A joint study by researchers from the Universities of Tübingen and Cambridge demonstrates that the earliest members of our genus Homo varied widely in body size. Until now, we knew little about the height and weight of our ancestors who lived between 2.5 and 1.5 million years ago.
Co-author of the study, Manuel Will, says even then, human populations varied in size. Will is a doctoral candidate at Tübingen’s institute of Early Prehistory and Quaternary Ecology. “These findings have important implications for the evolution of our genus,” he says. The study was published online yesterday in the Journal of Human Evolution.
Will worked with Cambridge anthropologist Jay Stock to compare the physiology of individuals from early human populations, using fossils from the famous Olduvai Gorge in Tanzania and from Koobi Fora in Kenya, as well as individuals from the “Cradle of Humankind” in South Africa. Their sample also included the oldest human fossils from outside Africa, from Dmanisi in Georgia.
They found significant differences in body sizes which strongly indicate that there were at least two differently sized species of Homo living between 2.5 and 1.5 million years ago. Individuals from Koobi Fora (1.7-1.5 million years ago) stood up to around 165 cm and weighed 70kg on average, whereas their contemporaries from Olduvai appear to have been on average 20cm smaller and 20kg lighter.
The comparison between the African and Eurasian fossils showed that early humans grew bigger only after the first migrations out of Africa and more specifically around 1.7-1.5 million years ago within Africa in the Koobi Fora region. Furthermore, the Georgian fossils still possessed smaller bodies. Taken together, this belies the theory that bigger size was the necessary physical condition for the first humans to migrate to Eurasia according to study authors Will and Stock.
The researchers used mathematical formulas to determine the size of the bodies in life, extrapolating from the fossil remains. Such fragments often reveal the genus but do not provide enough information for researchers to determine the species with certainty.
For this reason, the Tübingen-Cambridge study did not classify the fossils according to species, instead using time and geography to determine the body-size difference in these early human populations.
These two variables were easier to control, and at the same time, increased the sample size of early Homo individuals – because all the bone fragments from the right era and location could be included. “This innovative approach has allowed the researchers to shed new light on the evolution of body size within our genus,” says Professor Katerina Harvati-Papatheodorou, head of the Palaeoanthropology working group at Tübingen’s Institute of Prehistory and Medieval Archaeology.
The study is the most comprehensive of its kind to date and the first statistical investigation of body-size differences between early Homo species.
Universitaet Tübingen – Header Image Olduvai Gorge : Credit : Sabines Sunbird
The archaeological site at La Ferrassie, excavated throughout the 20th century, is a mythical enclave because it was where 7 Neanderthal skeletons, ranging from foetuses to almost complete skeletons of adults, were found.
Among the remains discovered at La Ferrassie is the skeleton of a 2-year-old Neanderthal child found between 1970 and 1973 and baptised La Ferrassie 8; over 40 years since its discovery it has turned out to be useful in shedding new light on the anatomy of this extinct species.
The study began by reviewing the collections at the Muséum National d’Histoire Naturelle in Paris and at the Museo d’Archéologie national de St. Germain-en-Laye linked to the excavations at La Ferrassie in 1970 and 1973; it was there that 47 new fossils belonging to La Ferrassie 8, which complete its skeleton further, were recovered. Remains of a skull, jaw, vertebrae, ribs and hand phalanges were found among the new fossils.
Featuring among the remains is a very complete left temporal bone and an auditory ossicle was found inside it: a complete stapes. Virtual 3D reconstruction techniques enabled this ossicle to be “extracted virtually” and studied.
This stapes is the most complete one in the Neanderthal record and certifies that there are morphological differences between our species and the Neanderthals even in the smallest ossicles in the human body. As Asier Gómez-Olivencia pointed out, “we do not yet know the relation between these morphological differences and hearing in the Neanderthals. This would constitute a new challenge for the future”.
The study of these new remains has been published in the prestigious Journal of Human Evolution, and has also had the participation of researchers of the CNRS (French National Centre for Scientific Research) in Paris and Bordeaux. The fact that a discovery of such significance has been made thanks to reviewing the remains excavated in the 1970s provides the researcher with proof of “the importance and need to review old excavations. We’re in no doubt about that”.
