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AIBU?

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Original poster

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

57 replies

Soubriquet · 02/12/2016 17:39

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.

OP posts:
ToastDemon · 02/12/2016 20:40

Wiffle that is brilliant, can you imagine the posts from women orcas on MN complaining about their nightmare orca MILs Grin

HerRoyalFattyness · 02/12/2016 20:46

olenna I'm about the size of an orca and have a partner attached to his mothers apron strings....

OlennasWimple · 02/12/2016 20:48

Arf HerRoyal Grin

Blossomdeary · 02/12/2016 20:50

And non-stop randiness is not the norm in other species.

Isawahatonce · 02/12/2016 21:10

I suppose most animals have multiple babies at once so they they don't 'need' to have more babies quickly, plus they're less able to when they've still got littlens to look after? Not that that's backed up with any scientific evidence to my knowledge, but it kinda makes sense? I don't know about orangutans or that though that don't have lots of multiple births.

BestZebbie · 02/12/2016 21:14

A lot of the animals that have a cycle where they don't mate again until the first offspring leave home do it that way because it fits in around the variability of the seasons (and availability of food and relative warmth).
You can't fit a human cycle into a year - for a start, we have 40 week pregnancies! Animals that are yearly based also manage to fatten themselves up to breeding condition in a very short time (like, two or three weeks) - it takes longer than that for a human female to get into good condition if they have been short on food for a while.

Original poster
Soubriquet · 02/12/2016 21:15

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.

Do they?

I know the females stay within the pod like elephants do but I'm sure the males go off on their own

OP posts:
Backingvocals · 02/12/2016 21:17

I read somewhere that in our nomadic era, humans had smaller families. Because multiple babies and pregnant women slowed the whole group and meant they couldn't roam as far. So somehow back then we were moderating our fertility. Larger families coincided with settled agriculture when excess food was achievable and bigger families could be sustained.

I've no idea how this pertains to the question at hand but thought it was interesting.

Laiste · 02/12/2016 22:31

Very interesting thread.

I'd like to know - and maybe this is linked to your question OP - why do women living together for any length of time all end up menstruating at the same time? I really can't think of a good reason for it.

MommaGee · 02/12/2016 23:03

I guess if you all love together and all have your period together there's less chance of your "d"h having a quickly with Mary cos you're out of action

fc301 · 02/12/2016 23:08

I think non nomadic communities can collaborate to raise multiple young, hence higher birth rate.
Nomadic peoples limit the number of young eg, by infanticide of a twin (Aborigines), or by developing taboos surrounding when a post partum /bf female returns to society /marriage etc

Original poster
Soubriquet · 02/12/2016 23:10

I thought the women menstruating together was hormonal based

Plus meant all babies can be born together so there's a crèche with all the mums

OP posts:
OlennasWimple · 02/12/2016 23:10

You can also wet nurse each others children more easily, if necessary, if you have similar aged babies

MommaGee · 02/12/2016 23:12

It probably is hormones as it has to technically work but I guess the evolutionary advantage is more cohesive society / more supportive society cos he's not off shagging Mary every time you get your period. People could still reasonably get pregnant on different months tho so not sure about everyone littering together. Would it make you too vulnerable of all the women were incapacitated at the same time?

havingabadhairday · 02/12/2016 23:28

Artandco I suspect things were different pre-agriculture and that on average there would be a longer gap between pregnancies than there would be today if no contraception were used.

TaraCarter · 03/12/2016 00:02

Starchild Sadly, things are a bit shitter than that for cats. Pregnant cats can go into season when significantly pregnant, and thus do deliver half-baked kittens. Sad

Ovulation during an established pregnancy, producing sort of twins, has been noted in human women, too, although it is incredibly rare.

On the subject of cats, domestic cats come into season much more frequently and at a much younger age than pure Scottish Wildcats, which have one litter a year.

trufflesnout · 03/12/2016 00:24

Women's menstruation cycles syncing up is a myth - it was debunked a few years ago. It was one of those medical 'theories' about women that somehow gained traction despite there being not-very-much behind it.

I think the most accepted theory at the moment is that cyclical fertility is a byproduct of evolution, rather than being something evolution 'worked' towards. Humans have long pregnancies, and so if an egg takes a while to get to the lining it might be past its best - it won't be able to embed into an ageing lining though and so the old, potentially bad egg will leave the uterus along with the next period, giving the woman a better chance at a younger (and therefore hopefully healthy) fertilised egg next month.

All the mammals who have human-esque cycles also have 'aggressive' embryos that burrow into the lining of the uterus rather than just sitting on top, so we may have developed a thicker uterine lining to prevent the embryo from attaching too deeply into the uterine wall - the pay off being that the lining is so thick that it needs to be replaced every month to keep it naice enough for a baby.

Ofc, these are just theories, but they're the most current theories I can remember/think of/know

MapMyMum · 03/12/2016 00:29

Breastfeeding as a contraceptive only works until the baby is approx 6 months

TaraCarter · 03/12/2016 00:41

Breastfeeding as a contraceptive only works until the baby is approx 6 months

It's intensely variable. I got three years period-free out of it. So did my mother, so I suspect it to be at least partially genetic. Other women ovulate before their six-free check!

Artandco · 03/12/2016 08:51

Yep breastfeeding didn't work here. Ds1 was breastfed almost every hour still. But still period returned around 8 weeks after birth and ds2 conceived soon after. ( luckily as we did want them close)

Artandco · 03/12/2016 08:52

I have heard of someone (in the news not personally), who apparently conceived twice with two different men and her 'twins' were actually about 4 weeks age different

KimmySchmidtsSmile · 03/12/2016 09:00

DS is a net result of the contraceptive effect of breastfeeding GrinWink

TheABC · 03/12/2016 09:06

Interesting thread. I think I want to be an orca on the next life!

The way our biology is set up does point to more social living arrangements than our current setup and it will be interesting to see if the nuclear family is just a product of the times (and we move back towards extended families/communal arrangements).

Badcat666 · 03/12/2016 09:33

I think it's down to a number of factors

  1. High death rates for human babies
  2. As babies take a long time to reach maturity the more babies you had then the higher chance of at least a couple reaching maturity.
  3. Monthly periods meant more chance of getting pregnant when you have a decent food source to ensure health of mum and baby in the past. This maximized the chance of conceiving when you had decent food source rather than relying on coming into season at a certain time of the year when food may be hard to find. Lack of food would mean less chance of being fertile.

Screw being an orca!

I envy kangaroos... They give birth to a teeny weeny baby (so no shelling a melon from a hole the size of a walnut) then it climbs into the pouch to feed and grow and you just kick it out when you have another one!

Why aren't we like kangaroos??! No birthing pain AND a free on board tummy bag to fill with crap like tissues/ sweets/ purse/keys etc when the baby is out! AND a bonus of no tummy rolls because the pouch will cover it up!

oh oh! AND your nips are in the pouch so no sagging boobs!

WINNING! :D God damn you mother nature....

BarbarianMum · 03/12/2016 12:27

Breastfeeding works much better as a form of contraception when you are in a tight energy budget a la hunter gatherer diet.