Scarabaeinae - the true dung beetles. Ancient Egyptians associated these scarabs with birth and renewal. Images depict the god of the rising sun, Khepri, as a dung beetle, rolling the sun over the horizon in the morning and chasing it back to darkness every night. (at The Field Museum)
All of our skin organs form from simple folds in skin tissue. Once this process was in place, it was modified to produce all kinds of skin organs — from a reptile’s scale to a bird’s feather to a mammal’s mammary glands.
Learn more tomorrow with Neil Shubin when Your Inner Fish continues tomorrow (4/16) on PBS at 10/9c.
Tanzania’s Hadza hunter-gatherers have guts teeming with bacteria much more diverse than what’s found in Italians’ intestines. But the foragers don’t have Biﬁdobacterium, which is considered healthy, and do have more Treponema and other microbes that signal disease in Western populations. Hadza men and women even have major differences in their gut microbes.
These differences reinforce the idea that a healthy collection of gut bacteria depends on the environment in which people live and their lifestyle, researchers report April 15 in Nature Communications. The results also show how gut microbes may have helped human ancestors adapt during the Paleolithic period 2.6 million to 10,000 years ago.
- by Colin Barras
“One of our closest long-lost relatives may never have existed. The fossils of Australopithecus sediba, which promised to rewrite the story of human evolution, may actually be the remains of two species jumbled together.
The first fossils of A. sediba were found at Malapa, South Africa, in 2008. At 2 million years old, they show a mix of features, some similar to the ape-like australopithecines, others more like our genus, Homo. To its discoverers, this hotchpotch means A. sediba was becoming human, and that the Homo genus first evolved in South Africa, not east Africa as is generally thought.
But a new analysis suggests A. sediba didn’t exist. “I think there are two different hominin genera represented at Malapa,” says Ella Been at Tel Aviv University in Israel. One is an Australopithecus and one an early Homo. We can’t yet tell if the australopithecine remains are distinct enough to call them a new species, Been says.
Been studies the spinal columns of ancient hominins, so she was curious when a paper was published last year focusing on the spine of A. sediba (Science, doi.org/r7k). There are fragments from two skeletons at Malapa, a juvenile male and an adult female. Looking at photographs of the vertebrae, she noticed familiar features on the young male. “I realised they looked a lot like the vertebrae of the Nariokotome Boy,” she says. Also known as Turkana Boy, this is a 1.5-million-year-old skeleton of Homo erectus, a widespread species that may be our direct ancestor. Its vertebrae, like ours, are much wider than they are tall.
In contrast, the adult female’s vertebrae are taller, says Been, a classic Australopithecus feature. She concludes that the spines belong to two different species. When Been shared her findings with Yoel Rak, also at Tel Aviv University, she found an ally. “He sees the same in the [lower jawbone]: an australopithecine and an early Homo,” says Been. But here the species are switched: a notch in the young male jaw looks like Australopithecus, while the same notch in the adult female jaw looks human. The pair conclude that there are not two but four individuals in the remains from Malapa: an adult and a juvenile of both Homo and Australopithecus. They presented their findings at a meeting of the Paleoanthropology Society in Calgary, Canada, this week.
Unsurprisingly, A. sediba’s discoverer, Lee Berger of the University of Witwatersrand in South Africa, doesn’t agree. For one thing, he says the positioning of the adult skeleton’s bones in the ground makes it likely they came from a single individual. Berger admits that the vertebrae of the young A. sediba look like those of H. erectus, but he says vertebrae grow taller throughout childhood. If the young A. sediba had grown up, his vertebrae may have become more Australopithecus-like. Been isn’t convinced. Fossils of other australopithecine children had tall vertebrae, she says.
Regardless, Berger says that Been and Rak’s observations make sense if A. sediba really was a transitional species between Australopithecus and Homo. “A central tenet of evolutionary theory is that variation within taxa becomes variation between taxa as species diverge,” he says. With anatomy in flux, it is possible that one A. sediba had an Australopithecus-like spine and Homo-like jaw, while another had a Homo-like spine and Australopithecus-like jaw. There are other features of the A. sediba vertebrae that might explain the differences Been found. Berger’s latest work hints that the young male’s vertebrae may show signs of disease. If so, they are not representative of the species.
***It took ~10 minutes for Berger to respond on facebook. It took New Scientist ~5 minutes to post Berger’s response. I don’t have facebook, so I’d reblog if someone would post his response if it differs from what was recounted here. Cheers.
So this is fascinating. As most of you know, MH-1 is a juvenile, partially articulated skeleton that includes the cranium, it is found in a single mostly in-situ layer and has no repeating elements. MH-2 is an adult female skeleton that is articulated - I repeat - articulated, and this fact has been published in a Ph.D. thesis by Aurore Val. This skeleton is in anatomical position, with the vertebrae actually attaching to the sacrum and the sacrum to the pelvis and the upper limb laying alongside this and the mandible laying, almost in anatomical position against the complete shoulder girdle. I would like to state again - MH-2 is an articulated skeleton in a curled death position in situ in hard matrix.
However, in these talks, Rak and Been argue that based on two single characters (one in the mandible and one in the vertebrae), that not only do these skeletons represent two different Genera, but that within them they are mixed. In short, the mandible and skull of MH-1 is Homo, the juvenile vertebrae associated with this skeleton are australopith; in MH-2 the mandible is ‘clearly’ australopith and the vertebrae are Homo! but the skeleton is articulated!
To me, Rak and Been’s argument is sort of the “saw the lady in half” cheap Magicians trick. Yes we can all see that the Magician has cut a lady that was perfectly in one piece in half and separated it, but we know that its just an illusion - Been and Rak have taken an articulated, anatomically correctly positioned skeleton (MH-2) and like the Magician just sliced it in half to fool us because of - yes - one character in two un-diagnostic areas of anatomy. Now that’s a trick. So now, every time an articulated skeleton doesn’t agree with our pre-existing strong ‘statistical methods’ (based on mere fragments and figments from the fossil record mind you), then we just cut them up rather than acknowledge the reality of what the fossil record is showing us. Science at its finest methinks - or not.
Lee sounds salty: is he the one with his name attached to the initial discovery?
Alphacaeli to the rescue. And yes, Berger is the one attached to the discovery.
The largest Pre-Columbian city in South America, Chan Chan is an archaeological site in the Peruvian region of La Libertad, five km west of Trujillo. Chan Chan covers 20 km² and had a dense urban center of 6 km². Chan Chan was constructed by the Chimor (the kingdom of the Chimú), a late intermediate period civilization which grew out of the remnants of the Moche civilization. The adobe city of Chan Chan, the largest in the world, was built around AD 850 and lasted until its conquest by the Inca Empire in AD 1470. It was the imperial capital where 30,000 people lived.
Chan Chan was added as a UNESCO World Heritage Site on November 28 of 1986. The city is severely threatened by storms from El Niño, which cause heavy rains and flooding on the Peruvian coast. It is in a fertile, well-watered section of the coastal plain. The city’s ruins are threatened by earthquakes and looters. Visitors to Chan Chan can enter the Tschudi Complex, a later citadel. There are other Chimú and Moche ruins in the area around Trujillo. This site was discovered by conquistador Francisco Pizarro.