Composition of Classical music, according to the Italian Renaissance principle of bel canto, ("beautiful singing") is one of the best examples of mankind's ability to discover an existing physical principle, and to use that discovery to create new works of science and art, which then increase humanity's power to build civilization.
The Schiller Institute describes six “species of human singing voice”
and describe them as soprano, alto or mezzosoprano, tenor, baritone, and bass. For the most part, women's voices make up the first two and men's voices the last two, with a fair bit of overlap in the middle. But as the chart at the link shows, there is a lot of overlap up and down the ranges, especially when you take vocal registers into account. Natural ability may cause someone to fall more closely into one of those ranges, but practice and training can extend that range. Desire can impact how much effort a person puts into extending that range. Lack of use (and even lack of belief in one's ability) can cause a range to contract over time.
Sometime in the 15th century, people realized that dividing a vocal range into a simple binary of “women's voices” and “men's voices” didn't fully describe the reality of human ability. I think we're in a similar position now when it comes to the concept of sexuality and gender. Growing up, I believed there were men and women, and each was attracted to each. Period, end of story, a neat binary that encompassed both sex and sexuality (“gay” existed only as an epithet on the school grounds. At least in my experience). But as I've grown older, I've met people who don't fit into those easy binaries. I've met people who describe themselves as gay/lesbian. But that didn't shake my world too much. I mean, that just meant that gender and sexual expression were two different binaries: male/female and gay/straight.
By high school I matured into a baritone by inclination and my range is is pretty low – I can sing bass and baritone but have always struggled in the upper registers. But in my youth I listened to popular rock and even the hair bands and most of those singers were tenors or even sang/screamed falsetto (upper register) to hit the highest notes. So, I wanted to sing along with Geddy Lee, Bret Michaels, Sammy Hagar. Because I wanted to, I pushed my voice – and my range – to the point where I can hit those notes. It may not sound good (or even feel good some of the times) but I wanted to so I can do it. Mostly, I enjoy being able to hit those high notes and will sing along with Van Halen as willingly as with Jethro Tull.
I've since discovered that gender and sexuality don't fit into binaries any easier (or with any better results) than singing. Male, female, trans and intersex. Hmm. Not just a simple either/or, zero/one there. Gay, lesbian, straight male, straight female, and bisexual. Nope. Not a simple approach at all. In my opinion, I find using a singing metaphor to be a better approach. It gets me out of thinking in binary terms and it fits my experiences more closely.
I know people who, whether by inclination or desire, have a wider range of sexual expression than I do. A whole host of ranges exist that don't fit neatly into any one set. For some, they love one gender primarily, but because of the person or because of the situation, they have become more comfortable with extending their sexual range to include a person or persons of their non-primary gender. Others show no inclination towards one set of gender, but see people first and slippery bits later. Others are attracted to only one gender or type, but may be curious or willing to expand that range in the right situation. It may not be something they do all the time or in any situation, but they have been able to “increase humanity's power to build civilization” by recognizing that who they love and desire isn't fixed to one of two points.
Now that's something to sing about.