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You could say that this is what you get societally when people are freer to express themselves... it often creates more categories. In my eyes, feminists are emerging as the new Luddites, in the face of things like transgenderism and recognition of variations in self-identity.

The difference between you and me on this issue is that you have decided a handful of trans-women will "set back women's sports", while I think we don't have the science, data and experience to draw that conclusion. At the hospital where my wife worked there was a big brouhaha going on between the doctors and nurses. The nurses were pushing hard to be allowed to perform tasks reserved for physicians and the physicians were none too keen to allow the nurses on their territory. About a year later the medical techs were pushing hard to be allowed to perform tasks reserved for nurses and the nurses were none too keen to allow the techs on their territory. It's always the same. Everybody feels justified going after a bit of what others 'above' them have, but cannot believe the temerity of of those below them attempting the same behavior.

This is not a porn website, sorry.

Every taxon is a set of organisms, but not every set of organisms is a taxon.

No, it's not quite so easy. The diffusion function you seem to be looking for is an appropriate solution to Fick's 2nd Law for your specific geometry. Have a look at https://en.wikipedia.org/wiki/Fick's_laws_of_diffusion and in particular the section "Example solution 1: constant concentration source and diffusion length".

I'm getting a bit bored with the repetition now, so if you have questions, I suggest you read back through the thread. So this is my last post on the subject, unless someone comes up with something new. Here is the definition of extinction. Again. Right from the top, first line : Extinction is the termination of a taxon by the death of its last member. https://en.wikipedia.org/wiki/Extinction Can you explain how that applies to homo erectus? The taxon was never terminated by the death of it's last member. It's been terminated arbitrarily, by an imaginary dividing line drawn in time by people. They don't know when that line falls, or who was the last homo erectus, and who was the first homo heidelbergensis, because it's an artificial imaginary distinction, it never happened in reality. So the taxon was never terminated, there never was a death of the last homo erectus, and therefor they never went extinct. They just had their name changed, two million years later.

And I debunked the claims in the other thread. The “pressure” includes buying clothes. The number they cite is medical or social transition. They don’t, IIRC, give a number for sex change operations. The citations don’t support your claim.

You really really confused. It is really simple; the class of mammals are not extinct because there mammals living, the species Homo erectus is extinct because there are none of them that are alive. If you can't understand this I guess it's alright it should not affect your everyday life.

It's a rare occurrence to die via cosmetic surgery too. But we don't consider outlawing cosmetic surgery just because someone can get it when it is not warranted. Citation that psychologists often push for a sex change against the instincts of dubious parents? Citation regarding 'parents pushing' for a sex change against the wishes of the child? These are two really important citations I'm asking for. After all, you are arguing against doctor/parent decisions regarding a minor child and to do so I think it is important that you have some data to back up your claim.

Extinction is actually fairly well defined. If there are not extant members of a particular species, the species is extinct, regardless of speciation events that may have predated the extinction event. You won't find anyone seriously arguing that the common ancestor of humans and chimpanzees is not extinct, for example. What you seem to mix up is the use of extinction in the context of higher taxonomic units, in which case a lineage would be fully extinct if they do not have any extant species. Classification is a bit messy from what I remember. But from what I remember (which might be outdated) the clade Dinosauria historically was divided into two groups: Saurischia (from which birds are eventually descended) and the perhaps confusingly named Ornithischia, (which are extinct). While there might have been considerable reshuffling, in all cases the clade Dinosauria would contain birds as their surviving member. It is fairly straightforward and you really just need to look whether there is an extant member on the species levels of whatever taxonomic unit you refer to.

As I'm researching this topic I ran across a story about Hanne Gaby Odiele, an XY model. It highlighted to me the difficulty of definitively declaring someone 'male' or 'female'. https://nationalpost.com/news/0125-na-intersex

I don't think so. The scientific meaning of extinction means no descendants. It doesn't mean change to something new. T Rex went extinct when the last one died. That was species extinction. Which means that homo erectus is not extinct, it's evolved. There never was a last homo erectus.