They are all surviving relatives of a newly identified species called Yawunik kootenayi, a marine creature with two pairs of eyes and prominent grasping appendages that lived as much as 508 million years ago – more than 250 million years before the first dinosaur.
The fossil was identified by an international team led by palaeontologists at the University of Toronto (U of T) and the Royal Ontario Museum (ROM) in Toronto, as well as Pomona College in California. It is the first new species to be described from the Marble Canyon site, part of the renowned Canadian Burgess Shale fossil deposit.
Yawunik had evolved long frontal appendages that resemble the antennae of modern beetles or shrimps, though these appendages were composed of three long claws, two of which bore opposing rows of teeth that helped the animal catch its prey.
“This creature is expanding our perspective on the anatomy and predatory habits of the first arthropods, the group to which spiders and lobsters belong,” said Cedric Aria, a PhD candidate in U of T’s Department of Ecology & Evolutionary Biology and lead author of the resulting study published this week in Palaeontology. “It has the signature features of an arthropod with its external skeleton, segmented body and jointed appendages, but lacks certain advanced traits present in groups that survived until the present day. We say that it belongs to the ‘stem’ of arthropods.”
The study presents evidence that Yawunik was capable of moving its frontal appendages backward and forward, spreading them out during an attack and then retracting them under its body when swimming. Coupled with the long, sensing whip-like flagella extending from the tip of the claws, this makes the frontal appendages of the animal some of the most versatile and complex in all known arthropods.
“Unlike insects or crustaceans, Yawunik did not possess additional appendages in the head that were specifically modified to process food,” said Aria. “Evolution resulted here in a combination of adaptations onto the frontal-most appendage of this creature, maybe because such modifications were easier to acquire.
“We know that the larvae of certain crustaceans can use their antennae to both swim and gather food. But a large active predator such as a mantis shrimp has its sensory and grasping functions split up between appendages. Yawunik and its relatives tell us about the condition existing before such a division of tasks among parts of the organism took place.”
The Marble Canyon site is located in British Columbia’s Kootenay National Park, 40 kilometres south from the original Burgess Shale in Yoho National Park. Aria was part of the team that discovered the site in 2012, led by Jean-Bernard Caron, an associate professor at U of T’s Departments of Earth Sciences and Ecology & Evolutionary Biology and curator of invertebrate palaeontology at the ROM, and Robert Gaines, associate professor at the Department of Geology at Pomona College in California, both co-authors of the study.
“Yawunik is the most abundant of the large new species of the Marble Canyon site, and so, as a predator, it held a key position in the food network and had an important impact on this past ecosystem,” said Caron. “This animal is therefore important for the study of Marble Canyon, and shows how the site increases the significance of the Burgess Shale in understanding the dawn of animals.”
The study benefited from cutting-edge techniques of fossil imagery, including so-called “elemental mapping,” which consists in detecting the atomic composition of the fossil and the sediment surrounding it.
“Our understanding of these organisms rests upon interpreting their fossil remains,” said Gaines. “These fossils are a composed of a mosaic of delicate original organic material and minerals that replicate parts of fossil anatomy.
“The scanning electron microscope allows us to make maps of the fossils that reveal their composition. This gives us a remarkable perspective on the fossils, allowing anatomical structures to be visualized more precisely. This technique also provides insight into the unusual fossilization process that was at work here.”
The new creature is named in tribute to the Ktunaxa People who have long inhabited the Kootenay area where the Marble Canyon locality was found. It owes its name to “Yawu?nik?”, a mythological figure described as a huge and fierce marine creature, killing and causing such mayhem that it triggered an epic hunt by other animals to bring the threat down.
“We wanted to acknowledge the Ktunaxa culture, and given the profile of Yawunik, it looked like a natural choice of name,” Aria said.
“Yawu?nik? is a central figure in the Ktunaxa creation story, and, as such, is a vital part of Ktunaxa oral history,” said Donald Sam, Ktunaxa Nation Council Director of Traditional Knowledge and Language. “I am ecstatic that the research team recognizes how important our history is in our territory, and chose to honour the Ktunaxa through this amazing discovery.”
- CBA History
- Support Us
- Group Publications