I'm not arguing that humans are somehow distinct from the rest of nature or that we are divinely imbued with some special nature. Of course we are just another species. Religion could not be further from my mind. I am saying that as a member of the species 'human' I recognise members of my own species as people but not members of other species except the cats. I am an unashamed 'speciesist' if you like.
I'm very happy with the qualities I consider to be essential to personhood, the first of which is to be human. No non-human has that quality, obviously.
I don't base my definition of personhood on levels of intelligence. I am happy to recognise the personhood of some really quite stupid people as well as people who are unable, because of disability, to develop their intellect and also people too young to have yet done so.
There may well be other intelligent species out there in the universe which may or may not have consideration for the interests of human beings. They might want to anihilate the lot of us or breed us for food. We might reach a point where AI can reason as well as us. Or better. Or differently in unpredictable and uncontrollable ways that are detrimental to basic human interests. This isn't what makes personhood. We might decide to ascribe those entities rights based on their ability to reason but that's for us to decide as a species, and in so doing it is not necessary to ascribe personhood.
I fully expect to be called a bigot for this view at some point over the next couple of decades but I don't give a shit.
If we consider artificial wombs may become a reality, what rights would a foetus not in a woman's body have? Could a parent decide to end a life not inside their body? If the reason a foetus doesn't have rights is that that would negatively impact the woman carrying be foetus, then what is the benchmark for a foetus not dependent on another human? If there would be a difference then is the quality we give to personhood lying not within the creature itself, but in its relationship to another? What would this mean?
Where did the foetus come from? How was it extracted? Was it produced in a dish from egg and sperm? Men can just jizz in a tube but how did they get the egg? What's involved in that process and how does it affect the woman? If it wasn't produced in a dish, what did the woman want to do about her pregnancy while the foetus was still in her body? What if she didn't want to produce another human being whatever space age tech was used? What if that has a massive negative impact for her?
What would this mean?
It would mean that for some people sci fi and navel gazing philosophy are far more fascinating than the mundane shit that is fighting for the basic rights of women to have control over their own bodies.
Women are people.