Childbirth can be extremely challenging for humans – but some other primates may have it even worse. A comprehensive analysis of primate anatomy concludes that many species must squeeze large-headed infants through too-narrow pelvises. The problem may have begun with the very first primates, which lived more than 50 million years ago.

It has been assumed for decades that evolution has left humans with unique childbirth difficulties. The conventional view is that the trouble began when our ancestors first walked on two legs, which required the pelvis to be narrow. A few million years later, hominin brains evolved to be larger and infant heads became bigger – but the pelvis was unable to expand to allow for their easy delivery.

Other primates were thought to have things easier, largely because that was the conclusion of an published by anthropologist Adolph Schultz in the 1940s. Schultz looked at a range of primate species and concluded that in the vast majority, the infant head could fit comfortably through the female pelvis.

But his analysis was flawed, says at University College London. “One of the main problems was that it applied measurements that were originally developed for the human pelvis to all primates,” she says.

Schultz identified landmark points on the human pelvis that define the maximum width and depth of a horizontal plane at the top of the birth canal. He then assumed those same landmarks would define the maximum width and depth of any primate birth canal. They don’t. The human pelvis has a very unusual shape, and when Schultz’s landmarks are mapped onto other primate pelvises, they typically define an inclined plane that sits slightly above the birth canal. This plane overestimates the size of the birth canal, because it is effectively an oblique, oval-shaped slice through a cylinder representing the birth canal.

Torres-Tamayo and her colleagues reassessed birth canal shape in 29 primate species, while also looking at data on newborn-skull size and shape in each species. They concluded that several primates have a pelvis that seems too narrow to give birth. Small primates including bush babies and tamarins have the most severe conflict. In these primates, the newborn’s head is almost twice the size of the birth canal.

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“I was not expecting to have a mismatch in quite such a large number of primates,” says research team member , also at University College London.

Birth difficulties may even be the ancestral condition in primates, says Betti, particularly considering that early primates were small.

“It’s super cool to have such a big sample,” says at the University of Zurich, Switzerland. “These species are doing very different things, living in different niches and they do tend to be quite anatomically diverse.”

Different primates have also found their own solutions to the problem. For instance, the bush babies and tamarins dislocate the bones of the pelvis, temporarily doubling the size of the birth canal. Humans can’t do this, says Betti: it would make walking unbearably painful for a large, bipedal species.

Torres-Tamayo and Betti and their colleagues also found that birth difficulties are much less likely to arise in the great apes, maybe because they are so much larger than the tiny tree-dwelling primates. In this sense, humans are still unique in having birth difficulties, because we are the only large ape with the problem, says Betti.

But Webb isn’t so sure about this point; in a study she and her colleagues published in 2024, they concluded that between the size of the birth canal and the infant’s head. “That discrepancy is strange. It’s probably a reflection of the methods used,” says Webb. “This new paper is providing a really nice incentive for us to revisit our own hypothesis.”

The artwork on a 4300-year-old silver goblet unearthed in the Palestinian West Bank appears to show the universe forming out of primordial chaos – making it the oldest known visual representation of a creation myth.

“I think it’s an ingenious design,” says at the Luwian Studies Foundation, a non-profit based in Switzerland. “With very few lines, it tells a very complex story.”

The ˁAin Samiya goblet stands about 8 centimetres tall. It was found 55 years ago in an ancient tomb a few miles to the north-east of Ramallah at the western tip of the Fertile Crescent – a region where early civilisations flourished.

There appear to be two scenes depicted on the goblet. In the first, a large snake rears up and faces a chimera with a human torso and the legs of an animal, who stands over a small flower-like circle. In the second, a snake lies on the ground beneath a much larger flower-like circle with a smiling face. The circle is being held up, probably by two fully humanoid figures – although only one is visible today because the goblet is broken.

Archaeologists in the 1970s suggested the two scenes came from EnĆ«ma EliĆĄ, a Babylonian creation myth in which a primordial entity named Tiamat is defeated in battle by the god Marduk, who then turns Tiamat’s body into the heavens and Earth. But, Zangger says, other researchers have pointed out flaws with this idea. Not only is there no battle scene on the goblet, but it was also made about 1000 years before EnĆ«ma EliĆĄ was first written down.

Because of this, other researchers have suggested alternative interpretations – for instance, that the goblet is a symbolic representation of the birth of the new year and the death of the old one.

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But Zangger and his colleagues – , an independent researcher in Toronto, and at the University of Zurich, Switzerland – think the original interpretation was nearer to the mark. They argue that the scenes do show the formation of the world and cosmos, but that they come from a creation story far older than EnĆ«ma EliĆĄ.

In the first scene, according to Zangger’s team, there is chaos. The chimera represents a weak god, fused with the animals. Beneath its legs, the small flower-like circle represents a powerless sun. Ruling over all of this chaos is a monstrous snake. But in the second scene, order has emerged peacefully from the chaos. The gods have been separated from the animals, becoming powerful humanoid characters. They hold the equally powerful sun aloft in a “celestial boat”, indicating that the heavens have now been separated from Earth. The monstrous serpent of chaos, defeated, lies beneath the sun.

Zangger points out that there are cuneiform texts from elsewhere in the Fertile Crescent that are similar in age to the goblet and that describe how the gods separated the heavens from Earth. As such, we know that the inhabitants of the region had developed stories about the creation of the world by the time the goblet was fashioned. “But the incredible thing about the goblet is that we now have a picture of what they imagined this creation to have looked like,” he says.

, an independent researcher based in the Netherlands, is unconvinced by the interpretation. “What may be depicted is the daily movement of the sun,” he says. “But definitely not ‘origin’ or ‘chaos’.”

at the University of Bern in Switzerland is more willing to accept the possibility that the goblet shows the creation of the world. But she sees problems with another aspect of the new analysis.

Zangger and his colleagues say that some of the images on the ˁAin Samiya goblet – such as a monstrous snake – appear in ancient cosmological stories from across the Fertile Crescent and nearby regions. They argue that this hints at deep connections among all of these creation myths, suggesting they may all draw from a single, even older myth. In line with this, they point out that a celestial boat similar to that on the goblet is carved onto a pillar at the 11,500-year-old site of Göbekli Tepe in what is now Turkey, to the north-west of the Fertile Crescent. “That’s 7000 years earlier than the goblet,” says Zangger.

But Schroer thinks it’s far too speculative to suggest all of the region’s creation stories are deeply connected like this. “Even if there are similarities, there is not always a demonstrable influence,” she says.

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