Happy 30th Intersex Awareness Day! Have a gynandromorph green honeycreeper to admire!
This is just a reminder that intersex statuses are found throughout the natural world--in mammals and monotremes, birds and crustaceans, insects and plants. But those intersex statuses vary wildly because there are multiple systems of sex characteristics found in nature, and they do not work the same way!
For example, while we humans have XY sex chromosomes, birds have ZW chromosomes. In humans, the typical female has XX chromosomes and the typical male XY; in birds it's the typical male who has two of the same chromosomes (ZZ) and typical females that have the mixed set (ZW). But that's just what is typical, and in reality, there's a great deal of variation! For example, in both humans and birds, some individuals have mosaicism, with some cells being of one genotype and others another. But only in the ZW sex system can that result in gynandromorphism, in which an individual is male on one side and female on the other, like this honeycreeper. Humans don't do mosiacism this way (circus sideshows notwithstanding). Humans who have intersex XX/XY genotypes have a wide range of bodily differences--some are born looking typically female, some looking typically male, and others with every variation on intermediate gentalia--but never male on one side and female on the other.
Think this is complicated? Consider the platypus! Platypi are sometimes called living fossils--they lay eggs, but give milk (though not from nipples but rather just sort of oozed out). They don't use the ZW system, they sort of use the XY system. . . but with five pairs of sex chromosomes per body cell! To be "normal," a platypus sperm must be XXXXX or YYYYY. That's a much more complicated system than the one we humans use, and has a lot more opportunity to introduce sex variance.
The point here is that there are multiple sex systems in nature, and within each, a wide spectrum of manifestations of those sexes! The sad thing is that today we live in a society that has suppressed this fact, out of a strange devotion to the idea that there must be two and only two sexes. That devotion today can be near-fanatical. The federal government has declared by executive order that there are only two sexes, immutably established at conception. But you can't just declare intersexuality not to exist. You can't make nature illegal. What a strange thing to wish to do!
Instead, we should all appreciate the endless variety of forms nature presents to us. We're not all as flashy as this honeycreeper, but we are all as worthy of admiration.
