How can I use magic to make this change in human reproduction feasible without hurting genetic diversity?

Question

There was a culture I read about that understood human biology to be very different from what we know today. This was a matrilineal culture which believed that men did not pass on their genes, but a piece of their spirit. The spirit was the life force of a human being which kept the body alive. It possessed the consciousness of a person; morals, values, strengths, etc. This would be passed on from the father to his offspring while the mother would pass on her characteristics through her genes. This culture saw a difference between the biological father (genitor) and the social father (pater). The genitor was basically a sperm donor who had no parent obligations to the child. The pater was usually a cousin or brother of the mother, and would be charged with helping her take care of the child.

In this scenario, Women are able to use magic by absorbing energy from a parallel dimension called the aether. They are able to access this dimension through a metaphysical organ in the body called the gate of life. By concentrating, this gate can "open" and absorb energy from the aether to produce spells in the real world. In this scenario, pregnancy would be treated like another spell, but over a nine month period. Energy would be absorbed through the gate from the aether to grow the fetus. This gate would remain continiously open during this time, and the process would be unable to be stopped once started. The life energy (spirit) from the male would be given during conception. this life energy is meant to help influence the development of the genes in some way.

Reproduction doesn't work this way, but I wanted to make it a reality for this setting. Since all genes are coming from the mother, How can I make these changes work without making offspring into clones of the female?

Answer 1

Reproduction doesn't work this way, but I wanted to make it a reality for this setting. What would be a good way to incorporate it into human biology? Should both parents pass on something different to the child?

You would need a completely different human biology. The phenotype being passed by the mother is comparatively easy to do, you basically posit that the female eggs are fully diploid and only need sperm to trigger maturation. It makes no sense from an evolutionary standpoint (actually it makes the opposite of sense) but you could imagine this setup to be bioengineered (alien intervention, Mother Earth techno-cult gone amok with Crispr-Cas9) or otherwise handwaved into the human race.

Now for the sperm to carry something - and a mental something at that - into the process, we unfortunately really need a not so short series of not so little miracles. The brain does not form early, and actually the whole neurulation process does not even begin for a good two or three weeks. Even then we're far and away from anything capable of accepting a spirit or morals.

So we need to steal a trick from other creatures and supply human females with a spermatheca (sort of). After fecondation - which is not triggered by spermatozoa-ova fusion - the semen is stored until it can be merged into the growing embryo. Its DNA is not used to determine the newborn's phenotype; rather its is decoded and used to bootstrap the newborn's memories and gene activation. This also means that sex is no longer connected with a Y chromosome, actually both females and males would now have a female genotype, with primary and secondary sexual characteristics being triggered by neuro-hormonal signaling. The mechanism is there, all that remains is to abuse it.

Several hard to avoid consequences of this crazy setup would be a decreased sexual dimorphism - males would be much closer to females aesthetically. And the possible birth of "soulless" parthenogenetic females if the process triggers without actual sperm available, or something goes wrong in the spermatheca.

A further effect would be the disappearance of true genetic diversity: there would be no DNA mixing between parents. There would also be no biological reasons to avoid incest, except the Westermarck inhibition. And with little effort you could plug in a mechanism to stop cancer and virus infections altogether.

Answer 2

Sounds to me like you want a species where the mother passes on physical characteristics, while the father passes on mental characteristics.

There are two ways I can think of to manage this. The first, involving the smallest (though still fairly large!) change to real-world biology, would be to arrange for all of the genes for neurological and mental development to grouped into one set of chromosomes, and then have male gametes eject most chromosomes other than those; females gametes, complementarily, would preferentially eject just those chromosomes. As a result, there would be very little crossover between chromosomes from different parents, which means each disjoint set of chromosomes would rapidly become clonal, with each new generation carrying an exact copy of their parent's genes, modulo de-novo mutations. You would have to allow for a little bit of crossover in the sex-related chromosomes, however, or else come up with some alternative, non-genetic method of sex determination.

The second option is to imagine that these alt-humans are not in fact single organisms, but chimeras of two different organisms in a very close symbiosis, each of which reproduces asexually (or else manages to exchange genetic material with others of its kind somehow covertly): a "female" dumb animal, which provides the bulk of the body, and a separate brain; perhaps something like a fungus which infects the animal body and provides or supplants the central nervous system. Sex, then, involves not a fusion of haploid gametes from each parent to produce a new diploid embryo, but rather the provision from the father of a spore of the neural symbiote that permits the animal embryo to properly develop. As in the first case, unless some additional covert method of sexual recombination is added, this will result in an entirely clonal population, modulo de-novo mutations, and you'll need a non-genetic mechanism for sex determination.

