Well, what I want to know is this ----- why are human females the Only primate to have swollen breasts all the time.
-Richard
-Richard
Ah come on, that's been on TV a dozen times and in any anthropology textbook. It's because we swapped doggy for missionary some millions of years ago.
Clearly evolution selected for ancestors that could reproduce more quickly than other primates. Human social organization also reinforced this because childcare could then be shared within the group.
Human females don't go into season (the males OTOH are continually 'in season') and they can fall pregnant almost immediately after giving birth during their subsequent monthly oestrous cycles. Hence, it makes more sense to keep the breasts in a state of continual readiness (enlarged) with only a small additional increase in size due to milk production while the offspring are suckling. Other large primates have much longer reproductive cycles (i.e. from one conception to the next), so it does not make sense to invest energy into carting around enlarged breasts when not pregnant - and this would also be difficult while swinging from trees. It should not go unnoticed that large primates are far more sedentary during pregnancy.
I some how doubt the selection of breast size has much to do with positional optics! It probably happened the other way around.
Disclaimer: this is entirely the opinion of Bonsai.
Human females don't go into season (the males OTOH are continually 'in season') and they can fall pregnant almost immediately after giving birth during their subsequent monthly oestrous cycles. Hence, it makes more sense to keep the breasts in a state of continual readiness (enlarged) with only a small additional increase in size due to milk production while the offspring are suckling. Other large primates have much longer reproductive cycles (i.e. from one conception to the next), so it does not make sense to invest energy into carting around enlarged breasts when not pregnant - and this would also be difficult while swinging from trees. It should not go unnoticed that large primates are far more sedentary during pregnancy.
I some how doubt the selection of breast size has much to do with positional optics! It probably happened the other way around.
Disclaimer: this is entirely the opinion of Bonsai.
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Other primates indicate oestrous with swollen buttocks (think chimp or baboon).
Note that lactating monkeys don't have large breasts either. They are entirely for show in Homo Sapiens. And with 7 billion odd of us doing a very good job of it.
(note wife currently lactating so I have more up to date field notes than most of you 😛)
EDIT: note that the transition from tree swinging to bipedalism with the change in pelvis shape and move of vagina from back to front took an awfully long time to evolve.
Note that lactating monkeys don't have large breasts either. They are entirely for show in Homo Sapiens. And with 7 billion odd of us doing a very good job of it.
(note wife currently lactating so I have more up to date field notes than most of you 😛)
EDIT: note that the transition from tree swinging to bipedalism with the change in pelvis shape and move of vagina from back to front took an awfully long time to evolve.
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Nice story. But don't forget the attractiveness angle. Well-endowned females will find it easier to attract high-quality mates, and evolution does the rest. Peacock tails anyone?
Jan
No need for the swollen buttocks as an indicator of oestrus cycle in adult human females: unless pregnant, they are effectively 'in season'.
Anatomical changes you mention are the result of going from all 4's perambulation to bipedalism surely? From that follows copulatory behaviour . . . of course after a few million years of evolution.
Separately, I am also fascinated about why human brains are as big as they are - over 3x a chimps and the highest rate of encephalisation in the animal kingdom as far as I know. How? Why? Even our jaw and associated muscles had to evolve to accommodate the brain size (or was it vice versa?). Chimps and gorillas have their jaw muscles tied to the top of their cranium - our attached to sides. Evolutionary biologists speculate that this fundamental anatomical change allowed brain size to balloon in humans over a short period.
Read 'the naked ape' by Desmond Morris. Most of it is still valid. Ascent of man is still worth watching (if you remember it from first time round in the 70s and I can lend you the DVD). Although much has been discovered since then, not least developments in mitocondrial DNA sequencing the basics have not been overturned.
There was a series a couple of years ago 'your inner fish' which showed evolution from fish to man. Our ears were gills!
Ah there is a book of the series Your Inner Fish: The amazing discovery of our 375-million-year-old ancestor: Amazon.co.uk: Neil Shubin: 9780141027586: Books
There was a series a couple of years ago 'your inner fish' which showed evolution from fish to man. Our ears were gills!
Ah there is a book of the series Your Inner Fish: The amazing discovery of our 375-million-year-old ancestor: Amazon.co.uk: Neil Shubin: 9780141027586: Books
In important news the Kii 3 review stereophile did is on their website now. They like it but squirm at the way it removes tweakiness!
Swollen is perhaps the wrong word, and implies something wrong or painful in a gland. It's just that the size change with lactation is not that great...
Try to walk on all fours with a big rack!* Especially when the years begin to count.
*Caution: this thought experiment may overstretch transgender empathy in some male participants.
*Caution: this thought experiment may overstretch transgender empathy in some male participants.
You ever seen a cow trying to run to the milking shed?
And the size change with lactation in humans is waaaay greater then with primates. Google images is full of stuff that I dare not put on here!
And the size change with lactation in humans is waaaay greater then with primates. Google images is full of stuff that I dare not put on here!
They look depressingly good... Those exposed cones worry me though - the grandchildren have fingers... 🙂
Agreed that swollen is the wrong word. IIRC, tissue volume variation between individuals in that location is mostly due to variation in fat cells. During lactation engorgement also may occur.
You could buy a decent car for the price of a pair of Kii 3's.... Which would you buy though? 😀
that's a good answer...... efficiency ? and why is each human female getting larger cup size from generation to generation.
? Why only humans?
-RM
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