Why do humans not have a more "animal" birth cycle?

[Soubriquet]

Sorry if that's worded correctly I just couldn't think of how to phrase it

I watch a lot of wildlife documentaries and you always see how the animals have their young, and then don't come back into season for the next litter until the young has been fully weaned and left home.

Orangutans for example won't have another baby until their infant is at least 7 years old so well beyond the weaning age.

Why do we not do this? Is it because humans take so long to reach adolescence?

It can't just be the breast feeding aspect of it because as soon as the baby is weaned and the feeds drop, the mother is fertile again and ready to have another if she so wishes.

Good question. I want to know the answer too.

I think it's because so many babies/children used to die before reaching adult hood.

Having said that breastfeeding can be used as natural family planning...so say your periods don't come back for 2-2.5 years (women in the past probably didn't have a lot of spare calories so may not have got their periods back until they completely stopped feeding) then by the time your next baby is born the older one is 3 and a bit more independent...baby every 3 years from 16-45ish is 9 kids which isn't loads really.

It could point to living in groups - once the baby is weaned the mother is fertile again and others in the group take more part in the care of older ones. It's one of the theories about why we live after becoming infertile too.

Early humans may also not been as fertile - nutrition and possibly breastfeeding for longer so realistically maybe gaps were bigger.

Natural selection. It works for humans, probably for a combination of the reasons mentioned. It works too well - we're overpopulating the planet and squeezing out less efficient breeders/survivors like the poor orangs.

I don't think it would be an option in terms of the survival of the species. Human babies are born so helpless and remain dependent on their parents for longer than any other animal. That would mean that the average human female would only manage two babies in their lifetimes, at best.

That's probably a good theory.

Though it would have helped prevent the over population we now have

I think that it's because we are domestic. If you look at many domesticated animals, they can breed far more often than their wild counterparts.

I think humans were supposed to breast feed on demand until about 7 years (about when the adult teeth come in). This would delay birth again (although not for 7 years...)

We don't feed on demand so much and certainly not for anywhere near as long.

Some animals do have older and younger babies at the 'same' time.

I don't mind the idea. I'd definitely object to licking my baby clean and eating the placenta.

Yes..I don't think I would be too keen on that either

Or licking my baby's bits and eating their poo to keep clean

Human child mortality rate is pretty high.
It also helps that humans are social animals and other members of a group can look after each others children.

Probably because in years gone by infant mortality would have been much higher. People would have had more children but if you had to wait ten or so years between babies you wouldn't have very many and might not be able to carry on your line.

I quite like the idea of "seasons" like a dog or something. I probably wouldn't have time to get any more humping in though :(

We do, I believe. It was kept to time by the length of the days, but since we now have bright light on demand it doesn't synchronise to anything anymore.

I gather there was a study run in Spain in the 1950s. Franco had a big push to get electric light in all the tiny little villages in the middle of nowhere. Before that you could see seasonal variation in birth rates in rural areas but not urban ones. After that there was no variation.

So I've been told, anyway.

I've read some evolutionary anthropologists who say it is more to do with the monogamous relationships issue. It is in the interest of the female to have dedicated male support for pregnancy and rearing offspring. Hence some fairly unique human traits like hidden ovulation - there is no externally perceptive fertile season so if they man is to procreate, it is in his interests to stick around all the time. Also permanently inflated female breasts - contrary to the breastfeeding literature, the primary purpose of adult female breasts is to attract a mate, hence they are swollen and prominent since puberty regardless of whether there is any offspring.

In short because a) human children have a very long dependency period and b) it is possible for us to simultaneously rear multiple young. Therefore any genes for not doing so would be selected against over the generations and be swamped by genes for having more babies.

Don't forget though many children did die.

Presumably early humans who had a baby every 2 - 3 years were more likely to successfully raise them to adulthood to reproduce themselves than mothers who perhaps had babies more frequently (availability of nutrition perhaps an issue) or less frequently (high infant mortality).

It's not working particularly well for orangutan and pandas though is it?

Camomila hahaha yeah I wouldn't count on that. As someone who's currently 31 weeks pregnant and breastfeeding an 18 month old and has had no periods between pregnancies...yeah. Family planning my foot!

No idea about humans but not all animals leave a gap - female cats can get pregnant with one partner while already pregnant by another, and then give birth to a litter of kittens with different fathers and slightly different dates of conception (although only by a day or so, you wouldn't want to be delivering half-cooked foetuses along with the full term ones).

Might not be relevant (or still academically sound) but I remember being taught about K and R type species in ecology- K type species evolved to be tough and weather out hard times through competition, increasing their chances of survival. R-type species produced many offspring, hence bolstering their chances of survival in a different manner. K species have fewer offspring.

Humans don't necessarily fit into that picture- we have many offspring, but we're also fantastic adapters and fierce competitors.

However, I think I remember reading something about the size of a human infants head relative to the female pelvis making child birth particularly difficult for humans relative to other mammals.

I wonder if the difficulty (and risk) or child birth for humans relative to other species might mean that there's an element of us being regular reproducers, but not through producing multiple offspring in the way a rabbit would?

Probably a bit of an incoherent theory (because wine)....

Female Orca whales also live long beyond breeding age. Interesting that they also live in large family groups, and have infrequent single babies.

The older females also have sex for pleasure, with the young males who like to practice before mating with a fertile female.

Male orcas also stay with their mother for the rest of their lives. They'll mature, go off to mate with a female, and then return home to their mother.

Fell pregnant when eldest was exclusively breastfed and 5 months old. So that stuffs the 3 year theory

I was thinking that I wouldn't mind being an older orca whale, but now I'm not sure I like the idea of having a partner who was permanently tied to his mother's apron strings