babies and teens are all capable to consent, the only thing that needs to change according to age is the action

[HumanBeing]

I think is quite obvious but everyone who has the ability to communicate (verbally or not verbally) with humans can consent.

the main (if not only) age-related issue people should be cautious about is what actions an X year old person body can handle or not, for example you can't penetrate a baby or toddler because their bodies aren't ready for such action and therefore will suffer severe harm if you do it regardless of consent.

[bnkywuv]

Animals too are capable of consent for that matter. They're nonverbal" by our narrow definition of language, but they have body language. Same with babies and toddlers.

[CantChainTheSpirit]

I would say that sex shouldn't be seen as some hyper taboo act that has to be treated so extremely uniquely to other acts. We are biological creatures, we eat, drink, poop, reproduce. To increase the success of that we've become a social species since there are far more adept predators out there if we tried to survive solo.

But sex is a very natural function, we are built literally for that function. Single celled organisms split, they don't make the splitting a taboo subject. They don't go red with embarrassment when cell splitting is mentioned. More complex forms of life don't make sex taboo, whether monkey's or wolves, they copulate and it's something they feel no shame of because it's what keep the troop or pack healthy. Continue up the tree to humans and for much of history and in most cultures, sex isn't so taboo. In many cultures in history and even some today, families live in one room buildings and so sex is something that happens not hidden away from family. Sex is normal, it isn't something to be ashamed of and isn't something to hide as if it's some unique event that would make peoples heads explode if they witnessed it.

Sex shouldn't be taboo, it's just dumb to make sex taboo and hide it away from kids as if they'll turn into sex gremlins if they encountered it. We could debate for years whether kids can consent to eating meat, can consent to going to church, can consent to learning science, can consent to being kissed goodbye by aunty Ruth, but we don't, because apparently consent isn't an issue in all these and countless other areas. But when it comes to sexual contact, one of the most natural things in creation and what we literally exist for, it becomes a subject for PhD's to discuss the nuances of consent and mental development. It's moronic really. If I said there's insufficient brain development to choose to eat meat, consuming another creature raised and killed for meat, people would think I was going mad. Why does mental development matter when it comes to matters of killing and eating flesh? Or going to church or other activities? But sexual contact alone suddenly needs heightened mental faculties, conveniently side-strepping that half of adults are below average IQ and many are significantly lower and yet not deprived of natural acts.

As you said, consent itself in a rational world wouldn't be the issue, it's the acts themselves. Most people know you can't penetrate someone young, but sex doesn't have to be penetration. Hugging, touching, kissing, stroking, even oral play can be enjoyable at different ages without having the same physical issues.

But we live in a world that is very selective in how it applies consent, conveniently, and so it's something young people are denied. Maybe some day it will be different.