Anatomy

[TeeDee]

Anatomy

Does anyone know why the human body isn't symmetrical? By that I mean , the Heart is offset to one side , slightly and the Liver as another major Organ also sits asymmetrically.

Is this the same in other animals and is there an obvious reason why?

 

[The Frightful]

Guessing evolution, human males and females have some organs in different places, guys bladders are directly above the 'outlet' females i believe are to one side because of the uterus, looking forward to other responses

 

[Toddy]

Evolution.
External symmetry and internal asymmetry is the result of our heritage from sea creatures evolving into land living ones with spines.
Basically so long as the weight is pretty equally balanced internally we're stable on our feet.
Symmetry works really well in water...the fastest fish/swimmer kind of thing.

There are a lot of academic research papers out there, but this quote is kind of relevant I think.

"Humans belong to the vast clade of species known as the bilateria, with a bilaterally symmetrical body plan. Over the course of evolution, exceptions to symmetry have arisen. Among chordates, the internal organs have been arranged asymmetrically in order to create more efficient functioning and packaging. The brain has also assumed asymmetries, although these generally trade off against the pressure toward symmetry, itself a reflection of the symmetry of limbs and sense organs. In humans, at least, brain asymmetries occur in independent networks, including those involved in language and manual manipulation biased to the left hemisphere, and emotion and face perception biased to the right. Similar asymmetries occur in other species, notably the great apes. A number of asymmetries are correlated with conditions such as dyslexia, autism, and schizophrenia, and have largely independent genetic associations. The origin of asymmetry itself, though, appears to be unitary, and in the case of the internal organs, at least, may depend ultimately on asymmetry at the molecular level."

So, as organs develop/change as we evolved, the body adjusted to suit.

 

[GNJC]

Probably starts with chirality.

 

[TeeDee]

Evolution.
External symmetry and internal asymmetry is the result of our heritage from sea creatures evolving into land living ones with spines.
Basically so long as the weight is pretty equally balanced internally we're stable on our feet.
Symmetry works really well in water...the fastest fish/swimmer kind of thing.

There are a lot of academic research papers out there, but this quote is kind of relevant I think.

"Humans belong to the vast clade of species known as the bilateria, with a bilaterally symmetrical body plan. Over the course of evolution, exceptions to symmetry have arisen. Among chordates, the internal organs have been arranged asymmetrically in order to create more efficient functioning and packaging. The brain has also assumed asymmetries, although these generally trade off against the pressure toward symmetry, itself a reflection of the symmetry of limbs and sense organs. In humans, at least, brain asymmetries occur in independent networks, including those involved in language and manual manipulation biased to the left hemisphere, and emotion and face perception biased to the right. Similar asymmetries occur in other species, notably the great apes. A number of asymmetries are correlated with conditions such as dyslexia, autism, and schizophrenia, and have largely independent genetic associations. The origin of asymmetry itself, though, appears to be unitary, and in the case of the internal organs, at least, may depend ultimately on asymmetry at the molecular level."

So, as organs develop/change as we evolved, the body adjusted to suit.

So would it be correct to assume if Chimpanzees are our closest relatives in terms of genetics their anatomy is the same?

 

[Toddy]

No, because we are different species......both 'great apes'....hominids....but we are hominins.

The last common ancestor was at least five million years ago, and most likely nearer seven. That said, I have read that thirteen was postulated

Basically we have the same organs, bones, etc., but they're all differently shaped, function slightly differently, etc.,

Immune systems don't quite work the same, pigs are actually closer to ours, that kind of thing.

Simplest way to look at it is that chimps, gorillas, oran utans, etc., communicate, but they don't speak like humans do, they're just different enough.

 

[Pattree]

………. but from a quick look their symmetries and asymmetries are similar.

 

[Kadushu]

Presumably in the case of the heart it's partly because it's function is asymmetrical - one half is pumping to the lungs while the other half is pumping to the rest of the body. Then the incoming and outgoing vessels are different (veins vs arteries) and connect various parts of the body in different directions. It's likely to be extremely efficient since it's just about the most vital part of the body which is one of the first to develop in an embryo and runs 24/7 until death. If a more symmetrical system would be less efficient then it'd be snuffed out Darwin style.