Would Simultaneously Hermaphroditic Humans Still be "Men" and "Women"?

Question

When looking exclusively at the muscular and skeletal systems of male and female humans, on average, we'd find what scientists call "sexual dimorphism".  Even their voices are sexually dimorphic--males average on the tenor-bass range, whereas females average on the alto-soprano range.

In this science fiction scenario, a disgruntled and hostile ecoterrorist, guilty of illegally terraforming a series of alternate Earths, had somehow cleared up the whole of North America of its prisons and injected all of the man, woman and child inmates of one same mutation--the "banana slug lover", a mutation that results in everyone having the reproductive organs of both men and women.  In short, turning all of North America's prisoners into simultaneous hermaphrodites.  Once every single one had been injected and engineered, they get systematically released to fend for themselves in any one of the terraformed alternate Earths of the "scientist"'s choosing.

Once they settle, that is where the question comes into play.  Will simultaneously hermaphroditic "men" and "women" still have the same kind of sexual dimorphism typical of other humans?

user3294068 · Accepted Answer

I think to achieve its goal, the mad scientist would have created a new chromosome, H, to replace the X and Y chromosome.  The H chromosome would provide most of the same genes as the X chromosome, allowing the bearer to live with an H instead of one or more X chromosomes.
One difficulty of producing functional simultaneous human hermaphrodites is that the female hormones (progesterone and estrogen) and the male hormones (testosterone) tend to interfere with one another.  Even if an individual had both sets of genitalia, only one set could be functional.  This new H chromosome would produce a new hormone, which I'll dub "androsterone".  Androsterone would promote both male and female sexual traits, and would allow both types of genetalia to be funcitonal.
Depending on the details, the H could be incompatible with the X or Y chromosomes (inability to breed with standard humans) or it could dominate/partially dominate the X and Y chromosomes.  It could be that HX and HY individuals would be sexually dimorphic (but still hermaphrodites), while HH would tend to be more androgynous.
Injecting this genetic change into existing adults and children will not cause them to suddenly sprout new genetalia; those grow in the womb.  For the purpose of the story, the genetic change would probably cause the bodies to start producing androsterone.  As the normal human hormones flushed from their systems to be replaced by androsterone, secondary sexual characteristics (breasts, beards, etc.) would start to emerge.
The next generation of people would all be hermaphrodites.  Since they would all be HH, they would not be sexually dimorphic.  Though, there could be variations on the H chromosome that lead to some level of dimorphism.  Maybe there are two versions of the relevant genes, H and h, where HH tends to present as more female and hh as more male, though both combinations would still yield hermaphrodites.  There are various modes of dominance, so Hh could be more androgynous, more one gender or the other, or in each individual, one could dominate (I believe that in women with two X chromosomes, one tends to completely dominate the other).
So, to explicitly answer the question: "Would there still be dimorphism?": The answer would be: "It could go either way, depending on the exact nature of the change."

Black · Answer

I was gonna leave this as a comment... but let's face it, it's an Answer.
Given that our mad scientist named his mutation "banana slug lover" and, crucially, he is mad: you probably already know there will still be "Men" and "Women"... "once they settle", aka, you have expression of this new mutation in their offspring.
(and ya know, all of them being from prison probably doesn't help too much)
.... for those that don't know here's a dangerous linky
Although to more qualify as a dimorphism, testes might be included because that would change hormone balances. Then again maybe that's not strict enough to meet the definition of dimorphism. Up to you really. Anything more strictly defined as a dimorphism would have to be encoded into the mutation a la clownfish or one of those other ones with a more flip-flop sex mutation.

History Professor · Answer

You have to follow the biological sciences here. They can possess both sets of genitals but only one set can be reproductive-functional. The reason is the hormones which are regulated by the hypothalamus (brain). It would produce one or the other but without serious reworking of human physiology you cannot explain reproduction of both hormones. For instance, progestin and estrogen are female - in sufficient quantities they would make your character appear female. Swap that around to testosterone and your character is growing a beard. They can't both be present as they sort of cancel one another out. That said, the brain can produce all three and men have a certain amount of female hormones and women a certain amount of male hormones - but one side has to dominate in order for reproductive processes to occur. Now you could of course create a hybrid alien creature which has some sort of dual-brain characteristic or get crazy where the character can shift hormone production at will, thereby shifting from male to female or something like that, but a normal human even with both sets of equipment, can't function as both at the same time. Not in a real world sense. But with fiction of course, you can just ignore that.

Answered by History Professor on September 3, 2021

Charlie Hershberger · Answer

If you only change the genitals then the dimorphism in adults will continue.
Muscle development, breasts, and voice range are mostly developed in adolescence, so while the hormones would eventually correct that to some degree, the difference would remain and be noticeable. For children though (the next generation) since the hormones would be between male and female each would have roughly the same traits. so the first generation would have dimorphism, but the remaining generations would not.

The Square-Cube Law · Answer

If the genetic mutation is done through the insertion of a gene, you may cause everyone to change their phenotype towards androgyny. A simple microscope checkup of some mouth tissue will reveal the original biological sex of each person (female cells have a little dot in them, which is a "deactivated" X).

For adults, and those in their later teens, transformation may or may not change all sexual physical  traits in such a way as to make their original sex detectable. Just look at transgender people - when the transition is done during early teen years and with proper hormonal treatment, they grow up to look more like the biological sex they identify with than if they start later in life.

So in short for the older people you might look at them and at a glance say "this one was originally a cis-man/cis-woman". For the ones in their teens you may need a throughout examination. For the ones who receive the mutation as children, years later you might need a microscope to determine their original biological sex.

Would Simultaneously Hermaphroditic Humans Still be "Men" and "Women"?

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