Answer 3

If the people in the alternate reality in question have a basic knowledge of genetics:

Females have only X sex chromosomes while males have both an X and a Y. The Y chromosome is inseparably connected to their spirit in a way that X chromosomes never are. Since these are the chromosomes responsible for developing a person's reproductive system, the reproductive contribution of a male is the spirit, where the female's is everything else.

If they don't:

To be honest, you probably don't even have to explain anything. Just state what happens as you did in the question and that'll be enough of an explanation on its own.

Answer 4

Humans work exactly the way you describe but on both sides, male and female. The biological "genitors" pass along DNA but may not have anything further to do with the product of their union. The persons who take the time to raise the child imbue that child with their morals, values and strengths. The mother and father might be the same as the genitors as was the case for me. Or the persons serving in that role might be the biological mother and her father, as was the case for my grandmother. Or the persons who raise that child and imbue it with their values might be unrelated persons who take on that role by choice. Or there might be more than two people. It can work in all those ways, and it can work in more than one way over the childs life.

I do not think you mean that values, morals etc magically appear in a newborn, somehow flying in from some man. That would actually be much less amazing than the culturally flexible and adaptable way that humans really have.

Answer 5

Alright, I am going to try and get past the fact that your story seems to have some sort of hybrid star-gate/vagina that teleports babies out of nothingness. On to your question, they can't produce genetically viable babies with only one genetic source. Bacteria and other organisms that reproduce asexually are far simpler, and still mutate rapidly. Bacteria can survive because they replicate so much that genetically nonviable offspring can simply die. If humans were to mutate rapidly they would lose to significant an amount of children, and if they didn't mutate and had a single parent they would be clones. (so again doesn't work in your story.) Also, if they were all genetic clones they would all be the same gender as their parents, and mutation would not reliably create males from females.

There must be a second gene source. If you want to avoid the male passing on genes, you need another gene source. Since you're already getting this magical aether involved, you could simply make them get genes from the aether magically.

Answer 6

We really have three issues here.

1. Mothers carry the full phenotype, thus daughters (in fact all children) would be physical clones of their mother
2. Males only contribute mental characteristics.
3. This quickly decreases genetic diversity

1 and 2 are neatly solved by LSerni's answer, so I'll defer to them for those. However there is a sticking point:

Several hard to avoid consequences of this crazy setup would be a decreased sexual dimorphism - males would be much closer to females aesthetically. And the possible birth of "soulless" parthenogenetic females if the process triggers without actual sperm available, or something goes wrong in the spermatheca.

A further effect would be the disappearance of true genetic diversity: there would be no DNA mixing between parents. There would also be no biological reasons to avoid incest, except the Westermarck inhibition. And with little effort you could plug in a mechanism to stop cancer and virus infections altogether.

You've mentioned that pregnancy can be considered a 9 month long spell. During that time, an organ in the woman's body is constantly leaching energy from an alternate dimension and using it to "feed" the fetus. This presents an interesting opportunity. We can treat this energy as radiation (for the purposes of this argument), and say it will randomly mutate the DNA of the fetus. This re-introduces genetic diversity (albeit rather forcefully).

One downside of this approach is that the miscarriage rate would be rather high, due to the random nature of the mutations. One could argue that a sufficiently skilled woman could gene-sculpt her child, and this could cause skilled maga to be in high demand for their ability to reliably birth children. I don't think there would be much stigma associated with this, as the mother only provides her phenotype, but it may be something kids get made fun of for.

This has serious implications for society, as it rather drastically restricts the reproductive rate, which would need to be addressed somehow.

Answer 7

Some options here ...

Denial

It is not necessary that things work this way; it is just necessary that the people believe it works this way. The easiest way to get this would be to have phenotype genes live on the X chromosome and be largely dominant. Hence kids will look way more like Mama than Papa. Or just have it be a cultural thing.

Aphid Sexuality

Have things usually be like what you describe (though you might tone down "values" being passed on to something more like strength of will and quickness of wits; things which arguably could sneak onto Y-chromosome). Matrilinear lines will be essentially clones apart from these few things.

Until...

Until things get hard. There are species on earth (plants, aphids) which have both sexual and asexual reproduction. The idea being that when times are good, clone yourself like mad. It's easy, safe, and fun. But when conditions get rough, the genetic roulette might just give your offspring the edge they need. You can modify this a bit for your people. Let's say that when times are tough -- when BMI gets lower than a certain point, for example -- you get a more typical gene mixing.

The people will be used to this. There might be the concept of "famine babies" who are known to be fey and strange. These children tend to start their own clans, and when times get better their lines settle into clone-licious normalcy.

Answer 8

This does not look very feasible, but we have to somehow reintroduce genetic diversity and, presumably, somehow produce male offspring sometimes.

You say that the life energy from the male would be given during conception and that this would help influence the development of the genes in some way.

