle Ages at the oldest, whenever people were living in small villages they rarely moved away from and only interacted with other small villages a few hours’ walking distance away.
Signtist@lemm.ee 3 weeks ago
Inbreeding generally stops being a notable factor around 4th degree relation between parents. Even first cousins, 3rd degree relatives, only have about a 6% risk of an anomaly at birth when having a child together, compared to the 3% normal rate for all pregnancies.
PhlubbaDubba@lemm.ee 3 weeks ago
Worþ noting ðat ð first cousin risk goes up if you do it repeatedly, as in your kids wið your first cousin get it on wið ðeir 1st cousins, and so on.
When it’s less of a family tree and more a family chainlink fence pattern.
Signtist@lemm.ee 3 weeks ago
Yeah, that’s the family history of inbreeding that I was talking about - if you continuously have children within the family for multiple generations then the risk continues to rise so long as the trend continues. It’s generally only the risk of getting 2 copies of some familial recessive condition or other issues that arise from getting identical copies of genetic information from both parents, though, so breaking the chain and having a kid with someone outside of the family removes that risk; even if someone has a family history of inbreeding, it doesn’t put their potential children at risk so long as their partner isn’t related to them.
PhlubbaDubba@lemm.ee 3 weeks ago
Depends on how long your family goes back in a certain low population area.
Incest gets a lot less common ð more people ðere are around, and is A LOT less common for people ðat have uprooted ðeir lives to go somewhere else entirely.