Periodic Reporting for period 3 - NewHuman (Pathways to humanity: Adaptive niche diversity at the origins of the human lineage)
Reporting period: 2022-07-01 to 2023-12-31
NewHuman is a project about the fossil record of humans and in particular about an enigmatic group of fossil species whose position in our branch of the Tree of Life is uncertain. Our novel approach to clarifying how these species fit into our evolutionary history is to study the structure of their bones and teeth to reconstruct how they lived and how they differed from other human ancestral species. In particular, we are employing cutting edge imaging techniques that detect how individuals moved around during their lifetime and how they are related to each other. This is important to society because it will clarify when, where and how we became the humans we are today and in particular what behaviours were key to the initial appearance of humans. NewHuman focuses on unexpected fossil discoveries over the last 20 years that have resulted in the identification of three new fossil human relatives. What made them unexpected was a combination of two things. First, they were unusually small-bodied and small-brained. Two of these new species are found at a time near the origins of our own our group Homo, while the other two are surprisingly recent, around 100-200,000 years ago. NewHuman is testing the hypothesis that these species could represent a previously unrecognized adaptive niche in the human evolutionary story that persisted until the time that modern humans appeared. The main objectives of NewHuman are to conduct excavations in South Africa and Indonesia to try and find more fossil remains of these enigmatic species, to CT scan all the fossils we have of these species in order to study the hidden structures of their bones and teeth, and to use this novel data to reconstruct how they behaved. How did they move around their environments? Did they spend considerable time climbing in an arboreal environment? Did they make and use stone tools? By answering these questions we hope to determine where these intriguing new fossil species fit into the story of human evolution.
The Covid pandemic has prevented us from looking for new fossils, however, we have found plenty already that we can study. We started the project by CT scanning the fossils in very high resolution which allows us to visualize the detailed anatomy hidden inside the bones and teeth. Based on the fact that bone is a living tissue and remodels during your life depending on how you use your skeleton, we have developed new software tools to map in 3D the bone distribution in the hands, feet and hips of two of the four fossil species we are studying. The first exciting finding was that fossil hip bones from South Africa that were discovered many decades ago were not used in the way we thought. Even though from the outside they look very similar to our own hip bones, the internal bone structure tells use that these species moved around differently to humans. Specifically, we think they spent considerable amounts of time climbing in trees which suggests a fundamentally different way of gathering food and perhaps avoiding predators. We can be sure of this because if they were not using their bodies in this way the internal bone structure would look different. This is exciting because this technique can show us what individuals actually did during their lives and not just what they could have done. We made a similar discovery when looking at the internal structure of the hand bones of Australopithecus sediba (a fossil human ancestor from South Africa that lived 1.9 million years ago). Since its discovery in 2008, there has been debates about whether this species climbed in trees a lot or whether it had abandoned this for a life on the ground. We have shown through studying the bones of the fingers that they used their hands for climbing much like other living apes do today (such as chimpanzees and orangutans). However, we have also shown that they used their thumbs much like you and I would, suggesting they could have made and used tools in a similar fashion to us. In March of 2022 we will CT scan for the first time the bones of the hands and feet of Homo floresiensis (found on the island of Flores, Indonesia and ~100,000 years old) and will explore what they can tell us about how this interesting species behaved. We are also hoping to restart our fieldwork in both South Africa and Indonesia this summer so who knows what exciting new discoveries we might make. Finally, one of the central themes of NewHuman is a focus on making digital data on human fossils available to the wider scientific community and public. We have made excellent progress and our new online archive The Human Fossil Record (https://human-fossil-record.org/(opens in new window)) has been live for over two years. It is the only archive of its kind focused on human evolution and provides hundreds of images and CT scans of human fossils and the bones of chimpanzees and other primates. We have received great support for museums around the world and will continue to build this one of a kind resource. Coincidentally, it was particularly helpful during Covid as many teachers need to teach in virtual environment. Students were able to use the online data from the archive in place of in person lab sessions and this was of great help to a number of teachers.
NewHuman is extracting important and never-before-seen data from human fossils, some of which have been in museum collections for over 70 years. Our virtual approach is unlocking secrets about our past and providing important insights into the daily lives of our ancestors. By the end of the project we expect to have a much deeper understanding of the daily lives of these new and enigmatic fossil humans species and reveal whether they represent a new lineage that existed alongside that which led to our species, Homo sapiens. Additionally, we will have made discoveries of new fossils (and perhaps even new species) that will change our ideas about the human family tree. The software tools that we are developing will be useful in other fields such as clinical medicine and particularly research focused on bone health (e.g. osteoporosis). The online archive of digital data will be the world leading source of for digital images and surface models of human fossils and will be of immense value to researchers, teachers and members of the public.