Suppose that influence included fixing damaged or mutated genes, which were relatively common due to an effect of the energy absorption from the aether. And suppose, also, that when repairs were made they were made from some magical blueprint stored in that life energy from the male, which would be the only source of reference for a correct version of those genes.

Would that work?

Answer 9

Since the women in your setup do not need a male to create a fertile egg you think to be in trouble with biodiversity (including how to produce a male).

This would be true with straight parthenogenesis, but you state pregnancy needs magical interaction with "aether" and during the whole period you have a very strong spell running.

Solution is to postulate that when starting the spell mother sends to ether a copy of her genetic material (or half of it, if that suits better to your plot) and receives back a new set to be inserted in the egg. This way you can control how much of the genetic material will be changed merging it with genes floating in the "aether".

As a special twist you can say very strong sorceress can "protect" their genes getting a copy almost identical, while "less gifted" women get a random copy, perhaps even very different from the original.

Process can also be influenced by "feelings" of the male, which may have an indirect influence on gene selection, either conscientiously or not (depends on plot).

Many variations on the theme are possible.

Have fun!

EDITED TO INCLUDE COMMENTS FROM OP

Conception is a very powerful spell that lasts (at least) till childbirth and it consists in several phases:

• The female choses a partner which will help her to start the spell (this is a necessary step, but happens before the spell takes place; it is very difficult to force spell from outside, as it requires the female to be in the right mood to start it).
• Female melds her mind with partner (may be male or otherwise, even of different species, but must be sentient and cooperate).
• In the early phase all genetic material of female egg (unfertilized) is sent to "aether".
• "Aether" interacts with the joined minds and selects, from what it finds there, a combination of genes "suitable" for the couple.
• Gene set will always be based on female gene pool, but certain genes may be expressed or not and others can come directly from the gene pool preserved in "aether".
• In very rare cases a strong partner can trigger creation of new pieces of genetic material.
• The genetic material returns to female egg fertilized.
• Mind melding is broken, but a link remains between partner and fetus.
• Each time partner thinks about the yet-to-be-born child this link becomes a bit stronger.
• Fetus can feel all partner thinks, even if it won't understand most things.
• At childbirth link with partner starts to wane.
• If partner was not very active it will terminate (almost) immediately.
• If partner was captivated it will remain some vestigial link resembling "voice of conscience".
• Female won't have any mental contact at all with fetus and can't have it even when he/she becomes a full adult.

Answer 10

One solution I can think of is to make souls and DNA the same thing and capable of change through osmosis. When two people are near each other, they exchange small bits of their souls.

I'll borrom @LSerni 's idea of a spermatheca and add a little twist.

After intercourse, the presence of sperm triggers the ova's maturation process. The sperm is stored away safely until the fetus has a brain developed enough to absorb some of the genitor's characteristics.

After some months of pregnancy, the fetus is ready to exposition to the father's soul. Sperm leaves the spermatheca and simply stands by the fetus for a while. Since souls change through osmosis, parts of the father's soul will move into the baby.

Through this model a child will be born with all of its behaviors and mental characteristics derived from the genitor and the mother, but coexistence with the pater means they will exchange bits of soul and the child will gradually become like his pater.

Here are some things you should consider:

• Children should exchange soul parts more often than adults, since they are way more impressionable.
• Unless you state that physical changes can only occur during pregnancy, children (and adults, to a lesser degree) will slowly change appearance and become all alike, losing genetic diversity. This could be avoided if you ruled that traits can never be "destroyed", only "tossed around", meaning that even if a trait is very rare, it will not disappear, only transit around the society. Maybe today I am the guy with blue eyes, but tomorrow they have become brown again and YOU have blue eyes.

This explanation is also capable of explaining cultural drifting, how we "pick up" behaviors and expressions from people we meet often and how isolated societies slowly become physically different from whatever they departed from.

Answer 11

Why does genetics even need to be considered in this universe?

Magic and Science are generally two opposing concepts that rarely mesh well. In this described universe why does genetics or even genetic diversity matter. By the current description you could just say humans are made of magic and inherit characteristics from their mother randomized by the aether.

If it truly matters:

If having the concept of DNA truly matters you could say that a side effect of the spell emits amounts of radiation on the embryonic DNA causing mutations which the spell then cleanses all debilitating mutations resulting in only cosmetic mutations (skin color, eyecolor, etc) to remain.

This opens up other possibilities:

• This allows you to make pregnancy costly to mothers (to many babies = cancer).
• Or dramatic, mother gets cancer after only 1 baby
• This could justify the existence of monsters in your world as the result of a botched spell.

PS: as for the fact that mothers only carry XX chromosomes so any off spring could only be a girl. Just make it so women in this universe carry the XY chromosomes instead of the male which would now be the XX holder.

• Might make for an interesting topic of what a YY offspring would be.