Is this why women have 2 breasts?

[TransformerRobot]

I just thought of something this morning regarding biology in women, and female gorillas.

 

Women have 2 breasts, not 4 teats like on a cow's utter.

 

Were women meant to give birth to twins? It seems to make more sense considering they only have 2 breasts.

 

If that's the case, why can cattle only have 1 calve each year when they have 4 teats?

[mooeypoo]

I am no biologist, and I *don't* know the answer to this. This is my attempt at a guess, so please don't take my input as authoritative.

 

I think that the issue here is symmetry. We have a general symmetry in the human body roughly "left/right", that could explain why there are two breasts and not, say, one.

 

That doesn't explain why women have two breasts instead of four, though, which is a good point. I would offer the guess that humans bear relatively low number of offspring per pregnancy (usually one, sometimes two, rarely more) which explains why we don't need more than one (and by symmetry 2) but I believe cows, too, bear one offspring at a time, and yet they have four utters.

 

That's a good point.

 

I did find this article: http://forwomenhealth.com/2010/02/07/why-do-women-have-only-two-breasts/

IT seems to shed some interesting light on things:

 

“The human being is judged objectively, is a mammal,” says Sabine Wenisch. “The number of teats in mammals is adapted to the average litter size.” As a rough rule of thumb: The teat number represents the average number of pups times two. This example also applies to the much tit mouse, it has supplied with its 24 teats usually 12 juveniles. Animals such as horses or goats, to get the average, only one cub, accordingly have only two stations at the milk bar. “In principle, this same man also is divided in,” says Wenisch. Only about 1.2 percent of cases occur in humans of a twin birth.

 

However, there are exceptions to this rule, such as in the cow. A cow’s udder has four teats, although twin births in cattle only about five percent of cases occur. In many animals has shown the nature of quasi-generously in favor of an additional pair of teats. In principle, however, is a minimalist principle in the evolution of living beings: wasted “Nature does not like,” says Wenisch. If only one pup must be attended to, the body also no effort for the training of many milk glands operate.

 

For the even number and arrangement of the pairs of mammary glands is a fundamental principle of the anatomy is responsible: “Mammals have a bilaterally symmetrical body,” Wenisch said. The mammary glands develop from the paired milk bars on both sides of the body. Depending on the species arise from the teats. In many animals, with only two mammary glands, they are located between the hind legs. In humans and monkeys, they have experienced a between the front limbs. One characteristic that unites us with the largest land animal in the world, too, female elephants have two breasts between his front legs.

 

 

 

So it seems to be symmetry indeed; animals are "bilaterally" symmetrical (explaining the four udders) and humans have the left/right symmetry.

 

Please someone post anything more constructive if you find it. It's an interesting question, indeed.

 

~mooey

[CharonY]

Most of the post is accurate, I would just be add that not all animals are bilaterally symmetric. Animals that are belong to the group of Bilateria (what's in a name, eh?). But there are animals with different forms of radial symmetry (think about anemones or jellyfish), for instance.

[Janus]

Bilateral Symmetry. It is something that has been part of our evolution for a long time. Cows most likely descended from an ancestor that had litters and thus required more teats. Evolution sometimes will take the " If It isn't broken, don't fix it" approach. There was no real advantage to losing the extra teats, so they were left as is.

[JustinW]

Sorry to get off topic, but the talk about symmetry made me think of something I once learned in psych class. Did you know that the human face is not symmetric? If you take a picture of someone smiling and covered half of their face, one half would look indifferent or bland. Just thought I'd throw that out there even though it has absolutely nothing to do with the thread.

 

It could be women have two breasts because...well...a child feeding off of one would be awfully painfull. Maybe the reason for the second is to give the first a break.

 

 

 

Just sayin'.

Edited March 2, 2012 by JustinW

[ewmon]

It could be women have two breasts because...well...a child feeding off of one would be awfully painfull. Maybe the reason for the second is to give the first a break.

Yeah, redundancy or backup or spare. If women had only one breast, then:

 

newborn baby + nonproducing/underproducing breast = dead baby

Symmetry allows for convenient redundancy. It's well known that

can get around quite well, but imagine the predicament that dashing

would be in if he lost one of his legs.

[Joatmon]

Thinking of symmetry caused me to have doubts about it. We have only 1 of certain organs and they are not always central. I knew someone who's whole internal structure was "back to front". For example his heart was more to the right than the left. It had no effect on his general health, but had to be well documented in case he needed an operation (it didn't help that he was in the armed forces). I think if something evolves and works it can exist even if it doesn't seem absolutely the most efficient "design". Two kidneys are supplied, but we can live with one, for example. If this is the case then why do we have two kidneys? Perhaps evolution hasn't got round to giving it a try?

[TransformerRobot]

Yeah, redundancy or backup or spare. If women had only one breast, then:

 

newborn baby + nonproducing/underproducing breast = dead baby

Symmetry allows for convenient redundancy. It's well known that

can get around quite well, but imagine the predicament that dashing

would be in if he lost one of his legs.

 

I'm going with your answers to this question. Having less strain put on the breasts sounds nice.

[Phi for All]

I'm going with your answers to this question. Having less strain put on the breasts sounds nice.

I thought the strain was why men had two hands.

[TransformerRobot]

I thought the strain was why men had two hands.

 

That made me chuckle. XD