There’s one big difference between humans and animals.
No, it’s not our brains.
Think lower.
Much lower.
Nope, the other side.
Butts.
Bonjour callipygian cuties, Jules here for DNews.
As the contemporary poet, Anthony Ray once said: “I like big butts and I cannot lie”.
But Mr. Mix-A-Lot never quite delineates why he is such a proponent of the posterior, and
personally, I think it has to do why we have butts in the first place.
Almost every single multicellular organism does have some sort of “anus”, that is,
an area where waste is excreted.
But butts themselves, specifically the big meaty, fatty bits that hang out in the back,
those are pretty special, and the human booty is different than any other in the animal
kingdom.
Even when we look at our closest genetic neighbors, bonobos and chimpanzees, their butts are,
what we in the scientific community call “puny”.
For a while, researchers have tried to figure out: why did humans, specifically, evolve
to have such big booties?
To find out, let’s take a look at what a butt actually is.
The most important and visible part is the Gluteus Maximus, one of three gluteal muscles,
including the gluteus medius and minimus.
Their primary existence is to provide extension for the hip and thigh, allowing us to bend
over while also keeping everything securely in place.
Standing up, walking up stairs, and even standing still are all extremely dependent on the gluteal
muscles.
Just like humans, all primates have the same three gluteal muscles.
On chimps, the gluteus maximus connects to the ischium, the lower portion of the pelvis.
This relatively short and tight muscle makes it easier for chimps to stick their butts
out, which is really useful for maneuvering up a tree.
But humans aren’t as interested in climbing trees; unlike our genetic ancestors, we’re
a bit more preoccupied with staying on two legs, and anthropologists believe that may
be the key to our badonks.
On humans, the gluteus maximus attaches to a part of the hip called the “ilium”,
which is the highest and largest bone of the pelvis.
This relatively high placement allows for trunk stability, since the amount of area
it covers, and the size of the muscle itself keeps us balanced.
Most researchers believe that we have big butts because it helps us stay upright, and
it helps balance us when running.
But now another question emerges: which came first?
Were we first sprung, that is, upright, or was there a round thing in our face?
Well, in 2002, a paper in the journal Human Evolution used an evolutionary simulator to
reveal how changes in the shape of our bones affected our muscles.
The computer model showed early hominids would have HAD to start walking upright BEFORE developing
large butts.
If the butts had developed first, it would have been more difficult for apes to walk
upright.
The paper concluded that our big butts are actually a consequence of walking on two feet.
This means that early human-primates first had some incentive to walk upright before
their bodies could evolve to catch up, at the divergence of chimps and humans around
5 to 7 million years ago.
Long story short: we have big butts so we can walk upright.
Also for twerking.
Butts are great for standing, but they’re also good for sitting and binge watching your
favorite shows - I like How It’s Made.
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So why exactly did we develop the ability to walk upright in the first place?
And why do baby humans take SO long to start walking compared to our animal counterparts?
Find out answers to both, and more, in this episode of DNews!
What’s your favorite animal butt?
Let us know in the comments, don’t forget to like this video, and be sure to subscribe
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